JP4720216B2 - Multilayer type common mode noise filter - Google Patents

Description

  The present invention relates to a small and stacked common mode noise filter used in various electronic devices.

As shown in FIG. 6, the conventional multilayer common mode noise filter of this type has first to fourth conductors 2a, 2b, 3a, 3b on the upper surfaces of the first to fourth insulating layers 1a to 1d, respectively. The first coil 2 is formed by connecting the first conductor 2a and the second conductor 2b via the via electrode 4a, and the third conductor 3a and the fourth conductor 3b are connected to the via. The second coil 3 was formed by connecting through the electrode 4b. A dummy insulating layer 5 is provided on the lower surface of the first insulating layer 1a and the upper surface of the fourth conductor 3b.

  With the configuration as described above, the second conductor 2b and the third conductor 3a facing each other with the third insulating layer 1c interposed therebetween are magnetically coupled, whereby the first coil 2 and the second conductor 2a are magnetically coupled. The common mode impedance of the coil 3 is increased to remove common mode noise, and the differential mode impedance is decreased to allow a differential signal (differential signal) to pass therethrough.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
JP 2003-1224028 A

In the above-described conventional laminated common mode noise filter, the first coil 2 and the second coil 3 have different impedances. Therefore, when a differential signal (differential signal) flows, the first coil 2 is generated in the first coil 2. The magnetic flux and the magnetic flux generated by the second coil 3 do not completely cancel each other out, so that an impedance corresponding to the difference between the impedances of the two coils 2 and 3 remains, so that the differential mode impedance increases. Had problems. In this common mode noise filter, if the differential mode impedance increases, the signal that is originally desired to pass through or the waveform is distorted.

  Here, the reason why the impedances of the first coil 2 and the second coil 3 are different is that the current flows in the first coil 2 in a reverse direction, so that the generated magnetic fluxes cancel each other out and the impedance is different. On the other hand, current flows in the same direction in a part of the second coil 3, so that the generated magnetic fluxes strengthen each other and the impedance increases.

  That is, in the first coil 2, as shown in FIG. 7A, the current directions of the first conductor 2a and the second conductor 2b are opposite at the position 6, and the second conductor is also at the position 7. Since the direction of the current is reversed between 2b, the impedance is reduced. However, in the second coil 3, as shown in FIG. 7B, the third conductor 3a and the fourth conductor 3b are located at the position 8. This is because the current increases in the same direction, so that the impedance increases. In the case of the laminated type, this occurs because the relationship between the conductors in the vertical direction and the lead conductor cannot be ignored.

  FIGS. 7A and 7B are diagrams in which two conductors constituting the coil are transmitted from above. The first conductor 2a and the fourth conductor 3b are indicated by broken lines, and the second conductor. 2b and the third conductor 3a are indicated by solid lines. The direction of the arrow represents the direction of current when a differential signal flows.

SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to provide a stacked common mode noise filter capable of reducing the differential mode impedance.

In order to achieve the above object, the present invention is configured such that the end portion of the first coil conductor is folded back, and the first coil conductor and the first lead conductor in the vicinity of the first via electrode in a top view. And a part of the first coil conductor and a part of the first lead conductor are overlapped in a top view, and when the current flows in the overlapped part, the first The first coil conductor and the first lead conductor are configured so that current flows in the same direction when viewed from above, and the end of the second coil conductor is not folded back, and the second coil conductor when viewed from above. The second coil conductor and the second lead conductor are prevented from overlapping in the vicinity of the via electrode, and a part of the second coil conductor and a part of the second lead conductor are viewed from above. When the current flows in this overlapping place, The second coil conductor and the second lead conductor when viewed from the top is obtained by a current flows in different directions.

