JP5193844B2 - Multilayer inductor - Google Patents

Description

  The present invention relates to a magnetic core type multilayer inductor having a structure in which a coil is embedded in a magnetic body, and particularly effective when applied to a rectangular chip inductor for surface mounting that is used in a DC superimposed state. For example, in a mobile information device such as a mobile phone, it is suitable for a micro DC-DC converter that converts a power supply voltage (electromotive force) obtained from a built-in battery into a predetermined circuit operating voltage.

  Transformers and choke coils used in power supply circuits such as DC-DC converters were once configured to have a coil wound around a magnetic core. However, in recent years, power supply circuit components have become smaller and thinner. In accordance with demands, chip components with a laminated structure have been developed and put into practical use.

  In multilayer inductors, electrically insulating magnetic layers and conductor patterns are alternately stacked, and the conductor patterns are sequentially connected to each other, so that a coil that wraps around in a spiral while overlapping in the stacking direction in the magnetic material. It is formed. Both ends of the coil are connected to electrode terminals on the outer surface of the multilayer chip through lead conductor pattern portions, respectively. That is, the coil is embedded in a chip-type magnetic body. The magnetic layer and the conductor pattern are formed and laminated by, for example, a screen printing technique.

  Such a multilayer inductor is characterized by the fact that the coil is surrounded by a magnetic material, so there is little magnetic leakage to the outside, and the required inductance can be obtained with a relatively small number of turns, making it suitable for downsizing and thinning. ing.

  However, since magnetic saturation of the magnetic material occurs even with a small coil current (excitation current), the variation in inductance is large even if the DC superimposed current is in a low current region. That is, there is a problem that the direct current superimposition characteristic is bad.

  Therefore, by replacing a part of the entire magnetic layer with an electrically insulating non-magnetic layer, a magnetic gap is interposed in the multilayer inductor, thereby increasing the magnetic saturation level, and a large rating as a transformer, choke coil, etc. A multilayer inductor has been proposed in which a current can be obtained (Patent Document 1).

A multilayer inductor has also been proposed that suppresses magnetic saturation due to leakage magnetic flux to reduce inductance fluctuation in a minute current region (Patent Document 2).
JP 2005-45108 A JP2008-21788

  Although the DC superposition characteristics of multilayer inductors have been improved for the time being by the above-mentioned technology, they do not effectively suppress all magnetic saturation caused by leakage magnetic flux, etc. Still remained.

  For example, FIG. 6 shows a configuration example of a multilayer inductor studied prior to the present invention, (a) is a plan view of each layer constituting the multilayer inductor, and (b) is a perspective view showing only a conductor pattern portion extracted. FIG. 4C is a longitudinal sectional view showing a laminated state.

  In the figure, 20 is a conductor pattern (or conductor), 20-1 to 20-6 are conductor pattern layers having the conductor pattern 20, 40-3 is a magnetic layer, 40-1 is an entire magnetic gap layer, 41 Denotes a magnetic material, and 45 denotes a non-magnetic pattern (or non-magnetic material).

  In this laminated inductor, the electrically insulating magnetic layer 40-3 and the conductor pattern layers 20-1 to 20-6 having the open loop conductor pattern 20 are alternately laminated, and the entire layer surface is electrically connected to the central layer. An entire magnetic gap layer 40-1 made of an insulating nonmagnetic material 45 is disposed.

The conductor patterns 20 of the respective layers (20-1 to 20-6) are sequentially coupled through vias 24, and a coil that spirals around the magnetic body 41 while overlapping in the stacking direction is formed.
Both ends of the coil are connected to electrode terminals (not shown) on the outer surface of the multilayer chip via lead conductor pattern portions 22 and 22, respectively.

  Furthermore, an electrically insulating nonmagnetic pattern 45 that overlaps the conductor pattern 20 in the layer direction is formed on the magnetic layer 40 disposed between the conductor pattern layers 20-1 to 20-6. That is, a loop-shaped nonmagnetic pattern 45 is formed so as to overlap the projection pattern in the layer direction of the coil, and the entire surface of the magnetic gap layer 40-1 is made of a nonmagnetic material 45 that is electrically insulating. Has been placed.

