JP5360130B2 - Common mode noise filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a common mode noise filter which can attenuate not only common mode noise but also differential mode noise in a specific frequency band. <P>SOLUTION: A common mode filter F1 consisting of spiral conductors 31-34 and a differential mode filter F2 consisting of spiral conductors 35 and 36 are laminated one on top of another on a magnetic substrate 11. The planar positions of the spiral conductors 31-34 are equal to each other, and the planar positions of the spiral conductors 35 and 36 are also equal to each other. The spiral conductors 35 and 36 respectively are formed in the same conductor layers as are the spiral conductors 31 and 32. These conductor layers are of underlayers close to the magnetic substrate 11. Since the spiral conductors 35 and 36 are formed in conductor layers close to the magnetic substrate 11, the frequency band of differential mode noise to be eliminated can be set exactly as designed. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention relates to a common mode noise filter, and more particularly to a common mode noise filter capable of attenuating not only common mode noise but also differential mode noise in a specific frequency band.

  In recent years, the USB 2.0 standard and the IEEE 1394 standard have become widespread as high-speed signal transmission interfaces, and are used in many digital devices such as personal computers and digital cameras. These interfaces employ a differential transmission method in which a differential signal (differential signal) is transmitted using a pair of signal lines, and signal transmission at a higher speed than the conventional single-ended transmission method is realized.

  A common mode filter is widely used as a filter for removing noise on the high-speed differential transmission line (see Patent Document 1). The common mode filter has a characteristic that an impedance with respect to a differential component (differential component) of a signal transmitted through a pair of signal lines is low and an impedance with respect to an in-phase component (common mode component) is high. Therefore, by inserting a common mode filter on a pair of signal lines, common mode noise can be blocked without substantially attenuating the differential mode signal.

JP-A-8-203737

  As described above, since the common mode filter has a low impedance to the differential component, the necessary signal component is hardly attenuated. However, the differential component may include unnecessary differential mode noise in addition to the necessary signal component. Such unnecessary differential mode noise is hardly removed by the conventional common mode filter, so that the noise countermeasures may be insufficient only by inserting the common mode filter into the pair of signal lines. In particular, when a signal line in a mobile phone becomes a source of differential mode noise, communication sensitivity may be reduced.

  From this point of view, the present inventors have conducted extensive research on a common mode noise filter capable of attenuating not only common mode noise but also differential mode noise in a specific frequency band (for example, a communication frequency band of a mobile phone). It was. As a result, it has been found that not only common mode noise but also differential mode noise in a desired frequency band can be removed by connecting one end of a pair of coils magnetically coupled to each other to a common mode filter and opening the other end of these coils. It was.

  Here, the frequency band of the differential mode noise to be removed is determined by LC resonance characteristics composed of an inductance component (L component) and a capacitance component (C component) of a pair of coils whose other ends are open. Therefore, in order to match the frequency band of the differential mode noise to be removed to a desired frequency band, it is necessary to accurately produce a pair of coils with the other ends open as designed.

  However, when the coil is constituted by a spiral conductor on the substrate, the accuracy of producing the spiral conductor depends on the flatness of the underlying insulating layer. For this reason, in order to accurately match the frequency band of the differential mode noise to be removed to a desired frequency band, it is necessary to sufficiently ensure the flatness of the base of the spiral conductor.

  Therefore, an object of the present invention is a common mode noise filter capable of attenuating not only common mode noise but also differential mode noise in a specific frequency band, and the frequency band of the differential mode noise to be removed is as designed. It is to provide a common mode noise filter that can be used.

  A common mode noise filter according to the present invention includes a substrate and first to fourth conductor layers provided in this order on the substrate, and the first conductor layer includes first and second conductors at different planar positions. A fifth spiral conductor is formed, the second conductor layer is formed with second and sixth spiral conductors at different planar positions, and the third and fourth conductor layers are respectively provided with a third spiral conductor. And the fourth spiral conductors are formed, the planar positions of the first to fourth spiral conductors overlap each other, and the planar positions of the fifth and sixth spiral conductors overlap each other, Two of the fourth spiral conductors are connected in series to form a first coil, and the remaining two spiral conductors of the first to fourth spiral conductors are connected in series. Thus, a second coil is formed, and the fifth spiral conductor has one end connected to one end of the first coil and the other end opened, and the sixth spiral conductor has one end Is connected to one end of the second coil paired with the one end of the first coil, and the other end is open.

