JP2016082029A - Common mode noise filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a common mode noise filter capable of preventing degradation of common mode noise attenuation characteristic.SOLUTION: The common mode noise filter includes: plural insulation layers 11a and 11b; first spiral coil 12 and second spiral coil 13 which are formed on the plural insulation layers 11a and 11b; and a metal layer 14 which has an annular part 14a formed at least above or under the first and second coil 12 and 13. The first and second coils 12 and 13 and the metal layer 14 are arranged so as not to oppose to each other in an upper plane view.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a common mode noise filter used in various electronic devices such as digital devices, AV devices, and information communication terminals.

  As shown in FIG. 6, the conventional common mode noise filter of this type includes a plurality of insulator layers 1 and spiral first coils 2 and second coils provided on the plurality of insulator layers 1. 3 and a metal layer 4 formed on the insulator layer 1 so as to cover the first and second coils 2 and 3.

  The shape of the metal layer 4 is substantially spiral, and is opposed to the first coil 2 and the second coil 3. Further, the metal layer 4 is connected to the ground, and high-frequency common mode noise is bypassed to the ground by the stray capacitance generated between the first and second coils 2 and 3 and the metal layer 4, so The mode noise was attenuated.

  As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.

JP 2009-10729 A

  In the above-described conventional common mode noise filter, since the shape of the metal layer 4 is substantially spiral, a residual inductance is generated between the ground and the first coil 2 and the second coil 3. Since the self-resonant frequencies of the first coil 2 and the second coil 3 are lowered, there is a problem that the attenuation characteristic of the common mode noise in a higher frequency region is lowered.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a common mode noise filter capable of improving the attenuation characteristics of common mode noise in a high frequency region.

  In order to achieve the above object, the present invention comprises a plurality of insulator layers, and spiral first and second coils provided on the plurality of insulator layers, and the first and second coils. A metal layer having an annular portion is formed on at least one of the upper and lower sides of the coil.

  In the common mode noise filter of the present invention, since the shape of the metal layer is not spiral, almost no residual inductance is generated between the ground and the first coil and the second coil. Since the self-resonant frequencies of the first coil and the second coil do not become low, an excellent effect of improving the attenuation characteristics of common mode noise in the high frequency region is obtained.

The top view of the principal part of the common mode noise filter in one embodiment of the present invention Top view of the main part of the common mode noise filter Cross section of the common mode noise filter Top view of the main part of another example of the common mode noise filter Top view of the main part of another example of the common mode noise filter Cross section of a conventional common mode noise filter

  Hereinafter, a common mode noise filter according to an embodiment of the present invention will be described with reference to the drawings.

  1 and 2 are top views of the main part of the common mode noise filter according to one embodiment of the present invention, and FIG. 3 is a sectional view of the common mode noise filter.

  As shown in FIGS. 1 to 3, the common mode noise filter according to one embodiment of the present invention includes a plurality of insulator layers 11 and a spiral first coil 12 formed on the plurality of insulator layers 11. The second coil 13 and the first coil 12 and the metal layer 14 formed above and below the second coil 13 are provided.

  The metal layer 14 has a plurality of annular portions 14a, and the annular portions 14a are arranged so as not to substantially face the first coil 12 and the second coil 13 in a top view.

  In the above configuration, the plurality of insulator layers 11 include a nonmagnetic layer 11a formed of a nonmagnetic material such as Cu—Zn ferrite or glass ceramic, and a magnetic body formed of a magnetic material such as Ni—Zn ferrite. And the layer 11b.

  The plurality of nonmagnetic layers 11 a constitute a nonmagnetic portion 15, and the first coil 12 and the second coil 13 are embedded in the nonmagnetic portion 15.

  In addition, the magnetic part 16 is configured by the plurality of magnetic layers 11 b, and the two magnetic parts 16 are stacked via the nonmagnetic part 15. Further, the metal layer 14 is embedded in the magnetic part 16.

  The first coil 12 and the second coil 13 are formed by spirally plating or printing a conductive material such as silver. The first coil 12 and the second coil 13 are connected to lead conductors 18 and 19 provided on the same surface via via electrodes 17, respectively. Furthermore, the first coil 12 and the second coil 13 are substantially opposed to each other when the first coil 12 is located above the second coil 13 and viewed from above.

  In addition, the 1st coil 12 and the 2nd coil 13 are not limited to the structure shown by FIG. 3, You may laminate | stack the 1st coil 12 and the 2nd coil 13 by turns. The first coil 12 may be sandwiched between the conductors constituting the second coil 13, and the lead conductor 18 and the lead conductor 19 may be formed in opposite directions in the stacking direction.

  Further, as shown in FIG. 1, the metal layer 14 includes a plurality of annular portions 14a and lead portions 14b connected to the ground, and the adjacent lead portions 14b are connected to each other by a connecting portion 20a. At this time, the plurality of annular portions 14a and the connection portion 20a connected by the connection portion 20a are continuous with the lead-out portion 14b.