In the above configuration, the entire magnetic gap layer reduces inductance fluctuation in a wide range of DC superimposed current region, and further suppresses magnetic saturation between the conductor pattern 20 and the conductor pattern 20 to reduce inductance fluctuation during low current DC superposition. The effect of mitigating is obtained.
However, the present inventors have found that magnetic saturation that fluctuates the inductance of the multilayer inductor can also occur at locations other than those described above.

  In this type of multilayer inductor, as shown in FIGS. 6B and 6C, the main magnetic flux Hz induced in the stacking direction orthogonal to the winding direction of the coil is a main parameter factor governing the characteristics of the inductor. However, there is also a leakage magnetic flux that is induced outside the stacking direction. Due to the magnetic saturation caused by the leakage magnetic flux, the inductor fluctuates in a minute DC superimposed current region.

  The DC-DC converter performs voltage conversion while switching a direct current with a high-frequency pulse, but the switching frequency tends to increase year by year. As the frequency becomes higher, the required inductance value is reduced, the number of coil turns is reduced, and the influence of the leakage magnetic flux on the DC superimposition characteristics has become prominent.

  According to what the present inventors have learned, in the multilayer inductor shown in FIG. 6, in addition to the main magnetic flux Hz, as shown in FIG. A leakage magnetic flux Hp in a direction different from the main magnetic flux Hz is locally induced, and magnetic saturation due to the leakage magnetic flux Hp has caused an increase in inductance fluctuation in a minute current region. That is, the direct current superimposition characteristic of the multilayer inductor is deteriorated.

  However, since this problem is caused by a local leakage magnetic flux Hp that is induced in a direction different from the stacking direction, it cannot be solved by a magnetic gap interposed between layers as disclosed in Patent Documents 1 and 2, for example.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a multilayer inductor having a DC superposition characteristic with a small inductance variation in a low current region.

  Other objects and configurations of the present invention will be clarified in the description of the present specification and the accompanying drawings.

The solution provided by the present invention is as follows.
(1) A layered conductor pattern layer in which a conductor pattern in which a part of a rectangular loop is opened is laminated in an electrically insulating magnetic material, and a nonmagnetic pattern is formed in the electrically insulating magnetic material. The conductive patterns are sequentially connected to each other while the magnetic layer is interposed between the conductive pattern layers, thereby forming a coil that spirals around the magnetic material while overlapping in the stacking direction. Are both rectangular inductors connected to the electrode terminals on the outer surface of the multilayer chip through the lead conductor pattern portions,
The lead conductor pattern portions at both ends of the coil are formed so as to extend straight portions of the open loop conductor pattern formed on the same layer surface, and extend in opposite directions to each other. Magnetic material is arranged on both sides with respect to the extending direction of the conductor pattern,
In the magnetic layer, a planar shape is rectangular, and a loop-like nonmagnetic pattern that overlaps with a projection pattern in the stacking direction of the coil is formed,
Among the magnetic layers, the magnetic layer laminated adjacent to the inside of the conductor pattern layer having the lead conductor pattern portion is caused by the current flowing in the lead conductor pattern in addition to the loop-shaped magnetic pattern. As a magnetic gap for blocking local leakage magnetic flux around the lead conductor pattern, including a straight portion connecting the lead conductor pattern portions extending in the opposite direction toward the outside of the loop An I-shaped non-magnetic pattern portion is formed which extends to the rectangular peripheral portion forming the planar shape,
A multilayer inductor characterized by that.

(2) In the above means (1), wherein among the magnetic layer, the I-shaped magnetic layer nonmagnetic pattern portion is not formed, the projected pattern in the stacking direction of the said coil lead conductor pattern portion A non-magnetic pattern is formed on the multilayer inductor.

(3) In the above means (1) or (2), wherein is nonmagnetic pattern portion electrically insulating the loop opening of the open loop-shaped conductor pattern is formed, substantially loop conductor pattern by the non-magnetic pattern portions laminated inductor, characterized by being closed Ji is.

(4) The multilayer inductor according to any one of the above means (1) to (3), wherein one or more entire magnetic gap layers made of an electrically insulating nonmagnetic material are disposed on the entire layer surface.

(5) In any one of the above means (1) to (4), the magnetic material pattern is formed only on the U-shaped portion along the peripheral edge of the layer surface that does not overlap the conductor pattern of any layer, and the remainder laminated inductor but is part magnetic gap layer all the non-magnetic pattern characterized that you have been placed one or more layers.