  According to the present invention, not only common mode noise is removed by the first to fourth spiral conductors, but also differential mode noise in a desired frequency band can be removed by the fifth and sixth spiral conductors. Become. Moreover, since the spiral conductor is of a type that is constituted by a single component and is provided on the substrate, it is possible to provide a common mode noise filter suitable for surface mounting.

  Further, since the fifth and sixth spiral conductors are provided in the conductor layer closer to the substrate, the flatness of the base is sufficiently ensured at the time of manufacture. As a result, the fifth and sixth spiral conductors can be manufactured with high accuracy, and the frequency band of the differential mode noise to be removed can be made as designed. In addition, since the fifth and sixth spiral conductors are arranged at different plane positions from the first to fourth spiral conductors constituting the common mode filter, the magnetic field between the common mode filter and the differential mode filter is determined. Interference is less likely to occur, and changes in filter characteristics due to magnetic interference are suppressed. Thus, when the common mode filter and the differential mode filter are arranged at different plane positions on the substrate, the required area of the substrate is increased. However, in the present invention, each coil constituting the common mode filter is formed on two conductor layers. Therefore, it is possible to secure a desired inductance while reducing the plane area required for the common mode filter.

  In the present invention, it is preferable that the first coil is constituted by the first and third spiral conductors, and the second coil is constituted by the second and fourth spiral conductors. According to this, since the spiral conductor constituting the first coil and the spiral conductor constituting the second coil are alternately arranged, the magnetic coupling and symmetry of both are enhanced, and the characteristics of the common mode filter are improved. It becomes possible to improve.

  In this case, the outer peripheral end of the first spiral conductor and the outer peripheral end of the fifth spiral conductor are connected in the first conductor layer, and the outer peripheral end of the second spiral conductor and the sixth spiral conductor are connected. An outer peripheral end is connected in the second conductor layer, an inner peripheral end of the first spiral conductor and an inner peripheral end of the third spiral conductor are connected via a first through-hole conductor, and the second More preferably, the inner peripheral end of the spiral conductor and the inner peripheral end of the fourth spiral conductor are connected via a second through-hole conductor. According to this, since the common mode filter and the differential mode filter can be connected without passing through the through-hole conductor, the layout of the conductor pattern becomes simple. As a result, the frequency band of the differential mode noise to be removed can be made closer to the design value more accurately.

  In the present invention, it is preferable that a magnetic member provided through the third and fourth conductor layers is disposed above the fifth and sixth spiral conductors. According to this, it is possible to increase the inductance of the differential mode filter.

  In this case, it is more preferable that the magnetic member is disposed at least on the inner peripheral portion of the fourth spiral conductor. According to this, it is possible to increase the inductance of the common mode filter.

  Thus, according to the common mode noise filter of the present invention, not only common mode noise is removed, but also differential mode noise in a desired frequency band can be removed. In addition, the frequency band of the differential mode noise to be removed can be made as designed.

1 is a schematic perspective view showing an overview structure of a common mode noise filter 100 according to a preferred embodiment of the present invention. 2 is a schematic exploded perspective view showing a layer structure of a common mode noise filter 100 in detail. FIG. It is a figure which shows the planar structure of insulating layers 15a-15e and conductor layers 16a-16d. It is a figure for demonstrating the plane position seen from the lamination direction of the spiral conductors 31-36. 2 is an equivalent circuit diagram of a common mode noise filter 100. FIG. It is a figure which shows the variation of the magnetic coupling direction of the spiral conductors 35 and 36, and a connection direction. It is a graph which shows the passage characteristic of a differential component.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic perspective view showing an external structure of a common mode noise filter 100 according to a preferred embodiment of the present invention, and shows a state in which the mounting surface faces upward.

