JP3204085B2 - Stacked noise filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a noise filter,
In particular, it relates to a multilayer noise filter for removing noise and the like radiated from high-frequency electronic devices.

[0002]

2. Description of the Related Art As a conventional noise filter, for example,
A three-terminal capacitor 51 shown in FIGS. 12 and 13 is known. The three-terminal capacitor 51 includes an insulator sheet 52 provided with signal line inner conductors 53 and 55 on the respective surfaces, an insulator sheet 52 provided with ground inner conductors 54 and 56 on the respective surfaces, and an outer layer insulator sheet 52. And so on. A capacitance is formed between the signal line internal conductors 53 and 55 and the ground internal conductors 54 and 56. These insulator sheets 52 are stacked and integrally sintered to form a laminate. Next, FIG.
As shown in FIG. 3, input / output external electrodes 58 and 59 are formed on the left and right side surfaces of the laminate, respectively, and ground external electrodes 60 and 61 are formed on the front and rear side surfaces, respectively.

An input / output external electrode 58 is electrically connected to one end of the signal line internal conductors 53 and 55, and an input / output external electrode 59 is electrically connected to the other end of the signal line internal conductors 53 and 55. The ground external electrode 60 is electrically connected to one end of the ground internal conductors 54 and 56, and the ground external electrode 61 is electrically connected to the ground internal conductors 54 and 56.
56 is electrically connected to the other end.

[0004]

In the conventional three-terminal capacitor 51, the residual inductance is as small as about 1/10 of that of the two-terminal capacitor, so that the noise elimination performance in a high frequency range is excellent. However, this performance is effective when the size of the three-terminal capacitor 51 is relatively large (for example, when the length is 2.0 mm and the width is 1.25 mm or more), but when the size is relatively small ( For example, when the length is 1.6 mm and the width is 0.8 mm or less). That is, as shown in FIG. 14, when the size of the three-terminal capacitor 51 becomes smaller, the grounding inner conductors 54, 56 become the input / output external electrodes 58, 5
9 and the stray capacitance Cs between them increases. Due to this stray capacitance Cs, for example, as shown in FIG.
There is a problem that noise that has entered the input / output external electrode 58 returns to the input / output external electrode 59 via the stray capacitance Cs, and the noise is not removed.

On the other hand, if the grounding internal conductors 54 and 56 are made thinner in order to reduce the stray capacitance Cs, the residual inductance increases and the noise removal performance in a high frequency range becomes unstable. Therefore, an object of the present invention is to provide a laminated noise filter having a small stray capacitance generated between an internal conductor for ground and an input / output external electrode.

[0006]

In order to achieve the above object, a laminated noise filter according to the present invention comprises an insulator layer provided with a signal line inner conductor, and an electrical connection between the insulator layer and the signal line inner conductor. A via hole to be connected; and an insulator layer provided with a ground inner conductor surrounding the via hole at a predetermined distance from the via hole.

Here, the signal line inner conductor may be, for example, a via hole or a coil conductor.

[0008]

According to the above construction, a capacitance is formed between the via hole surrounded by the grounding internal conductor and the grounding internal conductor. In addition, the distance between the grounding internal conductor and the input / output external electrodes is increased, and the grounding internal conductor having a large area is secured.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a laminated noise filter according to an embodiment of the present invention. [First Embodiment, FIGS. 1 to 4] In the first embodiment, a three-terminal capacitor will be described as an example of a multilayer noise filter. As shown in FIG. 1, the three-terminal capacitor 1 includes a dielectric sheet 2 provided with via holes 6a, 6b, 6d, 6e at the center, a dielectric sheet 2 provided with a grounding internal conductor 4, and a via hole 6c. It is configured.

The via hole 6c is provided at the center of the dielectric sheet 2. The inner conductor for ground 4 has a circular gap 4a surrounding the via hole 6c at a predetermined distance from the via hole 6c, and is provided on the surface of the sheet 2 with a wide area. One lead portion 4b of the ground inner conductor 4 is exposed on the left side of the sheet 2, and the other lead portion 4c is exposed on the right side of the sheet 2. And via hole 6
An electrostatic capacitance is formed between c and the internal conductor 4 for ground, and a capacitor is obtained. Via holes 6a-6
e is formed on the sheet 2 so that the axial direction is parallel to the thickness direction of the sheet 2. These via holes 6 a to 6 e are connected to form via conductors 6 whose axial direction is parallel to the thickness direction of sheet 2.

