WO2012144103A1

WO2012144103A1 - Laminated inductor element and method for manufacturing same

Info

Publication number: WO2012144103A1
Application number: PCT/JP2011/076987
Authority: WO
Inventors: 家田章弘; 大坪喜人
Original assignee: 株式会社村田製作所
Priority date: 2011-04-19
Filing date: 2011-11-24
Publication date: 2012-10-26

Abstract

Provided are a laminated inductor element wherein an inductance value is increased without increasing manufacturing steps, and a method for manufacturing the laminated inductor element. A laminated inductor element (1) is provided with a laminated body (2) having magnetic material layers (4) and non-magnetic material layers (5) laminated therein; and open loop-shaped conductive patterns (30), which are provided between the layers of the laminated body (2), and form inductors (3). Each of the conductive patterns (30) is provided with conductive patterns (31, 32) in the magnetic material layer (4) or the non-magnetic material layer (5), said conductive patterns (31, 32) being formed at an interval such that a void (33) is formed.

Description

Multilayer inductor element and manufacturing method

The present invention relates to a multilayer inductor element in which an inductor is formed on a laminate in which at least a plurality of magnetic layers are laminated, and a method for manufacturing the same.

In recent years, electronic components are becoming smaller or thinner. For example, there is a multilayer inductor element in which an inductor is formed inside a ceramic substrate on which insulating layers made of glass ceramics are laminated. In a multilayer inductor element, it is difficult to cause magnetic saturation (increasing DC superimposition characteristics), and the purpose is to increase the inductance value of the inductor or to relieve stress caused by the difference in thermal contraction rate of the magnetic material. For this purpose, it is known to provide a gap in the vicinity of the inductor (see, for example, Patent Document 1).

FIG. 1 is a cross-sectional view of a multilayer inductor element described in Patent Document 1. In the multilayer inductor element shown in FIG. 1, a circular coil 102 is formed in a magnetic body portion 101, and a conductor forming the circular coil 102 and the magnetic body portion 101 are not in direct contact with each other. The circumferential coil 102 is provided with a gap 103 around it, so that the stress in the peripheral portion of the circumferential coil 102 can be relieved, and the influence on the magnetic body portion 101 is not affected. As a result, the magnetic body portion 101 maintains the magnetic characteristics of the original magnetic material, and the deterioration of the inductance and impedance due to internal stress is eliminated, so that the multilayer inductor element described in Patent Document 1 has a high inductance, a high Impedance is realized.

Japanese Patent Laid-Open No. 11-219821

In the multilayer inductance element described in Patent Document 1, carbon or the like is decomposed and removed by printing a burnt material paste such as carbon or resin on each layer of the magnetic body 101 and then firing at a high temperature of 890 to 900 ° C. As a result, the gap 103 is formed. That is, in order to form the gap 103, it is necessary to additionally increase a manufacturing process such as printing of carbon or the like. For this reason, simplification of the manufacturing process when obtaining a high inductance of the multilayer inductance element is desired.

Therefore, an object of the present invention is to provide a multilayer inductor element and a manufacturing method capable of increasing the inductance value without increasing the manufacturing process.

A multilayer inductor element according to the present invention includes a multilayer body in which sheet layers including a plurality of magnetic bodies are laminated, and a conductive pattern that forms an inductor provided between the layers of the multilayer body. A first conductive pattern in an open loop shape provided between the layers of the stacked body, and along the first conductive pattern at a distance from the first conductive pattern in the same layer as the first conductive pattern And an open-loop second conductive pattern that is electrically connected to the first conductive pattern at both ends.

In this configuration, the inductor is formed by the first and second conductive patterns arranged in two rows (or more) with an interval (gap) therebetween. By this air gap, a air gap can be formed in the magnetic path, the direct current superposition characteristics of the inductor can be improved, and stress relaxation of the magnetic layer can be achieved. Moreover, since a space | gap is formed when providing a conductive pattern, the special process for providing a space | gap is not required.

A multilayer inductor element according to the present invention includes a laminate in which sheet layers including a plurality of magnetic bodies are laminated, an open-loop conductive pattern provided between the laminates to form an inductor, and the conductive pattern And a ceramic paste pattern provided along the first conductive pattern at an interval with respect to the conductive pattern.

In this configuration, a gap is formed by providing a ceramic paste pattern (preferably a magnetic paste containing a magnetic material) at a distance from the conductive pattern, thereby improving the DC superposition characteristics of the inductor, The body layer is stress-relieved. This ceramic paste pattern is generally provided in order to improve the coplanarity (flatness) of the multilayer inductor element, and the gap can be provided without increasing a special process for providing the gap.

