JPH09298115A - Multilayer inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a multilayer inductor whereby a high self resonance frequency can be attained. SOLUTION: Coil conductors 3-6 are electrically connected in series through via-holes 15a, 15b, 15c of sheets 2 to form a coil 20. Coil conductors 7-10 are electrically connected in series connected through via-holes 16a, 16b, 16c of the sheets 2 to form a coil 21. The axes of the coils 20, 21 are parallel in the laminating direction of the sheets 2 and aligned each other. The coils 20, 21 form a plane-symmetric structure in the sheet laminating direction. One end of the coil 20 is electrically connected to an output lead-out electrode 12 at the right side of the sheets 2. One end of the coil 21 is electrically connected to an output lead-out electrode 13 at the right side of the sheets 2. The electrodes 12, 13 are adjacent in the sheet stacking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated inductor, and more particularly to a high frequency laminated inductor.

[0002]

2. Description of the Related Art Conventionally, a laminated inductor in which two coils are electrically connected in parallel has been known as shown in FIG. 10 for the purpose of reducing the DC resistance. The laminated inductor 61 includes coil conductors 63, 64, 65, 6
6, 67, 68, 69, 70 are provided on the surface of the insulating sheet 62, the outer layer insulating sheet 62, and the like.

One end of each of the coil conductors 63 and 67 has an input lead electrode 71 or 73 provided on the left side of the sheet 62.
One end of each of the coil conductors 66 and 70 is connected to the output lead-out electrode 7 provided on the right side of the sheet 62.
2, 74 are respectively connected. Coil conductor 63 ~
66 is a via hole 78a provided in the insulator sheet 62,
The coils 75 are electrically connected in series via 78b and 78c to form a coil 75. Similarly, coil conductors 67-70
Are via holes 79a, 79 provided in the insulator sheet 62.
b, 79c electrically connected in series via the coil 7
6 is formed.

After the sheets 62 are stacked, they are integrally sintered into a laminated body. Next, as shown in FIG. 11, an input external electrode 81 and an output external electrode 82 are formed on the left and right end surface portions of the laminated body, respectively. The input external electrodes 81 are connected to the input extraction electrodes 71 and 73, and the output external electrodes 82 are connected to the output extraction electrodes 72 and 74. The current I that has entered the input external electrode 81 of the inductor 61 flows to the output external electrode 82 through the coils 75 and 76, as shown in FIG. 12 (schematically shown).

[0005]

However, in the conventional inductor 61, as shown in FIG. 13, between the output side of the coil 75 and the input side of the coil 76, specifically, the coil conductor 6 is used.
The stray capacitances Cs are distributed between 6 and 67. Since the potential difference between the coil conductors 66 and 67 is large, the stray capacitance Cs has a large numerical value, and the influence of the stray capacitance Cs cannot be ignored. Therefore, in the high frequency range, the input external electrode 81
A part of the input current I may flow to the output external electrode 82 via the stray capacitance Cs without passing through either the coil 75 or the coil 76, and the self-resonance frequency of the inductor 61 is lowered. There's a problem.

Therefore, an object of the present invention is to provide a laminated inductor capable of increasing the self-resonant frequency.

[0007]

In order to achieve the above object, in the laminated inductor according to the present invention, at least two coils are arranged adjacent to each other in the stacking direction of the coil conductor and the insulating layer. It is characterized in that the input extraction electrodes of the two coils or the output extraction electrodes of the two coils are brought close to each other.

The laminated inductor according to the present invention is
At least two coils are arranged so as to be stacked in the stacking direction of the coil conductor and the insulating layer, and the input extraction electrode or the output extraction electrode of two adjacent coils is made common, and this common extraction electrode is It is characterized in that the two adjacent coils have a plane symmetric structure with the plane including the plane as a reference plane.

[0009]

With the above structure, when the output extraction electrodes are brought close to each other, the multilayer inductor has the electrical equivalent circuit shown in FIG. That is, the stray capacitance is
It will be formed between each output side of two coils of a laminated inductor. Therefore, in the high frequency region, the current that has entered the input external electrode always flows through one of the at least two coils to the output external electrode. Moreover, since the potential difference between the output sides of the two coils is small, the numerical value of the stray capacitance is small. As a result, lowering of the self-resonant frequency of the inductor can be suppressed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a laminated inductor according to the present invention will be described below with reference to the accompanying drawings. [First Embodiment, FIGS. 1 to 5] As shown in FIG. 1, the laminated inductor 1 includes coil conductors 3, 4, 5, 6, 7,
Insulator sheet 2 provided with 8, 9, 10 on the surface,
The outer layer insulator sheet 2 and the like are used. The insulator sheet 2 is formed by kneading a dielectric powder or a magnetic powder together with a binder or the like to form a sheet.

The coil conductors 3 to 6 are electrically connected in series via the via holes 15a, 15b and 15c provided in the sheet 2 to form the coil 20. Coil conductor 7-1
0 is the via holes 16a, 16b, 1 provided in the sheet 2
The coil 21 is electrically connected in series via 6c to form the coil 21. The respective axial directions of the coil 20 and the coil 21 are parallel to the stacking direction of the sheets 2, and
The axes are aligned. Moreover, the coils 20 and 21 have a plane symmetric structure with respect to each other in the stacking direction of the sheets 2.