The dielectric sheet 2 is a sheet obtained by kneading dielectric powder together with a binder and the like. The inner conductor 4 for ground is made of Ag, Pd, Cu, Au, Ag-P
d, Ni, Pt, etc., and formed by means such as printing. The via holes 6a to 6e are made of Ag, Pd, C
It is formed by filling a hole provided in the dielectric sheet 2 with a conductive paste such as u, Au, Ag-Pd, Ni, and Pt. The sheet 2 provided with the via holes 6b and 6d is for adjusting the length of the three-terminal capacitor 1, and may be omitted in some cases.

After the sheets 2 are stacked, they are integrally sintered to form a laminate. Next, as shown in FIGS. 2 and 3, input / output external electrodes 10 and 11 are formed on the upper surface and lower surface of the laminate, respectively, and ground external electrodes 12 and 13 are formed on the left and right side surfaces, respectively. You. The external electrodes 10 to 13 are formed by means such as coating and baking, sputtering, or vapor deposition. I / O external electrode 10
Is connected to the upper portion of the via conductor 6, specifically, the upper surface of the via hole 6a. The lower portion of the via conductor 6, specifically, the lower surface of the via hole 6 e is connected to the input / output external electrode 11. The lead portions 4b and 4c of the grounding internal conductor 4 are connected to the ground external electrodes 12 and 13, respectively. FIG. 4 is an electric equivalent circuit diagram of the thus obtained through-type three-terminal capacitor 1.

In the three-terminal capacitor 1 described above, the distance between the inner conductor 4 for ground and the input / output external electrodes 10 and 11 can be set larger than that of a conventional three-terminal capacitor. Therefore, the stray capacitance generated between the inner conductor 4 for ground and the input / output external electrodes 10 and 11 can be suppressed, and even if the size of the capacitor 1 is reduced, excellent noise removal performance is obtained in a high frequency range. Can be. In addition, since the grounding inner conductor having a large area can be secured, the residual inductance can be reduced, and the noise removal performance in a high frequency range can be stably exhibited.

[Second Embodiment, FIGS. 5 to 8] In a second embodiment, an LC composite component will be described as an example of a laminated noise filter. As shown in FIG.
Are the coil conductors 23a, 23b, 23c, 25a, 25
an insulator sheet 22 having b and 25c provided on its surface,
Insulator sheet 22 provided with grounding internal conductor 24 and via hole 28f, via holes 28a, 28e, 28
g, 28k, and the like. The insulator sheet 22 is formed by kneading a dielectric powder or a magnetic powder together with a binder into a sheet.

The grounding internal conductor 24 has a circular gap 24a surrounding the via hole 28f at a predetermined distance from the via hole 28f provided at the center of the sheet 22, and is provided in a wide area on the surface of the sheet 22. . One of the lead portions 24b of the grounding internal conductor 24 is the sheet 2
2 and the other drawer portion 24c is
It is exposed on the right side of. Then, a capacitance is formed between the via hole 28f and the internal conductor 24 for ground, and a capacitor is obtained.

The coil conductors 23a, 23b and 23c are connected in series via via holes 28b and 28c provided in the sheet 22 to form a spiral coil 23. The coil conductors 25a, 25b, 25c are connected in series via via holes 28h, 28i provided in the sheet 22,
A spiral coil 25 is formed. The coil 23 and the coil 25 are connected to the via hole 2 provided in the sheet 22.
8d, 28e, 28f, and 28g are connected in series.

After the sheets 22 are stacked, they are integrally sintered to form a laminate. Next, as shown in FIGS. 6 and 7, input / output external electrodes 30 and 31 are formed on the upper surface and lower surface of the laminate, respectively, and ground external electrodes 32 and 33 are formed on the left and right side surfaces, respectively. You. One end of the coil 23, specifically, one end of the coil conductor 23a is connected to the input / output external electrode 30 via a via hole 28a. One end of the coil 25, specifically, one end of the coil conductor 25c is connected to the input / output external electrode 31 via via holes 28j and 28k. Further, the lead portions 24b and 24c of the ground inner conductor 24 are connected to the ground external electrodes 32 and 33, respectively. FIG. 8 is an electric equivalent circuit diagram of the LC composite component 21 thus obtained.

The above-described LC composite component 21 has the same function and effect as the three-terminal capacitor 1 of the first embodiment.

[Other Embodiments] The multilayer noise filter according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the gist.

