JP2002111422A - Noise filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise filter by which enough inductance value can be obtained and excellent effect of noise attenuation can be obtained. SOLUTION: This noise filter configures a capacitance element C laminated a lower electrode 2, a dielectric layer 3, an upper electrode 4 opposite to the lower electrode 2 and a protection layer 5 on the surface of an insulating substrate 1, configures an inductance device L laminated a magnetic substance layer 6, serpentine shaped coil-pattern 7 composed with metallic oxide resistor materials, a magnetic substance layer 8 and a protection layer 9 on the rear side of the insulating substrate 1, connects electrically the one edge of the coil-pattern 7 with the upper electrode 4 or the lower electrode 2 of the capacitance element C, and at the same time, arranges a pair of outer terminal electrodes 11 and 12 connecting to the both edges of the coil-pattern 7 and a gland terminal electrode 13 connecting to the lower electrode 2 or the upper electrode 4 of the capacitance element C on the edge side of the insulating substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a noise filter.

[0002]

2. Description of the Related Art Conventionally, an LC-integrated chip type noise filter manufactured by a green sheet laminating method has been known. This noise filter is manufactured, for example, by bonding an inductance element using ferrite and a capacitor element using a dielectric. Alternatively, a noise filter manufactured by mixing a dielectric material and a magnetic material to form a chip, forming an electrode on the chip, and integrally firing the chip and the electrode has been considered.

However, in manufacturing the above-described noise filter, it is necessary to bond an inductance element using ferrite and a capacitor element using a dielectric, or to form a chip by mixing a dielectric and a magnetic substance. Therefore, there is a problem that the manufacture of the noise filter is complicated. In addition, since all of the above-described noise filters are manufactured using the dielectric green sheet laminating method, not only is the manufacturing of the noise filter complicated, but also the integrated firing of the electrodes and the green sheets. There is also a problem that defects of the internal structure such as delamination easily occur.

Therefore, a noise filter as shown in FIG. 6 is disclosed in Japanese Patent No. 2638339 and Japanese Patent No. 273423.
No. 2 discloses this.

That is, a lower electrode 2, a dielectric layer 3, an upper electrode 4 facing the lower electrode 2, and a protective layer 5 are respectively laminated on the surface of the insulating substrate 1, and a coil pattern 7 is formed on the back surface of the insulating substrate 1. And the protective layer 9 are laminated.

[0006] Then, the lead portion 7 of the coil pattern 7
1 is electrically connected to the input terminal, and the lead portion 72 is electrically connected to the lead portion 42 of the upper electrode 4. Further, the lead portion 42 of the upper electrode 4 is connected to an output terminal, and the lead portion 21 of the lower electrode 2 is connected to a ground terminal.

According to FIG. 1, in order to form a capacitor element and an inductance element on the front and back surfaces of the magnetic layer substrate 1 by using a thick film printing method, the inductance element and the capacitor element are formed by using a green sheet laminating method. Thus, the manufacturing process can be greatly simplified as compared with the case where the noise filter is manufactured by laminating the noise filters. In addition, in the thick film printing method, baking is performed each time a thick film layer is printed, so that there is no occurrence of structural defects such as delamination in a noise filter manufactured using the green sheet laminating method.

[0008]

In the above-described noise filter 20, as the distribution constant (inductance component) of the coil pattern portion is larger, the resonance frequency can be shifted to the lower frequency side, and the noise removal in the lower frequency region is achieved. The effect becomes good.

However, since there is a magnetic flux loss on the insulating substrate 1 side and the protective layer 9 side, the inductance component of the coil pattern portion is small, and it has been difficult to obtain a steep attenuation characteristic.

[0010] Further, there is a problem in that a current suddenly flows near the resonance frequency, so that a waveform distortion occurs in a signal waveform due to reflection on a transmission line.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a distributed noise filter capable of improving a noise removing effect in a low frequency region. is there.

