JP2001060840A - Multiple connection type noise filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the dispersion of characteristics among each filter element by making the self-inductance of each of filter elements in a multiple connection type noise filter coincide. SOLUTION: In this multiple connection type noise filter where signal side coils 21d, 21e, 21g, 21f, 52,..., ground side coils 31e, 31g and 6, and ground side coil pattern 31e to 31g,... are oppositely arranged in a laminate 1 obtained by laminating dielectric layers 1a to 1k, and signal side terminal electrodes 41 to 54 connected to both sides of the signal side coils and ground side terminal electrodes 6 and 7 to which each of the ground side coils is commonly connected are formed on the end face of the laminate 1, the distance from an extraction electrode 30h to the electrodes 6 and 7 is formed to be length so that the self- inductance of each of the ground side coils can be matched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise filter for reducing unnecessary radiation noise generated from digital equipment, and more particularly to a multiple noise filter in which a plurality of filter elements are provided in a single laminate. is there.

[0002]

2. Description of the Related Art A conventional multiple noise filter has a structure shown in FIG. Here, an example including four filter elements is shown. That is, the laminated body 100 is formed by laminating the dielectric layers 100a to 100k, and the dielectric layer 10
Extraction electrodes 210d to 240d of the first to fourth filter elements are arranged between 0c and 100d.
Further, between the dielectric layer 100d and the dielectric layer 100e, the signal side coil patterns 210e to 240e and the ground side coil pattern 310 of the first to fourth filter elements are provided.
e to 340e are arranged. Similarly, signal side coil patterns 210f to 240g and ground side coil patterns 310d to 340g are arranged between the dielectric layers 100e and 100f and between the dielectric layers 100f and 100g, respectively.

The first filter element includes a lead electrode 210d, signal-side coil patterns 210e and 210e.
f, 210g are connected by through holes punching through the respective dielectric layers 100d to 100h and spirally circulate in the laminating direction. Similarly, the second to fourth filter elements also spirally circulate in the laminating direction. It consists of. Further, between the dielectric layers 100g and 100h, as shown in FIG.
To the extraction electrodes 210h to 2 of the fourth filter element
40h, and a common ground side extraction electrode 300h having common electrode tip portions 310h to 340h directly connected from the first to fourth filter elements, respectively. Although not shown in the figure, 11 dielectric layers 1
First to fourth signal-side terminal electrodes connected to the extraction electrodes 210d to 240d of the first to fourth filter elements are formed on one of the pair of end surfaces of the laminate 100 formed by laminating 00a to 100k. And the other end face has the first
To extraction electrode 210h to 240 of fourth filter element
h to the first to fourth signal side terminal electrodes are formed. Further, a ground-side terminal electrode connected to one end portions 301h and 302h of the common extraction electrode 300h is formed on the other pair of end surfaces of the multilayer body 100. With such a configuration, a multiple noise filter as shown in the equivalent circuit diagram of FIG. 7 is achieved.

[0004]

However, in the above-described multiple noise filter, one end of the first to fourth noise filter elements is connected to the common lead electrode 300h formed between the dielectric layers 100g to 100h. Since they are connected in parallel, each ground side coil pattern 310e
.. To 310 g, 320 e to 320 g... From the common electrode tip portions 310 e to 340 h formed at the ground side ends.
The distance to 02h was formed differently.

Accordingly, on the equivalent circuit, as shown in FIG. 7, the distance between each filter element and the terminal electrode is different, so that the inductance components Lg10 to Lg13 are present in the ground-side lead electrode 300h, Each of the ground side coil patterns 310e to 310g, 320e to 3
There is a problem that the self-inductance formed by 20 g... Changes at the positions where the first to fourth filter elements are arranged. Thereby, for example, as shown in FIG.
Filter characteristics of T10 obtained by the filter element of No. 4;
The filter characteristic of T20 obtained by the second and third filter elements disposed inside the filter element varies, and as a result,
A predetermined characteristic as a noise filter could not be secured.

Moreover, the common electrode tip portions 310h to 34h
In the above-described structure in which the distances from 0h to the ground-side terminal electrodes 301h and 302h are different, the spiral signal-side coil patterns 210e to 210g, 220e to 220g,.
And the ground-side coil patterns 310e to 340g may have different magnetic coupling depending on the position of each filter element, which makes it impossible to fine-tune the noise filter characteristics and obtain steep attenuation characteristics. Had a point.

