JPH04246807A - Laminated type inductor - Google Patents

Abstract

PURPOSE:To obtain excellent attenuation characteristics in a high frequency region by suppressing the capacitance of floatation between conductive patterns. CONSTITUTION:Two coils 17a and 17b are formed by the conductor patterns 11 to 14, to be used for coil, via through holes 20a to 20c on the upper surface of substrate sheets 1 to 6 consisting of magnetic material. To be more precise, only one coil was used in the past, but the coil is divided into two parts 17a and 17b, and they are connected in the same part in a separated state. The floating capacitance generating on the part of the coils 17a and 17b can be suppressed by dividing the coil into two parts, and the lowering of attenuation characteristics of the inductor in a high frequency region is suppressed. Besides, as the inductance larger than the mutual inductance generating between the coils 17a and 17b is obtained, the effect of noise removal can be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer inductor used as a noise filter or the like.

0002

[Prior Art and Problems] Conventionally, this type of laminated inductor has been constructed by laminating magnetic sheets provided with conductor patterns, and the conductor patterns are electrically connected in series using through holes. What was done was known. By the way, when using this multilayer inductor as a noise filter, the stray capacitance C generated between the conductor patterns
(0), the equivalent circuit of the inductor has self-inductance L(0) and stray capacitance C(0), as shown in Figure 10.
becomes a parallel circuit. As a result, there is a problem in that the self-resonant frequency of the inductor becomes low, and the damping characteristics in a high frequency region deteriorate.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a multilayer inductor with excellent attenuation characteristics in a high frequency range by suppressing stray capacitance between conductor patterns.

0004

[Means for Solving the Problems] In order to solve the above problems, a multilayer inductor according to the present invention has a coil formed by a conductor pattern provided on a magnetic sheet, which is divided into at least two parts, and The coil is characterized in that it forms a mutual induction circuit with positive mutual inductance.

[0005]

[Operation] With the above structure, the coil is divided into at least two parts, so the total value of the stray capacitances generated in the divided coils becomes smaller than the value of the stray capacitances generated in the coil before division. In addition, since the divided coils constitute a mutual induction circuit with positive mutual inductance,
The combined value of the self inductance and mutual inductance of the coil after division is larger than the value of the inductance of the coil before division.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a multilayer inductor according to the present invention will be described with reference to the accompanying drawings. [First embodiment, Figures 1 to 4] Figure 1 shows a two-terminal multilayer inductor in which the conventional single coil is divided into two coils and each coil is connected in series within the same component. It is an exploded perspective view.

The base sheets 1, 2, 3, 4, 5, 6 and the protective sheet 8 are rectangular sheets, and are made of a magnetic material such as ferrite. On the upper surface of the base sheet 1, a conductor pattern 1 for a coil is connected to a lead electrode 10 using a conductive paste such as Ag or Ag-Pd.
1 is formed by a method such as printing. The extraction electrode 10 is exposed on the left side of the base sheet 1. The through hole 20a provided in the base sheet 1 is located at one end of the conductor pattern 11. The conductor pattern 11 is an arcuate pattern wound 3/4 times in a clockwise direction.

A coil conductor pattern 12 is formed on the upper surface of the base sheet 2 using a conductive paste. A through hole 20 is provided at one end of the conductor pattern 12.
b is provided. The conductor pattern 12 is an arcuate pattern wound 1/2 turn in a clockwise direction. Similarly, coil conductor patterns 13 and 14 are formed on the upper surfaces of base sheets 5 and 6, respectively. A through hole 20e is provided at one end of the conductive pattern 13. The conductor pattern 13 is an arcuate pattern wound 3/4 times in a clockwise direction. The conductor pattern 14 is an arcuate pattern wound 1/2 turn clockwise, and is connected to the extraction electrode 15 .

Furthermore, only through holes 20c and 20d are provided in the base sheets 3 and 4, respectively. The base sheets 1 to 6 thus prepared are stacked and stacked with a plurality of protective sheets 8 sandwiched from above and below. In the stacked state, the through holes 20a provided in the conductor pattern 11 of the base sheet 1 overlap the ends of the conductor pattern 12 of the base sheet 2. Therefore, conductor patterns 11 and 12
are electrically connected in series to form a coil 17a. Similarly, the through hole 20e provided in the conductor pattern 13 of the base sheet 5 overlaps the end of the conductor pattern 14 of the base sheet 6, and the conductor patterns 13 and 14 form a coil 17b. Coils 17a and 1
7b is a through hole 20c provided in the base sheets 3 and 4.
, 20d, the conductor patterns 12 and 13 are electrically connected to each other, thereby being connected in series in a separated state.