[0012]

A noise filter according to the present invention, which achieves the above object, comprises a lower electrode,
A capacitor element in which a dielectric layer, an upper electrode facing the lower electrode, and a protective layer are respectively laminated is arranged, and a meandering coil pattern made of a magnetic material layer and a metal oxide resistor material is provided on the back surface of the insulating substrate. A magnetic material layer, a protective layer, and an inductance element in which a protective layer is laminated, and one end of the coil pattern of the inductance element is electrically connected to the upper electrode or the lower electrode of the capacitor element. A pair of external terminal electrodes connected to both ends of the coil pattern and a ground terminal electrode connected to a lower electrode or an upper electrode of the capacitor element were provided on an end surface of the insulating substrate.

According to the noise filter of the present invention, a capacitor element in which a lower electrode, a dielectric layer, an upper electrode facing the lower electrode, and a protective layer are respectively laminated on a surface of an insulating substrate is arranged. A magnetic layer, a meandering coil pattern made of a metal oxide resistor material, a magnetic layer, and an inductance element in which a protective layer is laminated are arranged on the back surface, and one end of the coil pattern and an upper electrode of the capacitor element are arranged. Alternatively, a pair of external terminal electrodes connected to both ends of the coil pattern and a ground terminal electrode connected to a lower electrode or an upper electrode of the capacitor element are provided on the end surface of the insulating substrate while electrically connecting the lower electrode to the lower electrode. It is characterized by becoming.

That is, since the coil pattern of the inductance element has a meandering shape, the current path can be lengthened without changing the size of the noise filter, and the upper and lower portions of the meandering coil pattern are filled with magnetic layers. Therefore, there is no loss of magnetic flux on the insulating substrate side and the protective layer side, a sufficient shielding effect is obtained, and a sufficient inductance value is obtained.

By using a metal oxide resistor material as the coil pattern material to be used, it is possible to prevent a damping effect, that is, a sudden current flow at the time of resonance, thereby preventing waveform distortion. Excellent noise attenuation effect can be obtained.

Further, since the capacitor element and the inductance element are formed on both surfaces of the insulating substrate, the manufacturing process is simple and the mounting area is small.

[0016]

Embodiments of the present invention will be described below. FIG. 1 is an external perspective view of the noise filter of the present invention, FIG. 2 is a cross-sectional view of the noise filter of FIG.
Is an exploded perspective view of the laminated body of the noise filter of FIG. 1, and FIG. 4 is an equivalent circuit diagram of the noise filter of FIG.

In the noise filter 10 shown in FIG. 1, a capacitor element C is arranged on the front surface side and an inductance element L is arranged on the back side centering on the insulating substrate 1.

The insulating substrate 1 is a heat-resistant insulating substrate such as alumina. On the front side of the insulating substrate 1, a lower electrode 2 extending in the length direction of the insulating substrate is formed.
Note that the lower electrode 2 includes a lead electrode 21 connected to the ground terminal 13.

On this lower electrode 2, a dielectric layer 3 is formed. The dielectric layer 3 is formed so as to expose the extraction electrode 21 of the lower electrode 2.

An upper electrode 4 is formed on the dielectric layer 3 and is led out to both ends of the insulating substrate 1 by lead electrodes 42. Further, a protective layer 5 is formed on the entire surface except for the extraction electrodes 21 and 42 of the lower electrode 2 and the upper electrode 4.

On the back side of the insulating substrate 1, a lower magnetic layer 6 is formed.

A meandering coil pattern 7 is formed on the lower magnetic layer 6, and is drawn out to both side surfaces of the insulating substrate 1 by lead electrodes 71 and 72. The extraction electrode 71 is connected to the input force terminal 11 and is connected to the extraction electrode 7.
2 is connected to the extraction electrode 42 of the upper electrode 4 and to the output terminal 12.

Here, as the material of the meandering coil pattern 7, a resistor material of metal oxide is used.

The material of the coil pattern 7 is R
It is appropriate to a main component u, Pb ₂ particularly RuO ₂
It is desirable to mix either Ru ₂ O ₇ or Bi ₂ Ru ₂ O ₇ . Thereby, the resistance value can be easily controlled, and the desired resistance value can be set by appropriately changing the length, area, and number of layers of the coil pattern. Further, the above Pb ₂ Ru ₂ O ₇ , Bi ₂ Ru ₂ O ₇
Is desirably 60 wt% or less. If it exceeds this, the resistance value will vary.

