JP6090348B2 - Coil-embedded substrate and DC-DC converter module having the same - Google Patents

Description

  The present invention relates to a coil-embedded substrate that includes a coil and is applied to a DC-DC converter module and the like, and a DC-DC converter module including the same.

An inductor in which a coil is formed inside a magnetic substrate is disclosed in Patent Document 1. FIG. 1 is a cross-sectional view of an inductor 21 disclosed in Patent Document 1. In FIG. In this example, the magnetic green sheets on which the coil conductors 3a to 3d are printed with the conductive paste and the magnetic green sheets on which the dielectric layers 22a to 22c are printed with the low dielectric constant material paste are alternately laminated. ing. Here, the dielectric layers 22a to 22c are formed in a pattern substantially similar to the coil conductors 3a to 3d. These laminates are baked to form the magnetic chip 10 having the coil 11 therein.
The inductor disclosed in Patent Literature 1 is said to be able to be used up to a high frequency range by reducing stray capacitance generated between adjacent coil conductors in the stacking direction.

  On the other hand, a multilayer electronic component module in which a coil is formed by alternately stacking a large-diameter outer coil conductor and a small-diameter inner coil conductor in a ferrite substrate so that the cross-sectional pattern of the coil is staggered is patented It is disclosed in Document 2.

  In the multilayer electronic component module of Patent Document 2, the unevenness of the surface is suppressed, so that it is possible to prevent poor connection of the mounted electronic component and poor mounting on the mounting destination substrate.

JP-A-5-6823 International Publication No. 2009/081865

  In order for a coil in which a plurality of coil conductors formed at different heights inside a magnetic substrate to be connected in series to function as an inductor, a large loop-shaped magnetic flux passing inside and outside the entire coil conductor is formed. Things are desirable. However, since the coil conductors are arranged at different heights in the magnetic layer, unnecessary magnetic flux is generated to individually wind the coil conductors. Since this unnecessary magnetic flux does not contribute to the inductance of the inductor due to the entire coil conductor, a large number of turns are required to obtain the required inductance, and if the coil conductor is thinned to increase the number of turns, the DC resistance Increases and the Q value decreases.

In either of Patent Documents 1 and 2, it is impossible to efficiently secure an inductance value by suppressing the generation of the unnecessary magnetic flux.
An object of the present invention is to provide a coil-embedded substrate that incorporates a coil with excellent electrical characteristics as an inductor while suppressing generation of unnecessary magnetic flux.

The coil-embedded substrate of the present invention is
In a coil-embedded substrate comprising a plurality of laminated magnetic layers and a plurality of coil conductors,
The plurality of coil conductors are stacked via a magnetic layer,
A low permeability region is provided between the coil conductors adjacent to each other in the stacked direction;
The low-permeability region is an interlayer cavity that disappears during firing of the heat-dissipating paste, filled in holes provided between the coil conductors adjacent to each other in the stacking direction,
The interlayer cavities are respectively in contact with the coil conductors adjacent in the stacking direction,
A plurality of the interlayer cavities are arranged along the coil conductor,
It is characterized by that.

The coil-embedded substrate of the present invention is
In a coil-embedded substrate comprising a plurality of laminated magnetic layers and a plurality of coil conductors,
The plurality of coil conductors are stacked via a magnetic layer,
A low permeability region is provided between the coil conductors adjacent to each other in the stacked direction;
The low magnetic permeability region is an interlayer nonmagnetic column formed by firing a nonmagnetic ceramic paste filled in a hole provided between the coil conductors adjacent to each other in the stacking direction,
The interlayer nonmagnetic pillars are in contact with the coil conductors adjacent to each other in the stacking direction,
A plurality of interlayer nonmagnetic pillars are arranged along the coil conductor.
It is characterized by that.

The DC-DC converter module of the present invention is
In a DC-DC converter module including a coil built-in substrate including a plurality of laminated magnetic layers and a plurality of coil conductors, and including a coil built in the coil built-in substrate in a converter circuit,
The coil-embedded substrate is:
The plurality of coil conductors are stacked via a magnetic layer,
A low permeability region is provided between the coil conductors adjacent to each other in the stacked direction;
The low-permeability region is an interlayer cavity that disappears during firing of the heat-dissipating paste, filled in holes provided between the coil conductors adjacent to each other in the stacking direction,
The interlayer cavities are respectively in contact with the coil conductors adjacent in the stacking direction,
A plurality of the interlayer cavities are arranged along the coil conductor,
It is characterized by that.

