JP2013207150A - Common mode filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a common mode filter that can reduce the overall thickness of a printed wiring board and also ensure packaging space for other electronic components.SOLUTION: A common mode filter 1 includes: an annular core 2 disposed inside a printed wiring board 10 formed by lamination; and a pair of coils 3A and 3B disposed line-symmetrically in the same orientation on the core 2. Each of the pair of coils 3A and 3B is comprised of: a plurality of first wiring patterns 4a and 4b disposed on a layer surface of an upper layer on the printed wiring board 10 than the core 2; a plurality of second wiring patterns 5a and 5b disposed on a layer surface of a lower layer on the printed wiring board 10 than the core 2; and a plurality of vias 6a and 6b for connecting the plurality of first wiring patterns 4a and 4b and the plurality of second wiring patterns 5a and 5b into a spiral shape along the core 2.

Description

  The present invention relates to a common mode filter.

  In the electronic control device, a large number of electronic components are mounted on a printed wiring board. However, when this electronic control device is operated, common mode noise may occur. For this reason, a common mode filter for removing common mode noise is mounted on the printed wiring board. As the common mode filter, a line-symmetric coil wound around the annular core in the same direction is used.

  Patent Document 1 below discloses a noise filter mounted on a printed wiring board. This noise filter is a surface mount type common mode noise filter and is mounted on a structural support. The structural support is provided with a set of input terminals and a set of output terminals. The noise filter is surface-mounted by connecting the wirings of the coil windings in pairs to one and the other of the input terminals and to one and the other of the output terminals, respectively.

JP 2004-95786 A

  By the way, in the said prior art, since the common mode filter containing a winding and a core is mounted on a structure support body, there exists a problem that the thickness of the whole printed wiring board will increase and it will enlarge. Moreover, since the common mode filter occupies a large mounting space on the printed wiring board, there is a problem that the mounting space for other electronic components is reduced.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a common mode filter capable of reducing the thickness of the entire printed wiring board and securing a mounting space for other electronic components. .

  In order to solve the above problems, the present invention includes an annular core provided inside a laminated printed wiring board, and a pair of coils provided symmetrically in the same direction on the core. Each of the pair of coils is provided on a lower layer surface of the printed wiring board than the core, and a plurality of first wiring patterns provided on an upper layer surface of the printed wiring board than the core. A plurality of second wiring patterns, and a plurality of vias that connect the plurality of first wiring patterns and the plurality of second wiring patterns in a spiral shape along the core. Adopt a filter.

  In the present invention, a configuration is adopted in which the core is a third wiring pattern provided on a layer surface between the upper layer surface and the lower layer surface of the printed wiring board.

  In the present invention, a configuration is adopted in which the third wiring pattern is provided on a plurality of layer surfaces between the upper layer surface and the lower layer surface of the printed wiring board.

  In the present invention, a configuration is adopted in which the core is made of ferrite or a dust core.

  In the present invention, a core is provided inside a printed wiring board having a laminated structure, and a common mode filter is three-dimensionally formed inside the printed wiring board by a combination of wiring patterns and vias. Since a function as a common mode filter can be added, the thickness of the entire printed wiring board can be reduced, and a mounting space for other electronic components can be secured.

It is a top view which shows the common mode filter in embodiment of this invention. It is a perspective view which shows the common mode filter in embodiment of this invention. It is sectional drawing which shows the common mode filter in embodiment of this invention. It is a top view which shows the core of the common mode filter in another embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing a common mode filter 1 according to an embodiment of the present invention. FIG. 2 is a perspective view showing the common mode filter 1 in the embodiment of the present invention. FIG. 3 is a cross-sectional view showing the common mode filter 1 in the embodiment of the present invention. FIG. 3 corresponds to a cross section taken along the line AA in FIG.
As is well known, the common mode filter 1 of the present embodiment removes common mode noise, and has a pair of coils 3A and 3B provided on the annular core 2 in line symmetry in the same direction. The common mode filter 1 is configured as follows.

