JP2012109326A - Common mode noise filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a common mode noise filter which can be used in high frequency band.SOLUTION: The common mode noise filter comprises a plurality of non-magnetic layers 11a-11c composed of a non-magnetic material, a first coil 12 and a second coil 13 provided, respectively, in the plurality of non-magnetic layers 11a-11c, magnetic layers 14a-14d provided either above and/or below the plurality of non-magnetic layers 11a-11c, and a magnetic part 15 which penetrates the non-magnetic layers 11a-11c in the central part of the first and second coils 12, 13 and are in contact with the upper magnetic layers 14c, 14d and the lower magnetic layers 14a, 14b. A metal layer 17 having a notch 16 that exposes the magnetic part 15, in plan view, is formed, respectively, on the magnetic layers 14a-14d.

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 is provided on the plurality of nonmagnetic layers 1a to 1c made of a nonmagnetic material and the plurality of nonmagnetic layers 1a to 1c. The first coil 2, the second coil 3, the magnetic layers 4a and 4b provided below and above the plurality of nonmagnetic layers 1a to 1c, and the first and second coils 2, 3 A magnetic part 5 penetrating through the nonmagnetic layers 1a to 1c in the central portion of the magnetic layer 5 and in contact with the upper magnetic layer 4b and the lower magnetic layer 4a; and the magnetic layers 4a and 4b And a rectangular metal layer 6 formed on substantially the entire surface of 4a and 4b.

  And the magnetic flux which generate | occur | produced in each of the 1st coil 2 and the 2nd coil 3 is made to penetrate the inside of the magnetic part 5, and this magnetic flux circulates the circumference | surroundings of the 1st coil 2 and the 2nd coil 3 Thus, the coupling between the first coil 2 and the second coil 3 is strengthened so that common mode noise can be removed. Further, the metal layer 6 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 6, so The mode noise attenuation characteristics were also improved.

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

JP 2004-194170 A

  In the conventional common mode noise filter described above, since the metal layer 6 faces the first and second coils 2 and 3, the magnetic flux generated in the first and second coils 2 and 3 is applied to the metal layer 6. This hinders the circuit from turning around, thereby weakening the coupling between the first coil 2 and the second coil 3, thereby causing a problem that the attenuation characteristic of the common mode noise deteriorates.

  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 preventing deterioration of attenuation characteristics of common mode noise.

  In order to achieve the above object, the present invention has the following configuration.

  The invention according to claim 1 of the present invention includes a plurality of nonmagnetic layers made of a nonmagnetic material, a first coil and a second coil provided on the plurality of nonmagnetic layers, A magnetic layer provided above and below the plurality of non-magnetic layers, and the non-magnetic layer penetrating in a central portion of the first and second coils, and below the upper magnetic layer and the lower magnetic layer; And a magnetic layer formed on the magnetic layer. The metal layer includes a magnetic portion that is in contact with the magnetic layer and has a notch that exposes the magnetic portion when viewed from above. The magnetic flux generated in the coil 2 and penetrating the inside of the magnetic part is not disturbed by the metal layer due to the notch, so that the magnetic flux is circulated, and thus, a large amount of the magnetic flux is transferred to the first and second magnetic fluxes. Coupling between the first coil and the second coil because it can circulate around the coil It can be enhanced, thereby, in which effect that the attenuation characteristic of the common mode noise can be prevented from being degraded can be obtained.

  The invention according to claim 2 of the present invention has a notch portion formed in the metal layer so that a part of the first and second coils are exposed in a top view, and according to this configuration, Since the magnetic flux generated in the first and second coils and penetrating through the inside of the magnetic part can be circulated around the notch part and part of the first and second coils, the first coil and the second coil Thus, it is possible to further strengthen the coupling between the two, thereby obtaining the effect of reliably preventing the deterioration of the attenuation characteristics of the common mode noise.