An upper magnetic layer 8 is formed on the meandering coil pattern 7. Further, a protective layer 9 is formed on the whole except for the lead-out electrode 72 of the meandering coil pattern 7.

The equivalent circuit shown in FIG. 4 has one end of an inductance element L connected to one end of a capacitor element C, the other end of the capacitor element C connected to a ground terminal 13, and the other end of the inductance element L Input terminal 11
In this circuit, the connection point between the meandering coil pattern of the inductance element L and the upper electrode of the capacitor element C is the output terminal 12.

The inductance element L includes a lower magnetic layer 6
And the upper magnetic layer 8 and the meandering coil pattern 7 formed therebetween. The capacitor element C is formed between the lower electrode 2 and the upper electrode 4 and between them. This is formed from the dielectric layer 3. This equivalent circuit is a circuit in which an inductance element L and a capacitor element C are connected in a T-shape.
Called C circuit.

Further, the lower magnetic layer 6 and the upper magnetic layer 8
Length of the meandering coil pattern 7 formed between
The value of inductance can be adjusted by adjusting the width, thickness, etc., and by adjusting the opposing area of the lower electrode 2 and the upper electrode 4, the thickness of the dielectric layer 3, the dielectric constant, etc. The value of the capacity can be adjusted.

The noise filter 1 configured as described above
0, since the coil pattern 7 of the inductance element L has a meandering shape, the current path can be lengthened without changing the size of the noise filter 10 and the upper and lower sides of the meandering coil pattern 7 are formed of a magnetic layer. Since it is filled with 6, 8, there is no loss of magnetic flux on the insulating substrate 1 side and the protective layer 9 side, a sufficient shielding effect is obtained, and a sufficient inductance value is obtained.

Further, by using a metal oxide resistor material as the material of the coil pattern 7 to be used, a damping effect, that is, an abrupt current flow at the time of resonance can be prevented, so that waveform distortion can be prevented. And an excellent noise attenuation effect can be obtained.

Further, since the capacitor element C and the inductance element L are formed on both surfaces of the insulating substrate 1, the manufacturing process is simple and the mounting area is small.

In the present embodiment, the inductance element L and the input terminal 11, and the capacitor element C and the output terminal 12
Are electrically connected to each other, but may be reversed. In addition, although mounted with the inductance element L down,
The reverse is also acceptable. That is, when it becomes the final part shape,
It is a component having no directionality of the input / output terminals and the mounting surface, and the alignment at the time of mounting becomes unnecessary. Further, the lead portion of the lower electrode may be connected to the lead portion of the coil pattern, and the lead portion of the upper electrode may be connected to the ground terminal.

Further, the noise filter 10 includes the insulating substrate 1
Although the lower magnetic layer 6 and the upper magnetic layer 8 are formed on the upper layer using a thick film printing method, they may be manufactured using a magnetic layer substrate.

FIG. 5 is an exploded perspective view of a laminated main body according to another embodiment of the noise filter of the present invention. In this manner, a plurality of noise filters may be arranged side by side to form an array type.

[0035]

Embodiments of the present invention will be described below.

The insulating substrate 1 is composed of a multi-piece flat substrate having a break line formed in a predetermined size. After forming a large number of noise filters on the substrate at once, the individual noise filters are formed along the break line. Into products. The substrate is not limited to alumina, and may be, for example, an insulating substrate having a laminated structure using glass ceramic mixed with glass and fired at a low temperature.

On the surface of the insulating substrate 1, a conductive film to be the lower electrode 2 is formed by printing with a conductive paste such as Ag-Pd or Ag-Pt and dried. Alternatively, Ag, Pt, Au, or the like may be used as the electrode material. Part of the lower electrode 2
The ground terminal 13 is pulled out to near the side surface of the insulating substrate.
It is a lead electrode 21 connected to the terminal.