As described above, the multilayer common mode noise filter of the present invention is configured to fold back the end portion of the first coil conductor, and in the vicinity of the first coil electrode in the vicinity of the first via electrode in a top view. The first lead conductor is overlapped, and a part of the first coil conductor and a part of the first lead conductor are overlapped with each other in a top view so that a current flows at the overlapped portion. A current is made to flow in the same direction as viewed from above in the first coil conductor and the first lead conductor when flowing, and the end portion of the second coil conductor is configured not to be folded, The second coil conductor and the second lead conductor are prevented from overlapping in the vicinity of the second via electrode when viewed from above, and a part of the second coil conductor and one of the second lead conductors are arranged. This part overlaps with the top view. Since the second coil conductor and the current in different directions viewed from the top to the second lead conductor is to flow when a current flows in place, when the differential signal is played back, the first coil Since the magnetic flux generated in the second coil and the magnetic flux generated in the second coil cancel each other almost completely, it is possible to prevent the impedance corresponding to the difference between the impedances of the two coils from remaining. There is an excellent effect that the impedance of the device can be reduced.

(Embodiment 1)
Hereinafter, with reference to the first embodiment will be described the invention described in particular claim 1 of the present invention.

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

As shown in FIG. 1, the stacked common mode noise filter according to the first exemplary embodiment of the present invention includes a first insulating layer 11, a second insulating layer 12, and the first insulating layer that are stacked in the vertical direction. 11, a first coil conductor 13 provided on the second insulating layer 12, a second coil conductor 14 provided on the second insulating layer 12 so as to face the first coil conductor 13, The first coil conductor 13 is connected to the first coil conductor 13 and the first coil conductor 13 constitutes the first coil 15; and the second coil conductor 14 is connected to the first coil conductor 13; The second coil conductor 14 and the second lead conductor 18 constituting the second coil 17 are provided.

  Further, the impedance of the first coil 15 and the impedance of the second coil 17 are the same, and the length of the first coil 15 and the length of the second coil 17 are also the same.

The first insulating layer 11 and the second insulating layer 12 in the above configuration are formed in a sheet shape from an insulating material such as ferrite based on Fe ₂ O ₃ or glass ceramic. A second insulating layer 12 is provided above the layer 11. A first via electrode 19 a is formed at the center of the first insulating layer 11.

  The first coil conductor 13 is formed by plating a conductive material such as silver in a spiral shape, and is provided on the upper surface of the first insulating layer 11.

  The second coil conductor 14 is formed by plating a conductive material such as silver in a spiral shape, and is provided on the upper surface of the second insulating layer 12. Further, the first coil conductor 13 and the second coil conductor 14 are configured to face each other with the second insulating layer 12 interposed therebetween. Thereby, since it can be made to magnetically couple between the 1st coil 15 and the 2nd coil 17, the common mode impedance of the 1st coil 15 and the 2nd coil 17 can be enlarged.

  The first lead conductor 16 is formed by plating a conductive material such as silver, and is provided on the upper surface of the third insulating layer 20 located below the first insulating layer 11. . The first lead conductor 16 is connected to the first coil conductor 13 via the first via electrode 19a, whereby the first coil conductor 13 and the first lead conductor 13 are connected. A first coil 15 composed of 16 is formed. In addition, a certain section of the first coil conductor 13 overlaps the first lead conductor 16 when viewed from above.

  The second lead conductor 18 is formed by plating a conductive material such as silver, and is provided on the upper surface of the fourth insulating layer 21 located above the second insulating layer 12. . A second via electrode 19b is formed at the center of the fourth insulating layer 21, and the second lead conductor 18 is connected to the second coil conductor 14 via the second via electrode 19b. As a result, a second coil 17 composed of the second coil conductor 14 and the second lead conductor 18 is formed. In addition, a certain section of the second coil conductor 14 overlaps the second lead conductor 18 when viewed from above.

  Further, the length of the first coil 15 and the length of the second coil 17 are the same, and if the lengths are made the same in this way, the differential signals transmitted through the two coils 15 and 17 Since the transmission time can be made the same, the quality of the differential signal can be prevented from deteriorating.

  A dummy insulating layer 22 is provided on the lower surface of the third insulating layer 20 and the upper surface of the second lead conductor 18, and the dummy insulating layer 22 is formed in a sheet shape and is insulated. It has sex. Further, the number of the first to fourth insulating layers 11, 12, 20, 21 and the dummy insulating layer 22 is not limited to the number shown in FIG.

  Then, by integrating the above-described components, a noise filter main body 23 as shown in FIG. 2 is formed, and first to fourth external electrodes 24, 25 are formed on both side surfaces of the noise filter main body 23. , 26, 27, and the first to fourth external electrodes 24, 25, 26, 27 are respectively connected to both ends of the first coil 15 and the second coil 17. is there.

