Patent ID: 12243670

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A common mode noise filter according to aspects of the present disclosure will now be described.

A common mode noise filter according to a first aspect includes a first insulator layer, a first conductor, and a second conductor. The first insulator layer includes a main surface and a back surface. The first conductor is disposed on the back surface of the first insulator layer. The second conductor is disposed on the main surface of the first insulator layer. The first conductor includes a first spiral body, a first pad, and a first connecting portion. The first spiral body is disposed at a position where at least part of the first spiral body overlaps the second conductor as viewed from a direction that the main surface of the first insulator layer faces. The first spiral body is in a spiral shape. The first pad is disposed inside the first spiral body on the back surface of the first insulator layer. The first connecting portion connects the first spiral body and the first pad on the back surface of the first insulator layer. The second conductor includes a second spiral body, a second pad, and a second connecting portion. The second spiral body is disposed at a position where at least part of the second spiral body overlaps the first conductor as viewed from the direction that the main surface of the first insulator layer faces. The second spiral body is in a spiral shape. The second pad is disposed inside the second spiral body on the main surface of the first insulator layer. The second connecting portion includes a pair of side edges. The second connecting portion connects the second spiral body and the second pad on the main surface of the first insulator layer. The first pad is disposed at a position where the first pad does not overlap the second spiral conductor as viewed from the direction that the main surface of the first insulator layer faces.

In the common mode noise filter according to a second aspect, the second pad is disposed at a position where the second pad does not overlap the first spiral conductor as viewed from the direction that the main surface of the first insulator layer faces in the first aspect.

In the common mode noise filter according to a third aspect, the first connecting portion includes a pair of side edges in the first or second aspect. Furthermore, the second pad includes a portion that does not overlap the first spiral conductor and a portion that overlaps the first connecting portion as viewed from the direction that the main surface of the first insulator layer faces. Moreover, the portion where the second pad overlaps the first connecting portion overlaps one of the pair of side edges of the first connecting portion and does not overlap the other one of the pair of side edges, as viewed from the direction that the main surface of the first insulator layer faces.

In the common mode noise filter according to a fourth aspect, the second connecting portion includes a pair of side edges in any one of the first to third aspects. Furthermore, the first pad includes a portion that does not overlap the second spiral conductor and a portion that overlaps the second connecting portion as viewed from the direction that the main surface of the first insulator layer faces. Moreover, the portion where the first pad overlaps the second connecting portion overlaps one of the pair of side edges of the second connecting portion and does not overlap the other one of the pair of side edges, as viewed from the direction that the main surface of the first insulator layer faces.

The common mode noise filter according to a fifth aspect includes a second insulator layer, a third insulator layer, a first lead-out conductor, and a second lead-out conductor in any one of the first to fourth aspects. The second insulator layer covers the first spiral body on the back surface of the first insulator layer. The third insulator layer covers the second spiral body on the main surface of the first insulator layer. The first lead-out conductor is disposed on the back surface of the second insulator layer. One end of the first lead-out conductor is connected to the first pad. The second lead-out conductor is disposed on the main surface of the third insulator layer. One end of the second lead-out conductor is connected to the second pad. The first lead-out conductor does not overlap the second lead-out conductor as viewed from the main surface of the first insulator layer.

The common mode noise filter according to a sixth aspect includes a magnetic core that passes through the first insulator layer in any one of the first to fifth aspects. The magnetic core is disposed inside the first spiral body as viewed from the direction that the main surface of the first insulator layer faces, the magnetic core being on neither the first pad nor the second pad.

The common mode noise filter according to a seventh aspect has the following characteristics in any one of the first to sixth aspects. Specifically, first line segment length w1is defined as the length of the shortest line segment that crosses the first pad and the second pad and connects two points on the inner peripheral side of the spiral shape of the first spiral conductor, as viewed from the direction that the main surface of the first insulator layer faces. Second line segment length w2is defined as the length of the shortest line segment that is parallel to the first line segment, crosses the magnetic core, and connects two points on the inner peripheral side of the spiral shape of the first spiral conductor. In this case, w1<w2.

In the common mode noise filter according to an eighth aspect, the first spiral conductor includes the first spiral body that has a linear portion and a curved portion in any one of the first to seventh aspects. Furthermore, the second spiral conductor includes the second spiral body that has a linear portion and a curved portion.

In the common mode noise filter according to a ninth aspect, the first lead-out conductor includes a portion that overlaps the linear portion of the first spiral conductor in the eighth aspect, as viewed from the direction that the main surface of the first insulator layer faces. The second lead-out conductor includes a portion that overlaps the linear portion of the second spiral conductor as viewed from the direction that the main surface of the first insulator layer faces.