The dielectric layer 3 is printed with a dielectric paste by a screen printing method so as to cover the lower electrode 2 and dried. The layer thickness is, for example, 5 to 10 μm. As the dielectric paste, a powder of a lead relaxer material or a titanium-based material is used, which is mixed with an organic vehicle to form a paste. Some glass may be added to enhance sinterability.

The conductive film to be the upper electrode 4 is formed by screen-printing the same conductive paste as the lower electrode 2 on the unfired dielectric film. The electrode pattern is
It has a predetermined facing area so that a capacitor can be formed facing the lower electrode 4. One end of the electrode pattern forms a lead electrode 42 connected to one end 72 of the coil pattern 7. Then, the electrode pattern is dried.

Next, the lead electrode 21 of the lower electrode 2 and the upper electrode 4
A glass paste made of crystallized glass, amorphous glass, or the like is formed by printing so that the extraction electrode 42 is exposed. Thereby, the protective layer 5 on the surface is formed on the upper electrode 4.
Is formed. The protective layer 5 preferably has a two-layer structure of a crystallized glass layer and an amorphous glass layer, each having a thickness of, for example, about 20 μm.

Next, the lower electrode 2, the dielectric layer 3, the upper electrode 4, and the protective layer 5 are fired. The firing temperature is about 900 ° C.

Thus, on the surface of the insulating substrate 1,
The capacitor element C is formed.

Next, on the back surface of the insulating substrate 1, a magnetic paste is printed as a lower magnetic layer 6 on a predetermined pattern substrate.
dry. Examples of the magnetic material include those having ferromagnetic properties typified by a metal oxide magnetic layer such as Mn-Zn ferrite, Ni-Zn ferrite, and Mn-Mg-Zn ferrite.

The coil pattern 7 is composed of RuO ₂ and Pb ₂ Ru.
₂ O ₇ and BiRu ₂ O ₇ are mixed by 60 wt% or less, and the mixture is formed by a resistance paste obtained by adding a varnish thereto. That is, the resistor film to be the coil pattern 7 is formed by screen-printing the resistor paste on the lower magnetic layer 6 and drying. This resistor film has a meandering shape such as a meander type or a zigzag type. One end is drawn out to near the end face of the insulating substrate 2 and serves as a lead-out electrode 71 connected to the input terminal 11, and the other end is drawn out to be connected to the lead-out electrode 42 of the upper electrode 4 and the output terminal 12 on the surface. An electrode 72 is provided.

The upper magnetic layer 8 is covered with the coil pattern 7 by screen printing so that only the extraction electrodes 71 and 72 of the coil pattern 7 are exposed.
Print and dry the same magnetic paste.

Next, the upper magnetic layer 8 and the coil pattern 7
And the extraction electrode 7 of the coil pattern 7
As in the case of the surface protection layer 5, a glass paste made of crystallized glass, amorphous glass, or the like is subjected to a printing process to expose 1, 72. Thus, the protective layer 9 on the back surface is formed on the upper magnetic layer 8. Next, the lower magnetic layer 6,
The coil pattern 7, the upper magnetic layer 8, and the protective layer 9 are fired. The firing temperature is about 900 ° C., and is preferably equal to or lower than the firing temperature of the capacitor element C.

Thus, on the back surface of the insulating substrate 1,
An inductance element L is formed.

Next, a large-sized insulating substrate is provided for each predetermined element region.
Split and cut.

Next, input / output terminals 11 and 12 for connecting the extraction electrode 71 of the coil pattern 7, the extraction electrode 42 of the upper electrode 4, and the extraction electrode 72 of the coil pattern 7 to an external circuit are formed on the protective layer 5. The conductive paste is formed by printing and baking. As a result, the noise filter 10 shown in FIG. 1 is obtained.

FIG. 7A shows a conventional noise filter 20.
(B) shows the attenuation characteristic of the noise filter 10 of the present invention, (c) shows the signal waveform of the conventional noise filter 20, and (d) shows the signal waveform of the noise filter 10 of the present invention.