  As shown in FIG. 1, the common mode noise filter 100 according to the present embodiment includes a magnetic substrate 11, a thin film coil layer 12 provided on one main surface (upper surface) of the magnetic substrate 11, and the main components of the thin film coil layer 12. Bump electrodes 13a to 13d provided on the surface (upper surface) and a magnetic resin layer 14 provided on the main surface of the thin film coil layer 12 excluding the formation positions of the bump electrodes 13a to 13d are provided. As shown in the drawing, the common mode noise filter 100 is a substantially rectangular parallelepiped surface-mounted chip component, and the bump electrodes 13a to 13d are outer peripheral surfaces of a laminate including the magnetic substrate 11, the thin film coil layer 12, and the magnetic resin layer 14. It is formed so as to be exposed. Among these, the bump electrodes 13a and 13c are exposed from the first side surface 10a along the longitudinal direction of the multilayer body, and the bump electrodes 13b and 13d are exposed from the second side surface 10b facing the first side surface 10a. ing. Needless to say, it is turned upside down at the time of mounting, and the bump electrodes 13a to 13d are used facing downward. In the present specification, for convenience of explanation, the vertical direction is defined with reference to the state in which the mounting surface shown in FIG. This coincides with the vertical direction when the common mode noise filter 100 is manufactured.

  The magnetic substrate 11 serves as a magnetic path while ensuring the mechanical strength of the common mode noise filter 100. As the material of the magnetic substrate 11, for example, a magnetic ceramic material such as sintered ferrite can be used. Although not particularly limited, when the chip size is 0.65 × 0.85 × 0.56 (mm), the thickness of the magnetic substrate 11 can be about 0.3 mm. However, it is not essential to use the magnetic substrate 11 in the present invention, and if the role as a magnetic path is not necessary, the substrate may be made of a material having no magnetism.

  The thin film coil layer 12 is provided between the magnetic substrate 11 and the magnetic resin layer 14 and includes a common mode filter and a differential mode filter. As will be described in detail later, the thin film coil layer 12 has a multilayer structure in which insulating layers and conductor layers are alternately laminated. As described above, the common mode noise filter 100 according to the present embodiment is a so-called thin film type, and is distinguished from a winding type electronic component having a structure in which a conducting wire is wound around a magnetic core.

  The bump electrodes 13a to 13d are thick film plating electrodes formed by plating, and are distinguished from those formed by thermocompression bonding of metal balls such as Cu and Au using a flip chip bonder. The thickness of the bump electrodes 13 a to 13 d is equal to or greater than the thickness of the magnetic resin layer 14. That is, the thickness of the bump electrodes 13 a to 13 d is preferably thicker than the conductor pattern in the thin film coil layer 12 and more than five times the thickness of the conductor pattern in the thin film coil layer 12.

  The magnetic resin layer 14 is a layer that constitutes the mounting surface (bottom surface) of the common mode noise filter 100, and is provided so as to fill the periphery of the bump electrodes 13a to 13d. The magnetic resin layer 14 protects the thin film coil layer 12 similarly to the magnetic substrate 11 and plays a role as a magnetic path of the common mode noise filter 100. However, since the mechanical strength of the magnetic resin layer 14 is smaller than that of the magnetic substrate 11, it has an auxiliary role in terms of strength. As the magnetic resin layer 14, an epoxy resin (composite ferrite) containing ferrite powder can be used. Although not particularly limited, when the chip size is 0.65 × 0.85 × 0.56 (mm), the thickness of the magnetic resin layer 14 may be about 0.06 to 0.1 mm. it can. However, it is not essential to use the magnetic resin layer 14 in the present invention, and when the role as a magnetic path is not necessary, the layer may be formed of a resin having no magnetism.

  FIG. 2 is a schematic exploded perspective view showing the layer structure of the common mode noise filter 100 in detail.