The common mode noise filter according to a tenth aspect includes a third lead-out conductor that is connected to an outer side of the first spiral body in any one of the first to ninth aspects. The common mode noise filter further includes a fourth lead-out conductor that is connected to an outer side of the second spiral body. The common mode noise filter includes a first lead-out portion that connects the outer side of the first spiral body and the third lead-out conductor. The common mode noise filter further includes a second lead-out portion that connects the outer side of the second spiral body and the fourth lead-out conductor. The first lead-out portion does not overlap the second lead-out portion as viewed from the direction that the main surface of the first insulator layer faces.

In the common mode noise filter according to an eleventh aspect, the first pad and the second pad do not overlap each other as viewed from the direction that the main surface of the first insulator layer faces in any one of the first to tenth aspects.

The following describes one exemplary embodiment of the present disclosure. Note that the size of the common mode noise filter according to the present disclosure and the material and size of each of the layers included in the filter are merely examples, and that the technical scope of the common mode noise filter according to the present disclosure is not limited to any value or material disclosed herein.

One Exemplary Embodiment

FIG.1is an exploded perspective view of a common mode noise filter according to one exemplary embodiment of the present disclosure.FIG.2is a cross-sectional view of the common mode noise filter according to one exemplary embodiment of the present disclosure.FIG.3is a perspective view of the common mode noise filter according to one exemplary embodiment of the present disclosure.

As illustrated inFIG.3, the common mode noise filter according to one exemplary embodiment of the present disclosure includes stacked body12and first to fourth external electrodes13ato13ddisposed outside stacked body12. As illustrated inFIGS.1and2, stacked body12includes first to fifth insulator layers11ato11estacked along a vertical direction. Stacked body12further includes first spiral conductor14, second spiral conductor15, first to fourth lead-out conductors16to19, first coil20, and second coil21, all of which are formed inside. First lead-out conductor16, first spiral conductor14, and third lead-out conductor18are connected to provide first coil20. Second lead-out conductor17, second spiral conductor15, and fourth lead-out conductor19are connected to provide second coil21.

Note that, inFIG.1, the direction along the longer side of stacked body12is denoted as X axis, the direction along the shorter side thereof is denoted as Y axis, and the direction along which first to fifth insulator layers11ato11eare stacked is denoted as Z axis.

Here, dimensions of the common mode noise filter are 2 mm long (X direction), 1.5 mm wide (Y direction), and 1.5 mm high (Z direction). Note that each of first to fifth insulator layers11ato11ehas a layer thickness of 60 μm.

First spiral conductor14and second spiral conductor15face each other across first insulator layer11a. First insulator layer11ahas a main surface (upper surface) and a back surface (lower surface) on the side opposite to the main surface. Second spiral conductor15is disposed on the main surface of first insulator layer11a. First spiral conductor14is disposed on the back surface of first insulator layer11a. One end16aof first lead-out conductor16is connected to first external electrode13a. One end17aof second lead-out conductor17is connected to third external electrode13c. One end18aof third lead-out conductor18is connected to second external electrode13b. One end19aof fourth lead-out conductor19is connected to fourth external electrode13d.

In the above configuration, fourth insulator layer11dis made of a magnetic material such as Cu—Ni—Zn ferrite or a non-magnetic material such as Cu—Zn ferrite or glass ceramics to be formed into a sheet and has insulating properties.

In addition, first lead-out conductor16and third lead-out conductor18are each formed by plating or printing a conductive material such as silver on the upper surface of fourth insulator layer11d. Note that first lead-out conductor16and third lead-out conductor18are led out from fourth insulator layer11din opposite directions. One end16aof first lead-out conductor16is connected to first external electrode13a, while one end18aof third lead-out conductor18is connected to second external electrode13b.

Second insulator layer11bis made of a non-magnetic material such as Cu—Zn ferrite or glass ceramics to be formed into a sheet, has insulating properties, and is disposed on the upper surfaces of first lead-out conductor16and third lead-out conductor18. In addition, second insulator layer11bincludes first via electrode22aand second via electrode22b.

Here, first lead-out conductor16and first via electrode22aare connected. Likewise, third lead-out conductor18and second via electrode22bare connected.

Furthermore, first spiral conductor14is formed by plating or printing a conductive material such as silver in a spiral manner. First spiral conductor14is disposed on the upper surface of second insulator layer11b. Furthermore, one end (inner end) of first spiral conductor14, that is, a portion in the center of the spiral, is connected to first via electrode22a. Accordingly, first spiral conductor14is electrically connected to first lead-out conductor16via first via electrode22a.

