JPH10126193A - Lc filter part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a multistage LC filter circuit within a limited size by preparing two or more capacitors between a ground electrode and each of different intermediate points of an inductor which is contained in a substrate material of a dielectric and magnetic substance mixture. SOLUTION: Conductor films 1, 2, 3 and 4 are formed on every layer of a dielectric and magnetic substance mixture material, and the conductor films constructing the adjacent layers are electrically connected to each other, via the conductors existing in through-holes 12a, 12b, 23a, 23b, 34a and 34b. The conductor films 1a, 2a, 3a and 4a and 1c, 2c, 3c and 4c are spirally formed at both ends covering four layers and function as inductors and are connected together via a conductor film 4b of a 4th layer. The conductor layers 2b, 4b form the capacitors with respect to the ground layers 1b and 3b, so that a multistage LC filter is obtained as a whole. The films 1a and 1c are exposed over the end face of a substrate as the electrodes, and the films 1b and 3b are exposed over the side face of the substrate as the ground electrodes. It is possible to secure sharper characteristic by increasing the number of layers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LC filter component having an LC filter formed in a base containing both a magnetic material and a dielectric material.

[0002]

2. Description of the Related Art Conventionally, EMI (Electro Magnetic) has been used as a measure against high frequency noise in electronic equipment.
Interference filter is used. Generally, an EMI filter is configured by combining individual elements of a capacitor and an inductor, and many types of EMI filters based on the combination of these individual elements have been proposed. As a typical example, for example, L which is a combination of one capacitor and one inductor
An EMI filter of a type and a π (pi) type EMI filter composed of a combination of two capacitors and one inductor are known, and these EMI filters take measures against noise in electronic devices.

As described above, when an EMI filter is configured by combining a capacitor and an inductor, each of which is an individual element, the entire EMI filter becomes large,
There is a problem that a large area is required to attach the MI filter to a circuit board or the like, and that it takes a lot of man-hours to combine individual elements. In recent years, there has been proposed a filter which solves these problems and incorporates a capacitor and an inductor in one chip (see JP-A-8-65080 and JP-A-8-148381).

[0004] These publications disclose that a conductive film acting as an inductor and a capacitor is formed on each of a plurality of layers made of a mixture of a dielectric material and a magnetic material, and the plurality of layers are laminated and fired. Has proposed a chip-shaped filter component in which an L-type or π-type LC filter is formed.

[0005]

In each of the inductors formed in the filter component described in the above-mentioned publication, a linear conductor film is sandwiched between a mixture of a dielectric material and a magnetic material. It is difficult to obtain a large inductance in a limited size. To configure an LC filter circuit having good filter characteristics, a multi-stage L
It is preferable to configure a C filter circuit. However, if an L-type LC filter circuit and a π-type LC filter circuit proposed in the above-mentioned document are applied as they are to form a multi-stage LC filter circuit, a large inductance is required. In order to obtain, the dimensions become too large, which is not practical.

In view of the above circumstances, an object of the present invention is to provide an LC filter component in which a multi-stage LC filter circuit is formed within a limited size.

[0007]

According to the present invention, there is provided an LC filter component comprising: a base containing both a magnetic material and a dielectric material; and a first filter formed on the outer surface of the base.
And a second terminal electrode, a ground electrode formed on the outer surface of the base, and a plurality of layers formed between the first terminal electrode and the second terminal electrode formed inside the base. An inductor made of a conductor film formed in a spiral shape across the substrate, and an inductor formed inside the base,
It is characterized by including two or more capacitors arranged between different intermediate points and a ground electrode.

[0008] The LC filter component of the present invention includes an inductor formed of a conductive film spirally formed over a plurality of layers, and can form an inductor having a large inductance in a small size. . Further, since the base of the LC filter component of the present invention is a mixture of a dielectric material and a magnetic material, the intermediate point of the inductor,
That is, a capacitor can be formed in the middle of a conductor film forming the inductor, and thus a multi-stage LC filter circuit can be formed in a small size.

[0009]

Embodiments of the present invention will be described below. FIG. 1 is an exploded perspective view of one embodiment of an LC filter component of the present invention, FIG. 2 is an external view thereof, and FIG. 3 is an equivalent circuit diagram thereof. As shown in FIG. 1, the LC filter component of this embodiment has conductor films 1, 2, and 2, which are hatched in FIG. 1, on each layer made of a mixture of a dielectric material and a magnetic material. It is composed of four layers in which 3, 4 are formed. The conductor film that constitutes the adjacent layer has a through hole 1
2a, 12b; 23a, 23b; 34a, 34b are electrically connected.