  As shown in FIG. 2, the thin film coil layer 12 includes insulating layers 15 a to 15 e that are sequentially stacked from the magnetic substrate 11 side to the magnetic resin layer 14 side, and first layers provided on the insulating layers 15 a to 15 d, respectively. To fourth conductor layers 16a to 16d. FIG. 3 shows a planar structure of the insulating layers 15a to 15e and the conductor layers 16a to 16d.

  The insulating layers 15a to 15e serve to insulate conductor patterns provided in different conductor layers and ensure the flatness of the base on which the conductor patterns are formed. In particular, the insulating layer 15a located at the lowest layer absorbs irregularities on the surface of the magnetic substrate 11 and plays a role of improving the processing accuracy of the conductor pattern. As a material of the insulating layers 15a to 15e, it is preferable to use a resin that is excellent in electrical and magnetic insulation and easy to process, and is not particularly limited, but a polyimide resin or an epoxy resin is used. it can.

  The conductor layers 16a to 16d are layers on which conductor patterns are provided. As the conductor pattern, it is preferable to use Cu, Al or the like excellent in conductivity and workability. The conductor pattern can be formed by a subtractive method in which a conductor is formed on the entire surface and then etched using photolithography, or an additive method in which a conductor pattern is selectively formed by plating.

  As shown in FIG. 3, the lowermost insulating layer 15a covers the entire top surface of the magnetic substrate 11, and no opening or the like is provided. In contrast, the insulating layers 15b to 15e are each provided with an opening or a through hole at a predetermined position. Specifically, the insulating layers 15b to 15e are each provided with openings 20a to 20d at positions corresponding to the bump electrodes 13a to 13d. The insulating layer 15b is provided with a through hole 21, the insulating layer 15c is provided with through holes 22 and 23, and the insulating layer 15d is provided with a through hole 24. Furthermore, an opening 25 is provided in the insulating layer 15d, and openings 26 and 27 are provided in the insulating layer 15e. The through holes 21 to 24 are portions in which through-hole conductors described later are embedded, and the openings 25 to 27 are portions in which the magnetic resin layer 14 is embedded.

  The conductor layer 16a is provided with bump electrodes 13a to 13d and first and fifth spiral conductors 31 and 35 arranged at different plane positions. As shown in FIG. 3, the outer peripheral ends 31a and 35a of the spiral conductors 31 and 35 are both connected to the bump electrode 13a. Further, the inner peripheral end 31b of the spiral conductor 31 coincides with the planar position of the through hole 21 provided in the insulating layer 15b, so that the through hole 21 can be removed even after the conductor layer 16a is covered with the insulating layer 15b. Exposed through. On the other hand, the inner peripheral end 35b of the spiral conductor 35 is open. In the present embodiment, when viewed from above, the winding direction from the outer peripheral end 31a of the spiral conductor 31 toward the inner peripheral end 31b is clockwise (clockwise), and the spiral conductor 35 has an outer peripheral end 35a to an inner peripheral end 35b. The winding direction toward is counterclockwise (counterclockwise). Further, a directional mark 50 is formed on the conductor layer 16a in the vicinity of the bump electrodes 13b and 13d.

  The conductor layer 16b is provided with bump electrodes 13a to 13d and second and sixth spiral conductors 32 and 36 arranged at different plane positions. As shown in FIG. 3, the outer peripheral ends 32a and 36a of the spiral conductors 32 and 36 are both connected to the bump electrode 13c. Further, the inner peripheral end 32b of the spiral conductor 32 coincides with the planar position of the through hole 23 provided in the insulating layer 15c, so that the through hole 23 remains after the conductor layer 16b is covered with the insulating layer 15c. Exposed through. On the other hand, the inner peripheral end 35b of the spiral conductor 35 is open. Furthermore, a through-hole conductor 41 is disposed on the conductor layer 16 b at the same plane position as the through-holes 21 and 22. In the present embodiment, when viewed from above, the winding direction from the outer peripheral end 32a of the spiral conductor 32 toward the inner peripheral end 32b is clockwise (clockwise), and the spiral conductor 36 has an outer peripheral end 36a to an inner peripheral end 36b. The winding direction toward is clockwise (clockwise). Directional marks 50 are also formed on the conductor layer 16b in the vicinity of the bump electrodes 13b and 13d.