  Reference numeral 10 denotes a printed wiring board. The printed wiring board 10 is a multilayer board formed by laminating a plurality of plate-like boards made of an insulating material such as a glass epoxy material or a glass composite material. As shown in FIG. 3, the printed wiring board 10 of the present embodiment is a four-layer board including a first layer 10A, a second layer 10B, a third layer 10C, and a fourth layer 10D. Note that the number of stacked printed wiring boards 10 may be two or more, for example, more than four.

  The printed wiring board 10 has a plurality of layer surfaces (20A to 20E). The first layer surface 20A is the surface of the printed wiring board 10 and is the upper surface of the first layer 10A. The second layer surface 20B is a connection surface between the lower surface of the first layer 10A and the upper surface of the second layer 10B. The third layer surface 20C is a connection surface between the lower surface of the second layer 10B and the upper surface of the third layer 10C. The fourth layer surface 20D is a connection surface between the lower surface of the third layer 10C and the upper surface of the fourth layer 10D. The fifth layer surface 20E is the lower surface of the fourth layer 10D and the back surface of the printed wiring board 10.

  The core 2 is formed in an annular shape as shown in FIG. The core 2 of this embodiment is formed in a rectangular ring shape in plan view. The core 2 is provided inside the printed wiring board 10. As shown in FIGS. 2 and 3, two cores 2 of the present embodiment are provided, and are arranged so as to overlap in a plan view. The core 2 is provided on the second layer surface 20B and the third layer surface 20C. The core 2 of the present embodiment is a conductor wiring pattern (third wiring pattern), and can be formed by etching, for example, similarly to a wiring pattern described later.

As shown in FIG. 1, the coil 3 </ b> A is provided along the core 2. In addition, the coil 3A is provided in a spiral shape around the core 2 as shown in FIG. The coil 3A includes a first wiring pattern 4a, a second wiring pattern 5a, and a via 6a.
The first wiring pattern 4a and the second wiring pattern 5a are conductors such as copper and can be formed by etching. The via 6 a is a conductor plating hole that connects the layers of the printed wiring board 10.

  As shown in FIG. 3, the first wiring pattern 4 a is provided on the first layer surface 20 </ b> A (the surface of the printed wiring board 10) of the first layer 10 </ b> A that is an upper layer than the core 2. As shown in FIG. 1, the first wiring pattern 4 a is provided so as to straddle the inner ring side and the outer ring side of the core 2 in a plan view. Further, a plurality of first wiring patterns 4a are provided in parallel on the one side 2a of the rectangular core 2 in plan view with a space therebetween. The plurality of first wiring patterns 4a are respectively provided so as to cross at an angle with respect to one side 2a of the core 2 having a rectangular shape in plan view.

  As shown in FIG. 3, the second wiring pattern 5 a is provided on the fourth layer surface 20 </ b> D of the fourth layer 10 </ b> D that is lower than the core 2. As shown in FIG. 1, the second wiring pattern 5 a is provided so as to straddle the inner ring side and the outer ring side of the core 2 in a plan view. In addition, a plurality of second wiring patterns 5a are provided in parallel at intervals on one side 2a of the rectangular core 2 in plan view where the first wiring patterns 4a are provided. The plurality of second wiring patterns 5a are provided so as to incline and intersect with one side 2a of the rectangular core 2 in plan view at a predetermined angle (an angle displaced by 180 ° with respect to the corresponding first wiring pattern 4a). Yes.

  As shown in FIG. 2, the via 6 a connects a plurality of first wiring patterns 4 a and a plurality of second wiring patterns 5 a along the core 2 in a spiral shape, and a plurality of vias 6 a are provided. Yes. As shown in FIG. 3, the via 6a electrically connects the first wiring pattern 4a on the first layer surface 20A and the second wiring pattern 5a on the fourth layer surface 20D. As shown in FIG. 1, the via 6 a connects the first wiring pattern 4 a and the second wiring pattern 5 a that overlap each other in plan view on the inner ring side and the outer ring side of the core 2. As shown in FIG. 2, the vias 6a alternately connect the first wiring patterns 4a and the second wiring patterns 5a in series to form a spiral coil 3A.