Here, the conductor films 1a,
2a, 3a, 4a; 1c, 2c, 3c, 4c form conductor films having a spiral structure, respectively, and form spirals in mutually opposite directions.
Further, they are connected to each other via a fourth-layer conductor film 4b. In addition, the conductor films 1b, 2
A capacitor is formed by b, 3b, and 4b.
As a result, a multi-stage LC filter circuit shown in the equivalent circuit of FIG. 3 is formed as a whole.

Here, the ends of the spiral structure at both ends are:
The first-layer conductor films 1a and 1c are connected to the terminal electrodes 51 and 52, respectively, as shown in FIG. 2 by being exposed from the end surface of the base body on which the respective layers are stacked.
The conductor film 1b at the center of the layer and the conductor film 3b at the center of the third layer are
By being exposed from the side surface of the base, it is connected to the ground electrode 53 shown in FIG.

FIG. 4 is a schematic layout diagram of the filter circuit having the structure shown in FIG. 1, and FIG. 5 is a schematic diagram showing a magnetic field over two spiral structures. As shown in FIG. 4, the filter circuit having the structure shown in FIG. 1 includes inductors having a spiral structure on both sides, and includes a capacitor in the center of the two spiral structures. The two spiral structures form opposite spirals, so that the magnetic fluxes inside the two spiral structures are parallel and opposite to each other, forming a magnetically closed circuit as shown in FIG. 5 as a whole. . For this reason, the magnetic field hardly acts on the portions of the capacitors arranged in the center of the two spiral structures, and these capacitors are
The desired characteristics can be exhibited as they are without being adversely affected by the magnetic field.

FIGS. 6 to 14 are views showing each manufacturing process of the LC filter component whose exploded perspective view is shown in FIG. (A) of each figure is a plan view, and (B) of each figure is a cross-sectional view along the arrow AA shown in FIG. Here, for example, Ni
-A magnetic material containing Zn ferrite as a main component is mixed and calcined, and a magnetic material calcined powder pulverized to an appropriate particle size and a dielectric material containing PbTiO ₃ as a main component, for example, are mixed and calcined. Baking and calcining dielectric calcined powder to an appropriate particle size, mixing at an appropriate ratio, adding a dispersing agent, binder, plasticizer, solvent, etc. to produce a dielectric magnetic material mixed paste Then, as described below, the dielectric magnetic material mixed paste thus manufactured and the conductive paste containing Ag or Pd as a main component are alternately laminated while being screen-printed, and if necessary, Cut to form a green laminate. The laminated body is subjected to a binder removal treatment, and further calcined to form a calcined body. The calcined body is subjected to terminal electrodes 51 and 52 and a ground electrode 53 (for example, using a conductive paste containing Ag as a main component). (See Fig. 2)
Is formed, thereby completing the LC filter component.

Hereinafter, each manufacturing process of the LC filter component shown in FIG. 1 will be described with reference to the drawings. First, as shown in FIG. 6, a base substrate 100 made of the dielectric / magnetic mixed paste produced as described above is formed, and the first conductive film 1 is formed on the base substrate 100 with a conductive paste.
a, 1b and 1c are formed by screen printing (FIG. 7). On top of that, a dielectric magnetic material mixed paste,
Screen printing is performed so that the through holes 12a and 12b are formed to form the dielectric / magnetic mixed layer 101 (FIG. 8). Further, similarly, the second conductive films 2a, 2b, and 2c are formed by the conductive paste (FIG. 9). At this time, the conductive paste is charged also in the through holes 12a and 12b, and the electrical connection with the first layer conductive film is made. Further, a dielectric / magnetic mixed layer 102 is formed thereon so as to form through holes 23a and 23b (FIG. 10), and third conductive films 3a, 3b and 3c are formed thereon (FIG. 10). 11). Furthermore, through holes 34
a, 34b so that the dielectric / magnetic material mixed layer 10 is formed.
3 (FIG. 12), and a fourth conductive film 4a,
4b and 4c are formed (FIG. 13), and a base substrate 104 is further formed thereon.

After forming such a laminated body, as described above, the laminated body is subjected to a binder removal treatment, and further baked to form a baked body, and the terminal electrodes 51, 5 shown in FIG.
2 and the ground electrode 53 are formed. Through such a manufacturing process, an LC filter component having the structure shown in FIGS. 1 and 2 is manufactured.