  As described above, the common mode noise filter of the present invention is formed in the first and second coils because the metal layer having the cutout portion that exposes the magnetic portion in the top view is formed on the magnetic layer. Then, the magnetic flux penetrating the inside of the magnetic part can be circulated without being interrupted by the metal layer by the notch part, thereby strengthening the coupling between the first coil and the second coil. Therefore, there is an excellent effect that the attenuation characteristic of the common mode noise can be prevented from deteriorating.

The disassembled perspective view of the common mode noise filter in one embodiment of this invention Perspective view of the common mode noise filter Top view of the main part of the common mode noise filter Equivalent circuit diagram of the common mode noise filter Top view of the main part of another example of the common mode noise filter Exploded perspective view 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.

  FIG. 1 is an exploded perspective view of a common mode noise filter according to an embodiment of the present invention, and FIG. 2 is a perspective view of the common mode noise filter.

  As shown in FIGS. 1 and 2, the common mode noise filter according to one embodiment of the present invention includes first to third nonmagnetic layers 11 a to 11 c made of a nonmagnetic material, and the first to first nonmagnetic layers. The first coil 12 and the second coil 13 provided in the nonmagnetic body 10 constituted by the third nonmagnetic layers 11a to 11c, and the first to third nonmagnetic layers 11a to 11c. First and second magnetic layers 14a and 14b provided below, third and fourth magnetic layers 14c and 14d provided above, and the first and second coils 12 and 13 The center portion includes the first to third nonmagnetic layers 11a to 11c, and the lower magnetic layers 14a and 14b and the magnetic portions 15 in contact with the upper magnetic layers 14c and 14d. . Then, the metal layer 17 having the notch portion 16 that exposes the magnetic portion 15 in a top view is disposed between the lower first magnetic layer 14a and the second magnetic layer 14b. Are formed between the magnetic layer 14c and the fourth magnetic layer 14d.

  In the above configuration, the first to third nonmagnetic layers 11 a to 11 c are laminated in order from the bottom, are formed of a nonmagnetic material made of Cu—Zn ferrite, and constitute the nonmagnetic body 10. The first coil 12 and the second coil 13 are formed on the nonmagnetic material 10.

  The first coil 12 includes a first spiral conductor 18a formed on the upper surface of the first nonmagnetic layer 11a, and a lower surface (second magnetic layer) of the first nonmagnetic layer 11a. 14b) and a first lead conductor 19a formed on the upper surface of 14b. The first spiral conductor 18a and the first lead conductor 19a are connected via a via electrode 20a formed in the first nonmagnetic layer 11a.

  The second coil 13 includes a second spiral conductor 18b formed on the upper surface of the second nonmagnetic material layer 11b and a second coil conductor formed on the upper surface of the third nonmagnetic material layer 11c. It is comprised with the lead conductor 19b. The second spiral conductor 18b and the second lead conductor 19b are connected via a via electrode 20b formed in the third nonmagnetic layer 11c. Here, the first spiral conductor 18a and the second spiral conductor 18b may not be spiral as described above but may be spiral.

  Further, the first spiral conductor 18a and the second spiral conductor 18b are provided so as to be substantially opposed to each other as viewed from above via the second nonmagnetic layer 11b.

  The first and second spiral conductors 18a and 18b and the first and second lead conductors 19a and 19b are formed by plating or printing a conductive material such as silver. Further, the via electrodes 20a and 20b are formed by drilling holes at predetermined locations of the first nonmagnetic material layer 11a and the third nonmagnetic material layer 11c by laser, punching, etc., and filling the holes with silver. Form.

  The first to fourth magnetic layers 14a to 14d are made of a magnetic material such as Ni-Zn ferrite, and the first and second magnetic layers 14a and 14b are formed of the first to third non-magnetic layers. Below the magnetic layers 11a to 11c (nonmagnetic body 10), the third and fourth magnetic layers 14c and 14d are above the first to third nonmagnetic layers 11a to 11c (nonmagnetic body 10). Each is formed. The number of the first to third nonmagnetic layers 11a to 11c and the first to fourth magnetic layers 14a to 14d may be different from the number shown in FIG.