The shape of the grounding internal conductor is arbitrary, and is limited by reasons such as restrictions on mounting (for example, when the ground pattern of the printed circuit board cannot be enlarged) and a conventional external electrode forming method. The extension of the grounding internal conductor may be modified. For example, as shown in FIG. 9, the drawer may be exposed on each side of the sheet 40 except for the four corners of the sheet 40, such as a ground inner conductor 43 surrounding a via hole 42 provided in the insulator sheet 40. . Further, as in the case of the ground inner conductor 44 shown in FIG. 10, the drawer may be exposed on the entire periphery of the sheet 40. Alternatively, the grounding internal conductor 45 shown in FIG.
The drawer may be exposed only on one side of the sheet 40 as described above.

Further, in the above embodiment, the sheets are stacked and then integrally sintered, but the present invention is not limited to this. The sheet may be a sheet sintered in advance. Alternatively, a noise filter having a laminated structure may be obtained by sequentially applying a paste-like dielectric material, a magnetic material, or a conductive material by means of printing or the like, drying the coating, and applying the paste again.

[0022]

As is apparent from the above description, according to the present invention, the insulating layer is provided with the via hole and the grounding internal conductor surrounding the via hole at a predetermined distance from the via hole. The distance between the internal conductor and the input / output external electrode is increased, and the stray capacitance generated between them can be suppressed. In addition, a large-area internal conductor for ground can be secured, and the residual inductance can be reduced. As a result, it is possible to obtain a laminated noise filter having excellent noise removal performance stably in a high frequency range.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of a multilayer noise filter according to the present invention.

FIG. 2 is a perspective view showing the appearance of the multilayer noise filter shown in FIG.

FIG. 3 is a sectional view taken along the line III-III of FIG. 2;

FIG. 4 is an electrical equivalent circuit diagram of the multilayer noise filter shown in FIG.

FIG. 5 is an exploded perspective view showing a second embodiment of the multilayer noise filter according to the present invention.

6 is a perspective view showing the appearance of the multilayer noise filter shown in FIG.

FIG. 7 is an internal perspective view of the multilayer noise filter shown in FIG. 6;

8 is an electrical equivalent circuit diagram of the multilayer noise filter shown in FIG.

FIG. 9 is a plan view of an insulator sheet provided with a ground inner conductor according to another embodiment.

FIG. 10 is a plan view of an insulator sheet provided with a ground inner conductor according to another embodiment.

FIG. 11 is a plan view of an insulator sheet provided with a grounding internal conductor according to still another embodiment.

FIG. 12 is an exploded perspective view showing a conventional laminated noise filter.

FIG. 13 is a perspective view showing the appearance of the multilayer noise filter shown in FIG. 2;

FIG. 14 is a sectional view taken along the line XIV-XIV of FIG. 13;

15 is an electrical equivalent circuit diagram of the multilayer noise filter shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 3 terminal capacitor 2 ... Dielectric sheet 4 ... Ground internal conductor 6c ... Via hole 6a, 6b, 6d, 6e ... Via hole (signal line internal conductor) 21 ... LC composite component 22 ... Insulator sheet 24 ... Ground inside Conductors 28f: Via holes 23a to 23c, 25a to 25c: Coil conductors (inner conductors for signal lines) 28a to 28e: Via holes (inner conductors for signal lines)

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshiki Kaneko 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd. (56) References JP-A-8-46471 (JP, A) JP-A Heihei 3-166809 (JP, A) JP-A-3-274814 (JP, A) JP-A-8-31695 (JP, A) JP-A-4-91416 (JP, U) (58) Fields investigated (Int. Cl. ^7, DB name) H03H 7/075 H01G 4/12 346 H01G 4/30 301 H01G 4/35

Claims (2)

(57) [Claims] A dielectric layer provided with an internal conductor for a signal line; a dielectric layer electrically connected to the internal conductor for a signal line ;
Have a gap surrounding the via hole via hole and the via hole you located in central portion a predetermined distance apart layers
A dielectric layer provided with inner conductor for grounding to said an external input and output electrode provided on the surface of the laminated body constituted by stacking a dielectric layer, inner conductor the signal line is a coil conductor, spiral The coil has an axial direction parallel to the stacking direction of the dielectric layers , and
The axis and the axis of the via hole are arranged substantially in the same straight line , the input / output external electrodes are arranged in a direction orthogonal to the axial direction of the coil, and the ground internal conductor and the input / output external electrodes are arranged in parallel. Stacking of said dielectric layers arranged
In the direction, the two spiral coils are
Two spirals arranged with a via hole therebetween
Electrically connected in series via the via hole
Multilayer noise filter according to claim, that are connected. 2. The multilayer noise filter according to claim 1, wherein the signal line inner conductor is a via hole.