Here, during the above manufacturing process, by repeating the process from the process shown in FIG. 8 to the process shown in FIG. 11, a further multi-stage LC filter component can be formed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment described above, when a pair of one inductor and one capacitor is taught as one layer of a filter circuit as shown in FIG.
), Which are referred to herein as "three-layer products". In the same manner, when the number of capacitors is one, five and seven,
The C filters are called “one-layer product”, “five-layer product”, “7
It is referred to as a “layer product”. These “one-layer products”, “five-layer products”, “7
The “layer product” is obtained by omitting the processes of FIGS. 8 to 11 (in the case of a one-layer product) or performing the processes of FIGS. 8 to 11 twice (FIG. 6 to FIG. 14). By repeating three times (in the case of a five-layer product) three times (in the case of a seven-layer product). Can be formed. Here, as can be seen from the above-described embodiment, even if the number of layers is increased, LC filter components having almost the same dimensions are configured.

FIG. 15 shows the structure formed as described above.
It is a figure which shows the experimental data of the filter characteristic of a 1-layer product (comparative example), a 3-layer product, a 5-layer product, and a 7-layer LC filter circuit.
Here, the following experimental conditions were adopted. (A) Material composition; Ni-Zn-Cu ferrite: Pb
TiO ₃ dielectric = 6: 4 (b) conductive material; Ag / Pd (c) interlayer thickness; 12 μm (d) inductor; inner cross-sectional area 0.71 mm ² , line width 0.
20 mm (e) Capacitor; counter electrode area 0.64 mm ² (per layer) Under the above conditions, LC filter parts having basically the structure shown in FIG. 1 and having different numbers of layers are manufactured, and their characteristics are measured. As a result of the measurement, as shown in FIG. 15, an LC filter circuit having a steep attenuation characteristic with an increase in the number of layers was formed. The attenuation coefficient for each layer number is 1-layer product; 25.8d
B / dec. , 3-layer product; 34.9 dB / dec. , 5-layer product; 37.1 dB / dec. , 7 layers product; 38.8dB /
dec. Met.

[0019]

As described above, according to the present invention,
A small LC filter component including a multi-stage LC filter circuit is configured.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an embodiment of an LC filter component of the present invention.

FIG. 2 is an external view of an embodiment of the LC filter component of the present invention.

FIG. 3 is an equivalent circuit diagram of an embodiment of the LC filter component of the present invention.

FIG. 4 is a schematic layout diagram of a filter circuit having the structure shown in FIG. 1;

FIG. 5 is a schematic diagram showing a magnetic field straddling two spiral structures.

FIG. 6 is a view showing a first step in a manufacturing process of the LC filter component whose exploded perspective view is shown in FIG. 1;

FIG. 7 is a view showing a second step in the manufacturing process of the LC filter component whose exploded perspective view is shown in FIG. 1.

FIG. 8 is a view showing a third step in the manufacturing process of the LC filter component whose exploded perspective view is shown in FIG. 1;

9 is a diagram illustrating a fourth step in the process of manufacturing the LC filter component whose exploded perspective view is illustrated in FIG. 1.

FIG. 10 is a view showing a fifth step in the manufacturing process of the LC filter component whose exploded perspective view is shown in FIG. 1;

FIG. 11 is a view showing a sixth step in the manufacturing process of the LC filter component whose exploded perspective view is shown in FIG. 1.

FIG. 12 is a view showing a seventh step in the manufacturing process of the LC filter component whose exploded perspective view is shown in FIG. 1.

FIG. 13 is a view showing an eighth step in the manufacturing process of the LC filter component whose exploded perspective view is shown in FIG. 1.

FIG. 14 is a view showing a ninth step in the process of manufacturing the LC filter component, the exploded perspective view of which is shown in FIG. 1.

FIG. 15 is a diagram showing experimental data of filter characteristics of LC filter circuits of one-layer product, three-layer product, five-layer product, and seven-layer product.

[Explanation of symbols]

1, 1a, 1b, 1c, 2, 2a, 2b, 2c, 3, 3
a, 3b, 3c, 4, 4a, 4b, 4c Conductive film 12a, 12b, 23a, 23b, 34a, 34b
Through hole 51, 52 Terminal electrode 53 Earth electrode 100, 104 Base substrate 101, 102, 103 Dielectric / magnetic mixed layer

Claims (1)

[Claims] A base containing both a magnetic material and a dielectric material; first and second terminal electrodes formed on an outer surface of the base; an earth electrode formed on an outer surface of the base; An inductor formed between the first terminal electrode and the second terminal electrode and formed of a conductor film spirally formed over a plurality of layers and formed inside the base; And two or more capacitors disposed between the different middle points of the inductor and the ground electrode.
C filter parts.