The other end (outer end) of first spiral conductor14is connected to second via electrode22b. Accordingly, first spiral conductor14is electrically connected to third lead-out conductor18via second via electrode22b.

This configuration results in forming first coil20that includes first spiral conductor14and first and third lead-out conductors16and18connected thereto.

Furthermore, on fourth insulator layer11d, there are first lead-out conductor16and third lead-out conductor18, both of which are connected to first spiral conductor14. Accordingly, first spiral conductor14is electrically connected to first external electrode13avia first lead-out conductor16. Likewise, first spiral conductor14is electrically connected to second external electrode13bvia third lead-out conductor18.

Note that third lead-out conductor18may be formed on second insulator layer11b. In this case, second via electrode22bis unnecessary.

First insulator layer11ais made of a non-magnetic material such as Cu—Zn ferrite or glass ceramics to be formed into a sheet, has insulating properties, and is disposed on the upper surface of first spiral conductor14.

In addition, second spiral conductor15is formed by plating or printing a conductive material such as silver in a spiral manner, and is disposed on the upper surface of first insulator layer11a. Furthermore, second spiral conductor15and first spiral conductor14face each other across first insulator layer11aso as overlap each other as viewed from above the upper surface of first insulator layer11a(from the direction that the main surface faces as viewed from first insulator layer11a, that is, from the positive direction of the Z axis), so that first and second spiral conductors14and15are magnetically coupled. Viewing from above the upper surface of first insulator layer11ais hereinafter referred to as “top view”.

Third insulator layer11cis made of a non-magnetic material such as Cu—Zn ferrite or glass ceramics to be formed into a sheet, has insulating properties, and is disposed on the upper surface of second spiral conductor15.

In third insulator layer11c, third via electrode22cand fourth via electrode22dare formed. One end (inner end) of second spiral conductor15, that is, a portion in the center of the spiral, is connected to third via electrode22c. The other end (outer end) of second spiral conductor15is connected to fourth via electrode22d.

Second lead-out conductor17and fourth lead-out conductor19are each formed by plating or printing a conductive material such as silver on the upper surface of third insulator layer11c. Note that second lead-out conductor17and fourth lead-out conductor19are led out from third insulator layer11cin opposite directions.

Second lead-out conductor17is connected to third via electrode22c. Accordingly, second lead-out conductor17is electrically connected to the inner end of second spiral conductor15via third via electrode22c. Fourth lead-out conductor19is connected to fourth via electrode22d. Accordingly, fourth lead-out conductor19is electrically connected to the outer end of second spiral conductor15via fourth via electrode22d.

This configuration results in forming second coil21that includes second spiral conductor15, second lead-out conductor17, and fourth lead-out conductor19.

Furthermore, on third insulator layer11c, second lead-out conductor17and fourth lead-out conductor19, both of which are connected to second spiral conductor15, are formed. Second spiral conductor15is connected to third external electrode13cvia second lead-out conductor17. In addition, second spiral conductor15is connected to fourth external electrode13dvia fourth lead-out conductor19.

Note that fourth lead-out conductor19connected to the outer end of second spiral conductor15may be formed on first insulator layer11a. In this case, fourth via electrode22dis unnecessary.

First via electrode22aand second via electrode22bare each formed by filling a hole that is created through second insulator layer11bwith a conductive material such as silver. Third via electrode22cand fourth via electrode22dare each formed by filling a hole that is created through third insulator layer11cwith a conductive material such as silver.

Fifth insulator layer11eis made of a magnetic material such as Cu—Ni—Zn ferrite or a non-magnetic material such as Cu—Zn ferrite or glass ceramics to be formed into a sheet, has insulating properties, and is disposed on the upper surfaces of second lead-out conductor17and fourth lead-out conductor19.

Furthermore, on the lower surface of fourth insulator layer11dand on the upper surface of fifth insulator layer11e, there is disposed dummy portion23in which magnetic material layers11fand non-magnetic material layers11gare stacked alternately. Magnetic material layers11fand non-magnetic material layers11gare each formed into a sheet and have insulating properties. Note that dummy portion23may include magnetic material layer11fonly or non-magnetic material layer11gonly.

In addition, the number of layers constituting first to fifth insulator layers11ato11eand dummy portion23is not limited to the number shown inFIG.1.