The present invention has been devised in view of the above problems, and has as its object to prevent variations in self-inductance in the ground-side coil pattern of each filter element and reduce variations in characteristics between filter elements. An object of the present invention is to provide a multiple noise filter which has been eliminated.

[0008]

In order to solve the above-mentioned problems, a multiple noise filter according to the present invention comprises a plurality of dielectric layers which are stacked in a rectangular parallelepiped shape. Along with providing a plurality of filter elements formed by opposing the side coil and the ground side coil, a signal-side terminal electrode connected to both ends of the signal-side coil of each of the filter elements on the end surface of the laminate, In the multiple noise filter, wherein each of the ground-side coils forms a ground-side terminal electrode commonly connected via an extraction electrode, a connection portion of each of the ground-side coils connected to the extraction electrode is connected to the ground-side terminal electrode. The length of the ground side coil is formed so that the self-inductance of each of the ground side coils matches.

According to the present invention, the distance from the connection portion connected to the extraction electrode of the ground-side coil of each filter element formed in multiples to the ground-side terminal electrode is such that the self-inductance of each ground-side coil matches. Therefore, good characteristics can be ensured by eliminating the characteristic variation of each filter element.

Note that the self-inductance of each ground side coil is formed by forming the distance from the connection portion connected to the extraction electrode of the ground side coil to the ground side terminal electrode formed on the shortest end face to be substantially the same. Can be matched.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a multiple noise filter according to the present invention will be described in detail with reference to the drawings. FIG. 1 is an external perspective view of a multiple noise filter of the present invention, and FIG. 2 is an exploded perspective view showing a connection state of conductors such as coil patterns.
FIG. 3 is an equivalent circuit of the multiple noise filter. In addition,
The description will be made using a multiple noise filter provided with four filter elements.

The multiple noise filter comprises a laminated body 1, signal-side terminal electrodes 41 and 51 of a first filter element, signal-side terminal electrodes 42 and 52 of a second filter element, and a signal of a third filter element. Side terminal electrodes 43 and 53, signal side terminal electrodes 44 and 54 of the fourth filter element, and ground side terminal electrodes 6 and 7 common to the first to fourth filter elements.

The laminated body 1 includes a dielectric layer made of a dielectric material such as barium titanate or barium titanate zirconate, or a magnetic layer containing a ferrite material (referred to as a dielectric layer in the present invention). It is configured to be laminated. The reference numerals are 1a to 1k.

The signal side coil patterns 2 constituting the signal side coils Ls1 to Ls4 in the first to fourth filter elements of FIG. 3 are provided between the dielectric layers 1d to 1h of the multilayer body 1.
1e to 21g, 22e to 22g..., Ground side coil patterns 31e to 31g, 32e to form the ground side coils Lg1 to Lg4 of the first to fourth filter elements.
32g are formed. Between the dielectric layers 1c and 1d, one ends of the signal side coils Ls1 to Ls4 of the first to fourth filter elements and the terminal electrodes 41 to 4 are provided.
4 to lead electrodes 21d to 24d for connection to
Is attached. Further, between the dielectric layers 1g and 1h, the signal side coils Ls1 to Ls4 of each filter element are provided.
Lead electrodes 21h to 24h for connecting the other ends of the electrodes to the terminal electrodes 51 to 54, respectively, are common electrode tips 31h to 34h commonly connected from the first to fourth filter elements.
The common extraction electrode 30h having the following structure is formed. Each of the dielectric layers 1d to 1h has a signal side coil Ls
In order to form 1 to Ls4 and the ground side coils Lg1 to Lg4, via hole conductors penetrating between the dielectric layers 1d to 1h are formed. In the drawing, via-hole conductors are indicated by dotted lines.

The internal structure of the laminate 1 will be described in more detail. The signal side coil pattern 21e and the ground side coil pattern 31e between the dielectric layer 1d and the dielectric layer 1e are described.
Has a substantially U-shape, and the signal side coil pattern 2
The openings 1e and the ground-side coil pattern 31e are arranged so as to face each other. A via-hole conductor connected to one end of the signal-side coil pattern 21f is formed in the dielectric layer 1e at the other end of the signal-side coil pattern 21e, and the dielectric layer 1e of the ground-side coil pattern 31e is connected to the ground side. A via-hole conductor connected to one end of the coil pattern 31f is formed.

