JPH0653049A - Chip type lc filter - Google Patents

Abstract

PURPOSE:To enable the compact and integrated surface package to be made feasible with high precision capable of absorbing high-frequency noise and discharging pi type LC function. CONSTITUTION:The title filter is composed of a laminated body comprising dielectric sheets 10 and 20 in square shape while the dielectric sheet 10 is provided with inner conductors 11 and 12 connected to a pair of sides insulated from another pair of sides as well as zigzag conductor 15 arranged between both conductors 11 and 12 electrically connected to these conductors 11, 12 but likewise insulated from another pair of sides. The other dielectric sheet 20 is provided with grounding conductors 21, 22 insulated from the sides corresponding to the pair of sides connected to the inner conductors 11, 12 but connected to the other pair of sides. The zigzag conductor 15 is composed to be the inductance component to high-frequency noise so that capacitances may be formed respectively between the inner conductors 11, 12 and grounding conductors 21, 22 through the intermediary of the sheet 20. Furthermore, a pair of signal electrodes 51, 52 connecting to the inner conductors 11, 12 as well as a grounding electrode connecting to the grounding conductors 21, 22 are to be formed on the side of the laminated body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type LC filter suitable for absorbing high frequency noise in a signal line. More specifically, it relates to a π-type LC filter.

[0002]

2. Description of the Related Art In digital equipment such as a computer, there is a problem that if high-frequency noise is mixed in, malfunctions are likely to occur, and that unnecessary electromagnetic waves that may damage other electronic equipment are emitted from the wiring. Therefore, a noise filter that removes high frequency noise is used in the signal line. An LC filter is used as the noise filter. The electronic components of this LC filter are provided for each signal line, and an LC filter in which a capacitor element and an inductor element are combined is used.

As an LC filter that combines a capacitor element and an inductor element, a three-terminal type capacitor 5 as shown in FIG. 10 is used. This three-terminal type capacitor 5 has electrodes 1 on both sides of a disk-shaped dielectric 6.
(The opposite side is not shown) is formed so that a capacitance is formed between both electrodes. The electrode 1 is electrically connected to a U-shaped lead wire 2 and further connected to an external electrode via a ferrite bead 4. Further, a lead wire 3 for grounding is connected to an electrode (not shown). An equivalent circuit of the three-terminal type capacitor 5 is shown in FIG. Other than this, there is an LC filter made by combining a chip component such as a chip capacitor and an inductor element.

[0004]

In a conventional LC filter such as a three-terminal type capacitor, lead wires and ferrite beads protrude from the dielectric, so that it is difficult to mount it on a substrate at high density, resulting in a small device. Cannot be transformed. Therefore, there has been a demand for the development of an LC filter that is compatible with the surface mounting technique and does not require a large component space. Further, an LC filter made by combining a two-terminal chip component and an inductor element has a problem that high-frequency noise cannot be removed due to resonance due to residual inductance on the ground side of the chip capacitor as the signal frequency becomes faster. It was

It is an object of the present invention to provide a chip type LC filter which can remove high frequency noise and does not require a large component space when it is surface-mounted on a substrate. Another object of the present invention is to provide a chip type LC filter capable of removing high frequency noise even under a high signal frequency.

[0006]

The structure of the present invention for achieving the above object will be described with reference to FIGS. 1 and 3, the ceramic sheet portion is shown in an enlarged manner in the thickness direction for ease of explanation. The LC filter of the present invention includes a laminated body 40 in which a rectangular first dielectric sheet 10 and a second dielectric sheet 20 having the same shape and size as the sheet 10 are laminated and integrated. The first dielectric sheet 10 is electrically connected to a pair of sides and electrically insulated from a pair of sides different from the pair of sides.
First and second inner conductors 11, 12 having 3, 14;
An interval 13, which is arranged between the first and second inner conductors 11 and 12 and is electrically connected to the first and second inner conductors and electrically insulated from another pair of sides,
A meandering conductor 15 having a meandering shape 14 is provided on the sheet surface. In addition, the second dielectric sheet 20
Is the first and second inner conductors 1 of the first dielectric sheet 10.
A pair of sides 1 and 12 electrically connected to a pair of sides corresponding to a pair of sides electrically insulated from each other, and electrically connected to another pair of sides. The first and second ground conductors 21 and 22 are provided on the surface of the sheet.
In addition, the first and second inner conductors 1 of the first dielectric sheet 10
Reference numerals 1 and 12 are configured to serve as inductance components with respect to high-frequency noise, and the first and second inner conductors 11 and 12 and the first and second ground conductors 21 and 22 are interposed via the second dielectric sheet 20. Configured to form a capacitance therebetween. Further, the first exposed on the side surface of the laminated body 40.
The first and second signal electrodes 51 and 52 connected to the first and second inner conductors 11 and 12, respectively, are formed on this side surface and are exposed on the other side surface of the laminated body 40.
Grounding electrodes 61 and 62 respectively connected to 1 and 22 are formed on this side surface. The equivalent circuit of the chip type LC filter of the present invention can be expressed as shown in FIG. 9 (a) or 9 (b).