One end of the coil conductor 3 forming a part of the coil 20 is electrically connected to the input lead-out electrode 11 provided on the left side of the sheet 2, and one end of the coil conductor 6 is It is electrically connected to the output extraction electrode 12 provided on the right side portion of the sheet 2. One end of the coil conductor 7 forming a part of the coil 21 is electrically connected to the output extraction electrode 13 provided on the right side portion of the sheet 2, and the coil conductor 1
One end of 0 is electrically connected to the input extraction electrode 14 provided on the left side of the sheet 2.

Coil conductors 3 to 10 and extraction electrodes 11 to 11
14 is made of Ag, Pd, Ag-Pd, Cu or the like, and is formed on the surface of the sheet 2 by a known printing method, a sputtering method, a vacuum deposition method, or the like. The sheets 2 are stacked and integrally sintered to form a laminated body. Next, as shown in FIG. 2, an input external electrode 25 and an output external electrode 26 are formed on the left and right end surface portions of the laminated body, respectively. The input external electrode 25 has an input extraction electrode 1
1, 14 are connected, and the output extraction electrodes 12, 13 are connected to the output external electrode 26. These external electrodes 2
5, 26 are formed by a method such as a sputtering method, a vacuum vapor deposition method, or printing and printing.

The inductor 1 having the above structure is shown in FIG.
As shown in (schematically shown), the coils 20 and 21 are
The input external electrode 25 and the output external electrode 26 are electrically connected in parallel. Therefore, the current I that has entered the input external electrode 25 passes through the coils 20 and 21 and the output external electrode 2
Flow to 6. The output extraction electrodes 12 and 13 are the sheet 2
Since they are close to each other in the stacking direction, stray capacitance Cs is generated between them as shown in FIG. However, the stray capacitance Cs is not so large as to form a bypass path for the coil 20 or 21. That is, in the high frequency region, the current I that has entered the input external electrode 25 always flows through either the coil 20 or 21 to the output external electrode 26.

As a result, as shown in FIG. 5, the self-resonant frequency of the inductor can be increased (see the solid line 28 in the figure). For comparison, FIG.
The impedance characteristic of the conventional inductor 61 having the structure shown in 0 is shown by the dotted line 29. Moreover, since the potential difference between the output extraction electrodes is small, the stray capacitance Cs
Is small and its effect is small. Also, the coil 20
Since the coil 21 has a plane symmetric structure in the stacking direction of the sheets 2, the directions of the magnetic fluxes generated in the two coils 20 and 21 are the same, and the magnetic fluxes do not cancel each other out. Therefore, desired impedance characteristics can be efficiently obtained.

[Second Embodiment, FIGS. 6 to 9] As shown in FIG. 6, the laminated inductor 31 includes coil conductors 33 and 3.
4, 35, 36, 37, 38, 39 are provided on the surface of the insulating sheet 32, the outer layer insulating sheet 32, and the like. The coil conductors 33 to 36 are electrically connected in series via the via holes 45a, 45b, 45c provided in the sheet 32 to form the coil 50. The coil conductors 36 to 39 are the via holes 46 provided in the sheet 32.
electrically connected in series via a, 46b, 46c,
The coil 51 is formed. That is, the coil conductor 36 is
The coil 50 and the coil 51 form a common portion. The coils 50 and 51 have their respective axial directions parallel to the stacking direction of the sheets 32 and have the same axes.

One end of the coil conductor 33 forming a part of the coil 50 is electrically connected to the input extraction electrode 40 provided on the left side of the sheet 32. One end of the coil conductor 36 forming the common portion of the coil 50 and the coil 51 is electrically connected to the output common extraction electrode 41 provided on the right side portion of the sheet 32. One end of the coil conductor 39 forming a part of the coil 51 is electrically connected to the input extraction electrode 42 provided on the left side of the sheet 32. The coils 50 and 51 have a plane-symmetrical structure with respect to the stacking direction of the sheets 32 with the plane including the output common extraction electrode 41 as a reference plane. Here, the coil conductor 36
The conductor thickness of the output common extraction electrode 41 is preferably thicker than the other conductors 33 to 35, 37 to 39 and the extraction electrodes 40 and 42 in order to reduce the DC resistance.

The sheets 32 are stacked and integrally sintered to form a laminated body. Next, as shown in FIG. 7, an input external electrode 55 and an output external electrode 56 are formed on the left and right end surface portions of the laminated body, respectively. The input external electrodes 55 are connected to the input extraction electrodes 40 and 42, and the output external electrodes 56 are connected to the output common extraction electrode 41.