Further, another signal side coil pattern 22e
24e and the ground side coil patterns 32e to 34e have the same configuration as the signal side coil pattern 21e and the ground side coil pattern 31e.

Further, between the dielectric layers 1e and 1f,
Signal-side coil patterns 21e to 24e and ground-side coil pattern 3 disposed between dielectric layers 1d to 1e
1e to 34e, the signal side coil patterns 21f to 21e
24f, and ground side coil patterns 31f to 34f are arranged. In addition, the signal side coil patterns 21e-2e
4e, the ground side coil patterns 31e to 34e are different from the signal side coil patterns 21f to 24f and the ground side coil patterns 31f to 34f via the above-mentioned via hole conductors.
e, the signal side coil pattern and the ground side coil pattern are formed so as to be interchanged so as to be connected to the ground side coil patterns 31e to 34e to form a coil of about one turn.

Further, between the dielectric layers 1g and 1h, the signal side coil patterns 21e to 21g and 22e to 2e
2g and one end of each of the signal-side terminal electrodes 52 to
Signal-side lead-out electrodes 21h to 24 for connection to
, and ground-side lead-out electrodes commonly drawn to connect one end of each of the ground-side coil patterns 31e to 31g, 32e to 32g. 30h are formed.

As described above, between the dielectric layers 1d to 1g, the signal side coils 21d to 21e to 21g to 21h
~ 52, 22d ~ 22e ~ 22g ~ 22h ~ 53 ...
・ Ground side coils 31e to 31g to 6, 32e to 3
2g to 6 ... are formed.

The ground side extraction electrode 30h is formed to have a length that matches the self inductance of each of the ground side coils 31e to 31g to 6 .... For example, as shown in FIG. 4, the ground-side lead electrode 30h is connected to the ground-side terminal electrodes 6, 7 at one end portions 36h, 3h.
7h, a main line 35h traversing 7h, a ground-side coil pattern 3 in the first filter element
The sub-line 361h connected to the main line 35h from the common electrode tip 31h connected to the ground side end (31g side) of 1e to 31g, and the ground side end (32g) of the ground side coil patterns 32e to 32g in the second filter element. Side), a sub-line 361h connecting from the common electrode tip 32h to the main line 35h, and similarly from the sub-lines 363h and 364h.

In particular, the sub-lines 361h and 362h are formed in a substantially V-shape at the center of the first and second filter elements and intersect at a position X on the main line 35h. The sub-lines 363h and 364h are located at the center positions of the third and fourth filter elements, and
It crosses at a position Y 5h above to form a V-shape. In this case, the arrangement conditions of the common electrode tip portions 31h and 32h are, for example, a distance m at a center line M passing through the position X in the vertical direction.
It is arranged at a position where 1 and the distance m2 are equal. The same applies to the positions of the common electrode tips 33h and 34h. In the present invention, the filter element may be formed so as to intersect the position on the main line 35h at the center position of each filter element, and its shape is not limited. For example, it may be formed in a Y shape or a T shape.

Such a ground-side lead-out pattern 30
Due to the shape of h, the distances between the electrodes 36h and 37h on the end faces closest to the common electrode tips 31h to 34h are also the same. Similarly, the distance between the one end portions 36h and 37h of the end surface farthest from the common electrode tip portions 31h to 34h is substantially the same. For example, looking at the common electrode tips 31h and 33h, one end near the end face of the common electrode tip 31h is a terminal 36h, while one end near the end face of the common electrode tip 33h is a terminal 37h. As shown by the dotted line in FIG. 4, they are substantially the same.

In the present invention, the common ground-side lead-out electrode 30h is formed on the same dielectric layer. However, the present invention is not limited to this. If at least two filter elements are provided, different dielectric layers may be used. It may be formed. In this case, a main line 35h crossing the dielectric layer is formed for each layer, and the above-described arrangement conditions are required.

In the present invention, the shape of the above-mentioned ground side lead-out pattern has been described. However, the present invention is not limited to this, and each of the ground side coils 31e to 31g to 6, 32e to 32g to 6
.. May be any shape as long as they can match the self-inductance of. For example, a common ground plane may be formed on the entire surface of the dielectric layer 1h. In this case, it is necessary to prevent a short circuit between the ground plane formed on the entire surface and the signal side extraction electrodes 21h to 24h.