As shown in FIG. 2, the laminated inductor 18 is coated with a conductive paste such as Ag on both ends so as to be electrically conductive with the extraction electrodes 10 and 15, and then baked to form external electrodes (A), ( B). FIG. 3 is an equivalent electrical circuit diagram of the inductor 18 thus obtained. Stray capacitance C(1) generated in the coil 17a portion and stray capacitance C(2) generated in the coil 17b portion are respectively connected to the coil 17.
The self-inductances L(1) and L(2) of a and 17b
) are connected in parallel, and stray capacitances C(1) and C(2) are connected in series. Coils 17a and 17b are magnetically closely coupled, and constitute a mutual induction circuit having positive mutual inductance (+M(1)).

[0011] Therefore, by separating and dividing what was conventionally constructed as one coil into two coils 17a and 17b, the following relational expression can be obtained.

0012

[Math 1]

C': Combined stray capacitance of coils 17a and 17b L': Combined inductance C of coils 17a and 17b
(0): Conventional stray capacitance of one coil L (0): Conventional inductance of one coil (however, coil 17a
and 17b are 100% magnetically coupled) In this way, by separating and dividing one coil into two coils, stray capacitance is suppressed, and the attenuation characteristics of inductor 18 in the high frequency region are reduced. It becomes difficult to do. Furthermore, since a larger inductance can be obtained through electromagnetic coupling, the noise removal effect is improved.

FIG. 4 shows the multilayer inductor 18 of this embodiment.
This shows an example of how the inductor 18 is connected to the signal line 1.
9. Suppress the noise emitted from 9. Here, V is a signal source, R(0) is an internal resistance on the signal source side, and R(L) is a load resistance on the receiving side. [Second Embodiment, FIGS. 5 to 8] FIG. 5 is an exploded perspective view of a four-terminal multilayer inductor in which two coils are independently included in the same component.

Base sheet 25, 26, 27, 28, 29
, 30 and the protective sheet 31 are rectangular sheets made of magnetic material, and are stacked and laminated as shown in FIG. A coil conductor pattern 33 connected to an extraction electrode 32 is formed on the upper surface of the base sheet 25 . The conductor pattern 33 has a through hole 43 at one end.
a is provided, and in the stacked state, it is connected to a coil conductor pattern 36 formed on the upper surface of the base sheet 27 via a through hole 43b provided in the base sheet 26. Further, the conductor pattern 36 is connected to a coil conductor pattern 38 formed on the upper surface of the base sheet 29 via a through hole 43e provided at one end and a through hole 43f provided in the base sheet 28. There is. The conductor pattern 38 is connected to an extraction electrode 39. In this way, a coil 47a having one and a half turns in the clockwise direction is formed between the extraction electrodes 32 and 39. Similarly, extraction electrodes 35 and 41 formed on base sheets 26 and 30
In between, the coil conductor patterns 34, 37, 40 formed on the base sheets 26, 28, 30 are formed in the through holes 43c, 43d provided in the base sheets 26, 27 and in the base sheets 28, 29, respectively. through hole 43g, 4
The coil 47b is connected in series through 3h to form a coil 47b having one and a half turns clockwise.

As shown in FIG. 6, external electrodes (A1) and (B1) are electrically connected to the extraction electrodes 32, 35, 39, and 41 at the four corners of the stacked inductor 48, respectively.
, (A2), and (B2) are provided. FIG. 7 is an equivalent electrical circuit diagram of the inductor 48 thus obtained. Stray capacitances C(3) and C(4) generated in respective portions of coils 47a and 47b are connected in parallel with self-inductances L(3) and L(4) of coils 47a and 47b,
Further, the coils 47a and 47b constitute a mutual induction circuit having positive mutual inductance (+M(2)). Incidentally, the coils 47a and 47b are wound in an alternately overlapping manner, and are designed to have a large value of mutual inductance M(2).