  Bump electrodes 13a to 13d and a third spiral conductor 33 are provided on the conductor layer 16c. As shown in FIG. 3, the outer peripheral end 33a of the spiral conductor 33 is connected to the bump electrode 13b. Further, the inner peripheral end 33b of the spiral conductor 33 coincides with the planar position of the through hole 22 provided in the insulating layer 15c, and is thereby connected to the inner peripheral end 31b of the spiral conductor 31 through the through hole conductor 41. Is done. Furthermore, a through-hole conductor 42 is disposed on the conductor layer 16c at the same plane position as the through-holes 23 and 24. In this embodiment, when viewed from above, the winding direction from the outer peripheral end 33a of the spiral conductor 33 toward the inner peripheral end 33b is counterclockwise (counterclockwise).

  Bump electrodes 13a to 13d and a fourth spiral conductor 34 are provided on the conductor layer 16d. As shown in FIG. 3, the outer peripheral end 34a of the spiral conductor 34 is connected to the bump electrode 13d. Further, the inner peripheral end 34 b of the spiral conductor 34 coincides with the planar position of the through hole 24 provided in the insulating layer 15 d, and is thereby connected to the inner peripheral end 32 b of the spiral conductor 32 via the through hole conductor 42. Is done. In the present embodiment, when viewed from above, the winding direction from the outer peripheral end 34a to the inner peripheral end 34b of the spiral conductor 34 is counterclockwise (counterclockwise).

  As shown in FIG. 4, the planar positions of the spiral conductors 31 to 34 viewed from the stacking direction overlap each other, and the planar positions of the spiral conductors 35 and 36 viewed from the stacking direction also overlap each other.

  The spiral conductors 31 and 33 constitute the first coil (C1) by connecting the inner peripheral ends 31b and 33b in series via the through-hole conductors 41, respectively. One end of the first coil is connected to the bump electrode 13a, and the other end is connected to the bump electrode 13b. Similarly, the spiral conductors 32 and 34 constitute the second coil (C2) by connecting the inner peripheral ends 32b and 34b in series via the through-hole conductors 42, respectively. One end of the second coil is connected to the bump electrode 13c, and the other end is connected to the bump electrode 13d. One end (or the other end) of the first coil and one end (or the other end) of the second coil form a pair and are connected to the input side or the output side of the differential signal transmitted through the pair of signal lines. The pair of signal lines is formed on a printed board (not shown) on which the common mode noise filter 100 is mounted.

  As shown in FIG. 2, since the magnetic resin layer 14 is embedded in the openings 25 and 26, the magnetic resin layer 14 is disposed above the spiral conductors 35 and 36 through the conductor layers 16c and 16d. become. The reason why the magnetic resin layer 14 can be arranged in this portion is that the space above the spiral conductors 35 and 36 is an empty space, and by arranging the magnetic resin layer 14 here, the spiral conductors 35 and 36 are arranged. The inductance component (L component) can be increased.

  Furthermore, since the magnetic resin layer 14 is also embedded in the opening 27, the magnetic resin layer 14 is disposed through the inner peripheral portion of the spiral conductor 34. Thereby, the inductance of the common mode filter comprised by the spiral conductors 31-34 is raised. If such an opening 27 is also provided in the insulating layers 15b to 15d, the inductance of the common mode filter can be further increased, but higher manufacturing accuracy is required to realize this. The reason why the opening 27 is provided only in the insulating layer 15e in the present embodiment is to increase the inductance of the common mode filter as much as possible while ensuring mass productivity.

  FIG. 5 is an equivalent circuit diagram of the common mode noise filter 100 according to the present embodiment.

  As shown in FIG. 5, the common mode noise filter 100 according to the present embodiment includes a common mode filter F1 inserted between a pair of bump electrodes 13a and 13c and a pair of bump electrodes 13b and 13d, and a bump electrode. Differential mode filter F2 connected to 13a, 13c is included. The bump electrodes 13a to 13d are connected to a wiring pattern on a printed board on which the common mode noise filter 100 is to be mounted.