The DC-DC converter module of the present invention is
In a DC-DC converter module including a coil built-in substrate including a plurality of laminated magnetic layers and a plurality of coil conductors, and including a coil built in the coil built-in substrate in a converter circuit,
The coil-embedded substrate is:
The plurality of coil conductors are stacked via a magnetic layer,
A low permeability region is provided between the coil conductors adjacent to each other in the stacked direction;
The low magnetic permeability region is an interlayer nonmagnetic column formed by firing a nonmagnetic ceramic paste filled in a hole provided between the coil conductors adjacent to each other in the stacking direction,
The interlayer nonmagnetic pillars are in contact with the coil conductors adjacent to each other in the stacking direction,
A plurality of interlayer nonmagnetic pillars are arranged along the coil conductor.
It is characterized by that.

  With the above structure, generation of unnecessary magnetic flux passing between adjacent coil conductors is suppressed. Therefore, the magnetic flux that individually circulates the coil conductors or circulates the coil conductors with a small number of layers in a small area is suppressed, and the magnetic flux that circulates the entire coil conductor forming layer increases accordingly, so that the inductance can be efficiently generated. It can be secured.

  It is preferable that the low magnetic permeability region is divided into a plurality of sections by bars made of the magnetic layer extending in a direction in which the magnetic layers are stacked. With this structure, the coil conductor can be prevented from dropping into the low magnetic permeability region.

  If the low magnetic permeability region is an interlayer nonmagnetic column formed by firing a nonmagnetic ceramic paste filled in a hole provided between layers, strength deterioration due to the provision of the low magnetic permeability region in the substrate Can be prevented.

  The width direction dimension of the coil conductor in the low permeability region is preferably smaller than the line width of the coil conductor. With this structure, the inner and outer periphery of the coil conductor can be reliably supported by the magnetic layer.

  According to the present invention, generation of unnecessary magnetic flux is suppressed, and a coil built-in substrate having a coil with excellent electrical characteristics as an inductor can be configured. In addition, a DC-DC converter module with high conversion efficiency can be obtained.

FIG. 1 is a cross-sectional view of an inductor 21 disclosed in Patent Document 1. In FIG. FIG. 2 is a cross-sectional view showing the configuration of the coil-embedded substrate of the first embodiment and a DC-DC converter module including the same. FIG. 3 is a diagram showing the conductor patterns formed in each layer of the coil-embedded substrate 101 in order. FIG. 4 is a circuit diagram of the DC-DC converter module according to the first embodiment. 5A and 5B are cross-sectional views showing the configurations of the coil-embedded substrate of the second embodiment and a DC-DC converter module including the same. 6A and 6B are cross-sectional views showing the configurations of the coil-embedded substrate of the third embodiment and a DC-DC converter module including the same. 7A and 7B are partially enlarged plan views showing the relationship between the size and position of the coil conductor 9 and the low magnetic permeability region 80. FIG. FIG. 8 is a circuit diagram of a DC-DC converter module according to the fifth embodiment.

<< First Embodiment >>
The configuration of the coil-embedded substrate and the DC-DC converter module including the same according to the first embodiment will be described with reference to FIGS.
FIG. 2 is a cross-sectional view showing the configuration of the coil-embedded substrate of the first embodiment and a DC-DC converter module including the same. The DC-DC converter module 111 includes a coil built-in substrate 101 and electronic components 70 and 71 mounted on the upper surface of the coil built-in substrate 101.

  The coil built-in substrate 101 includes an intermediate nonmagnetic layer 60, a first magnetic layer 61, a second magnetic layer 62, and nonmagnetic layers 31 and 32. The intermediate nonmagnetic layer 60 and the nonmagnetic layers 31 and 32 are layers in which a nonmagnetic ferrite sheet is laminated, and the first magnetic layer 61 and the second magnetic layer 62 are layers in which a magnetic ferrite sheet is laminated. is there.

  A coil conductor 9 is formed on a predetermined ferrite sheet in a part of the first magnetic layer 61 and the second magnetic layer 62 and the intermediate nonmagnetic layer 60.