First, in the attenuation characteristic, for example, 400
The attenuation in MHz is the same as that of the conventional noise filter 20.
-18 dB, the noise filter 1 of the present invention.
At 0, the gain is -30 dB, and the improvement of the attenuation characteristic is recognized. Moreover, in the conventional noise filter 20, FIG.
As shown in (a), although the steepness of the attenuation curve was not obtained, in the noise filter 10 of the present invention, FIG.
As shown in (b), a steep characteristic of the attenuation curve is obtained.

In the signal waveforms of FIGS. 7 (c) and 7 (d), as shown in FIG. 7 (c), in the conventional noise filter 20, the waveform rises due to reflection on the transmission line. Although the waveform distortion occurs in the falling part, the waveform distortion as described above is eliminated in the noise filter 10 of the present invention as shown in FIG. 7D. This is because a metal oxide resistor material is used as a material to be the coil pattern 7 and a damping effect, that is, an abrupt current flow at resonance can be prevented, thereby preventing waveform distortion. This indicates that an excellent noise attenuation effect can be obtained.

In the conventional noise filter 20, the resistance value of the coil pattern was 0.47Ω, the inductance between the input and output terminals was 15 nH, and the capacitance was 47 pF. On the other hand, in the noise filter 10 of the present invention, the resistance value of the coil pattern was 47Ω, the inductance between the input / output terminals was 60 nH, and the capacitance was 47 pF. That is, since the coil pattern 7 of the inductance element L has a meandering shape, the current path can be lengthened without changing the size of the noise filter 10, and the upper and lower portions of the meandering coil pattern 7 , 8, there is no magnetic flux loss on the insulating substrate 1 side and the protective layer 9 side, a sufficient shielding effect is obtained, and a sufficient inductance value is obtained.

[0054]

As described above, in the noise filter of the present invention, the coil pattern of the inductance element has a meandering shape, and the upper and lower portions of the meandering coil pattern are filled with the magnetic material layers. Value is obtained.

Further, by using a metal oxide resistor material as the coil pattern material to be used, a damping effect, that is, an abrupt current flow at the time of resonance can be prevented, so that waveform distortion can be prevented. Excellent noise attenuation effect can be obtained.

Further, since the capacitor element and the inductor element are formed on both surfaces of the insulating substrate, the manufacturing process is simple and the mounting area can be small.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of the noise filter of FIG.

FIG. 3 is an exploded perspective view of a laminated main body of the noise filter of FIG.

FIG. 4 is an equivalent circuit diagram of the noise filter of FIG.

FIG. 5 is an exploded perspective view of a laminated main body according to another embodiment of the noise filter of the present invention.

FIG. 6 is an exploded perspective view of a laminated main body of a conventional noise filter.

7A and 7C are an attenuation characteristic diagram and a signal waveform diagram of the present invention and a conventional noise filter, respectively. FIGS. 7A and 7C are an attenuation characteristic diagram and a signal waveform diagram of a conventional noise filter, respectively, and FIGS. FIG. 4 is a diagram illustrating an attenuation characteristic and a signal waveform of a noise filter according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10, 20 Noise filter 1 Insulating substrate 2 Lower electrode 21 Leader 3 Dielectric layer 4 Upper electrode 42 Leader 5 Surface protective layer 6 Lower magnetic layer 7 Coil pattern 71,72 Leader 8 Upper magnetic layer 9 Back surface Protective layer 11, 12 Input / output terminal 13 Ground terminal C Capacitor element L Inductance element

Claims (1)

[Claims] 1. A capacitor element in which a lower electrode, a dielectric layer, an upper electrode facing the lower electrode, and a protective layer are respectively laminated on a surface of an insulating substrate, and a magnetic layer, A meandering coil pattern made of a resistor material of metal oxide, a magnetic layer, and an inductance element in which a protective layer is laminated are arranged, and one end of the coil pattern of the inductance element and the upper electrode of the capacitor element Or, while electrically connecting the lower electrode, a pair of external terminal electrodes connected to both ends of the coil pattern and a ground terminal connected to the lower electrode or the upper electrode of the capacitor element, on an end surface of the insulating substrate. A noise filter comprising electrodes.