JPH11205063A - Band stop filter component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain miniaturization and to make a component suitable for high density mounting by providing a substrate composed of a magnetic substance material and a ceramic material containing a dielectric material and a double terminal type passive filter circuit, formed inside the substrate and serially connected to a signal line so as to block the transmission of a signal component in a prescribed frequency band inside a signal to be transmitted through the signal line. SOLUTION: At both the terminal parts of a substrate 11 consisting of the ceramic material, terminal electrodes 12a and 12b are formed for connecting the internal filter circuit and the signal line. The filter circuit is composed of plural parallel resonance circuits which are successively serially connected. The resonance frequency of the plural parallel resonance circuits is gradually decreased, and the bandwidth of two parallel resonance circuits having adjacent resonance frequencies is partially overlapped each other, and the transmission of the signal component in a certain prescribed frequency band is blocked as a whole. These plural parallel resonance circuits are formed as a double terminal type filter as a whole. Thus, the miniaturization of a filter component 10 and high-density mounting can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band stop filter component for preventing transmission of a signal component within a predetermined frequency band.

[0002]

2. Description of the Related Art Conventionally, a band stop type EMI (Ele) has been used in various electronic devices that handle signals in a microwave band.
ctro Magnetic Interferenc
e) A filter is used. 9 and 10 are equivalent circuit diagrams of T-type and π (pi) -type filters, respectively.

A band stop type EM which is already commercially available
The I filter is represented as shown in FIG. 9 or FIG. 10, and has a total of three external electrodes of two terminal electrodes 12a and 12b for inserting in series with a signal line and a ground electrode 13 for connecting to a ground line. have.

[0004]

However, in a three-terminal type as shown in FIG. 9 or FIG.
Since there are three external electrodes, there is a limit to miniaturization of the filter component. In the case of a three-terminal shape,
Since the routing of signal lines and ground lines on the substrate becomes complicated, the area occupied on the substrate required for mounting the filter component on the substrate increases, and there is a limit to high-density mounting.

[0005] In view of the above circumstances, it is an object of the present invention to provide a band-stop filter component which can reduce the size of the filter component compared to the conventional one and is suitable for high-density mounting.

[0006]

According to the present invention, there is provided a band-stop filter component comprising a base made of a porcelain material containing both a magnetic material and a dielectric material, and a signal formed inside the base. A two-terminal passive filter circuit connected in series to the line and for preventing transmission of a signal component within a predetermined frequency band in a signal transmitted through the signal line.

[0007] The band-stop filter component of the present invention comprises:
Because it is composed of a two-terminal passive filter circuit,
Suitable for miniaturization and high-density mounting. Here, in the band-stop filter component of the present invention, the passive filter circuit includes, for example, a plurality of parallel resonance circuits, each including an inductor and a capacitor connected in parallel with each other and having different resonance frequencies, sequentially connected in series. May be done.

In this case, the resonance frequency and the band of each of the plurality of parallel resonance circuits are adjusted so that the bandwidths of two parallel resonance circuits having resonance frequencies adjacent to each other partially overlap each other. Preferably, the width is determined. By connecting a plurality of such parallel resonance circuits in series, a two-terminal passive filter circuit having desired characteristics can be realized.

[0009]

Embodiments of the present invention will be described below. FIG. 1 is a circuit diagram of a parallel resonance circuit, and FIG. 2 is a circuit diagram of a plurality of parallel resonance circuits sequentially connected in series. As shown in FIG.
Are connected in parallel to form a parallel resonance circuit 14. With only one parallel resonance circuit 14, the passage of only a specific resonance frequency (frequency having a very narrow bandwidth) determined by the inductance L of the inductor 15 and the capacitance C of the capacitor 16 is prevented.

