JPH0653048A - 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 T 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 zigzag conductors 11 and 12 connected to a pair of sides insulated from another pair of sides as well as an inner conductor 15 arranged between both conductors 11 and 12 electrically connected to these conductors 11 and 12 but likewise insulated from another pair of sides. The other dielectric sheet 20 is provided with a grounding conductor 25 insulated from the sides corresponding to the pair of sides connected to zigzag conductors 11, 12 but connected to the other pair of sides. The zigzag conductors 11, 12 are composed to be the inductance component to high-frequency noise so that capacitances may be formed respectively between the inner conductor 15 and the grounding conductor 25. Furthermore, a pair of signal electrodes 51, 52 connecting to the zigzag conductors 11, 12 as well as a grounding electrode connecting to the grounding conductor 25 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 T-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 in which a capacitor element and an inductor element are combined, a three-terminal type capacitor 5 as shown in FIG. 8 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.
The first and second meandering conductors 11 and 12, which are formed in a meandering shape having the third and the third meandering conductors, are arranged between the first and second meandering conductors 11 and 12 and electrically connected to the first and second meandering conductors. The sheet surface is provided with internal conductors 15 having intervals 13 and 14 which are electrically connected to each other and electrically insulated from another pair of sides. In addition, the second dielectric sheet 20
Is the first and second meandering conductors 1 of the first dielectric sheet 10.
A ground having a pair of sides 23 and 24 electrically insulated from a pair of sides corresponding to a pair of sides to which 1 and 12 are electrically connected, and electrically connected to another pair of sides. The conductor 25 is provided on the sheet surface. In addition, the first and second meandering conductors 11 and 12 of the first dielectric sheet 10 are configured to be an inductance component with respect to high frequency noise, and the inner conductor 15 and the ground conductor via the second dielectric sheet 20. 25 to form a capacitance. Further, first and second signal electrodes 51 and 52 respectively connected to the first and second meandering conductors 11 and 12 exposed on the side surface of the stacked body 40 are formed on this side surface, and on the other side surface of the stacked body 40. Grounding electrodes 53 and 54 respectively connected to the exposed ground conductor 25 are formed on the side surfaces.
The equivalent circuit of the chip type LC filter of the present invention is shown in FIG.
Can be expressed as

[0007]

[Function] First dielectric sheet 10 and second dielectric sheet 20
The first and second meandering conductors 11 and 12 between and function as inductors when a high frequency signal flows. This is because the first and second meandering conductors 11 and 12 meander and thus have a long conductor distance. Since a capacitance is formed between the inner conductor 15 on the first dielectric sheet 10 and the ground conductor 25 on the second dielectric sheet 20 via the second dielectric sheet 20, the inner conductor 15 in a conducting state A potential difference is generated between the ground conductor 25 and the ground conductor 25, which 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. The meandering first and second meandering conductors 11, 1 having
2 and the first and second meandering conductors 11 and 12 are electrically connected to the first and second meandering conductors and electrically insulated from the other pair of sides. , 14 are printed on.
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 meandering conductors 11 and 12 of the first dielectric sheet 10 are electrically connected. A grounding conductor 25 is formed by printing, which has a gap 23, 24 and is 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 was barrel-polished to expose the first meandering conductor 11, the second meandering conductor 12 (not shown in FIG. 3), and the ground conductor 25 on the peripheral side surface of the sintered body.

Next, as shown in FIG. 4, a conductive paste containing Ag as a main component is applied to the exposed portions of the meandering conductors 11 and 12 and the ground conductor 25 on the peripheral side surface of the sintered body,
By baking, the signal electrodes 51 and 52 and the ground electrodes 53 and 54 were formed, respectively. This electrically connects the first meandering conductor 11 to the first signal electrode 51, the second meandering conductor 12 to the second signal electrode 52, and the grounding conductor 23 to the first and second grounding electrodes 53 and 54, respectively. Chip type L connected to
A C filter was obtained. Note that, as shown in FIG. 5, the first and second ground electrodes may be electrically connected to form one ground electrode 55.

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 53 and 54 are grounded via an 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 first and second meandering conductors having an inductance component are arranged so as to sandwich the inner conductor of the first dielectric sheet used for signal transmission, Since a capacitance is formed between the internal conductor and the ground conductor, a chip type LC filter having a T-type circuit having an inductance component before and after the capacitance component in the central portion as a whole can be 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 characteristic diagram of an LC filter.

FIG. 7 is an equivalent circuit diagram of the chip type LC filter of the present invention.

FIG. 8 is a configuration diagram of a conventional LC filter.

FIG. 9 is an equivalent circuit diagram thereof.

[Explanation of symbols]

10 First Dielectric Sheet (First Ceramic Green Sheet) 11 First Meandering Conductor 12 Second Meandering Conductor 13, 14 Electrically Insulated Space 15 Inner Conductor 20 Second Dielectric Sheet (Second Ceramic Green Sheet) 23 , 24 electrically insulated spacing 25 ground conductor 30 third dielectric sheet (third ceramic green sheet) 40 laminated body 51 first signal electrode 52 second signal electrode 53 first ground electrode 54 second ground Electrode 55 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. The first and second meandering conductors (11, 12) which are formed in a meandering shape and are arranged between the first and second meandering conductors (11, 12).
Intervals (13, 12) electrically connected to the meandering conductors (11, 12) and electrically insulated from the other pair of sides, respectively.
An inner conductor (15) having an inner conductor (15) on the surface of the sheet, and the second dielectric sheet (20) is the first dielectric sheet (1).
The first and second meandering conductors (11, 12) of (0) have a space (23, 24) electrically insulated from a pair of sides corresponding to a pair of sides electrically connected to each other, and separate A ground conductor (25) electrically connected to the pair of sides of the first dielectric sheet (10), and the first and second meandering conductors (11,
12) is configured to be an inductance component with respect to high frequency noise, and forms a capacitance between the internal conductor (15) and the ground conductor (25) via the second dielectric sheet (20). And the first and second signal electrodes (51, 52) respectively connected to the first and second meandering conductors (11, 12) exposed on the side surface of the laminate (40). The ground conductor (25) formed and exposed on the other side surface of the laminate (40)
A chip type LC filter characterized in that grounding electrodes (53, 54) respectively connected to the are formed on this side surface. 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).