  The non-magnetic layer 31 is formed on the electronic component mounting surface side (first main surface side) and includes the surface conductor film 7. The non-magnetic layer 32 is formed on the mounting surface side (second main surface side) with respect to the wiring board to be mounted, and includes the surface conductor film 7.

The magnetic layers 61 and 62 and the nonmagnetic layers 31 and 32 are provided with in-plane wiring conductors 6 and interlayer connection conductors 8 as necessary.
In the coil conductor 9, an outer coil conductor 9L having a large diameter and an inner coil conductor 9S having a diameter smaller than that of the outer coil conductor are alternately stacked via magnetic or non-magnetic layers. A coil is formed by serial connection in the order in which the coil conductors 9 are stacked. The outer coil conductors 9L and the inner coil conductors 9S are alternately arranged.

  Low magnetic permeability regions 80 are provided between the outer coil conductors 9L and the inner coil conductors 9S adjacent to each other in the stacking direction. In this example, the low-permeability region 80 is an interlayer cavity that disappears when the filled heat-dissipating paste is fired. Specifically, a hole is formed in the magnetic ferrite green sheet and the non-magnetic ferrite green sheet by a laser processing method, and a heat-dissipating paste such as a carbon paste or a resin paste is filled in the hole. It disappears at the time of firing and is made into a cavity.

  The low magnetic permeability region 80 may be configured by firing a nonmagnetic ceramic paste filled in the holes. In this case, holes may be formed in the magnetic ferrite green sheet and the non-magnetic ferrite green sheet, and the non-magnetic ceramic paste may be filled in the holes. The nonmagnetic ceramic paste becomes a nonmagnetic ceramic by firing the laminate. The low magnetic permeability region 80 is configured as an interlayer nonmagnetic column of nonmagnetic ceramic.

  The low-permeability region 80 may be formed by firing a low-permeability magnetic ceramic paste filled in the holes. In that case, a hole may be formed in the magnetic ferrite green sheet and the non-magnetic ferrite green sheet, and a low-permeability magnetic ceramic paste may be filled in the hole. By firing the laminate, the low-permeability magnetic ceramic paste becomes a magnetic ceramic having a lower magnetic permeability than the magnetic layers 61 and 62. The low-permeability region 80 is configured as an interlayer nonmagnetic column of low-permeability magnetic ceramic.

  Thus, by providing the low magnetic permeability region 80 between the adjacent coil conductors 9 in the stacking direction among the coil conductors 9 formed in a plurality of layers, it is unnecessary to pass between the adjacent coil conductors 9. Generation of magnetic flux is suppressed. Therefore, the magnetic flux that individually circulates the coil conductors 9 or circulates the coil conductors with a small number of layers in a small area is suppressed, and the magnetic flux that circulates the entire coil conductor forming layer increases accordingly, so that the inductance is efficiently increased. Can be secured.

  FIG. 2B is a cross-sectional view illustrating a configuration of a coil-embedded substrate as a comparative example and a DC-DC converter module including the substrate. This coil-embedded substrate is not provided with the low magnetic permeability region 80 as shown in FIG. As described above, in the structure in which the low magnetic permeability region 80 is not provided between the coil conductors 9 adjacent to each other in the stacking direction among the coil conductors 9 formed in the plurality of layers, the voids passing between the adjacent coil conductors 9 are invalid. Magnetic flux φs is likely to occur. Therefore, the effective magnetic flux φm that is originally required is reduced.

According to the first embodiment shown in FIG. 2A, the invalid magnetic flux φs shown in FIG. 2B is suppressed, and the effective magnetic flux φm is increased.
According to the first embodiment, since the intermediate nonmagnetic layer 60 is provided in the formation layer of the coil conductor 9, it acts as an inductor having a magnetic gap.

  The coil conductor width direction dimension of the low magnetic permeability region 80 is smaller than the line width of the coil conductor 9. Therefore, the inner and outer periphery of the coil conductor 9 can be reliably supported by the magnetic layer.