  Further, the magnetic part 15 is provided in the central part of the first and second coils 12 and 13 so as to penetrate the first to third nonmagnetic layers 11a to 11c. Further, the magnetic part 15 is drilled by laser, punching or the like at predetermined positions of the first to third nonmagnetic layers 11a to 11c, and a magnetic material such as Ni-Zn ferrite is filled in the holes. To form. At this time, the magnetic portion 15 is located at the center of the first and second coils 12 and 13 in a top view, that is, the innermost conductor of the first and second spiral conductors 18a and 18b. It is formed inside so as not to contact the first and second spiral conductors 18a and 18b and the first and second lead conductors 19a and 19b. Further, the three magnetic portions 15 have substantially the same size and are arranged at the same position in a top view.

  Furthermore, the metal layer 17 is formed in a sheet shape by plating or printing a conductive material such as silver or copper, or by attaching a metal plate or metal foil, and the first magnetic layer 14a and the first magnetic layer 14a. Between the second magnetic layer 14b and the third magnetic layer 14c and the fourth magnetic layer 14d. The metal layer 17 has only two lead portions 17a that are part of the metal layer 17 exposed at the side surfaces of the first to fourth magnetic layers 14a to 14d.

  Further, a notch 16 that penetrates the metal layer 17 is provided at the center of the metal layer 17. At this time, the resist corresponding to the notch portion 16 of the metal layer 17 is provided and plated, or screen-printed, or the metal plate and metal foil are cut in advance and laser-irradiated to provide a through hole. A metal layer 17 having a portion 16 is formed. Due to the notches 16, the three magnetic portions 15 made of a magnetic material can be used not only for the second and third magnetic layers 14b and 14c made of a magnetic material, but also for the first and fourth magnetic layers 14a. , 14d are continuous. Note that the notch 16 may be formed on only one of the two metal layers 17 positioned above and below.

  And the main-body part 21 of a common mode noise filter is formed by the above-mentioned structure. Further, the first to fourth external electrodes 22 to 25 are provided on both end surfaces of the main body portion 21 after the main body portion 21 is fired. 1. Connected to both ends of the second coils 12 and 13 (one end of each of the first spiral conductor 18a, the first lead conductor 19a, the second spiral conductor 18b, and the second lead conductor 19b). ing. Furthermore, fifth and sixth external electrodes 26 and 27 connected to the lead portion 17 a of the metal layer 17 are formed on both side surfaces of the main body portion 21. And the said 1st-6th external electrodes 22-27 are formed by printing silver on the end surface of the main-body part 21, and while forming a nickel plating layer on these surfaces by plating, this nickel plating layer A low melting point metal plating layer such as tin or solder is formed on the surface of the substrate by plating. In FIG. 2, the first to fourth external electrodes 22 to 25 are formed on both end surfaces of the main body 21, and the fifth and sixth external electrodes 26 and 27 are formed on a total of four surfaces on both sides of the main body 21. However, all of the first to sixth external electrodes 22 to 27 may be formed on two sides of the main body 21.

  Here, as shown in FIG. 3, the notch 16 of the metal layer 17 is formed so that the magnetic part 15 is exposed in a top view. Further, the metal layer 17 excluding the notch 16 covers the entire surface of the second spiral conductor 18b (first and second coils 12, 13) in a top view. 3 shows only the second spiral conductor 18b, the second nonmagnetic layer 11b, the metal layer 17, the notch portion 16, and the magnetic portion 15 for the sake of simplicity. A portion covered with the metal layer 17 in the conductor 18b is represented by a broken line.

  FIG. 4 is an equivalent circuit diagram of the common mode noise filter according to the embodiment of the present invention.