[0007]

[Function] First dielectric sheet 10 and second dielectric sheet 20
The meandering conductor 15 between and functions as an inductor when a high-frequency signal flows. This is because the meandering conductor 15 meanders and thus has a long distance as a conductor. Between the first and second inner conductors 11 and 12 on the first dielectric sheet 10 and the first and second ground conductors 21 and 22 on the second dielectric sheet 20 via the second dielectric sheet 20. Since a capacitance is formed, a potential difference is generated between the first and second inner conductors 11 and 12 and the first and second ground conductors 21 and 22 which are in a conducting state, and functions as a capacitor to absorb high frequency noise. .

[0008]

EXAMPLES Examples of the present invention will be described below. The invention is not limited to this embodiment. Chip type L of the embodiment
The C filter will be described with reference to FIGS. First, three dielectric green sheets were prepared. This dielectric green sheet is obtained by coating the upper surface of a polyester base sheet with, for example, a barium titanate-based dielectric slurry having JIS-R characteristics by a doctor blade method.
It is formed by drying. One each was used as the first ceramic green sheet, the second ceramic green sheet, and the third ceramic green sheet.

Then, a conductive paste containing Pd as a main component was screen-printed on each surface of the first ceramic green sheet and the second ceramic green sheet in different patterns, and dried at 80 ° C. for 4 minutes. That is, as shown in FIG. 2, the first ceramic green sheet 10 is provided with spaces 13 and 14 electrically connected to a pair of sides and electrically insulated from a pair of sides different from the pair of sides. First and second inner conductors 11 and 12 having the first and second inner conductors
Formed in a meandering shape having intervals 13, 14 arranged between the inner conductors 11, 12 and electrically connected to the first and second inner conductors respectively, and electrically insulated from another pair of sides. The meandering conductor 15 thus formed is printed and formed.
In addition, the second ceramic green sheet 20 is electrically insulated from a pair of sides corresponding to a pair of sides to which the first and second inner conductors 11 and 12 of the first dielectric sheet 10 are electrically connected. First and second grounding conductors 21 and 22 are formed by printing, which have the spaces 23 and 24 and are electrically connected to another pair of sides.

Two sheets of the screen-printed first and second ceramic green sheets 10 and 20 are laminated in this order, and a third ceramic green sheet 30 on which no conductive paste is printed is superposed on the uppermost layer. I matched it. The laminated body 40 shown in FIG. 3 was thermocompression-bonded and integrated, and then sintered at 1300 ° C. for about 1 hour to obtain a sintered body. Figure 3
As shown in FIG. 3, the sintered body is barrel-polished and the first inner conductor 11, the second inner conductor 12 (not shown in FIG. 3), the first ground conductor 21, and the second ground conductor are formed on the peripheral side surfaces of the sintered body. 22 was exposed.

Next, as shown in FIG. 4, the inner conductors 11 and 12 and the first and second ground conductors 21 and 22 on the peripheral side surfaces of the sintered body are formed.
The conductive paste containing Ag as a main component is applied to the exposed portions of each and baked to form the signal electrodes 51, 5 respectively.
2 and the electrodes 61 and 62 for grounding were formed. As a result, the first inner conductor 11 serves as the first signal electrode 51, the second inner conductor 12 serves as the second signal electrode 52, and the first ground conductor 21 serves as the first
A chip-type LC filter was obtained in which the ground electrode 61 and the second ground conductor 22 were electrically connected to the second ground electrode 62, respectively. In addition, as shown in FIG. 5, the first and second
A structure in which the ground electrodes are electrically connected to form one ground electrode 63, a structure in which each surface of the sintered body is covered with the first and second ground electrodes as shown in FIG. 6, and shown in FIG. As described above, the first and second ground electrodes of FIG. 6 may be electrically connected to form one ground electrode 68.

In order to investigate the characteristics of this chip type LC filter, this chip type LC filter was mounted on a separately prepared conductor wiring board by using solder. Signal electrode 5
1, 52 are soldered to the signal line. Further, the ground electrodes 61 and 62 are grounded via the external line.

In this state, a high frequency signal was input from one end of the signal line and the output signal was measured at the other end to obtain the insertion loss. As a result, it was found that the insertion loss sharply increased as the frequency increased, and the chip LC filter of the present invention had good filter characteristics as shown in FIG.