According to the above means, it is possible to effectively suppress magnetic saturation due to local leakage magnetic flux and to obtain a multilayer inductor having a DC superposition characteristic with little inductance fluctuation in a low current region.
The operations / effects other than the above will be clarified in the description of the present specification and the accompanying drawings.

  1A and 1B are diagrams showing the main part of the multilayer inductor according to the first embodiment of the present invention, wherein FIG. 1A is a plan view of each layer constituting the multilayer inductor, and FIG. (C) is a longitudinal sectional view showing a laminated state.

  In the figure, 20 is a conductor pattern (or conductor), 20-1 to 20-6 are conductor pattern layers having the conductor pattern 20, 40-3 is a magnetic layer, 41 is a magnetic body, and 45 is a non-magnetic pattern. (Or non-magnetic material) is shown respectively.

  The multilayer inductor shown in FIG. 1 forms a rectangular chip inductor for surface mounting, and includes conductor pattern layers 20-1 to 20- having an electrically insulating magnetic layer 40-3 and an open loop conductor pattern 20. 6 are alternately stacked, and the conductor patterns 20 of the respective layers (20-1 to 20-6) are sequentially connected to each other through the vias 24, thereby spiraling while being superimposed in the stacking direction in the magnetic body 41. A coil that circulates in a shape is formed. On the uppermost layer and the lowermost layer, a magnetic layer made of a magnetic material is laminated (reference numerals omitted).

  Both ends of the coil are connected to electrode terminals (not shown) on the outer surface of the multilayer chip via lead conductor pattern portions 22 and 22, respectively.

  In the magnetic layer 40-3 disposed between the conductor pattern layers 20-1 to 20-6, an electrically insulating nonmagnetic pattern 45 overlapping the conductor pattern 20 in the layer direction is formed. That is, a loop-shaped nonmagnetic pattern 45 is formed so as to overlap the projection pattern in the layer direction of the coil.

  Further, the lead conductor pattern portions 22 at both ends of the coil respectively form a linear extension portion of the conductor pattern 20 in the same layer, and both the extension portions are extended in opposite directions.

  Further, the magnetic layer 40-3 adjacent to the conductor pattern layers 20-1 and 20-6 having the lead conductor pattern portion 22 from the inside has an I-shape overlapping the lead conductor pattern portion 22 and the outer peripheral edge portion. The non-magnetic pattern part 52 is formed.

  In the above-described multilayer inductor, in addition to the main magnetic flux Hz in the lamination direction orthogonal to the winding direction of the coil, as shown by the wavy line in FIG. Although induced, the I-shaped nonmagnetic pattern portion 52 is interposed as a magnetic gap in the induction magnetic path of the leakage magnetic flux Hp.

  For this reason, the surrounding magnetization by the leakage magnetic flux Hp is suppressed, and the inductance fluctuation | variation by magnetic saturation can be suppressed. As a result, it was found that a multilayer inductor having a DC superposition characteristic with a small inductance variation in a low current region can be obtained.

  2A and 2B are diagrams showing the main part of the multilayer inductor according to the second embodiment of the present invention, in which FIG. 2A is a plan pattern diagram of a conductor pattern layer and a magnetic layer, which are components of the multilayer inductor, FIG. ) Is a longitudinal sectional view showing a laminated state.

  In the multilayer inductor according to the second embodiment shown in the same drawing, in addition to the configuration of the first embodiment described above, the entire surface of the magnetic gap layer 40-1 composed of the electrically insulating nonmagnetic material 45 is disposed. . The entire magnetic gap layer 40-1 is interposed in the magnetic path (Hz) in the stacking direction.

  In the second embodiment, the entire magnetic gap layer 40-1 is disposed in the center layer, and the same number (two layers) of the magnetic layers 40-3 are disposed on the upper layer side and the lower layer side thereof.

  According to this configuration, in addition to the effect of suppressing the magnetic saturation due to the leakage magnetic flux Hp, it is possible to effectively suppress the magnetic saturation due to the main magnetic flux Hz induced in the stacking direction. Superimposition characteristics can be further improved.