[0017] Like the multilayer inductor of the first embodiment, this inductor 48 has a suppressed stray capacitance, so its attenuation characteristics in the high frequency range are less likely to deteriorate. Moreover, since a larger inductance is obtained through electromagnetic coupling, the noise removal effect is excellent. FIG. 8 shows an example of the use of the multilayer inductor 48 of the second embodiment, and the inductor 48 suppresses noise radiated from the signal line 49.

[Third Embodiment, FIG. 9] FIG. 9 is an exploded perspective view of a four-terminal multilayer inductor having a structure in which two coils are arranged vertically and separately. Coil conductor patterns 51, 52, 53 formed on the base sheets 25, 26, 27 are placed between the extraction electrodes 50 and 54 formed on the base sheets 25, 27, respectively.
A coil 65a is formed by connecting in series through through holes 60a and 60b provided in 6. Similarly, between the extraction electrodes 55 and 59 formed on the base sheets 28 and 30, the base sheets 28, 29, 3
Coil conductor patterns 56, 57, 58 formed at 0
are connected in series through through holes 60c and 60d provided in the base sheets 28 and 29, respectively, to form a coil 65.
b will be formed.

Although this inductor has a smaller value of mutual inductance than the laminated inductor of the second embodiment, it produces the same functions and effects as the inductor of the second embodiment. [Other Embodiments] Note that the multilayer inductor according to the present invention is not limited to the embodiments described above, and can be modified in various ways within the scope of the gist. In particular, the coil formed by the conductor pattern is not limited to being divided into two parts, but may be divided into three or more parts.

[0020]

As is clear from the above explanation, according to the present invention, since the coils divided into at least two parts form a mutual induction circuit having positive mutual inductance, each coil after division The total value of stray capacitance generated in the multilayer inductor becomes smaller than that before division, and the amount of attenuation in the high frequency region is improved, resulting in a multilayer inductor with excellent high frequency attenuation characteristics. Furthermore, since a larger inductance can be obtained through electromagnetic coupling, the noise removal effect is improved.

[Brief explanation of the drawing]

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

FIG. 2 is a perspective view showing the appearance of the multilayer inductor shown in FIG. 1.

FIG. 3 is an equivalent electrical circuit diagram of the multilayer inductor shown in FIG. 1.

FIG. 4 is an electric circuit diagram to which the multilayer inductor shown in FIG. 1 is applied.

FIG. 5 is an exploded perspective view showing a second embodiment of the multilayer inductor according to the present invention.

6 is a perspective view showing the appearance of the multilayer inductor shown in FIG. 5. FIG.

7 is an equivalent electrical circuit diagram of the multilayer inductor shown in FIG. 5. FIG.

FIG. 8 is an electrical circuit diagram to which the multilayer inductor shown in FIG. 5 is applied.

FIG. 9 is an exploded perspective view showing a third embodiment of a multilayer inductor according to the present invention.

FIG. 10 is an equivalent electrical circuit diagram of a conventional multilayer inductor.

[Explanation of symbols]

1, 2, 3, 4, 5, 6...Base sheet (magnetic sheet)
11, 12, 13, 14... Coil conductor pattern 17a
, 17b... Coil 18... Laminated inductor 20a, 20b, 20c, 20d, 20e... Through hole 25, 26, 27, 28, 29, 30... Base sheet (magnetic sheet) 33, 34, 36, 37, 38 ...Coil conductor patterns 43a, 43b, 43c, 43d, 43e, 43f, 4
3g, 43h...Through hole 47a, 47b...Coil 48...Laminated inductor 51, 52, 53, 56, 57, 58...Coil conductor pattern 60a, 60b, 60c, 60d...Through hole 65a
, 65b...Coil C(1), C(2), C(3), C(4)...Stray capacitance L
(1), L(2), L(3), L(4)...Self inductance

Claims (1)

[Claims] 1. A laminated inductor in which magnetic sheets provided with a conductor pattern are laminated such that the conductor pattern constitutes a coil, wherein the coil has at least two
What is claimed is: 1. A multilayer inductor, characterized in that the coil is divided into individual coils forming a mutual induction circuit having positive mutual inductance.