JPH06152300A - Laminated emi filter - Google Patents

Abstract

PURPOSE:To make the filter compact, high-density, and high performance by operating a wide-band noise elimination filter equipped with both an in-phase component elimination function and an antiphase component elimination function which are enough to eliminate noise with one part. CONSTITUTION:A zigzag conductor 4 is embedded in a dielectric consisting of plural dielectric layers. As a conductor for inductance formation, both ends 4' and 4' are extended to the end face of the laminated body and are connected with film terminals A and B located at the sides of the laminated body after burning. A conductor 2 and the conductor 4 are opposed each other through a dielectric layer 3. As a volume formation conductor to superimpose routes in the laminated direction, its one end is connected to a film terminal C located at the sides of the laminated body. Thus, the distributed constant form is taken for the conductor 4 forming the inductor component near the conductor 2, which is inserted as an LPF into an electronic circuit, and then the wide-band noise elimination filter is formed with a simple structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter for use in electronic circuits, and more particularly to a simple and high-performance LC filter structure suitable for applications such as noise removal from low frequencies to high frequencies.

[0002]

2. Description of the Related Art As is well known, when removing noise from an electronic circuit, it is necessary to take measures against either the in-phase component or the anti-phase component of noise, or both. As a countermeasure against this, there is known a method of mounting either an inductor or a capacitor in the circuit, or a combination of the two to form a low-pass filter to reduce the noise level.

4 (a) to 4 (l) are conventional laminated EMs.
FIG. 4 is a diagram showing a manufacturing process of an example of the I filter element, and FIG.
(M) is a figure which shows the equivalent circuit of this filter element.
The conventional filter element shown here is a component using a laminating means as shown. To manufacture this part
After printing the capacitor-forming conductor 102 having the side end portion 103 extending to one end of the insulator substrate 101 on the insulator substrate 101 as shown in (a), as shown in FIG. As shown in FIG. 4C, the second capacitor having the side end portion 106 that extends through the dielectric layer 104 to the side edge of the dielectric layer 104 as shown in FIG. 4D. The forming conductor 105 is printed, and further, as shown in FIG.
The magnetic layer 107 is overlaid to form a capacitor section. Next, as shown in FIG. 4F, a conductor pattern 108 for forming a coil of about half a turn is printed, and as shown in FIG. After printing the body layer 110, as shown in FIGS. 4 (h) to 4 (k), the conductor patterns 111, 113, 1 are formed.
An inductor is formed by alternately printing 15 and the magnetic layers 112, 114, 117. Then, as shown in FIG. 4 (l), the side end portions 103 and 106 of the two capacitance forming conductors 102 and 105 and the both end portions 109 and 116 of the coil forming pattern are respectively formed on the side end surfaces of the laminated body. Membrane terminals 1 that are pulled out and provided on these side end surfaces
It was connected to 21, 122 and 123 to obtain the LC composite element structure as shown in the equivalent circuit of FIG. Mn-Zn ferrite powder is used as the magnetic material, Ag-Pd, Cu, Au, Al powder is used as the conductor material, and barium titanate is used as the dielectric material.

[0004]

However, recent demands for downsizing, lower pitch, higher density, and lower cost in electronic equipments and devices are remarkable, and the filter element as described in the above-mentioned prior art. In the configuration of, laminated,
Although it is possible to reduce the size to some extent by printing means, since the Indac proposed here is composed of a laminated body of insulating ferrite thin plates, the actual capacitance is a zigzag bend through the insulating magnetic layer. It is formed between the shaped conductor and the capacitance-forming conductor, and only a very small capacitance can be obtained, which is a great obstacle to the required needs (electrical characteristics).

SUMMARY OF THE INVENTION Therefore, a technical object of the present invention is to eliminate the drawbacks of the prior art and provide an economical and high-performance laminated EMI filter.

[0006]

According to the present invention, there is provided a laminated body in which a plurality of conductors facing each other and whose paths overlap in the laminating direction are embedded in a dielectric body composed of a plurality of dielectric layers. A first conductor in which one end of a conductor of the plurality of conductors is extended to one end face of the laminated body, and both ends of the plurality of conductors to both end faces adjacent to one end face of the laminated body Second conductors extended respectively, and the first and second conductors provided on the end face of the laminate and extended to the end face.
A laminated EMI filter having an electrode terminal connected to the end of the conductor is obtained.

[0007]

With this configuration, the first conductor having a shape such as a meandering or linear shape in which a part of the conductor extends to the side end surface has a dielectric layer embedded between the other conductor, or By taking a similar track that faces the conductor of the dielectric layer in the stacking direction, it functions as a capacitance forming conductor, and the second conductor having both ends extended to the end faces functions as an inductor forming conductor. At least equipped.

Therefore, if the capacitance forming conductor and the inductor forming conductor are considered to be opposed to each other with the dielectric interposed, the inductor component is formed and the capacitance component is formed with the conductor forming the inductor component. A configuration is obtained that functions as a distributed constant-parameter LC composite element having a pole with a terminal connected to the capacitance forming conductor as a reference, and is effective for applications such as a broadband noise elimination filter. Moreover, if the both ends of the conductor are extended to the side end faces as the capacitance forming conductor, the above-mentioned polarity can be avoided.