  As is clear from FIG. 4, the coupling between the first coil 12 and the second coil 13 is strengthened so that common mode noise can be removed, and the fifth and sixth external electrodes 26 and 27. Is connected to the ground, and the high-frequency common mode noise is bypassed to the ground by the stray capacitance C0 generated between the first and second coils 12 and 13 and the metal layer 17, thereby attenuating the common mode noise in the high frequency region. The characteristics are improved. The differential signal is hardly attenuated because its frequency is lower than that of the common mode noise.

  As described above, in one embodiment of the present invention, the metal layer 17 having the notch portion 16 that exposes the magnetic portion 15 in top view is formed by using the first magnetic layer 14a and the second magnetic layer. 14b, and between the upper third magnetic layer 14c and the fourth magnetic layer 14d, respectively, and is generated in the first and second coils 12 and 13 and the magnetic portion 15 The magnetic flux penetrating through the interior extends to the first magnetic layer 14a and the fourth magnetic layer 14d without being obstructed by the metal layer 17 by the notch 16, so that the magnetic flux wraps around greatly. Many magnetic fluxes can circulate around the first and second coils 12 and 13. As a result, since the coupling between the first coil 12 and the second coil 13 can be strengthened, it is possible to obtain an effect that the attenuation characteristic of the common mode noise can be prevented from deteriorating.

  Even in this configuration, the first and second coils 12 and 13 and the metal layer 17 can be opposed to each other, so that the first and second coils 12 and 13 and the metal layer 17 are disposed between each other. It is also possible to improve the attenuation characteristics of high-frequency common mode noise by bypassing high-frequency common mode noise to the ground due to the generated stray capacitance.

  In the common mode noise filter according to the embodiment of the present invention, the metal layer 17 covers the entire surfaces of the first and second coils 12 and 13 when viewed from above. As shown, the metal layer 17 may be configured to cover only a part of the first and second coils 12 and 13 in a top view.

  With this configuration, it is possible to increase the space around which the magnetic flux generated by the first and second coils 12 and 13 and penetrating the inside of the magnetic portion 15 can be increased, so that the space between the first coil 12 and the second coil 13 can be increased. Can be further strengthened, thereby preventing the attenuation characteristics of the common mode noise from deteriorating.

  In particular, as shown in FIG. 5, if the metal layer 17 covers only the outer peripheral portions of the first and second coils 12 and 13 in a top view, the magnetic flux penetrating the inside of the magnetic portion 15 is changed in the vertical direction. Since it circulates so that it spreads toward the center, a large amount of magnetic flux can circulate around the first and second coils 12 and 13, thereby reliably preventing the deterioration of the attenuation characteristics of the common mode noise. it can. In FIG. 5, only the second spiral conductor 18b, the second nonmagnetic layer 11b, the metal layer 17, the notch portion 16, and the magnetic portion 15 are shown for the sake of simplicity. The portion covered with the metal layer 17 of the conductor 18b is represented by a broken line.

  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.

DESCRIPTION OF SYMBOLS 10 Nonmagnetic material 11a-11c Nonmagnetic material layer 12 1st coil 13 2nd coil 14a-14d Magnetic material layer 15 Magnetic part 16 Notch part 17 Metal layer

Claims (2)

A plurality of nonmagnetic layers made of a nonmagnetic material; a first coil and a second coil provided on a nonmagnetic material formed by laminating the plurality of nonmagnetic layers; A magnetic layer provided on at least one of the upper side and the lower side of the non-magnetic layer, and the central portion of the first and second coils that penetrates the non-magnetic layer and below the upper magnetic layer. And a magnetic part in contact with the magnetic material layer, and a metal layer having a notch that exposes the magnetic part in a top view, formed on the magnetic material layer. The common mode noise filter according to claim 1, wherein the notch is formed in the metal layer so that a part of the first and second coils is exposed in a top view.

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