  In the second embodiment, the nonmagnetic pattern 45 of the magnetic layer 40-3 is formed in a projected pattern shape in the layer direction of the coil and the lead conductor pattern portion 22.

  The nonmagnetic pattern 45 of the magnetic layer 40-3 has a nonmagnetic pattern portion corresponding to the lead conductor pattern portion 22 interposed as a magnetic gap with respect to a magnetic path that circulates in the layer surface direction. It has the effect of suppressing magnetic saturation due to the leakage magnetic flux. Thereby, the direct current superimposition characteristics can be further improved.

  3A and 3B are diagrams showing the main part of the multilayer inductor according to the third embodiment of the present invention, in which FIG. 3A is a plan pattern diagram of a conductor pattern and a magnetic layer that are components of the multilayer inductor, and FIG. FIG. 3 is a longitudinal sectional view showing a laminated state.

  In the multilayer inductor of the third embodiment shown in the figure, in addition to the configuration of the second embodiment described above, an electrically insulating nonmagnetic pattern portion 53 is formed in the loop opening portion of the conductor pattern 20, and this nonmagnetic The pattern portion 53 is characterized in that the loop of the conductor pattern 20 is substantially closed.

  In the third embodiment, an effect of selectively suppressing magnetic saturation due to local leakage magnetic flux induced near the interlayer connection portion of the conductor pattern 20 is obtained.

  As shown in FIG. 1B, the conductor pattern 20 forms a coil that spirals around while being overlapped in the stacking direction by being successively connected in layers by vias 24. Therefore, the leakage flux is locally induced in a direction different from the main magnetic flux Hz, and the inductance is changed by the local magnetic saturation caused by the leakage flux.

  However, since the nonmagnetic pattern portion 53 is interposed in the induction magnetic path of the leakage magnetic flux, local magnetic saturation due to the leakage magnetic flux can be accurately suppressed, and thereby, the DC superposition characteristics in the low current region can be suppressed. Can be further improved.

  4A and 4B are diagrams showing a main part of a multilayer inductor according to a fourth embodiment of the present invention, in which FIG. 4A is a plan pattern diagram of a conductor pattern layer and a magnetic layer, which are constituent elements of the multilayer inductor, FIG. ) Is a longitudinal sectional view showing a laminated state.

  In the multilayer inductor according to the fourth embodiment shown in the figure, a partial magnetic gap layer 40-2 is arranged as a magnetic gap layer in the multilayer direction with respect to the configuration of the second embodiment described above.

  In this partial magnetic gap layer 40-2, the magnetic pattern (41) is formed only on the U-shaped portion along the peripheral edge that does not overlap the conductor patterns 20 and 22 of any layer of the layer surface, and all the remaining portions are formed. This is a nonmagnetic pattern (45), which is arranged in the central layer.

  In the fourth embodiment, similarly to the second embodiment, it is possible to suppress the magnetic saturation caused by the leakage magnetic flux Hp and the main magnetic flux Hz and improve the DC superposition characteristics.

  Furthermore, the partial magnetic gap layer 40-2 interposed in the stacking direction has the magnetic pattern (41) in the U-shaped portion, so that the stacking direction of the partial magnetic gap layer 40-2 is larger than that of the entire magnetic gap layer 40-1. Magnetic resistance can be reduced.

  Thereby, the fall of the inductance accompanying the magnetic gap layer can be reduced. That is, the direct current superimposition characteristic can be improved without significantly reducing the inductance.

FIG. 5 shows the DC superposition characteristics of the multilayer inductor according to the present invention.
In the same figure, the graph line B shows the change state of the inductance with respect to the DC superimposed current of the multilayer inductor (Example 2) having the configuration of the second embodiment shown in FIG. 2, and the graph line C is shown in FIG. The change state of the inductance to the direct current superposition current of the multilayer inductor (example 3) which has the composition of the 3rd embodiment which shows was shown. Further, the graph line A represents a change in inductance with respect to a DC superimposed current of a multilayer inductor (comparative example) using a conductor pattern layer and a magnetic layer (see FIG. 6) that do not have any of the features of the first and second embodiments. Indicates the state.

  As is clear from the figure, in the multilayer inductor of the present invention, the inductance fluctuation with respect to the DC superimposed current is reliably suppressed. As a result, it is possible to obtain a DC superposition characteristic with a small inductance variation in a low current region.