  FIG. 3 is a view showing the conductor patterns formed in each layer of the coil-embedded substrate 101 in order. In FIG. 3, (1) is the lowermost conductor pattern, and (14) is the uppermost conductor pattern. (2) to (13) are conductor patterns of each layer between the lowermost layer and the uppermost layer. In the lowermost conductor pattern shown in (1), GND is a ground electrode, Vin is a power input electrode, Vout is a power output electrode, and EN is an enable signal input electrode. These electrodes are connected to the land of the mounting board. Coil conductors 9a to 9h are formed on the layers (4) to (11). Among these coil conductors, 9a, 9c, 9e, and 9g are outer coil conductors, and 9b, 9d, 9f, and 9h are inner coil conductors. These coil conductors are connected in series via interlayer connection conductors (via conductors). Moreover, the low magnetic permeability area | region 80 is formed in the (5)-(10) layer. In the (14) layer, control IC mounting electrodes GND, Vin, EN, FB, Lo are formed. Chip capacitor mounting electrodes Ca and Cb are also formed.

  In this way, the inner coil conductor and the outer coil conductor are alternately stacked, and the low permeability region 80 is disposed at a position where the inner coil conductors correspond to each other and a position where the outer coil conductors face each other. The low permeability region 80 can be arranged without increasing the number.

  FIG. 4 is a circuit diagram of the DC-DC converter module according to the first embodiment. 4, the capacitor C1 is a capacitor connected to the chip capacitor mounting electrodes Ca and Cb in FIG. 3, and corresponds to the electronic component 71 shown in FIG. The inductor L1 is an inductor constituted by the coil conductors 9a to 9h and the magnetic layer in FIG. The electronic component 70 is a control IC. The terminals GND, Vin, EN, FB, Lo of the control IC are connected to the control IC mounting electrodes GND, Vin, EN, FB, Lo in FIG. A smoothing capacitor C2 is connected between the power output electrode Vout and the ground. The control IC and the capacitor may be mounted on the coil-embedded substrate 101, or may be wired together with the coil-embedded substrate 101 on the parent substrate. When mounted on the coil built-in substrate 101, the area occupied by the parent substrate can be reduced. When the coil-embedded substrate 101 is arranged on the parent substrate, the height can be further reduced.

  The electronic component 70 (control IC) receives the voltage of the power supply output electrode Vout at the feedback terminal FB, and controls the duty ratio of the current flowing through the inductor L1 so that the output voltage becomes constant.

  As described above, since the coil of the coil-embedded substrate of this embodiment functions as an inductor having a magnetic gap, high DC superposition characteristics can be obtained.

<< Second Embodiment >>
5A and 5B are cross-sectional views showing the configurations of the coil-embedded substrate of the second embodiment and a DC-DC converter module including the same. A DC-DC converter module 112A shown in FIG. 5A includes a coil built-in substrate 102A and electronic components 70 and 71 mounted on the upper surface of the coil built-in substrate 102A. A DC-DC converter module 112B shown in FIG. 5B includes a coil built-in substrate 102B and electronic components 70 and 71 mounted on the upper surface of the coil built-in substrate 102B.

In the example of FIG. 5A, the low magnetic permeability region 80 is provided between the inner coil conductors 9S, and the low magnetic permeability region 80 is not provided between the outer coil conductors 9L.
In the example of FIG. 5B, the low magnetic permeability region 80 is provided between the outer coil conductors 9L, and the low magnetic permeability region 80 is not provided between the inner coil conductors 9S. Other configurations in both FIG. 5A and FIG. 5B are the same as those in the first embodiment.

  Thus, the low magnetic permeability region 80 may be provided only on either the inner coil conductor 9S side or the outer coil conductor 9L side. Since the total volume of the low-permeability region 80 is small compared to the first embodiment, the effect of suppressing invalid magnetic flux passing between adjacent coil conductors 9 in the stacking direction is small, but the strength deterioration of the coil-embedded substrate is reduced. As a result, the unevenness of the module substrate surface is reduced. That is, shape deterioration is also suppressed. For this reason, it is possible to prevent breakage and cracks from occurring when the parent substrate is divided into child substrates (pieces). Which side of the outer coil conductor and the inner coil conductor is to be formed with the interlayer connection cavity may be selected based on the inductance value or the coil efficiency side.

<< Third Embodiment >>
6A and 6B are cross-sectional views showing the configurations of the coil-embedded substrate of the third embodiment and a DC-DC converter module including the same. A DC-DC converter module 113A shown in FIG. 6A includes a coil built-in substrate 103A and electronic components 70 and 71 mounted on the upper surface of the coil built-in substrate 103A. A DC-DC converter module 113B shown in FIG. 6B includes a coil built-in substrate 103B and electronic components 70 and 71 mounted on the upper surface of the coil built-in substrate 103B.