A plurality of parallel resonance circuits 14_1, 14_2,..., 14_n connected in series shown in FIG. 2 have resonance frequencies slightly different from each other, and furthermore have a bandwidth of two resonance circuits having adjacent resonance frequencies. Some overlap each other. For this reason, it acts as a band stop filter as a whole to prevent transmission of signal components within a certain frequency band. Moreover, the band stop filter shown in FIG. 1 and composed of a plurality of parallel resonance circuits is a two-terminal filter as a whole, no matter how many parallel resonance circuits are connected in series.

Hereinafter, more specific embodiments will be described. FIG. 3 is an external perspective view of the band stop filter component of the present invention. The band stop filter component 10 shown in FIG. 3 has terminal electrodes for connecting an internal filter circuit of the filter component 10 and an external signal line, for example, a substrate, to both ends of a base 11 made of a porcelain material. 12a and 12b are formed. As described below, a filter circuit including a plurality of (three in the following example) parallel resonance circuits sequentially connected in series is formed inside the filter component 10.

FIG. 4 is a schematic diagram showing a filter circuit formed inside the band stop filter component shown in FIG. This filter circuit includes an inductor 15 (three inductors 15_1, 15_2, and 1 connected in series).
5_3) and three capacitors 16_1, 16_1 connected in parallel to the three inductors 15_1, 15_2, 15_3, respectively.
2, 16_3.

FIG. 5 to FIG. 7 are views showing each manufacturing process of the filter circuit shown in FIG. Here, a magnetic material containing Ni-Zn ferrite as a main component and a dielectric material containing lead titanate as a main component are used. First, Ni-Zn
Fe ₂ O ₃ , NiO, Zn, which are ferrite starting materials
O and the like are mixed, calcined, and pulverized to an appropriate particle size to obtain a calcined powder of a magnetic material having a desired particle size. On the other hand, PbO, TiO _2, etc., which are the starting materials of lead titanate, are also mixed,
The powder is calcined and pulverized to obtain a calcined powder of a dielectric material having a desired particle size.

Next, the calcined powder of the magnetic material and the calcined powder of the dielectric material are mixed at a predetermined ratio, and at the same time, a dispersant, a binder, a plasticizer, a solvent and the like are added to prepare a printing material paste. . The material paste thus produced and the conductive paste containing Ag or Pd as a main component are alternately laminated while being screen-printed, and cut as necessary to form a green laminate. The laminated body is subjected to a binder removal treatment, and further fired to form a fired body, and the fired body is subjected to terminal electrodes 12a and 12b by using, for example, a conductive paste mainly containing Ag (see FIG. 3).
To form a band stop filter component 10
Is completed.

Hereinafter, the respective manufacturing steps shown in FIGS. 5 to 7 will be described. First, as shown in FIG. 5A, a base substrate 111 made of the material paste manufactured as described above is prepared. This base substrate 111 becomes the first layer of the base in the finished product. Next, the base substrate (first layer) 1
A conductive film 121 made of a conductive paste is formed on 11 (FIG. 5B). The left half of the conductor film 121 is for the inductor, and the right half is for the capacitor.

Next, the material paste is applied to the through holes 11.
A second layer 112 having 2a is formed (FIG. 5C), and a conductive film 122 is formed with a conductive paste (FIG. 5D).
When forming the conductor film 122, the through holes 112a
Is filled with conductive paste, and the through holes 11
The conductive film 121 and the conductive film 122 are electrically connected by the conductive paste filled in 2a. The through holes described below all have the same role.

Similarly, a third layer 113 is formed using a material paste (FIG. 5E), a conductive film 123 is formed using a conductive paste (FIG. 5F), and a third layer having a through hole 114a is formed. Four layers 114 are formed (FIG. 6
(G)), a conductive film 124 is formed (FIG. 6H), and a fifth layer 115 having a through hole 115a is formed (FIG. 6).
(I)), a conductive film 125 is formed (FIG. 6J), and a sixth layer 116 having a through hole 116a is formed (FIG. 6).
(K)), a conductor film 126 is formed (FIG. 6 (L)), and a seventh layer 117 having a through hole 117a is formed (FIG. 7).
(M)), a conductor film 127 is formed (FIG. 7 (N)), and an eighth layer 118 having a through hole 118a is formed (FIG. 7 (N)).
(O), a conductor film 128 is formed (FIG. 7 (P)), and a ninth layer 119 is formed on the entire surface (FIG. 7 (Q)).