  Moreover, the connection part 20a opposes the 1st coil 12 and the 2nd coil 13 in top view. For the sake of simplicity, FIG. 1 shows a state in which the upper metal layer 14 and the magnetic layer 11b are viewed from above.

  With this configuration, high-frequency common mode noise is bypassed to the ground by stray capacitance generated between the first and second coils 12 and 13 and the metal layer 14, and the common mode noise in the high frequency region is attenuated. It becomes possible to make it.

  Furthermore, as shown in FIG. 2, the annular portion 14 a of the metal layer 14 does not substantially face the first coil 12 and the second coil 13 in a top view. As shown in FIG. 2, a part (curved part) 20 b of the annular part 14 a must face the annular part 14 a, so this part faces the first coil 12 and the second coil 13. ing. That is, the annular portion 14 a of the metal layer 14 excluding a portion that inevitably opposes is located on the space between the conductors of the first coil 12 and the second coil 13. Here, a portion 20b of the annular portion 14a is opposed to connect the space between the conductors of the first coil 12 and the second coil 13 and the space inside the annular portion 14a because the annular portion 14a is not completely spiral. I have to do it. For this reason, the annular portion 14 a of the metal layer 14 does not oppose “substantially” the first coil 12 and the second coil 13. 2 shows a state in which the upper metal layer 14, the magnetic layer 11b, and the first coil 12 are viewed from above for the sake of simplicity.

  The metal layer 14 is formed by plating or printing a conductive material such as silver or copper, or by attaching a metal plate or metal foil. Furthermore, although the metal layer 14 is formed above and below the first coil 12 and the second coil 13 in FIG. 1, it may be formed on one of the upper and lower sides.

  The number of nonmagnetic layers 11a and magnetic layers 11b may be different from the number shown in FIG.

  As described above, in the embodiment of the present invention, the metal layer 14 having the plurality of annular portions 14a is formed both above and below the first and second coils 12 and 13, and the metal layer 14 is formed. Since it is not spiral, almost no residual inductance is generated between the ground and the first coil 12 and the second coil 13, so that the self-resonant frequencies of the first coil 12 and the second coil 13 are reduced. Since it does not become low, the effect of improving the attenuation characteristics of common mode noise in the high frequency region can be obtained.

  Further, since the spiral first and second coils 12 and 13 and the annular portion 14a of the metal layer 14 are not substantially opposed to each other in a top view, the first and second coils 12 and 13 are generated. The magnetic flux circulates without being obstructed by the metal layer 14, thereby strengthening the coupling between the first coil 12 and the second coil 13, thereby preventing deterioration of the attenuation characteristics of the common mode noise. .

  The width of the annular portion 14a is particularly preferably 0.7 to 0.9 times the space between the conductors of the first coil 12 and the second coil 13. If it is smaller than 0.7 times, it is difficult to attenuate the common mode noise in the high frequency region. If it is larger than 0.9 times, the annular portion 14a and the first and second coils 12, 13 are opposed to each other due to misalignment. This is because there is a possibility.

  Furthermore, as shown in FIG. 4, one or a plurality of other connecting portions 20c that connect the plurality of annular portions 14a may be formed. With this configuration, since the area where a part of the metal layer 14 and the first coil 12 and the second coil 13 face each other can be widened, the attenuation characteristics fluctuate depending on the capacitance component between them. The attenuation characteristics can be easily fine-tuned by the number and area of the connecting portions 20c.

  Moreover, as shown in FIG. 5, you may provide the cyclic | annular part 14a of the metal layer 14 not only in the space between the conductors of the 1st coil 12 and the 2nd coil 13, but in other places.

  4 and 5 show a state in which the upper metal layer 14 and the magnetic layer 11b are viewed from above for the sake of simplicity.

  If the metal layer 14 is arranged at a location sandwiched between the first coil 12 and the second coil 13, only one metal layer 14 is generated between the first and second coils 12, 13. The stray capacitance can be bypassed to the ground, so that the height can be reduced.

  The common mode noise filter according to the present invention has an effect of preventing the attenuation characteristic of the common mode noise from being deteriorated, and particularly as a noise countermeasure for various electronic devices such as digital devices, AV devices, and information communication terminals. This is useful in the common mode noise filter used.

11a Non-magnetic layer (insulator layer)
11b Magnetic layer (insulator layer)
12 1st coil 13 2nd coil 14 Metal layer 14a Annular part of metal layer

Claims (4)

A plurality of insulator layers, and a spiral first coil and a second coil provided on the plurality of insulator layers, and at least one above and below the first and second coils, A common mode noise filter in which a metal layer having an annular portion is formed. The common mode noise filter according to claim 1, wherein the first and second coils and the annular portion of the metal layer do not substantially face each other when viewed from above. The common mode noise filter according to claim 1, wherein another connecting portion that connects the plurality of annular portions is formed. A plurality of insulator layers, and a spiral first coil and a second coil provided in the plurality of insulator layers, at a location sandwiched between the first coil and the second coil, A common mode noise filter in which a metal layer having an annular portion is formed.

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