As described above, stacked body12is formed by stacking first to fifth insulator layers11ato11eand dummy portions23. Furthermore, first to fourth external electrodes13ato13dare disposed on both end faces of stacked body12. First external electrode13ais electrically connected to one end16aof first lead-out conductor16. Second external electrode13bis electrically connected to one end17aof second lead-out conductor17. Third external electrode13cis electrically connected to one end18aof third lead-out conductor18. Fourth external electrode13dis electrically connected to one end19aof fourth lead-out conductor19.

Note that, through first to fifth insulator layers11ato11e, a through hole is provided in a portion corresponding to the inside of first spiral conductor14and second spiral conductor15in top view. The through hole is filled with a magnetic material to provide magnetic core24so as to increase the common mode impedance of the common mode noise filter.

FIG.4is a schematic diagram mainly showing a positional relationship among components. Referring toFIG.4, the following describes first spiral conductor14, second spiral conductor15, and first to fourth lead-out conductors16to19in detail.

FIG.4shows, from top to bottom, top views of second lead-out conductor17and fourth lead-out conductor19present in third insulator layer11c, second spiral conductor15present in first insulator layer11a, first spiral conductor14present in second insulator layer11b, and first lead-out conductor16and third lead-out conductor18present in fourth insulator layer11d.

On the upper surface of third insulator layer11c, there are disposed second lead-out conductor17, fourth lead-out conductor19, one end17aconnected to third external electrode13c, one end19aconnected to fourth external electrode13d, third via electrode22c, another end17bconnected to third via electrode22c, fourth via electrode22d, and another end19bconnected to fourth via electrode22d. One end17aand another end17bof second lead-out conductor17each have a larger line width than remaining portions.

On the upper surface of first insulator layer11a, second spiral conductor15is formed. Second spiral conductor15includes second spiral body15a, which is in a spiral shape, and inner end15band outer end15cthereof.

Inner end15bis connected to another end17bof second lead-out conductor17via third via electrode22c. Outer end15cis connected to another end19bof fourth lead-out conductor19via fourth via electrode22d.

On the upper surface of second insulator layer11b, first spiral conductor14is formed. First spiral conductor14includes first spiral body14a, which is in a spiral shape, and inner end14band outer end14cthereof.

Inner end14bis connected to first via electrode22a, while outer end14cis connected to second via electrode22b.

On the upper surface of fourth insulator layer11d, there are disposed first lead-out conductor16, one end16aconnected to first external electrode13a, third lead-out conductor18, one end18aconnected to second external electrode13b, another end16bconnected to first via electrode22a, and another end18bconnected to second via electrode22b. One end16aand another end16bof first lead-out conductor16each have a larger line width than remaining portions.

Inner end14bof first spiral body14ais connected to another end16bof first lead-out conductor16via first via electrode22a. Outer end14cis connected to another end18bof third lead-out conductor18via second via electrode22b.

First spiral body14aof first spiral conductor14and second spiral body15aof second spiral conductor15include curved portions being curved in top view and linear portions. Because of the curved portions, the coil length of each of the spiral bodies can be made shorter. As a result, the direct current resistance value can be reduced. Note that the curved portions have a relatively large curvature radius of 150 μm to 250 μm.

A linear portion of first spiral conductor14overlaps first lead-out conductor16in top view. A linear portion of second spiral conductor15overlaps second lead-out conductor17in top view. Curved portions of first spiral conductor14are present near inner end14bof first spiral body14aand near magnetic core24. Curved portions of second spiral conductor15are present near inner end15bof second spiral body15aand near magnetic core24. Both the portion near inner end14bof first spiral conductor14and the portion near inner end15bof second spiral conductor15are smaller in curvature radius than the portion near magnetic core24.

Here, inner end14bof first spiral body14ais connected to first pad25via first connecting portion14d. Inner end15bof second spiral body15ais connected to second pad26via second connecting portion15d. Outer end14cof first spiral body14ais connected to third pad28via first lead-out portion27. Outer end15cof second spiral body15ais connected to fourth pad30via second lead-out portion29.

Therefore, first pad25, third pad28, first connecting portion14d, and first lead-out portion27form part of first coil20. Second pad26, fourth pad30, second connecting portion15d, and second lead-out portion29form part of second coil21. First pad25, second pad26, third pad28, and fourth pad30each have a line width of 90 μm, which is wider than the line width (10 μm) of first spiral conductor14and the line width (10 μmm) of second spiral conductor15.

Magnetic core24is disposed inside first spiral conductor14and second spiral conductor15in top view. In top view, magnetic core24is located between either of inner end14bof first spiral body14aand inner end15bof second spiral body15aand the innermost periphery of either of first spiral conductor14and second spiral conductor15, and is located so that magnetic core24, inner end14bof first spiral body14a, and inner end15bof second spiral body15aare aligned along first direction X.