  In the example of FIG. 6A, a low permeability region 80 is provided at a position near the intermediate nonmagnetic layer 60. In the example of FIG. 6B, a low magnetic permeability region 80 is provided at a position away from the intermediate nonmagnetic layer 60.

  As described above, the low magnetic permeability region 80 may be provided only at either the position near the intermediate nonmagnetic layer 60 or the position away from the intermediate nonmagnetic layer 60. Since the total volume of the low-permeability region 80 is small compared to the first embodiment, the effect of suppressing invalid magnetic flux passing between adjacent coil conductors 9 in the stacking direction is small, but the strength deterioration of the coil-embedded substrate is reduced. As a result, the unevenness of the module substrate surface is reduced. That is, shape deterioration is also suppressed. For this reason, it is possible to prevent breakage and cracks from occurring when the parent substrate is divided into child substrates (pieces). Whether the interlayer connection cavity is to be formed on the side closer to the intermediate nonmagnetic layer 60 or the position away from the intermediate nonmagnetic layer 60 may be selected based on the inductance value and the coil efficiency side.

<< Fourth Embodiment >>
In 4th Embodiment, the example of the planar shape of a low-permeability area | region is shown.
7A and 7B are partially enlarged plan views showing the relationship between the size and position of the coil conductor 9 and the low magnetic permeability region 80. FIG. In any example, the coil conductor width direction dimension of the low magnetic permeability region 80 is smaller than the line width of the coil conductor 9.

  The individual planar shape of the low magnetic permeability region 80 may be circular as shown in FIG. 7A, or is roughly rectangular or bent along the shape of the coil conductor 9 as shown in FIG. It may be a shape. Such non-circular holes can be formed by drilling by laser beam scanning. In the example of FIG. 7B, the low magnetic permeability region 80 is divided into a plurality of sections by a crosspiece GR formed by a magnetic layer or an intermediate nonmagnetic layer that extends in the direction in which the magnetic layers are stacked. With this structure, the coil conductor 9 can be prevented from dropping into the low magnetic permeability region 80.

<< Fifth Embodiment >>
The configuration of the coil-embedded substrate of the fifth embodiment and the DC-DC converter module 115 having the same will be described with reference to FIG.
FIG. 8 is a cross-sectional view showing the configuration of the coil-embedded substrate of the fifth embodiment and the DC-DC converter module 115 having the same. The DC-DC converter module 115 includes a coil built-in substrate 105 and electronic components 70 and 71 mounted on the upper surface of the coil built-in substrate 105.

In the first embodiment, the outer coil conductor 9L having a larger diameter and the inner coil conductor 9S having a smaller diameter than the outer coil conductor are alternately stacked via a magnetic or non-magnetic layer and connected in series. It was. In the fifth embodiment, in the coil, a plurality of coil conductors 9 are stacked via a magnetic layer. The plurality of coil conductors all have the same diameter. A coil is formed by being connected in series in the order of stacking. A low magnetic permeability region 80 is provided between the layers of adjacent coil conductors 9 in the stacking direction. The low magnetic permeability region 80 is an interlayer cavity that has disappeared during firing of the filled heat-dissipating paste. Specifically, a hole is formed in the magnetic ferrite green sheet and the non-magnetic ferrite green sheet by a laser processing method, and a heat-dissipating paste such as a carbon paste or a resin paste is filled in the hole. It disappears at the time of firing and is made into a cavity.
The other configuration of the fifth embodiment is the same as that of the first embodiment.

  Also in the fifth embodiment, similarly to the first embodiment, the low magnetic permeability region 80 is provided between the coil conductors adjacent to each other in the stacking direction among the coil conductors 9 formed in a plurality of layers. Thus, generation of unnecessary magnetic flux passing between adjacent coil conductors 9 is suppressed. Therefore, the magnetic flux that individually circulates the coil conductors 9 or circulates the coil conductors with a small number of layers in a small area is suppressed, and the magnetic flux that circulates the entire coil conductor forming layer increases accordingly, so that the inductance is efficiently increased. Can be secured.

  Further, since the coil of the coil-embedded substrate 105 acts as an inductor having a magnetic gap, high DC superposition characteristics can be obtained.