  As shown in FIG. 1, the coil 3 </ b> B is provided symmetrically in the same direction as the coil 3 </ b> A with a straight line L that bisects the core 2 in a plane as a target axis. The coil 3 </ b> B is provided along the core 2. The coil 3 </ b> B is provided in a spiral shape around the core 2. Note that the basic configuration of the coil 3B is the same as that of the coil 3A, and therefore the description of the same or equivalent components as the coil 3A is simplified or omitted.

The coil 3B includes a first wiring pattern 4b, a second wiring pattern 5b, and a via 6b.
The first wiring pattern 4b and the second wiring pattern 5b are conductors such as copper, and can be formed by etching simultaneously with the first wiring pattern 4a and the second wiring pattern 5a. The via 6 b is a plated hole for a conductor that connects the layers of the printed wiring board 10.

  The first wiring pattern 4b is provided on the same first layer surface 20A as the first wiring pattern 4a. A plurality of first wiring patterns 4b are provided in parallel on the opposite side 2b on one side 2a of the rectangular core 2 in plan view where the coil 3A is provided. The plurality of first wiring patterns 4b are respectively provided so as to incline and intersect with the opposite side 2b of the rectangular core 2 in plan view at a predetermined angle (an angle displaced by 180 ° with respect to the first wiring pattern 4a).

  The second wiring pattern 5b is provided on the same fourth layer surface 20D as the second wiring pattern 5a. A plurality of second wiring patterns 5b are provided in parallel on the opposite side 2b of the rectangular core 2 in plan view at intervals. The plurality of second wiring patterns 5b are respectively provided so as to incline and intersect with the opposite side 2b of the rectangular core 2 in plan view at a predetermined angle (an angle displaced by 180 ° with respect to the corresponding first wiring pattern 4b). Yes.

  The via 6b connects the plurality of first wiring patterns 4b and the plurality of second wiring patterns 5b so as to form a spiral along the core 2, and a plurality of vias 6b are provided. The via 6b connects the first wiring pattern 4b and the second wiring pattern 5b, which overlap each other in plan view on the inner ring side and the outer ring side of the core 2, respectively. By this via 6b, the first wiring pattern 4b and the second wiring pattern 5b are alternately connected in series to form a spiral coil 3B.

  According to the common mode filter 1 having the above-described configuration, the core 2 is provided inside the printed wiring board 10 that is a multilayer substrate having a multilayer structure, and the first wiring patterns 4a and 4b, the second wiring patterns 5a and 5b, and the vias 6a, A pair of line-symmetrical coils 3A and 3B can be provided by the combination of 6b, and the common mode filter 1 can be formed three-dimensionally inside the printed wiring board 10. Therefore, the function as the common mode filter 1 can be added to the printed wiring board 10 without mounting a large common mode filter in the surface layer mounting space of the printed wiring board 10. In addition, by forming the coils 3A and 3B with the wiring pattern in this way, a pair of line symmetrical coils 3A and 3B can be formed accurately and easily.

  According to the common mode filter 1 configured as described above, the thickness of the entire printed wiring board 10 can be reduced. In addition, according to the common mode filter 1 having the above configuration, for example, an electronic component can be mounted on the fifth layer surface 20 </ b> E that is the back surface of the printed wiring board 10. Therefore, according to the present embodiment, it is possible to secure a mounting space for electronic components on the printed wiring board 10.

In the present embodiment, since the core 2 is a wiring pattern, the core 2 can be formed by etching or the like like other wiring patterns, and the printed wiring board 10 including the common mode filter 1 is efficiently manufactured. be able to.
In the present embodiment, since the core 2 and the pair of coils 3A and 3B are formed by a wiring pattern by etching, the common mode filter 1 can have a precise line symmetrical structure. For this reason, the filter performance can be improved as compared with the conventional case.
In the present embodiment, the core 2 is provided on the second layer surface 20B and the third layer surface 20C between the upper first layer surface 20A and the lower fourth layer surface 20D of the printed wiring board 10. Inductance increases, leakage magnetic flux can be reduced, and generation of eddy current can be suppressed because the second layer 10B as an insulating substrate is sandwiched therebetween.