  Note that it is not always necessary to provide an insulating layer between the first coil conductor 13 and the first lead conductor 16 and between the second coil conductor 14 and the second lead conductor 18.

  The first coil conductor 13, the second coil conductor 14, the first lead conductor 16, the second lead conductor 18, and the first to fourth outer electrodes 24, 25, 26, 27 are: It is not necessarily formed by plating, and may be formed by other methods such as printing and vapor deposition.

Next, a method for manufacturing the stacked common mode noise filter according to the first embodiment of the present invention will be described.

  1 and 2, first, a predetermined number of rectangular first to fourth insulating layers 11, 12, 20, and 21 and dummy insulating layers 22 are respectively produced from a mixture of powder and resin as raw materials. To do. At this time, holes are formed in predetermined portions of the first insulating layer 11 and the fourth insulating layer 21 by laser, punching, or the like, and the holes are filled with silver so that the first via electrode 19a and the second The via electrode 19b is formed.

  Next, the third insulating layer 20 is disposed on the upper surface of the predetermined number of dummy insulating layers 22.

  Next, the first lead conductor 16 is formed on the upper surface of the third insulating layer 20 by plating.

  Next, the first insulating layer 11 provided with the first via electrode 19 a is disposed on the upper surface of the first lead conductor 16. At this time, the first lead conductor 16 and the first via electrode 19a are connected.

  Next, the first coil conductor 13 is formed on the upper surface of the first insulating layer 11 by plating. At this time, the first coil conductor 13 and the first via electrode 19a are connected. Further, a certain section of the first coil conductor 13 is overlapped with the first lead conductor 16 in a top view.

  Next, the second insulating layer 12 is disposed on the upper surface of the first coil conductor 13.

  Next, a spiral second coil conductor 14 is formed on the upper surface of the second insulating layer 12 by plating.

  Next, the fourth insulating layer 21 provided with the second via electrode 19 b is disposed on the upper surface of the second coil conductor 14. At this time, the second coil conductor 14 and the second via electrode 19b are connected.

  Next, the second lead conductor 18 is formed on the upper surface of the fourth insulating layer 21 by plating. At this time, the second lead conductor 18 and the second via electrode 19b are connected. Further, a certain section of the second coil conductor 14 is overlapped with the second lead conductor 18 in a top view.

  The first coil conductor 13, the second coil conductor 14, the first lead conductor 16, and the second lead conductor 18 are formed in a predetermined pattern on a separately prepared base plate (not shown). A conductor having a shape is formed by plating, and the conductor is then transferred to each insulating layer.

  Next, a predetermined number of dummy insulating layers 22 are arranged on the upper surface of the second lead conductor 18 to constitute the noise filter body 23.

  In the above manufacturing process, in order to improve manufacturing efficiency, the first coil conductor 13, the second coil conductor 14, the first lead conductor 16, and the second lead conductor are provided on each insulating layer. A plurality of noise filter main bodies 23 may be obtained at the same time by providing a plurality of 18 and then cutting them into individual pieces.

  Next, the noise filter body 23 is fired at a predetermined temperature and time.

  Next, silver is printed on both side surfaces of the noise filter main body 23 so as to be connected to both end portions of the first and second coils 15 and 17, respectively. 25, 26, 27 are formed.

  Finally, a nickel plating layer is formed on the surfaces of the first to fourth external electrodes 24, 25, 26, and 27 by plating, and further, a low melting point metal plating layer such as tin or solder is formed on the surface of the nickel plating layer by plating. Form.

  As described above, in the first embodiment of the present invention, since the impedance of the first coil 15 and the impedance of the second coil 17 are the same, when the differential signal flows, the first Since the magnetic flux generated in the second coil 15 and the magnetic flux generated in the second coil 17 cancel each other almost completely, no impedance corresponding to the difference in impedance between the two coils remains. The effect that the differential mode impedance can be reduced is obtained. As a result, the common mode impedance of the first coil 15 and the second coil 17 can also be increased.

  Furthermore, since the first coil conductor 13 and the second coil conductor 14 are stacked in the vertical direction, an effect that the size can be easily reduced can be obtained.

  Here, the same impedance means that the impedance is within the range of the impedance requested by a set manufacturer or the like, for example, that the difference in impedance between the two coils is within 5%.

  Further, as a method of making the impedance of the first coil 15 and the impedance of the second coil 17 the same, when a differential signal flows, one of the first coil 15 and the second coil 17 is used. There is a method in which the magnetic fluxes strengthen each other and in the other coil, the magnetic fluxes cancel each other.

  This method will be described below with reference to FIGS.

  3A is a view in which the two conductors 13 and 16 constituting the first coil 15 are transmitted from above, and FIG. 3B is the two conductors 14 and 16 constituting the second coil 17. The first and second lead conductors 16 and 18 are indicated by broken lines, and the first and second coil conductors 13 and 14 are indicated by solid lines. The direction of the arrow represents the direction of current when a differential signal flows.

  In the conventional first coil 2 in FIG. 7A, the current direction of the first conductor 2a and the second conductor 2b is reversed, and thus the impedance is reduced, but in FIG. If the position of the conductor is changed as in the first coil 15, the current direction of the first coil conductor 13 and the first lead-out conductor 16 becomes the same direction at the position 28, so that the impedance increases conversely.

  On the other hand, in the conventional second coil 3 in FIG. 7B, the directions of the currents of the third conductor 3a and the fourth conductor 3b are the same, so that the generated magnetic fluxes strengthen each other and the impedance is increased. If the position of the conductor is changed as in the second coil 17 in FIG. 3B, the current directions of the second coil conductor 14 and the second lead conductor 18 are reversed at the position 29. Therefore, the generated magnetic fluxes cancel each other, and the impedance decreases conversely. At this time, if a certain section of the first and second coil conductors 13 and 14 overlaps the first and second lead conductors 16 and 18 in a top view, the first coil conductor 13 And the first lead conductor 16 and the distance between the second coil conductor 14 and the second lead conductor 18 can be minimized, so that the magnetic flux generated in each conductor 13, 14, 16, 18 can be reduced. Can have the greatest effect on the other conductors, thereby making it possible to more efficiently cause the generated magnetic fluxes to reinforce each other and to cancel each other. The impedance of the first coil 15 and the impedance of the second coil 17 can be easily made the same. Further, the impedances of the first coil 15 and the second coil 17 can be easily adjusted by changing the overlapping length.

  In this way, by making the magnetic fluxes intensify each other in the coil with the smaller impedance and canceling out the magnetic fluxes in the coil with the larger impedance, the impedance of the first coil 15 can be reduced. The impedance of the second coil 17 can be easily made the same.

  Further, at this time, the impedance of the first coil 15 and the impedance of the second coil 17 are made by strengthening the magnetic fluxes with each other only in the coil with the smaller impedance while keeping the coil with the larger impedance. Since the impedance of the first coil 15 and the impedance of the second coil 17 are the same at the largest value, the common of the first coil 15 and the second coil 17 is the same. The mode impedance can be further increased.

(Embodiment 2)
Hereinafter, another embodiment of the present invention will be described using the second embodiment.

FIG. 4 is an exploded perspective view of a laminated common mode noise filter according to another invention of the present invention. In the other inventions of the present invention, those having the same configuration as that of the first embodiment of the present invention described above are denoted by the same reference numerals and the description thereof is omitted.

The laminated common mode noise filter according to another invention of the present invention shown in FIG. 4 is different from the above-described first embodiment of the present invention in that the distance between the conductors is increased at one end of the first coil conductor 13. This is the point where the first and second coil conductors 13 and 14 and the first and second lead conductors 16 and 18 are orthogonal to each other when viewed from above.

  According to this configuration, since the decrease in impedance can be suppressed in the coil having the smaller impedance as in the conventional first coil 2 in FIG. 7A, the impedance of the first coil 15 and the second coil The impedance of 17 can be made the same. This is because, as shown in FIG. 5A, the direction of the current between the conductors is reversed when one end of the first coil conductor 13, that is, the conductor is folded in the vicinity where it is connected to the external electrode and a differential signal flows. This is because the distance between the conductors is long at the position 30 where the impedance is reduced by the magnetic fluxes canceling each other, so that the amount of magnetic flux canceling each other is reduced. In addition, if the shape of the 1st coil conductor 13 is made into a curve shape like FIG. 4, the distance between conductors can be lengthened easily. Further, if the shapes of the first coil conductor 13 and the second coil conductor 14 are curved, the first and second lead conductors 16 and 18 can be made substantially straight by simply making the first and second conductors 16 and 18 straight. The coil conductors 13 and 14 and the first and second lead conductors 16 and 18 can be easily orthogonalized in a top view.

  The first and second coil conductors 13 and 14 and the first and second lead conductors 16 and 18 are orthogonal to each other at positions 31 and 32 in FIGS. 5A and 5B in a top view. Therefore, the direction of the current flowing in the first and second coil conductors 13 and 14 and the direction of the current flowing in the first and second lead conductors 16 and 18 are not reversed or the same, Thereby, the impedance of the first coil 15 and the impedance of the second coil 17 are influenced by the arrangement relationship between the first and second coil conductors 13 and 14 and the first and second lead conductors 16 and 18. It can be easily made the same without receiving.

  Here, FIG. 5A is a diagram in which the two conductors 13 and 16 constituting the first coil 15 are transmitted from above, and FIG. 5B is the two conductors 14 and 16 constituting the second coil 17. The first and second lead conductors 16 and 18 are indicated by broken lines, and the first and second coil conductors 13 and 14 are indicated by solid lines. The direction of the arrow represents the direction of current when a differential signal flows.

In the multilayer common mode noise filter according to the present invention , one first coil 15 and one second coil 17 are provided, but a plurality of first coils 15 and a plurality of second coils 17 are provided. It may be an array type. In this case, the plurality of first coils 15 and second coils 17 may be stacked in the stacking direction or arranged in the horizontal direction.

The multilayer common mode noise filter according to the present invention can reduce the impedance of the differential mode of the coil, and is useful as a noise filter used as a noise countermeasure for cellular phones, information devices, and the like.

1 is an exploded perspective view of a multilayer common mode noise filter according to Embodiment 1 of the present invention. Perspective view of the common mode noise filter (A), (b) Top view of the main part of the common mode noise filter The exploded perspective view of the lamination type common mode noise filter in other inventions of the present invention (A), (b) Top view of the main part of the common mode noise filter Exploded perspective view of a conventional multilayer common mode noise filter (A), (b) Top view of the main part of the common mode noise filter

DESCRIPTION OF SYMBOLS 11 1st insulating layer 12 2nd insulating layer 13 1st coil conductor 14 2nd coil conductor 15 1st coil 16 1st extraction conductor 17 2nd coil 18 2nd extraction conductor

Claims (1)

First and second insulating layers stacked in the vertical direction, a spiral first coil conductor provided in the first insulating layer, provided in the second insulating layer, and the first insulating layer A spiral second coil conductor formed so as to face the coil conductor, and the first coil conductor is connected to the first coil conductor via the first via electrode , and the first coil conductor The first coil -shaped lead-out conductor constituting the coil of the first coil, the second coil conductor and the second via electrode are connected to each other, and the second coil conductor constitutes the second coil. An L-shaped second lead conductor, and each of the first coil conductor, the second coil conductor, the first lead conductor, and the second lead conductor is connected to an external electrode. And connecting the first coil conductor to the end portion of the first coil conductor so that the first coil conductor is folded back. The first coil conductor and the first lead conductor overlap each other in the vicinity of the via electrode, and a part of the first coil conductor and a part of the first lead conductor are viewed from above. When the current flows in the overlapping portion, the first coil conductor and the first lead conductor are caused to flow in the same direction when viewed from above, and the second coil An end portion of the conductor is configured not to be folded, the second coil conductor and the second lead conductor are not overlapped in the vicinity of the second via electrode in a top view, and the second coil A part of the conductor and a part of the second lead conductor are overlapped with each other in a top view, and when current flows in the overlapped portion, the second coil conductor and the second lead conductor are connected to each other. Stacking that allows current to flow in different directions when viewed from above Common mode noise filter.

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