In the multilayer inductor element according to the present invention, it is preferable that the ceramic paste pattern includes a magnetic material.

In the multilayer inductor element according to the present invention, the conductive pattern is provided on a sheet layer including the plurality of magnetic bodies of the multilayer body, and is connected in the stacking direction of the multilayer substrate to form one inductor. It may be configured.

In this configuration, since one inductor is formed from a conductive pattern provided on a sheet layer including a plurality of magnetic bodies, a multilayer inductor element having a higher inductance value can be obtained.

According to the present invention, the inductance value of the multilayer inductor element can be increased without increasing the number of manufacturing steps.

Sectional view of multilayer ceramic electronic component described in Patent Document 1 Schematic cross section of multilayer inductor element Schematic diagram showing the conductive pattern composing the inductor Schematic cross section of another example of multilayer inductor element Schematic diagram showing another example of the conductive pattern constituting the inductor

FIG. 2 is a schematic cross-sectional view of a multilayer inductor element. In the cross-sectional view shown in FIG. 2, the upper side of the paper is the upper surface side of the multilayer inductor element 1 and the lower side of the paper is the lower surface side of the multilayer inductor element. The multilayer inductor element 1 is used in, for example, a non-insulated DC-DC converter or a step-down converter mounted on a mobile phone or the like.

The multilayer inductor element 1 includes a multilayer body 2 in which a total of 14 magnetic layers 4 and non-magnetic layer 5 ceramic green sheets are laminated. The first layer, the second layer, the seventh layer, the thirteenth layer, and the fourteenth layer counted from the upper surface (upper side of the sheet) of the laminate 2 are the nonmagnetic layer 5, and the other layers are the magnetic layers. 4

2 is provided on the upper surface of each layer (magnetic layer 4 or nonmagnetic layer 5) of the laminate 2, the laminate 2 shown in FIG. Each layer is formed so that its upper surface is on the lower side. For example, the upper surface of the first layer is on the lower side and is joined to the lower surface of the second layer.

The magnetic layer 4 is composed mainly of a ferrite containing nickel, zinc, and copper and a ceramic material, for example. The nonmagnetic layer 5 is mainly composed of ferrite containing iron, zinc, and copper and a ceramic material.

An inductor 3 is formed inside the laminate 2. The inductor 3 has a conductive conductive pattern 30 made of Ag provided on a part of the ceramic green sheets constituting the multilayer body 2, and a via-hole conductor (not shown) is formed with the lamination direction of the multilayer body 2 as an axial direction. Via a spiral connection. In FIG. 2, the conductive pattern 30 is provided on the upper surfaces (lower sides in the drawing) of the third layer, the fifth layer, the seventh layer, the ninth layer, and the eleventh layer of the stacked body 2.

An external electrode (not shown) is formed on the first nonmagnetic material layer 5 which is the uppermost layer of the multilayer body 2, and an IC (Integrated Circuit) 10 a and

capacitors

10 b and 10 c are mounted on the external electrode. Has been. As a result, the multilayer inductor element becomes an electronic component module (such as a DC-DC converter or a step-down converter).

In addition, a terminal electrode (not shown) is formed on the 14th nonmagnetic layer 5 which is the lowest layer of the multilayer body 2, and the multilayer inductor element 1 is shipped as an electronic component module to this terminal electrode. Thereafter, an electronic component module is mounted in the product manufacturing process of the electronic device. That is, it becomes a terminal electrode to be connected to a land electrode or the like on the mounting substrate side.

The non-magnetic layer 5 of the seventh layer substantially functions as a magnetic gap, and the DC superposition characteristic can be improved by adopting a configuration in which the magnetic gap is provided in the middle of the inductor 3, so that the inductor 3 in the heavy load region can be improved. The inductance value can be improved.

Further, the nonmagnetic layer 5 in this embodiment has a lower thermal shrinkage rate than the magnetic layer 4. Therefore, by sandwiching the magnetic layer 4 having a relatively high thermal contraction rate with the nonmagnetic layer 5 having a relatively low thermal contraction rate, the entire element can be compressed by firing to improve the strength. .

Hereinafter, the inductor 3 formed in the multilayer body 2 will be described. FIG. 3 is a schematic diagram showing the conductive pattern 30 constituting the inductor 3. FIG. 3 is a top view of one of the layers (for example, the third layer) of the stacked body 2 provided with the conductive pattern 30. Other layers provided with the conductive pattern 30 are the same as in FIG. 3 and are electrically connected via via-hole conductors formed in the respective layers. 2 is a cross-sectional view taken along the line II-II in FIG.