  Therefore, according to the above-described embodiment, the annular core 2 provided inside the laminated printed wiring board 10 and the pair of coils 3A, 3B provided in the core 2 in line symmetry with the same direction. Each of the pair of coils 3A and 3B has a plurality of first wiring patterns 4a and 4b provided on the upper first layer surface 20A of the printed wiring board 10 than the core 2 and the core 2 The plurality of second wiring patterns 5a and 5b provided on the lower fourth layer surface 20D of the printed wiring board 10 and the plurality of first wiring patterns 4a and 4b and the plurality of second wiring patterns 5a and 5b are used as the core 2. By adopting the common mode filter 1 formed by a plurality of vias 6a and 6b connected so as to be spiral along, the thickness of the entire printed wiring board 10 can be reduced, One, it is possible to ensure a mounting space for other electronic components.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be employ | adopted.
FIG. 4 is a diagram showing the core 2 of the common mode filter 1 according to another embodiment of the present invention.

(1) In the present embodiment, the core 2 is a wiring pattern, but the present invention is not limited to this configuration. For example, as shown to Fig.4 (a), you may comprise so that the core 2 may consist of a ferrite or a dust core. According to this configuration, the core 2 has a high magnetic permeability, and the electrical resistance is increased, so that the generation of eddy current can be effectively suppressed. When this configuration is adopted, the core 2 can be formed by incorporating a ferrite or a dust core as a component into the printed wiring board 10.

(2) In the present embodiment, the core 2 is formed in a strip shape when it is a wiring pattern, but the present invention is not limited to this configuration. For example, since the shape of the wiring pattern can be easily adjusted by etching, the concentric annular core 2 may be formed by dividing the wiring pattern into a plurality of parts in the width direction, as shown in FIG. 4B. Since an insulating material (such as an adhesive) (not shown) is filled between the two patterns, generation of eddy current can be effectively suppressed.

(3) For example, as a countermeasure against eddy currents, a configuration may be adopted in which a plurality of holes are provided in the wiring pattern forming the core 2 to increase the electrical resistance.

(4) Further, for example, as a measure against copper loss, the connection portion between the first wiring pattern 4a and the via 6a is thick, and the connection portion between the second wiring pattern 5a and the via 6a is thick. A configuration may be employed in which the electrical resistance in the connection portion is lowered by partially thickening the vias 6a and 6b in the connection portion and increasing the plating thickness.

(5) Also, for example, when the core 2 is formed with a wiring pattern, the width can be easily adjusted. For example, the portion where the pair of coils 3A and 3B is wound is made thicker and larger than the other portions. Such a configuration may be adopted.

  DESCRIPTION OF SYMBOLS 1 ... Common mode filter, 2 ... Core, 3A, 3B ... A pair of coils, 4a, 4b ... 1st wiring pattern, 5a, 5b ... 2nd wiring pattern, 6a, 6b ... Via, 10 ... Printed wiring board, 10A ... 1st layer, 10B ... 2nd layer, 10C ... 3rd layer, 10D ... 4th layer, 20A ... 1st layer surface, 20B ... 2nd layer surface, 20C ... 3rd layer surface, 20D ... 4th layer surface, 20E ... 5th Layer

Claims (4)

An annular core provided inside the laminated printed wiring board;
A pair of coils provided in line symmetry in the same direction in the core,
Each of the pair of coils is
A plurality of first wiring patterns provided on an upper layer surface of the printed wiring board from the core, a plurality of second wiring patterns provided on a lower layer surface of the printed wiring board from the core, and the plurality Formed by a plurality of vias that connect the first wiring pattern and the plurality of second wiring patterns in a spiral shape along the core,
A common mode filter characterized by that.   The common mode filter according to claim 1, wherein the core is a third wiring pattern provided on a layer surface between the upper layer surface and the lower layer surface of the printed wiring board.   The common mode filter according to claim 2, wherein the third wiring pattern is provided on a plurality of layer surfaces between the upper layer surface and the lower layer surface of the printed wiring board.   The common mode filter according to claim 1, wherein the core is made of a ferrite or a dust core.

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