The extraction electrodes 21d to 24d, the signal side coil patterns 21e to 21g, 22e to 22g,..., The extraction electrodes 21h to 24h, and the ground side coil pattern 31e arranged between the above-mentioned dielectric layers 1a to 1l.
~ 31g, 32e ~ 32g ..., extraction electrode 30h,
The via hole is made of a conductor mainly composed of Ag-based (Ag or Ag alloy) or Cu-based (Cu or Cu alloy) as a main component. Also, the signal side terminal electrodes 41 to 4
4, 51 to 54 and the ground-side terminal electrodes 6, 7 are made of a base conductor mainly composed of Ag or the like, and a layer such as Ni plating or solder plating may be formed on the surface thereof.

With the above configuration, the first filter element constitutes the signal side coil Ls1 of FIG. 3 by the spiral connection of the signal side coil patterns 21e, 21f and 21g. One end of the signal side coil Ls1 is connected to the extraction electrode 21.
d, and the other end of the signal side coil Ls1 is connected to the terminal electrode 5 via the extraction electrode 21h.
Connected to 1. At the same time, the ground side coil Lg1 is formed by the spiral connection of the ground side coil patterns 31e, 31f and 31g, and this ground side coil Lg
1 is connected to ground-side terminal electrodes 6 and 7 formed at both ends of the end face of the multilayer body 1 via a ground-side lead electrode 30h. The signal side coils Ls2 to Ls4 of the second to fourth filter elements have the same structure as the first filter element. Further, the configuration of the ground side coils Lg2 to Lg4 in the second to fourth filter elements is
Has the same structure as the ground-side coil Lg1 in the filter element of FIG. In addition, the common electrode tip portions 31h to 3h
Pull out coil Lg from 4h to terminals 36h and 37h
6, Lg7 is formed. Therefore, an equivalent circuit diagram as shown in FIG. 4 is obtained.

Thus, for example, the first filter element is composed of the signal side coil Ls1 and the ground side coil Lg1, and the signal side coil patterns 21e to 21g and the ground side coil pattern Lg1 which constitute the signal side coil Ls1. Constituting ground side coil patterns 31e-3e
1g is opposed to each other via the dielectric layers 1d to 1h, thereby forming a predetermined capacitance component C. As a result, an LC filter is formed. Similarly, the same applies to the second to fourth filter elements.

Therefore, the self-inductance of the first to fourth filter elements is equal to the ground-side coil pattern 31e.
３１31g, 32e 側 32g... From the ground side end (common electrode tip 31h to 34h) to the ground side terminal electrodes 6 and 7 (electrodes 36h and 37h) are almost the same, so there is no variation. Thereby, it is possible to operate with stable characteristics.

The magnetic coupling state can be changed by changing the position of the intersection XY between the sub-lines 31h to 34h on the main line 35h of the ground-side extraction electrode 30h. Thereby, a steep attenuation characteristic can be easily obtained. In addition, as a condition for changing the intersection position XY, in FIG. 4, the sub-lines 361h and 362h
Has an intersection position X on a line M that is the axis of symmetry in the lateral direction,
Similarly, the intersection position Y exists on the line N which is the axis of symmetry of 363h and 364h.
N, and move it to the upper side of the paper, and at the intersection position X, Y
Are set at the same position in the upper direction, a steep attenuation characteristic can be formed. Next, the attenuation characteristics of such a multiple noise filter will be described with reference to FIG. The solid line shown in FIG. 5 indicates, among the four noise fill elements, T1 indicates the attenuation characteristics of the first and fourth filter elements arranged at both ends of the laminate 1, and T2 indicates the second filter element.
3 shows the attenuation characteristics of the third filter element.

As can be understood from FIG. 5, there is no variation in both attenuation characteristics, and very stable characteristics can be obtained as compared with the conventional characteristic diagram of FIG.