  As mentioned above, although this invention was demonstrated based on the typical Example, this invention can have various aspects other than having mentioned above.

  Magnetic saturation due to local leakage magnetic flux is effectively suppressed, and thereby a multilayer inductor having a DC superposition characteristic with little inductance fluctuation in a low current region can be obtained.

FIG. 2 is a plan pattern diagram, a perspective view, and a longitudinal sectional view showing a main part of the multilayer inductor constituting the first embodiment of the present invention. It is the plane pattern figure and longitudinal cross-sectional view which show the principal part of the multilayer inductor which comprises 2nd Embodiment of this invention. It is the plane pattern figure and longitudinal cross-sectional view which show the principal part of the multilayer inductor which comprises 3rd Embodiment of this invention. It is the plane pattern figure and longitudinal cross-sectional view which show the principal part of the multilayer inductor which comprises 4th Embodiment of this invention. It is a graph which shows the direct current superposition characteristic of the multilayer inductor concerning the present invention. FIG. 4 is a plan pattern diagram, a perspective view, and a longitudinal sectional view showing a main part of a multilayer inductor studied as a comparative example of the present invention.

Explanation of symbols

20 Conductor pattern (or conductor)
20-1 to 20-6 Conductive pattern layer 22 Leading conductive pattern portion 24 Via 40-1 Entire magnetic gap layer 40-2 Partial magnetic gap layer 40-3 Magnetic layer 41 Magnetic body 43 Magnetic pattern 45 Nonmagnetic pattern (or nonmagnetic pattern) body)
52,53 Nonmagnetic pattern part Hz Main magnetic flux (magnetic path)
Hp Leakage magnetic flux (magnetic path)

Claims (5)

A layered conductor pattern layer in which a conductor pattern in which a part of a rectangular loop is opened is laminated in an electrically insulating magnetic material, and a magnetic material in which a nonmagnetic pattern is formed in an electrically insulating magnetic material. While the layers are interposed between the layers of each conductor pattern layer, the conductor patterns are sequentially connected to each other, thereby forming a coil that spirals in a magnetic material while overlapping in the stacking direction. Each of the rectangular laminated inductors connected to the electrode terminals on the outer surface of the laminated chip via the lead conductor pattern portions,
The lead conductor pattern portion of the coil ends, respectively, with is formed so as to extend the linear portion of the open looped conductor pattern formed on the same layer surface, extending in opposite directions, the lead Magnetic material is arranged on both sides with respect to the extending direction of the conductor pattern,
In the magnetic layer, a planar shape is rectangular, and a loop-like nonmagnetic pattern that overlaps with a projection pattern in the stacking direction of the coil is formed,
Among the magnetic layers, the magnetic layer laminated adjacent to the inside of the conductor pattern layer having the lead conductor pattern portion is caused by the current flowing in the lead conductor pattern in addition to the loop-shaped magnetic pattern. As a magnetic gap for blocking local leakage magnetic flux around the lead conductor pattern, including a straight portion connecting the lead conductor pattern portions extending in the opposite direction toward the outside of the loop An I-shaped non-magnetic pattern portion is formed which extends to the rectangular peripheral portion forming the planar shape ,
A multilayer inductor characterized by that. According to claim 1, wherein among the magnetic layer, the I-shaped magnetic layer nonmagnetic pattern portion is not formed, the non-magnetic pattern of the projected pattern in the stacking direction of the coil and the lead conductor pattern portion A multilayer inductor characterized by being formed . According to claim 1 or 2, wherein is nonmagnetic pattern portion electrically insulating the loop opening of the open loop-shaped conductor pattern is formed and the loops of the conductor pattern is substantially closed Ji is the nonmagnetic pattern portion Characteristic multilayer inductor. 4. The multilayer inductor according to claim 1, wherein at least one whole surface magnetic gap layer made of an electrically insulating nonmagnetic material is disposed on the entire layer surface. 5. The magnetic material pattern according to claim 1, wherein a magnetic material pattern is formed only on a U-shaped portion along a peripheral edge portion that does not overlap a conductor pattern of any layer, and the remaining portion is a nonmagnetic pattern. partial laminated inductor magnetic gap layer is characterized that you have been placed one or more layers.

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