The conductive pattern 30 has two

conductive patterns

31 and 32 formed in an open loop shape with the substantially central portion of the layer (the magnetic layer 4 in FIG. 3) as the center. The

conductive patterns

31 and 32 are provided with a slit-shaped gap 33 therebetween, and are electrically connected at both ends of the open loop. Via

hole conductors

34 and 35 are formed at both ends, and are electrically connected to the conductive pattern 30 of the other layer. As a result, the conductive patterns 30 of the respective layers are spirally connected to form one inductor 3.

The widths of the two

conductive patterns

31 and 32 are determined by determining the width of the conductive pattern 30 and dividing the determined width into two. For example, when a single conductive pattern having no gap 33 is provided in each layer of the multilayer body 2 to form an inductor of a multilayer inductor element as in the prior art, a necessary width (for example, 100 μm) of the conductive pattern is required. When determined, the width of each of the two

conductive patterns

31 and 32 is determined to be a value obtained by dividing the determined width into two (for example, 50 μm).

In addition, since the inductor 3 is provided with the air gap 33 between the two rows of the

conductive patterns

31 and 32, that is, in the magnetic path, the magnetic flux density of the inductor 3 is unlikely to be excessive. A predetermined inductance value can be obtained even in the load region. That is, the direct current superimposition characteristic of the inductor 3 can be improved. Since the magnetic sheet is generally harder than the dielectric sheet and has a property of not easily deforming even when the sheet is pressed, the space formed between the

conductive patterns

31 and 32 is not easily filled with the magnetic sheet.

Since the air gap 33 for increasing the inductance value of the inductor 3 is formed by providing the

conductive patterns

31 and 32, a process for forming the air gap 33, for example, a process of printing carbon or the like and flying it by firing. Is not required separately.

Further, even when pressure is applied to the multilayer body 2 at the time of impact or the like, since the gap 33 is sandwiched between the

conductive patterns

31 and 32, the impact is alleviated and no crack is generated in the gap 33. 1 damage can be suppressed.

It is preferable that the gap 33 between the

conductive patterns

31 and 32 has a width that is not buried by the

conductive patterns

31 and 32 due to the pressure when the laminate 2 is crimped. For example, when the thickness of the layer provided with the

conductive patterns

31 and 32 is 6 to 20 μm, the width of the gap 33 is preferably 35 to 250 μm. The relationship between the width of the gap 33 and the thickness of the layer is not limited to this, and can be changed as appropriate.

It is preferable that the gap 33 is not filled with the

conductive patterns

31 and 32. However, even if the gap 33 is buried, the

conductive patterns

31 and 32 are electrically connected to each other at the end portions. The characteristics are not greatly affected. Therefore, the unusable multilayer inductor element 1 is not wasted.

Next, the manufacturing process of the multilayer inductor element 1 will be described. The multilayer inductor element is manufactured by the following process.

First, an alloy (conductive paste) containing Ag or the like is applied on the ceramic green sheets to be the magnetic layer 4 and the nonmagnetic layer 5 to form a conductive pattern that forms the inductor 3 and the like.

At this time, the alloy is applied so that the

conductive patterns

31, 32 that are conductive at both ends are formed at a predetermined interval. Thereby, after each layer is pressure-bonded and fired, a gap 33 is formed between the

conductive patterns

31 and 32.

Next, each ceramic green sheet is laminated. That is, in order from the lower surface side, a ceramic green sheet to be the nonmagnetic layer 5, a ceramic green sheet to be the magnetic layer 4, a ceramic green sheet to be the nonmagnetic layer 5, a ceramic green sheet to be the magnetic layer 4, and Ceramic green sheets to be the nonmagnetic layer 5 are laminated and subjected to temporary pressure bonding. Thereby, the mother laminated body before baking is formed.

At this time, the thickness of each layer is adjusted by adjusting the number of ceramic green sheets or the thickness of each sheet.

Next, an electrode paste whose main component is silver is applied to the surface of the formed mother laminate to form external electrodes and terminal electrodes, and then fired. Thereby, the fired mother laminated body is obtained.

Finally, the surface of the external electrode of the mother laminate is plated. The plating process is performed by immersing the mother laminate in a plating solution and swinging. The multilayer inductor element 1 thus manufactured becomes an electronic component module by mounting electronic components such as the IC 10a and the

capacitors

10b and 10c.

As described above, since the gap 33 for improving the DC superposition characteristics of the inductor 3 is formed by forming the

conductive patterns

31 and 32 in the manufacturing process, a special process for forming the gap 33 is performed. There is no need to do extra.

The specific configuration and the like of the multilayer inductor element 1 can be changed as appropriate, and the actions and effects described in the above-described embodiments are merely a list of the most preferable actions and effects resulting from the present invention. The operations and effects of the present invention are not limited to those described in the above embodiment.