In the inductor 31 having the above structure, as shown in FIG. 8 (schematically shown), the coils 50 and 51 are electrically connected in parallel between the input external electrode 55 and the output external electrode 56. There is. Therefore, the current I that has entered the input external electrode 55 flows to the output external electrode 56 through the output common extraction electrode 41 after passing through the coils 50 and 51. That is, as shown in FIG. 9, in the high frequency region, the current I that has entered the input external electrode 55 always flows through either the coil 50 or 51 to the output external electrode 56. As a result, the self-resonant frequency of the inductor 31 can be increased. Further, since the output extraction electrode of the coil 50 and the output extraction electrode of the coil 51 are commonly used, no stray capacitance is generated between the coil 50 and the coil 51,
As compared with the inductor 1 of the first embodiment, more excellent high frequency characteristics can be obtained.

In addition, the coil 50 and the coil 51 use the surface including the output common extraction electrode 41 as a reference surface, and the sheet 3
Since the two coils have a plane-symmetrical structure in the stacking direction, the directions of the magnetic fluxes generated in the two coils 50 and 51 are the same, and the magnetic fluxes do not cancel each other out. Therefore, desired impedance characteristics can be efficiently obtained.
Furthermore, since the output lead-out electrodes of the two coils are made common, the number of insulator sheets 32 provided with coil conductors on the surface can be increased accordingly, and a larger impedance can be obtained.

[Other Embodiments] The multilayer inductor according to the present invention is not limited to the above embodiment,
Various modifications can be made within the scope of the gist. In the above-described embodiment, the output extraction electrodes are arranged close to each other in the sheet stacking direction. However, the input extraction electrodes may be arranged close to each other in the sheet stacking direction. It need not be formed wide.
Furthermore, the number of turns of the two coils may be different. However, in order to reduce the DC resistance, it is preferable that the number of windings of the two coils be substantially equal. The number of coils may be three or more.

Further, in the above embodiment, the sheets are stacked and then integrally sintered, but the present invention is not necessarily limited to this. The sheet may be a sheet sintered in advance. Alternatively, an inductor having a laminated structure may be obtained by sequentially applying a paste-like insulator material or a conductor material by means of printing or the like, drying and recoating.

[0023]

As is apparent from the above description, according to the present invention, the input lead-out electrodes or the output lead-out electrodes of two adjacent coils are close to each other. A stray capacitance is formed between the input side or the output side, and the current that has entered the input external electrode always flows to the output external electrode through at least one of the two coils. As a result, the self-resonant frequency of the inductor can be increased. Moreover, the numerical value of the stray capacitance formed between the input side or the output side of the two coils is small, and the influence thereof is small.

Further, by making the input extraction electrode or the output extraction electrode of two adjacent coils common,
No stray capacitance is generated between two adjacent coils, and more excellent high frequency characteristics can be obtained. Further, by making the input or output lead-out electrodes of the two coils common, it is possible to omit one insulator sheet provided with the input or output lead-out electrodes. It is possible to increase the number of insulation sheets provided in
A larger impedance can be obtained. Since the two adjacent coils adopt the plane symmetric structure, the directions of the magnetic fluxes generated in the two coils are equal to each other, the magnetic fluxes do not cancel each other out, and the desired impedance characteristic can be efficiently obtained. it can.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of a laminated inductor according to the present invention.

FIG. 2 is a perspective view showing the appearance of the laminated inductor shown in FIG.

3 is an internal perspective view of the multilayer inductor shown in FIG.

FIG. 4 is an electrical equivalent circuit diagram of the laminated inductor shown in FIG.

5 is a graph showing impedance characteristics of the laminated inductor shown in FIG.

FIG. 6 is an exploded perspective view showing a second embodiment of the laminated inductor according to the present invention.

FIG. 7 is a perspective view showing the external appearance of the laminated inductor shown in FIG.

FIG. 8 is an internal perspective view of the multilayer inductor shown in FIG.

9 is an electrical equivalent circuit diagram of the multilayer inductor shown in FIG.

FIG. 10 is an exploded perspective view showing a conventional laminated inductor.

11 is a perspective view showing the appearance of the laminated inductor shown in FIG.

12 is an internal perspective view of the multilayer inductor shown in FIG.

13 is an electrical equivalent circuit diagram of the laminated inductor shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Multilayer inductor 2 ... Insulator sheet 3,4,5,6,7,8,9,10 ... Coil conductor 11,14 ... Input extraction electrode 12,13 ... Output extraction electrode 20,21 ... Coil 31 ... Multilayer inductor 32 ... Insulator sheet 33, 34, 35, 36, 37, 38, 39 ... Coil conductor 40, 42 ... Input extraction electrode 41 ... Output common extraction electrode 50, 51 ... Coil

Claims (2)

[Claims] 1. At least two electrically connected in parallel
In a laminated inductor having a plurality of coils built therein, the at least two coils are arranged in a stacking direction of a coil conductor and an insulating layer, and two adjacent coils are connected to each other for an input lead electrode or an output lead. A laminated inductor characterized in that electrodes are brought close to each other. 2. At least two electrically connected in parallel
In a laminated inductor having a plurality of coils built therein, the at least two coils are arranged in a stacking direction of a coil conductor and an insulating layer, and two adjacent coils are used as input extraction electrodes or outputs. A multilayer inductor, wherein a lead electrode is made common, and the two adjacent coils have a plane symmetric structure with a plane including the common lead electrode as a reference plane.