FIG.5is a diagram of first spiral conductor14, second spiral conductor15, and first to fourth lead-out conductors16to19, as viewed from above.

As can be seen fromFIG.5, each of first pad25and second pad26is disposed so as not to overlap first spiral conductor14or second spiral conductor15in top view.

That is, first pad25does not overlap any portion of second spiral conductor15, and second pad26does not overlap any portion of first spiral conductor14. Note that first pad25does not overlap first spiral conductor14, and second pad26does not overlap second spiral conductor15.

In addition, first pad25may include, in top view, a portion that does not overlap second spiral conductor15and a portion that overlaps second connecting portion15d. In this case, in top view, the portion where first pad25overlaps second connecting portion15doverlaps one of a pair of side edges of second connecting portion15dand does not overlap the other one. The pair of side edges of second connecting portion15drefers to the line portions facing each other in the line width direction of second connecting portion15d.

Likewise, second pad26may include, in top view, a portion that does not overlap first spiral conductor14and a portion that overlaps first connecting portion14d. In this case, in top view, the portion where second pad26overlaps first connecting portion14doverlaps one of a pair of side edges of first connecting portion14dand does not overlap the other one.

Although first pad25and second pad26may overlap each other in top view, it is preferable that first pad25and second pad26do not overlap each other in top view as illustrated inFIG.5. As a result, the stray capacitance between first pad25and second pad26can be reduced.

In addition, third pad28and fourth pad30are disposed so as not to overlap each other in top view, whereby the stray capacitance between third pad28and fourth pad30is reduced.

In top view, the distance between third pad28and fourth pad30is larger than the distance between first pad25and second pad26. As a result, the stray capacitance between third pad28and fourth pad30can be reduced. Note that the distance between first pad25and second pad26can be increased only to a limited extent because first pad25and second pad26are located inside first spiral conductor14and second spiral conductor15.

Furthermore, first lead-out conductor16and second lead-out conductor17do not overlap each other in top view, and first lead-out portion27and second lead-out portion29do not overlap with each other in top view. Moreover, third lead-out conductor18and fourth lead-out conductor19do not overlap each other in top view. As a result, the stray capacitance between first lead-out conductor16and second lead-out conductor17and the stray capacitance between first lead-out portion27and second lead-out portion29can be reduced.

In addition, a linear portion of first spiral body14aand a linear portion of second spiral body15aoverlap first lead-out conductor16and second lead-out conductor17in top view. Curved portions of first spiral body14aand curved portions of second spiral body15aoverlap neither first lead-out conductor16nor second lead-out conductor17in top view. Curved portions can be protected from a load that may be applied by a stress caused during stacking.

Here, first line segment length w1is defined as, in top view, the length of the shortest line segment that crosses the centers of first pad25and second pad26along direction Y orthogonal to first direction X and connects two points on the innermost periphery of the spiral shape of first spiral conductor14. In addition, second line segment length w2is defined as the length of the shortest line segment that is parallel to the first line segment, crosses the center of magnetic core24, and connects two points on the innermost peripheral of the spiral shape of first spiral conductor14. In this case, w1is shorter than w2. That is, w1<w2.

Note that inner end14bof first spiral body14aand inner end15bof second spiral body15aare aligned along Y direction.

This configuration provides a larger area in which magnetic core24can be formed. As the area of magnetic core24is larger in top view, the magnetic flux in magnetic core24can be increased, and thus the common mode impedance can be further increased.

Note that magnetic core24is on neither first pad25nor second pad26.

FIG.5shows that second connecting portion15dof second spiral conductor15directed to second pad26passes outside first pad25; however, second connecting portion15dmay pass between first pad25and magnetic core24(on the inner side of first pad25).

As described above, in the common mode noise filter according to one exemplary embodiment of the present disclosure, first pad25, second pad26, first spiral conductor14, and second spiral conductor15are disposed so that neither first pad25nor second pad26overlaps each of first spiral conductor14and second spiral conductor15in top view. Therefore, the stray capacitance between each of first pad25and second pad26and each of first spiral conductor14and second spiral conductor15can be reduced. This can prevent inconsistent differential signals from being generated in a high-frequency band to suppress an increase in insertion loss, providing an effect of enabling the use of the common mode noise filter in a high-frequency band.

The common mode noise filter according to the present disclosure provides an effect of enabling the use of the common mode noise filter in a high-frequency band, and is particularly useful for, for example, small and thin common mode noise filters used in digital devices, AV devices, information communication terminals, and the like.