  The common mode filter F1 is a circuit in which two coils C1 and C2 are magnetically coupled in the same direction. That is, the winding direction from one end C1a (31a) of the coil C1 to the other end C1b (33a) and the winding direction from the one end C2a (32a) of the coil C2 to the other end C2b (34a) are the same. In addition, since the planar positions overlap, the coils C1 and C2 are magnetically coupled to each other in the same direction. More specifically, the coil C1 is composed of spiral conductors 31 and 33, and the winding direction from one end C1a to the other end C1b is clockwise (clockwise). Similarly, the coil C2 is composed of spiral conductors 32 and 34, and the winding direction from the one end C2a to the other end C2b is clockwise (clockwise).

  Here, “magnetic coupling in the same direction as each other” means that magnetic coupling is performed so that the magnetic flux is strengthened with respect to the in-phase component and the magnetic flux is canceled with respect to the differential component. On the other hand, “magnetic coupling in directions opposite to each other” means that magnetic coupling is performed so that the magnetic flux is strengthened with respect to the differential component and the magnetic flux is canceled with respect to the in-phase component. It is arbitrary whether one end side (C1a, C2a side) of the common mode filter F1 is a signal input side or the other end side (C1b, C2b side) of the common mode filter F1 is a signal input side. The selection can be confirmed by the direction mark 50.

  On the other hand, the differential mode filter F2 is composed of spiral conductors 35 and 36. The spiral conductors 35 and 36 are capacitively coupled to each other by their overlapping planar positions, the outer peripheral ends 35a and 36a are connected to the bump electrodes 13a and 13c, and the inner peripheral ends 35b and 36b are both open.

  With this configuration, a necessary differential signal component of the differential signal flowing through the common mode filter F1 is transmitted without being substantially affected by the common mode filter F1 and the differential mode filter F2. On the other hand, the common mode noise component of the differential signal flowing through the common mode filter F1 is attenuated by the common mode filter F1. Further, among the differential signals flowing through the common mode filter F1, differential mode noise in a desired frequency band is attenuated by the differential mode filter F2.

  The reason why the differential mode noise is attenuated by the spiral conductors 35 and 36 is that the inductance component (L component) of the spiral conductors 35 and 36 and the capacitance component (C component) between the spiral conductors 35 and 36 cause LC resonance. is there. Therefore, the frequency band to be attenuated by the spiral conductors 35 and 36 can be adjusted by these L component and C component.

  Here, since the common mode filter F1 only has to pass the differential signal component over a wide band and attenuate the common mode noise, the spiral conductors 31 to 34 constituting the common mode filter F1 are designed to meet the design value. Deviation between the L component and the C component is allowed to some extent. On the other hand, the differential mode filter F2 needs to attenuate the differential signal component in a desired frequency band without attenuating the necessary differential signal component, and therefore, the L component and the C component of the spiral conductors 35 and 36. For, it is necessary to set the value as designed very accurately.

  In consideration of this point, in the common mode noise filter 100 according to the present embodiment, as shown in FIGS. 2 and 3, the spiral conductors 35 and 36 constituting the differential mode filter F2 are formed on the lower conductor layers 16a and 16b. It is arranged. This is because the lower conductor layer has higher flatness and can be manufactured with higher accuracy. In this embodiment, the spiral conductor 35 is formed on the lowermost conductor layer 16a, and the spiral conductor 35 is formed on the second conductor layer 16b from the lowermost layer. The planar overlap can be controlled with high accuracy, and as a result, the designed L and C components can be realized.

  6A to 6D are diagrams showing variations in the magnetic coupling direction and connection direction of the spiral conductors 35 and 36. FIG.

  In the example shown in FIG. 6A, one ends 35a and 36a (outer ends) of the spiral conductors 35 and 36 are connected to the bump electrodes 13a and 13c, respectively, and the spiral conductors 35 and 36 are magnetically coupled in the same direction. An example is shown. In this example, since the winding directions from the one end 35a, 36a to the other end 35b, 36b are the same and the connection direction is the same, the magnetic coupling is in the same direction.