For example, in the above-described embodiment, the gap 33 is formed in all the layers (the magnetic layer 4 or the nonmagnetic layer 5) where the conductive pattern 30 is formed, but the present invention is not limited to this. FIG. 4 is a schematic cross-sectional view of a multilayer inductor element having a conductive pattern in which no gap is formed. As shown in FIG. 4, the conductive patterns 30 formed in the fifth layer and the ninth layer have gaps 33, but the conductive patterns 30A formed in the third layer, the seventh layer, and the eleventh layer are , Does not have voids. In this way, by mixing conductive patterns without providing a gap, the inductance value of the inductor 3 can be adjusted.

In the above-described embodiment, the gaps 33 are formed in the inductor 3 by forming the

conductive patterns

31 and 32 at intervals. However, the present invention is not limited to this. FIG. 5 is a schematic diagram showing another example of the conductive pattern constituting the inductor 3. In FIG. 5, one conductive pattern 36 is formed in an open loop shape around the substantially central portion of the layer 2 (magnetic layer 4 in FIG. 5). The conductive pattern 36 is formed with via-

hole conductors

37 and 38 at both ends, and is electrically connected to the conductive patterns in the other layers. As a result, the conductive patterns of the respective layers are spirally connected to form one inductor 3.

In the magnetic layer 4, ceramic patterns 40 are formed along the conductive patterns 36 at intervals. The ceramic pattern 40 is preferably formed by applying a ceramic paste containing a magnetic material. The space between the conductive pattern 36 and the ceramic pattern 40 has the same function as the gap 33 described in the above embodiment. The ceramic pattern 40 is generally provided in order to eliminate unevenness caused by forming the conductive pattern 36 and to improve the coplanarity (flatness) of the multilayer inductor element.

Therefore, since the gap is provided using the ceramic pattern 40 that is not for providing the gap, the gap can be provided without increasing the number of special steps. Further, in the case of FIG. 5, since the diameter of the inductor is not reduced in comparison with the case of FIG. 3, a higher impedance value can be obtained without changing the impedance value. Instead of the ceramic pattern 40, another resin pattern may be used.

In the layer manufacturing process shown in FIG. 5, the ceramic pattern 40 is preferably formed after the conductive pattern 36 is formed.

1-layered inductor element 2-laminated body 3-inductor 4-magnetic layer (dielectric layer)
5-Non-magnetic layer (dielectric layer)
30-conductive pattern 31, 32-conductive pattern 33-gap 40-ceramic pattern

Claims

A laminate in which sheet layers including a plurality of magnetic bodies are laminated;
A conductive pattern forming an inductor provided between the layers of the laminate;
With
The conductive pattern is
An open loop-shaped first conductive pattern provided between the layers of the laminate;
In the same layer as the first conductive pattern, an open loop shape is provided along the first conductive pattern at an interval with respect to the first conductive pattern, and is electrically connected to the first conductive pattern at both ends. A second conductive pattern of
A multilayer inductor element.
A laminate in which sheet layers including a plurality of magnetic bodies are laminated;
An open loop conductive pattern provided between the layers of the laminate and forming an inductor;
In the same layer as the conductive pattern, a ceramic paste pattern provided along the first conductive pattern at an interval from the conductive pattern;
A multilayer inductor element comprising:
3. The multilayer inductor element according to claim 2, wherein the ceramic paste pattern includes a magnetic material.
The conductive pattern is
Provided in a sheet layer including a plurality of the magnetic bodies of the multilayer body, connected in the stacking direction of the multilayer body to form one inductor,
The multilayer inductor element according to any one of claims 1 to 3.
In a method for manufacturing a multilayer inductor element in which a multilayer body is formed by laminating a plurality of sheet layers including a magnetic layer including a magnetic layer provided with a conductive pattern that forms an inductor.
Forming an open-loop first conductive pattern for forming an inductor on the sheet layer containing the magnetic material;
In the same layer as the first conductive pattern, the second conductive in an open loop shape that is electrically connected to the first conductive pattern at both ends along the first conductive pattern at an interval from the first conductive pattern. Providing a pattern;
A manufacturing method comprising:
In a method for manufacturing a multilayer inductor element in which a multilayer body is formed by laminating a plurality of sheet layers including a magnetic layer including a magnetic layer provided with a conductive pattern that forms an inductor.
Forming an open loop conductive pattern for forming an inductor on the sheet layer containing the magnetic material;
Providing a ceramic paste pattern along the conductive pattern at an interval from the conductive pattern in the same layer as the conductive pattern;
A manufacturing method comprising:
The manufacturing method according to claim 6, wherein the ceramic paste pattern includes a magnetic material.