Further, in this structure, if the dielectric material is a material having a low specific resistance, a higher reliability can be obtained by interposing an insulating coated conductor pattern inside.

As described above, in the present invention, a filter having desired characteristics can be constructed by any combination of the internal conductors.

Further, according to the present invention, the capacitance between the conductors is set to an appropriate value by adjusting the film thickness of the dielectric layer and the inductor component of the conductor, and easily designed to have a desired filter characteristic. It can be possible.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a laminated EM according to an embodiment of the present invention.
2 is an exploded perspective view of the laminated body of the I filter, FIG. 2 is a perspective view showing the overall structure of the laminated EMI filter including the laminated body shown in FIG. 1, and FIG. 3 is an equivalent circuit diagram of the laminated EMI filter shown in FIG. Is. The laminated EMI filter according to this example is manufactured as follows.

In FIG. 1, on a dielectric layer (plate) 1 formed by kneading unfired ferrite powder and a binder resin, first, a first zigzag shape is formed by using a conductor paste such as Ag-Pd. Print conductor 2 (for capacitance formation). Next, a dielectric paste is printed on the entire surface to form a dielectric layer 3, and then a second conductor 4 having a serpentine shape is printed thereon. Next, the above-mentioned dielectric paste is printed on the entire surface to form a dielectric layer (plate) 5, and a laminated body (laminated printed body) is formed. In the above manufacturing process, a plurality of chips are formed in parallel on one dielectric sheet, cut into individual chips, and then integrally fired.

The dielectric paste and the conductor paste are
Since they are integrally fired, they both have the same shrinkage ratio when sintered.

Here, the zigzag-shaped second conductor 4 is embedded in a dielectric composed of a plurality of dielectric layers, and both ends 4 ', 4'are laminated bodies as a zigzag-shaped inductor forming conductor. Membrane terminals A and B extending to the end faces and provided on the side end faces of the laminated body after firing as shown in FIG.
Connected with. In addition, the first conductor 2 having a zigzag shape
Is a capacitance-forming conductor which is opposed to the zigzag-shaped second conductor 4 via the dielectric layer 3 and has a path overlapping in the stacking direction. Since it is connected to the film-like terminal C provided on the side end surface of the laminated body in the same manner as the above, the inductor component is formed around the first conductor 2 and the capacitance component forms the inductor component described above. Since it is a distributed constant type with respect to the conductor 2 of 2, a wide band noise elimination filter can be obtained with a simple configuration by inserting this into the electronic circuit as a low pass filter as shown in the equivalent circuit of FIG.

As in the case of the inductor-forming conductor, a conductor in which both ends of the conductor are extended to side end faces different from both end faces of the inductor-forming conductor in the laminated body is applied as the capacitor-forming conductor in this embodiment. A configuration that avoids the polarity described above is also possible, and an electrode terminal as shown in FIG. 2 can be used.

Therefore, if the terminal for the capacitance is grounded by being inserted in the electronic circuit, a low-pass filter for removing the broadband common-mode noise can be obtained with a simple structure.

The capacitance component between the first and second conductors and the capacitance forming conductor is increased or set to an appropriate value so that a desired filter characteristic can be set to the coupling coefficient. be able to.

In the description of the laminating means in the present embodiment, the laminating structure mainly composed of screen printing is used, but the structure of the present invention is formed finer mainly by a vacuum technique such as a sputtering method. It is clear that this is also included in the scope of the present invention, but it should be added as a precaution.

[0021]

As described above, according to the laminated EMI filter of the present invention, a wide band noise having both the in-phase component removing function and the anti-phase component removing function, which is a single component, is sufficient for noise removal. The removal filter and the like can be downsized, increased in density, and improved in performance with a simple configuration. In addition, it is possible to provide a configuration that enables desired filter design by arbitrarily setting the component ratio, or the inductance component, or the capacitance component, and thus the industrial value for electronic devices and devices is extremely large. Can be said.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a laminated body of a laminated EMI filter according to an embodiment of the present invention.

FIG. 2 is a laminated EMI comprising the laminated body shown in FIG.
It is a perspective view which shows the structure of the whole filter.

FIG. 3 is an equivalent circuit diagram of the laminated EMI filter shown in FIG.

4 (a) to (l) are views showing a manufacturing process of an example of a conventional laminated EMI filter element, and FIG. 4 (m) is a view showing an equivalent circuit of this filter element.

[Explanation of symbols]

 1 Dielectric Layer 2 First Conductor 2'End 3 Dielectric Layer 4 Second Conductor 4'End 5 Dielectric Layer A Membrane Terminal B Membrane Terminal C Membrane Terminal

Claims (1)

[Claims] 1. A laminate having a plurality of conductors facing each other and having their paths overlapping in the stacking direction embedded in a dielectric body composed of a plurality of dielectric layers, wherein the conductors among the plurality of conductors are A first conductor having one end extended to one end face of the laminated body, a second conductor having both ends extended to both end faces adjacent to one end face of the laminated body, among the plurality of conductors; A laminated EMI filter, comprising: an electrode terminal provided on the end face of the laminate and extending to the end face and connected to the end portions of the first and second conductors.