  In the example shown in FIG. 6B, the ends 35a and 36a (outer ends) of the spiral conductors 35 and 36 are connected to the bump electrodes 13a and 13c, respectively, and the spiral conductors 35 and 36 are magnetically coupled in the opposite direction. An example is shown. In this example, since the winding directions from the one end 35a, 36a to the other end 35b, 36b are opposite to each other and the connection direction is the same, the magnetic coupling is opposite to each other. This example corresponds to an equivalent circuit of the common mode noise filter 100 shown in FIGS.

  In the example shown in FIG. 6C, one end 35a (outer peripheral end) of the spiral conductor 35 and the other end 36b (inner peripheral end) of the spiral conductor 36 are respectively connected to the bump electrodes 13a and 13c, and the spiral conductor 35, An example is shown in which 36 is magnetically coupled in the opposite direction when viewed from one end 35a and the other end 36b (magnetically coupled in the same direction when viewed from one end 35a, 36a). In this example, since the winding directions from the one end 35a, 36a to the other end 35b, 36b are the same and the connection direction is opposite, the magnetic coupling is in the opposite direction.

  In the example shown in FIG. 6D, one end 35a (outer peripheral end) of the spiral conductor 35 and the other end 36b (inner peripheral end) of the spiral conductor 36 are connected to the bump electrodes 13a and 13c, respectively, 36 shows an example in which 36 is magnetically coupled in the same direction when viewed from one end 35a and the other end 36b (magnetically coupled in the opposite direction when viewed from one end 35a, 36a). In this example, since the winding directions from the one end 35a, 36a to the other end 35b, 36b are opposite to each other and the connection direction is also opposite, the magnetic coupling is in the same direction.

  In both the pattern shown in FIG. 6A and the pattern shown in FIG. 6D, the spiral conductors 35 and 36 are magnetically coupled in the same direction, and therefore, these patterns have almost the same characteristics. Specifically, differential mode noise in a relatively low frequency band is removed. On the other hand, in both the pattern shown in FIG. 6B and the pattern shown in FIG. 6C, the spiral conductors 35 and 36 are magnetically coupled in the opposite directions, so that these patterns have almost the same characteristics. It is done. Specifically, differential mode noise in a relatively high frequency band is removed.

  FIG. 7 is a graph showing the pass characteristic of the differential component.

  A characteristic A shown in FIG. 7 is a pass characteristic of the common mode noise filter having the pattern shown in FIG. A characteristic B shown in FIG. 7 is a pass characteristic of the common mode noise filter having the pattern shown in FIG. 6B or 6C. Furthermore, a characteristic C shown in FIG. 7 is a pass characteristic of a common mode noise filter obtained by removing the spiral conductors 35 and 36 from the patterns shown in FIGS. All the common mode noise filters have the same shape and size as the common mode filter F1. In the common mode noise filter having the characteristics A and B, the shapes and sizes of the spiral conductors 35 and 36 are substantially the same.

  As shown in FIG. 7, an ordinary common mode filter in which the spiral conductors 35 and 36 are not provided has less attenuation of the differential component over a high frequency range as indicated by the characteristic C. In contrast, when the spiral conductors 35 and 36 that are magnetically coupled in the same direction are connected, as shown in the characteristic A, an attenuation peak appears at the frequency f1. When the spiral conductors 35 and 36 that are magnetically coupled in the opposite direction are connected, as shown in the characteristic B, an attenuation peak appears at the frequency f2 (> f1). Thus, by adding the spiral conductors 35 and 36, the differential component in a specific frequency band can be attenuated, and the frequency band can be adjusted by the direction of magnetic coupling.

  As described above, the common mode noise filter 100 according to the present embodiment can remove not only common mode noise but also differential mode noise in a desired frequency band. In addition, since it is configured by a single component and each spiral conductor is provided on the substrate, surface mounting can be performed on the printed circuit board.