Although only one filter component is shown here, usually, a plurality of similar patterns are simultaneously formed and cut to produce a large number of laminates for one filter component. After forming the laminate in this manner, as described above, the laminate is subjected to a binder removal process, and further baked to form a baked body, and the terminal electrode 1 shown in FIG.
2a and 12b are formed.

Through such manufacturing steps, the filter component 10 having the structure shown in FIGS. 3 and 4 is manufactured.
FIG. 8 shows a filter circuit having the structure shown in FIG. 4 (a configuration in which three parallel resonance circuits are connected, so this is called a “three-stage product”) and only one stage of the parallel resonance circuit (“one-stage product”). Is called)
FIG. 6 is a diagram showing filter characteristics in the case of FIG.

In the one-stage product, transmission of signals is blocked only in an extremely narrow bandwidth, whereas in the three-stage product, a band stop filter over a considerably wide frequency band is realized.

[0021]

As described above, according to the present invention, a band-stop filter for a desired frequency band can be realized with a two-terminal circuit, and miniaturization of components and high-density mounting can be realized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a parallel resonance circuit.

FIG. 2 is a circuit diagram of a plurality of parallel resonance circuits sequentially connected in series.

FIG. 3 is an external perspective view of a band stop filter component of the present invention.

4 is a schematic diagram showing a filter circuit formed inside a band stop filter component whose appearance is shown in FIG.

FIG. 5 is a diagram showing a manufacturing process of the filter circuit shown in FIG. 4;

FIG. 6 is a diagram showing a manufacturing process of the filter circuit shown in FIG. 4;

FIG. 7 is a view showing a manufacturing process of the filter circuit shown in FIG. 4;

8 is a diagram showing a filter circuit having the structure shown in FIG. 4 and filter characteristics in the case of only one stage of a parallel resonance bottleneck.

FIG. 9 is an equivalent circuit diagram of a T-type filter.

FIG. 10 is an equivalent circuit diagram of a π (pi) type filter.

[Description of Signs] 10 Band stop filter component 11 Base 12a, 12b Terminal electrode 14, 14_1, 14_2, ..., 14_n Parallel resonance circuit 15, 15_1, 15_2, 15_3 Inductor 16, 16_1, 16_2, 16_3 Capacitor 111 Base substrate 112 2nd layer 112a through hole 113 3rd layer 113a through hole 114 4th layer 114a through hole 115 5th layer 115a through hole 116 6th layer 116a through hole 117 7th layer 117a through hole 118 8th layer 118a through hole 119 ninth Layers 121, 122, 123, 124, 125, 126, 1
27,128 conductor film

Claims (3)

[Claims] 1. A base made of a porcelain material containing both a magnetic material and a dielectric material, and a predetermined part of a signal formed in the base, connected in series to a signal line and transmitted through the signal line. A band-stop filter component comprising: a two-terminal passive filter circuit that blocks transmission of a signal component in a frequency band. 2. The passive filter circuit according to claim 1, wherein a plurality of parallel resonance circuits having inductors and capacitors connected in parallel with each other and having different resonance frequencies are sequentially connected in series. Claim 1
The described band-stop filter component. 3. The resonance frequency and the bandwidth of each of the plurality of parallel resonance circuits are adjusted such that the bandwidths of two parallel resonance circuits having resonance frequencies adjacent to each other among the plurality of parallel resonance circuits partially overlap each other. 3. The band-stop filter component according to claim 2, wherein the component is determined.