The method of manufacturing the above-described multiple noise fill will be briefly described. First, green sheets to be the dielectric layers 1a to 1k are prepared. Next, through holes serving as via-hole conductors are formed at predetermined positions of the green sheets to be the dielectric layers 1d to 1h. Next, the lead electrodes 21d to 24d and 21h are formed on the green sheets to be the dielectric layers 1d to 1h by using, for example, a conductive paste containing Ag as a main component.
~ 24h, 30h, signal side coil pattern 21e ~ 24
g, a conductor film to be the ground side coil patterns 31e to 34g is formed by printing and drying. Next, the above-mentioned green sheet and the green sheet to be a dielectric layer are laminated and pressed in consideration of the lamination order. Thereafter, if necessary, the laminate is cut into a shape. Next, the green sheet laminate 1 is fired at 800 to 1050 ° C. in the air atmosphere. Thereafter, the end faces of the stacked body are polished by barrel polishing or the like, and signal-side lead-out electrodes 21d to 24d connected to the signal-side terminal electrodes from one of the pair of end faces of the stacked body 1.
And the signal-side lead-out electrodes 21h to 24h from the other surface,
Further, a part of the ground side extraction electrode 30h is exposed from the other pair of end surfaces. Next, one of the pair of end surfaces of the laminate 1, that is, the extraction electrodes 21 d to 24
d is exposed on each of the extraction electrodes 21 d-2.
4d, terminal electrodes 41 to 44 are connected to the other surface,
That is, the terminal electrodes 51 to 54 are connected to the exposed surfaces of the extraction electrodes 21h to 24h so as to be connected to the respective extraction electrodes 21h to 24h, and the other pair of end surfaces are connected to the ground-side extraction electrode 30h. As described above, the terminal electrodes 6 and 7 are each formed by baking a conductive paste containing Ag as a main component. If necessary, Ni plating, solder plating, or the like is applied on the baked Ag conductor film.

Further, in order to improve the high frequency characteristics, it is conceivable that each conductor inside the laminate 1 is made of a Cu-based material. In this case, the integrally sintered dielectric layers 1a to 1l
A non-reducing dielectric material composed mainly of calcium zirconate titanate or the like is used as a material constituting the material, and firing is performed in a reducing or neutral atmosphere. Note that C
An auxiliary material such as a glass material that can be fired at a low temperature can be added to the composite oxide so as not to reach the melting point of u. In addition, the terminal electrode is made of Cu in addition to baking Ag.
After applying to a predetermined position using a resin paste containing, a drying treatment and a curing treatment can be performed to perform a plating treatment.

[0033]

As described above, according to the structure of the present invention, the distance from the connection part connected to the extraction electrode to the ground electrode of the ground side coil of each filter element formed in multiples is set to the ground side coil. Are formed so as to have the same self-inductance, so that it is possible to provide a multiple noise filter in which good characteristics are secured by eliminating variations in filter characteristics.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a multiple noise filter according to the present invention.

FIG. 2 is an exploded perspective view showing a connection state of each coil pattern and the like in the multiple noise filter of the present invention.

FIG. 3 is an equivalent circuit of a multiple noise filter according to the present invention.

FIG. 4 is a diagram illustrating a configuration of a ground-side lead electrode formed on a dielectric layer according to the present invention.

FIG. 5 is a diagram illustrating an attenuation characteristic of the multiple noise filter according to the present invention.

FIG. 6 is an exploded perspective view showing a connection state of each coil pattern and the like in a conventional multiple noise filter.

FIG. 7 is an equivalent circuit of a conventional multiple noise filter.

FIG. 8 is a diagram illustrating a configuration of a ground-side lead electrode formed on a conventional dielectric layer.

FIG. 9 is a diagram illustrating an attenuation characteristic of a conventional multiple noise filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Laminated body 21e-21g ... Signal side coil pattern 22e-22g ... Signal side coil pattern 23e-23g ... Signal side coil pattern 24e-24g ... Signal side coil pattern 31e-31g. Ground-side coil pattern 32e to 32g Ground-side coil pattern 33e to 33g Ground-side coil pattern 34e to 34g Ground-side coil pattern 21b to 24b Leader electrode 30h: ground-side lead electrode 41-44: signal-side terminal electrode 51-54: signal-side terminal electrode 6, 7, ... ground-side terminal electrode Ls1- Ls4: Signal side coil Lg1 to Lg4: Ground side coil

Claims (1)

[Claims] 1. A plurality of filter elements formed by arranging a signal-side coil and a ground-side coil with a dielectric layer interposed therebetween in a rectangular parallelepiped laminate in which a plurality of dielectric layers are stacked. A signal-side terminal electrode connected to both ends of a signal-side coil of each of the filter elements and a ground-side terminal electrode to which each of the ground-side coils is commonly connected via an extraction electrode are formed on an end surface of the laminate. In the multiple noise filter, the distance from the connection portion of each ground side coil connected to the extraction electrode to the ground side terminal electrode is formed to have a length such that the self inductance of each ground side coil matches. A multiple noise filter, characterized in that: