JP4147904B2 - Noise filter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a noise filter used as a noise countermeasure for mobile phones, information devices, and the like.
[0002]
[Prior art]
This type of conventional noise filter has a configuration as shown in FIG.
[0003]
FIG. 5 is an exploded perspective view of a conventional noise filter (laminated common mode choke coil). The configuration of the conventional noise filter will be described with reference to FIG.
[0004]
In FIG. 5, 1 is a 1st insulating sheet and has provided the 1st coil conductor 2 on the surface. 3 is a 2nd insulating sheet, and has provided the 2nd coil conductor 4 on the surface. Reference numeral 5 denotes a third insulating sheet having a third coil conductor 6 on the surface. 7 is a 4th insulating sheet, and has provided the 4th coil conductor 8 on the surface. The other end portion of the first coil conductor 2 is formed by sequentially laminating the first insulating sheet 1, the second insulating sheet 3, the third insulating sheet 5, and the fourth insulating sheet 7. Is electrically connected in series to one end of the second coil conductor 4 via a via hole 1a provided in the first insulating sheet 1, and the other end of the second coil conductor 4 is 2 is electrically connected in series to one end of the third coil conductor 6 through a via hole 3a provided in the insulating sheet 3, and the other end of the third coil conductor 6 is connected to the third insulation. Electrically connected in series to one end of the fourth coil conductor 8 through a via hole 5a provided in the conductive sheet 5, and thus the first insulating sheet 1 and the second insulating sheet By sequentially laminating the conductive sheet 3, the third insulating sheet 5, and the fourth insulating sheet 7 , In which the first helical coil 9 having an axis parallel with respect to the vertical direction of stacking the insulating sheets 1,3,5,7 are configured.
[0005]
Reference numeral 10 denotes a fifth insulating sheet, and a fifth coil conductor 11 is provided on the surface. Reference numeral 12 denotes a sixth insulating sheet having a sixth coil conductor 13 on the surface. A seventh insulating sheet 14 has a seventh coil conductor 15 on the surface. Reference numeral 16 denotes an eighth insulating sheet, and an eighth coil conductor 17 is provided on the surface. The other end portion of the fifth coil conductor 11 is formed by sequentially laminating the fifth insulating sheet 10, the sixth insulating sheet 12, the seventh insulating sheet 14, and the eighth insulating sheet 16. Is electrically connected in series to one end of the sixth coil conductor 13 via a via hole 10a provided in the fifth insulating sheet 10, and the other end of the sixth coil conductor 13 is 6 is electrically connected in series to one end of the seventh coil conductor 15 via a via hole 12a provided in the insulating sheet 12, and the other end of the seventh coil conductor 15 is connected to the seventh insulation. Electrically connected in series to one end of the eighth coil conductor 17 through a via hole 14a provided in the conductive sheet 14, and thus the fifth insulating sheet 10 and the sixth insulating sheet Sheet 12, seventh insulating sheet 14, eighth By sequentially laminating an insulating sheet 16, in which the second helical coil 18 having an axis parallel with respect to the vertical direction of stacking the insulating sheets 10, 12, 14, 16 are configured.
[0006]
Reference numeral 19 denotes a ninth insulating sheet having a ninth coil conductor 20 on the surface. Reference numeral 21 denotes a tenth insulating sheet having a tenth coil conductor 22 on the surface. Reference numeral 23 denotes an eleventh insulating sheet having an eleventh coil conductor 24 on the surface. A twelfth insulating sheet 25 has a twelfth coil conductor 26 on the surface. The other end portion of the ninth coil conductor 20 is formed by sequentially laminating the ninth insulating sheet 19, the tenth insulating sheet 21, the eleventh insulating sheet 23, and the twelfth insulating sheet 25. Is electrically connected in series to one end of the tenth coil conductor 22 through a via hole 19a provided in the ninth insulating sheet 19, and the other end of the tenth coil conductor 22 is 10 is electrically connected in series to one end of the eleventh coil conductor 24 via a via hole 21a provided in the insulating sheet 21, and the other end of the eleventh coil conductor 24 is connected to the eleventh insulation. Electrically connected in series to one end of the twelfth coil conductor 26 via a via hole 23a provided in the conductive sheet 23. Thus, the ninth insulating sheet 19 and the tenth insulating sheet Sheet 21, eleventh Insulating sheet 23 and twelfth insulating sheet 25 are sequentially stacked to form third spiral coil 27 having an axis parallel to the vertical direction in which insulating sheets 19, 21, 23, and 25 are stacked. It is what is done.
[0007]
Then, cover sheets 28 and 29 are positioned above the first spiral coil 9 and below the third spiral coil 27 so that the first spiral coil 9, the second spiral coil 18, and the third Are laminated to form a laminated common mode choke coil (noise filter) made of a laminated body.
[0008]
The laminated common mode choke coil (noise filter) made of the laminated body is provided with input electrodes 28a, 28b, 28c and output electrodes 29a, 29b, 29c. The input electrode 28a and the output electrode 29a The input electrode 28a and the output electrode 29a of the first spiral coil 9 are electrically connected to the first spiral coil 9, and the input electrode 28b and the output electrode 29b are connected to the second spiral coil 18. The input electrode 28b and the output electrode 29b of the second spiral coil 18 are electrically connected to each other, and the input electrode 28c and the output electrode 29c are electrically connected to the third spiral coil 27 to be An input electrode 28c and an output electrode 29c of the third helical coil 27 are configured.
[0009]
As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-186056
[Problems to be solved by the invention]
However, in the conventional noise filter, the structures of all the coils, that is, the first spiral coil 9, the second spiral coil 18, and the third spiral coil 27 are independent spirals. Therefore, the number of stacked layers increases, and as a result, the coupling coefficient between the first helical coil 9 and the second helical coil 18 and the coupling coefficient between the second helical coil 18 and the third helical coil 27. Therefore, there is a limit to the increase in the resistance, and therefore, the first spiral coil 9 and the third spiral coil 27 have a problem of having almost no coupling.
[0012]
SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to provide a noise filter that can increase a common mode impedance value and also has a high common mode noise removal characteristic.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has the following configuration.
[0014]
The invention according to claim 1 of the present invention includes a magnetic body, a first coil, a second coil, and a third coil provided in the magnetic body, the first coil, the second coil, and An external electrode electrically connected to each end of each of the third coils, and the first coil is electrically connected to the spiral first conductor and the first conductor; And a second conductor formed in a spiral shape above the first conductor, and the third coil is formed in a spiral shape facing the upper side of the second conductor. 5 conductor and a sixth conductor that is electrically connected to the fifth conductor and formed in a spiral shape above the fifth conductor, and the second coil includes A third conductor formed in a double spiral on the same plane as the first conductor; And the fourth conductor formed in a double spiral on the same plane as the sixth conductor. According to this configuration, the first conductor Since the coupling coefficient between the coil and the second coil, the coupling coefficient between the second coil and the third coil, and the coupling coefficient between the third coil and the first coil are all increased, the number of layers is also a coil conductor. As the layer, only four layers can provide a three-line noise filter having a high coupling coefficient, and an effect can be obtained.
[0015]
The invention according to claim 2 of the present invention is particularly applicable to the length of the conductor between the external electrodes of the first coil, the length of the conductor between the external electrodes of the second coil, and the distance between the external electrodes of the third coil. The lengths of the conductors are the same, and according to this configuration, an effect of providing a three-line noise filter with balanced DC resistance can be obtained.
[0016]
In the invention according to claim 3 of the present invention, in particular, the distance between the first conductor and the third conductor and the distance between the fourth conductor and the sixth conductor are longer than 30 μm and from 150 μm, respectively. According to this configuration, an effect of providing a three-line noise filter having a high coupling coefficient can be obtained.
[0017]
In the invention according to claim 4 of the present invention, in particular, the distance between the first conductor and the third conductor and the distance between the fourth conductor and the sixth conductor are made the same. According to this, an effect of providing a three-line noise filter with a balanced coupling coefficient can be obtained.
[0018]
In the invention according to claim 5 of the present invention, in particular, the distance between the surface on which the second conductor is formed and the surface on which the fifth conductor is formed is defined as the second conductor. The distance between the surface and the surface on which the third conductor is formed and the distance between the surface on which the fourth conductor is formed and the surface on which the fifth conductor is formed are shorter than According to this configuration, it is possible to obtain an operational effect that a three-line noise filter with a balanced coupling coefficient can be provided.
[0019]
In the invention according to claim 6 of the present invention, in particular, the first coil, the second coil, and the third coil are formed by electroforming, respectively. The effect of providing a line noise filter can be obtained.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a noise filter according to an embodiment of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is an exploded perspective view of a noise filter according to an embodiment of the present invention, and FIG. 2 is a perspective view of the noise filter.
[0022]
In FIGS. 1 and 2, reference numeral 31 denotes a first coil. The first coil 31 is a spiral first conductor 32 and a spiral formed above the first conductor 32. 2 conductors 33. The first conductor 32 has a first lead part 32a and a first via electrode 32b located inside the spiral, and the second conductor 33 has a second lead part 33a and a spiral. And a second via electrode 33b located inside.
[0023]
Reference numeral 34 denotes a second coil, and the second coil 34 includes a spiral third conductor 35 and a fourth conductor 36 formed in a spiral shape above the third conductor 35. Has been. The third conductor 35 has a third lead portion 35a and a third via electrode 35b located inside the spiral, and the fourth conductor 36 has a fourth lead portion 36a and a spiral. And a fourth via electrode 36b located inside.
[0024]
Reference numeral 37 denotes a third coil, and the third coil 37 includes a spiral fifth conductor 38 and a sixth conductor 39 formed in a spiral shape above the fifth conductor 38. Has been. The fifth conductor 38 has a fifth lead portion 38a and a fifth via electrode 38b located inside the spiral, and the sixth conductor 39 has a sixth lead portion 39a and a spiral. And a sixth via electrode 39b located inside.
[0025]
Reference numeral 40 denotes a first magnetic material sheet having a square shape. The first magnetic material sheet 40 is disposed between the first conductor 32 and the second conductor 33, and the first via hole 40a. And a second via hole 40b. The first via electrode 32b and the second via electrode 33b are electrically connected to each other by the first via hole 40a, whereby the first conductor 32 and the second conductor 33 are electrically connected. To form a first coil 31.
[0026]
Reference numeral 41 denotes a second magnetic sheet having a rectangular shape. The second magnetic sheet 41 is disposed between the second conductor 33 and the fifth conductor 38 and has a third via hole 41a. have. The second magnetic sheet 41 insulates the second conductor 33 and the fifth conductor 38 from each other.
[0027]
Reference numeral 42 denotes a third magnetic sheet having a square shape. The third magnetic sheet 42 is disposed between the fifth conductor 38 and the sixth conductor 39 and has a fourth via hole 42a. And a fifth via hole 42b. The third via electrode 35b and the fourth via electrode 36b are electrically connected to each other by the fourth via hole 42a, the second via hole 40b, and the third via hole 41a. Thus, the third conductor 35 and the fourth conductor 36 are electrically connected to form the second coil 34. Further, the fifth via electrode 38b and the sixth via electrode 39b are electrically connected to each other by the fifth via hole 42b, whereby the fifth conductor 38 and the sixth conductor 39 are electrically connected. Are connected to form a third coil 37.
[0028]
The first conductor 32, the second conductor 33, the third conductor 35, the fourth conductor 36, the fifth conductor 38, and the sixth conductor 39 are each made of a conductor such as silver. However, the length, width, and thickness thereof may be adjusted so as to match predetermined characteristics.
[0029]
The second conductor 33 and the fifth conductor 38 oppose each other, and the second magnetic sheet 41 is insulated between the second conductor 33 and the fifth conductor 38. The first conductor 32 and the third conductor 35, the second conductor 33 and the fifth conductor 38, the fourth conductor 36 and the sixth conductor 39 are drawn out in the same direction. When a current flows from the second lead portion 32a, the third lead portion 35a, and the fifth lead portion 38a to the second lead portion 33a, the fourth lead portion 36a, and the sixth lead portion 39a, the fourth conductor 36 and the sixth conductor 39 are formed so that currents flow in the same direction from above in plan view.
[0030]
By forming the first conductor 32, the second conductor 33, the third conductor 35, the fourth conductor 36, the fifth conductor 38, and the sixth conductor 39 so as to have the above-described arrangement relationship. Since the first conductor 32 and the third conductor 35 are formed in a double spiral shape on the same plane, if a current in the same direction flows through the first conductor 32 and the third conductor 35, The magnetic fluxes generated by the first conductor 32 and the third conductor 35 can be strengthened with each other, and as a result, the effect that the common-mode impedance value can be increased is obtained.
[0031]
Further, since the second conductor 33 and the fifth conductor 38 are respectively formed in a spiral shape so as to face each other with the second magnetic material sheet 41 interposed therebetween, the second conductor 33 and the fifth conductor 38 If the current flows in the same direction, the magnetic fluxes generated by the second conductor 33 and the fifth conductor 38 can be strengthened with each other, so that the common mode impedance value can be increased. It is what
[0032]
Reference numeral 43 denotes a fourth magnetic sheet having a square shape. The fourth magnetic sheet 43 is disposed on the lower surfaces of the first conductor 32 and the third conductor 35.
[0033]
Reference numeral 44 denotes a fifth magnetic sheet having a square shape. The fifth magnetic sheet 44 is disposed on the upper surfaces of the fourth conductor 36 and the sixth conductor 39.
[0034]
The first magnetic sheet 40, the second magnetic sheet 41, the third magnetic sheet 42, the fourth magnetic sheet 43, and the fifth magnetic sheet 44 are made of an oxide of ferrite powder. As shown in FIG. 2, a plate-like magnetic body 45 having a square shape is formed by laminating them in the vertical direction as described above. The magnetic body 45 is not plate-shaped and may have a certain thickness. The magnetic body 45 does not necessarily have a square shape. Further, the first magnetic sheet 40, the second magnetic sheet 41, the third magnetic sheet 42, the fourth magnetic sheet 43, and the fifth magnetic sheet 44 constituting the magnetic body 45. Each thickness may be adjusted as appropriate according to predetermined characteristics (withstand voltage, etc.), and the thickness is further adjusted by changing the thickness of the magnetic sheet itself or changing the number of magnetic sheets.
[0035]
46a, 46b, 46c are external electrodes formed on one end face of the magnetic body 45, and 47a, 47b, 47c are formed on the other end face of the magnetic body 45 so as to face the external electrodes 46a, 46b, 46c. External electrode. These external electrodes 46a, 46b, 46c, 47a, 47b, 47c are configured by applying a low melting point metal plating such as nickel plating, tin or solder on the surface of a conductor such as silver.
[0036]
Then, both ends of the first coil 31, that is, the first lead portion 32a and the second lead portion 33a, the first lead portion 32a is the external electrode 46a, and the second lead portion 33a is the external electrode 47a. Are electrically connected to each other. Further, both ends of the second coil 34, that is, the third lead portion 35a and the fourth lead portion 36a, the third lead portion 35a is the external electrode 46b, and the fourth lead portion 36a is the external electrode 47b. Each is electrically connected. Further, both ends of the third coil 37, that is, the fifth lead portion 38a and the sixth lead portion 39a, the fifth lead portion 38a is the external electrode 46c, and the sixth lead portion 39a is the external electrode 47c. Are electrically connected to each other.
[0037]
If the lengths of the first coil 31, the second coil 34, and the third coil 37 are made the same, the direct current resistance values of the coils 31, 34, and 37 become equal. The balance will not be lost when it is incorporated into the product.
[0038]
The coupling coefficient between the first coil 31 and the second coil 34 and the coupling coefficient between the second coil 34 and the third coil 37 are the distance between the first conductor 32 and the third conductor 35. It is determined by the distance between the fourth conductor 36 and the sixth conductor 39.
[0039]
FIG. 3 is a diagram showing the relationship between the distance between the first conductor 32 and the third conductor 35, the coupling coefficient K, and the withstand voltage of the noise filter according to the embodiment of the present invention.
[0040]
Note that the withstand voltage represents the ratio of non-defective products (insulation resistance of 100 MΩ or more) when 100 V is applied between the first conductor 32 and the third conductor 35 for 1 minute. 2 shows the distance (μm) between the first conductor 32 and the third conductor 35, and the vertical axis shows the coupling coefficient K and the withstand voltage failure rate (%).
[0041]
As is apparent from FIG. 3, it can be seen that the distance between the first conductor 32 and the third conductor 35 may be longer than 30 μm and shorter than 150 μm. That is, with such a range, the withstand voltage between the first conductor 32 and the third conductor 35 can be maintained, the withstand voltage failure rate can be reduced to 0%, and the first conductor 32 Since the coupling coefficient with the third conductor 35 is also increased, the effect that the impedance value of the common mode can be increased is obtained. This is also true for the relationship between the fourth conductor 36 and the sixth conductor 39. The distance between the first conductor 32 and the third conductor 35, and the fourth conductor If the distance between the conductor 36 and the sixth conductor 39 is the same, the coupling coefficient between the first coil 31 and the second coil 34 and the coupling coefficient between the second coil 34 and the third coil 37 are as follows. Accordingly, it is possible to provide a common mode noise filter in which the common mode impedance is balanced.
[0042]
FIG. 4A shows the common mode impedance between the coils of the conventional noise filter, and FIG. 4B shows the common mode impedance between the coils of the noise filter according to the embodiment of the present invention. Is shown. As apparent from FIGS. 4A and 4B, in the conventional noise filter, only the common mode impedance between the first coil 9 and the third coil 27 is low and not balanced. In the noise filter according to the embodiment of the present invention, all common mode impedances are balanced, and it can be seen that this is an excellent common mode noise filter.
[0043]
If the first conductor 32, the second conductor 33, the third conductor 35, the fourth conductor 36, the fifth conductor 38, and the sixth conductor 39 are formed by electroforming, the narrow conductor Since the width and the fine pitch between the conductor lines can be realized, the length of each of the conductors 32, 33, 35, 36, 38, 39 can be increased, and thereby the respective conductors 32, 33, 35, 36, Since the magnetic fluxes generated at 38 and 39 can be further strengthened, the common mode impedance value can be further increased.
[0044]
【The invention's effect】
As described above, the noise filter of the present invention includes a magnetic body, the first coil, the second coil, and the third coil provided in the magnetic body, the first coil, the second coil, and the second coil. Each of both ends of each of the three coils and an external electrode electrically connected thereto, and the first coil is electrically connected to the spiral first conductor and the first conductor, and And a second conductor formed in a spiral shape above the first conductor, and the third coil is formed in a spiral shape facing the upper side of the second conductor. And a sixth conductor that is electrically connected to the fifth conductor and is formed in a spiral shape above the fifth conductor, and the second coil further includes the second coil. A third conductor formed in a double spiral on the same plane as the one conductor; And the fourth conductor which is electrically connected to the third conductor and is formed in a double spiral shape on the same plane as the sixth conductor. The coupling coefficient with the second coil, the coupling coefficient between the second coil and the third coil, and the coupling coefficient between the third coil and the first coil are all increased. As a layer, there is an excellent effect that a three-line noise filter having a high coupling coefficient can be provided with only four layers.
[Brief description of the drawings]
1 is an exploded perspective view of a noise filter according to an embodiment of the present invention. FIG. 2 is a perspective view of the noise filter. FIG. 3 is a distance between a first conductor 32 and a third conductor 35 of the noise filter. FIG. 4A is a diagram showing a relationship between a coupling coefficient K and a withstand voltage. FIG. 4A is a diagram showing a common mode impedance between coils of a conventional noise filter. FIG. Diagram showing common mode impedance between coils [Fig. 5] Exploded perspective view of conventional noise filter [Explanation of symbols]
31 1st coil 32 1st conductor 33 2nd conductor 34 2nd coil 35 3rd conductor 36 4th conductor 37 3rd coil 38 5th conductor 39 6th conductor 40 1st magnetism Body sheet 41 second magnetic sheet 42 third magnetic sheet 43 fourth magnetic sheet 44 fifth magnetic sheet 45 magnetic bodies 46a to 46c, 47a to 47c external electrodes

Claims (6)

The magnetic body, the first coil, the second coil, and the third coil provided in the magnetic body, and both ends of the first coil, the second coil, and the third coil are electrically connected to each other. The first coil is formed in a spiral shape above the first conductor and electrically connected to the first conductor. The third coil includes a fifth conductor formed in a spiral shape so as to be opposed to the upper side of the second conductor, and the fifth conductor and the second conductor. And a sixth conductor that is spirally formed above the fifth conductor, and the second coil is doubled on the same plane as the first conductor. A third conductor formed in a spiral shape and electrically connected to the third conductor; and Serial sixth fourth noise filter constituted by a conductor formed in a double spiral on the conductor flush with. The length of the conductor between the external electrodes of the first coil, the length of the conductor between the external electrodes of the second coil, and the length of the conductor between the external electrodes of the third coil are the same. The noise filter according to 1. The noise filter according to claim 1, wherein a distance between the first conductor and the third conductor and a distance between the fourth conductor and the sixth conductor are longer than 30 μm and shorter than 150 μm, respectively. The noise filter according to claim 1, wherein a distance between the first conductor and the third conductor and a distance between the fourth conductor and the sixth conductor are the same. The distance between the surface on which the second conductor is formed and the surface on which the fifth conductor is formed is defined as the distance between the surface on which the second conductor is formed and the surface on which the third conductor is formed. The noise filter according to claim 1, wherein the noise filter is shorter than both the distance and the distance between the surface on which the fourth conductor is formed and the surface on which the fifth conductor is formed. The noise filter according to claim 1, wherein each of the first coil, the second coil, and the third coil is formed by electroforming.

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