Although the first and second ceramic green sheets are laminated one by one in the embodiment, the number of laminated first and second ceramic green sheets of the present invention is not limited to this. . By appropriately increasing the number of layers, the capacitance formed by the inner conductor and the ground conductor and the inductance formed by the meandering conductor can be changed to change the insertion loss. For example, the total number of layers of the first ceramic green sheet and the second ceramic green sheet may be odd, or a plurality of the same sheets may be continuously laminated to adjust the inductance and the capacitance or to adjust the allowable current amount. May be. Further, by changing the shape such as the width or the curvature of each of the meandering conductors of the meandering conductor, the inductance can be changed and the insertion loss can be changed. Further, by changing the area of the electrode surface of the internal conductor, the allowable current value can be changed without destroying the LC filter. Further, the example in which the uppermost third dielectric sheet is one is shown, but a plurality of layers may be laminated. When another protective means is provided on the second dielectric sheet, the third dielectric sheet may not be laminated.

[0015]

As described above, according to the present invention, the meandering conductor having an inductance component is arranged between the first and second inner conductors of the first dielectric sheet used for signal transmission, Since two capacitances are formed between the first and second inner conductors and the first and second ground conductors, a π-type circuit having capacitance components before and after the central inductance component is provided as a whole. A chip type LC filter is obtained. In addition, by reducing the residual inductance on the ground side and shifting the resonance frequency to the high frequency side as much as possible, the high frequency noise absorption performance is superior to the conventional LC filter with a lead wire, and compact and integrated surface mounting is possible. A chip type LC filter can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view taken along the line AA of FIG. 4 of a chip type LC filter according to an embodiment of the present invention.

FIG. 2 is a perspective view of the laminated body before being laminated.

FIG. 3 is a perspective view of a sintered body obtained by firing the laminated body.

FIG. 4 is a perspective view of a chip type LC filter manufactured by providing external electrodes around the sintered body.

FIG. 5 is a perspective view of a chip-type LC filter manufactured by providing another external electrode for grounding around the sintered body.

FIG. 6 is a perspective view of a chip type LC filter manufactured by providing another grounding external electrode around the sintered body.

FIG. 7 is a perspective view of a chip-type LC filter manufactured by further providing another external electrode for grounding around the sintered body.

FIG. 8 is a characteristic diagram of an LC filter.

FIG. 9 is an equivalent circuit diagram of the chip type LC filter of the present invention.

FIG. 10 is a configuration diagram of a conventional LC filter.

FIG. 11 is an equivalent circuit diagram thereof.

[Explanation of symbols]

10 First Dielectric Sheet (First Ceramic Green Sheet) 11 First Inner Conductor 12 Second Inner Conductor 13, 14 Electrically Insulated Interval 15 Meandering Conductor 20 Second Dielectric Sheet (Second Ceramic Green Sheet) 21 First ground conductor 22 Second ground conductor 23, 24 Electrically insulated space 30 Third dielectric sheet (third ceramic green sheet) 40 Laminated body 51 First signal electrode 52 Second signal electrode 61, 66 First grounding electrode 62,67 Second grounding electrode 63,68 Grounding electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuo Seki 972 Urasa, Yamato-cho, Minamiuonuma-gun, Niigata Prefecture Mitsubishi Materials Corporation Ceramics Research Laboratory Urasa Branch (72) Inventor Atsushi Yamada 972 Urasa, Minamiuonuma-gun, Niigata Prefecture Address Mitsubishi Materials Corporation Ceramics Research Laboratory Ura Sabuchi Chamber

Claims (2)

[Claims] 1. A laminated body (40) in which a rectangular first dielectric sheet (10) and a second dielectric sheet (20) having the same shape and size as the sheet (10) are laminated and integrated. The first dielectric sheet (10) includes a space (13, 14) electrically connected to a pair of sides and electrically insulated from a pair of sides different from the pair of sides. Having first and second
Inner conductors (11, 12) and the first and second inner conductors (11, 12)
A meander having a space (13, 14) electrically connected to the first and second inner conductors (11, 12) and electrically insulated from the other pair of sides. And a meandering conductor (15) formed in a strip shape on the surface of the sheet, and the second dielectric sheet (20) includes the first dielectric sheet (1
0) the first and second inner conductors (11, 12) are electrically isolated from each other by a pair of sides corresponding to a pair of sides electrically connected to each other. The first and second ground conductors (21, 22) electrically connected to the pair of sides of the sheet are provided on the sheet surface, and the meandering conductor (15) of the first dielectric sheet (10) is a high frequency noise. To the first and second inner conductors (11, 12) and the first and second ground conductors (21, 22) via the second dielectric sheet (20). And a first and second signal electrode (which are configured to form a capacitance between the first and second inner conductors (11, 12) exposed on the side surface of the laminate (40), respectively. 51, 52) is formed on this side surface, and the first and second exposed on another side surface of the laminate (40).
Grounding electrodes (61, 62) connected to the grounding conductors (21, 22) respectively
Chip-type LC characterized in that
filter. 2. The chip type LC filter according to claim 1, wherein the third dielectric sheet (30) having no conductor formed on the sheet surface is laminated and integrated on the uppermost layer of the laminated body (40).