  Furthermore, since the spiral conductors 35 and 36 are provided on the conductor layers 16a and 16b closer to the magnetic substrate 11, the flatness of the base is sufficiently ensured at the time of manufacture. This is because the film formation at the time of fabrication is sequentially performed from the side closer to the magnetic substrate 11, so that the insulating layer closer to the magnetic substrate 11 has higher flatness. Thereby, since the spiral conductors 35 and 36 can be produced with high accuracy, the resonance frequency of the differential mode filter F2 can be made as designed. In addition, since the spiral conductors 35 and 36 are disposed at different plane positions from the spiral conductors 31 to 34 constituting the common mode filter F1, magnetic interference between the common mode filter F1 and the differential mode filter F2 is prevented. It can also be suppressed. Moreover, the increase in the planar area of the magnetic substrate 11 caused by this is suppressed by forming the spiral conductors constituting the common mode filter F1 over four layers.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

  For example, in the above embodiment, the coils C1 and C2 constituting the common mode filter F1 are each constituted by two spiral conductors, but each coil C1 and C2 may be constituted by three or more spiral conductors. Absent.

  In the above embodiment, the coil C1 is formed by the spiral conductors 31 and 33 formed in the first and third layers from the lowest layer, and the spiral conductors 32 and 33 formed in the second and fourth layers are formed. Although the coil C2 is formed by 34, this point is not essential in the present invention. However, if the spiral conductors formed in each layer are connected alternately as in the above embodiment, the magnetic coupling and symmetry of the coils C1 and C2 can be enhanced, and the characteristics of the common mode filter F1 can be improved. .

  Further, the planar shape of each of the spiral conductors 31 to 36 is not particularly limited, and may be substantially rectangular as shown in FIG. 3 or the like, or may be circular or elliptical.

11 Magnetic substrate 12 Thin film coil layers 13a to 13d Bump electrode 14 Magnetic resin layers 15a to 15e Insulating layers 16a to 16d Conductive layers 20a to 20d Openings 21 to 24 Through holes 25 to 27 Openings 31 to 36 Spiral conductors 41 and 42 Through Hall conductor 50 Directional mark 100 Common mode noise filter C1, C2 Coil F1 Common mode filter F2 Differential mode filter

Claims (5)

A substrate, first to fourth insulating layers provided in this order on the substrate, and first to fourth conductor layers respectively provided on the first to fourth insulating layers;
In the first conductor layer, first and fifth spiral conductors are formed at different planar positions,
In the second conductor layer, second and sixth spiral conductors are formed at different planar positions,
Third and fourth spiral conductors are formed in the third and fourth conductor layers, respectively.
The planar positions of the first to fourth spiral conductors overlap each other,
The planar positions of the fifth and sixth spiral conductors overlap each other,
Of the first to fourth spiral conductors, two spiral conductors constitute a first coil by being connected in series,
The remaining two spiral conductors of the first to fourth spiral conductors are connected in series to form a second coil,
The fifth spiral conductor has one end connected to one end of the first coil and the other end open.
The sixth spiral conductor has one end connected to one end of the second coil that forms a pair with the one end of the first coil, and the other end is open. .   2. The common according to claim 1, wherein the first coil is constituted by the first and third spiral conductors, and the second coil is constituted by the second and fourth spiral conductors. Mode noise filter. An outer peripheral end of the first spiral conductor and an outer peripheral end of the fifth spiral conductor are connected in the first conductor layer;
An outer peripheral end of the second spiral conductor and an outer peripheral end of the sixth spiral conductor are connected in the second conductor layer;
An inner peripheral end of the first spiral conductor and an inner peripheral end of the third spiral conductor are connected via a first through-hole conductor provided through the second and third insulating layers ,
An inner peripheral end of the second spiral conductor and an inner peripheral end of the fourth spiral conductor are connected via a second through-hole conductor provided through the third and fourth insulating layers. The common mode noise filter according to claim 2, wherein 4. The magnetic member provided so as to penetrate the fourth insulating layer is disposed above the fifth and sixth spiral conductors. 5. Common mode noise filter as described.   The common mode noise filter according to claim 4, wherein the magnetic member is also disposed at least on an inner periphery of the fourth spiral conductor.

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