Ca, Cb ... Chip capacitor mounting electrode GR ... Crosspiece 6 ... In-plane wiring conductor 7 ... Surface conductor film 8 ... Interlayer connection conductor 9 ... Coil conductors 9a to 9h ... Coil conductor 9L ... Outer coil conductor 9S ... Inner coil conductor 31 32 ... Nonmagnetic layer 60 ... Intermediate nonmagnetic layer 61 ... First magnetic layer 62 ... Second magnetic layer 70, 71 ... Electronic component 80 ... Low permeability region 101 ... Built-in coil substrate 102A, 102B ... Built-in coil Substrate 103A, 103B ... Coil built-in substrate 105 ... Coil built-in substrate 111 ... DC-DC converter module 112A, 112B ... DC-DC converter module 113A, 113B ... DC-DC converter module 115 ... DC-DC converter module

Claims (9)

In a coil-embedded substrate comprising a plurality of laminated magnetic layers and a plurality of coil conductors,
The plurality of coil conductors are stacked via a magnetic ferrite layer,
A low permeability region is provided between the coil conductors adjacent to each other in the stacked direction;
A low magnetic permeability region is a layer between cavity provided between the coil conductors which are adjacent in a direction that is the stacked,
The interlayer cavities are respectively in contact with the coil conductors adjacent in the stacking direction,
A plurality of the interlayer cavities are arranged along the coil conductor,
A coil-embedded substrate characterized by the above.   2. The coil-embedded substrate according to claim 1, wherein the low magnetic permeability region is divided into a plurality of sections by bars made of the magnetic layer extending in a direction in which the magnetic layers are stacked. In a coil-embedded substrate comprising a plurality of laminated magnetic layers and a plurality of coil conductors,
The plurality of coil conductors are stacked via a magnetic ferrite layer,
A low permeability region is provided between the coil conductors adjacent to each other in the stacked direction;
A low magnetic permeability region is a layer between the nonmagnetic pillar which is arranged between the coil conductors which are adjacent in a direction that is the stacked,
The interlayer nonmagnetic pillars are in contact with the coil conductors adjacent to each other in the stacking direction,
A plurality of the interlayer non-magnetic columns are arranged along the extending direction of the coil conductor, and a plurality are arranged in the width direction of the coil conductor .
A coil-embedded substrate characterized by the above.   The coil-embedded substrate according to any one of claims 1 to 3, wherein the low magnetic permeability region is provided at a position near an outer layer or an intermediate layer in a layer range in which the coil conductor is formed.   5. The coil-embedded substrate according to claim 1, wherein the magnetic layer is a magnetic layer formed by firing a magnetic ferrite sheet.   The coil built-in substrate according to claim 1, wherein a width direction dimension of the coil conductor in the low magnetic permeability region is smaller than a line width of the coil conductor.   The coil built-in substrate according to claim 6, wherein a plurality of the low magnetic permeability regions are arranged in a width direction of the coil conductor. In a DC-DC converter module including a coil built-in substrate including a plurality of laminated magnetic layers and a plurality of coil conductors, and including a coil built in the coil built-in substrate in a converter circuit,
The coil-embedded substrate is:
The plurality of coil conductors are stacked via a magnetic ferrite layer,
A low permeability region is provided between the coil conductors adjacent to each other in the stacked direction;
A low magnetic permeability region is a layer between cavity provided between the coil conductors which are adjacent in a direction that is the stacked,
The interlayer cavities are respectively in contact with the coil conductors adjacent in the stacking direction,
A plurality of the interlayer cavities are arranged along the coil conductor,
The DC-DC converter module characterized by the above-mentioned. In a DC-DC converter module including a coil built-in substrate including a plurality of laminated magnetic layers and a plurality of coil conductors, and including a coil built in the coil built-in substrate in a converter circuit,
The coil-embedded substrate is:
The plurality of coil conductors are stacked via a magnetic ferrite layer,
A low permeability region is provided between the coil conductors adjacent to each other in the stacked direction;
A low magnetic permeability region is a layer between the nonmagnetic pillar which is arranged between the coil conductors which are adjacent in a direction that is the stacked,
The interlayer nonmagnetic pillars are in contact with the coil conductors adjacent to each other in the stacking direction,
A plurality of the interlayer non-magnetic columns are arranged along the extending direction of the coil conductor, and a plurality are arranged in the width direction of the coil conductor .
The DC-DC converter module characterized by the above-mentioned.

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