JP2004014549A - Magnetic core multilayer inductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a wide linear range of magnetic flux density while reducing an inductor in size and thickness for the magnetic core multilayer inductor formed by laminating an electrical insulated magnetic layer and conductor patterns, so that the inductor is preferably used for the inductor with superposed dc like in a DC-DC converter. <P>SOLUTION: In the magnetic core multilayer inductor, the electrical insulated magnetic layer and the conductor patterns are laminated, the conductor patterns are laminated in the layer direction while sandwiching the magnetic layer to form a coil wound in spiral, and the magnetic layer forms a closed magnetic circuit for annularly guiding a magnetic field from the coil, The magnetic circuit balance is obtained for the closed magnetic circuit for guiding a magnetic field from the coil. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnetic core type laminated inductor, and is suitably used, for example, for a micro DC-DC converter.
[0002]
[Prior art]
Magnetic core type inductors such as transformers and choke coils used in power supply circuits such as DC-DC converters are constructed by winding coils around magnetic cores, so they are smaller and especially thinner than electronic components such as semiconductor integrated circuits. Was difficult. Thus, the present inventors have studied a magnetic core type multilayer inductor as shown in FIG.
[0003]
FIGS. 9A and 9B show the configuration of a magnetic core type laminated inductor studied by the present inventors prior to the present invention. FIG. 9A shows an external configuration, FIG. 9B shows a part of a conductor pattern, and FIG. (B) is an AA cross-sectional view, and (d) is an enlarged view in the thickness direction of (c). The non-magnetic core type laminated inductor having no magnetic core is formed by laminating a non-magnetic electric insulating layer and a conductor pattern by screen printing or the like. The magnetic core type laminated inductor 10 ′ shown in FIG. It is formed by laminating the body layer (soft magnetic layer) 30 and the conductor pattern 20 by screen printing or the like. The conductor pattern 20 overlaps in the layer direction while sandwiching the electrically insulating magnetic layer 30 to form a coil L 'that spirals around. The electrically insulating magnetic layer 30 forms a closed magnetic path for guiding the magnetic field from the coil L 'in an annular shape. Both ends of the coil L are connected to the electrode terminals 11 and 12 located at both ends of the inductor chip via the conductor patterns 21 and 22 for extraction.
[0004]
The magnetic core type laminated inductor 10 'has been studied by the present inventors prior to the present invention, and is treated as a conventional technique in the present invention, but is not necessarily a known technique.
[0005]
[Problems to be solved by the invention]
However, it has been clarified by the present inventors that the following problems occur in the above-described technology. That is, in the above-described magnetic core type laminated inductor 10 ′, as shown in FIG. 10, the electrically insulating magnetic material layer 30 forms a closed magnetic path for guiding the magnetic field from the coil L ′ in a ring shape. The cross-sectional area of the road is not uniform and greatly varies depending on the position of the magnetic path. That is, there is a large variation in the magnetic path cross-sectional area in the magnetic path length direction.
[0006]
FIG. 10 shows a cross-sectional model of the magnetic core type multilayer inductor shown in FIG. As shown in the figure, the closed magnetic circuit circulates through each part of abcd, and the effective magnetic circuit cross-sectional area of the closed magnetic circuit is, as shown in FIG. It differs greatly depending on the position (abcd). The difference between the portion where the magnetic path cross-sectional area is large (middle of a and b and the middle of d and a) and the small portion (b and d) are large. That is, the magnetic path imbalance is large.
[0007]
This magnetic path imbalance degrades the linearity of the change in magnetic flux density with respect to the magnetomotive force of the coil L '. That is, even if the magnetomotive force is increased by increasing the coil current, a portion having a small magnetic path cross-sectional area is magnetically saturated earlier than other portions, and the inductance value is rapidly reduced accordingly. That is, the locations (b and d) where the magnetic path cross-sectional area is minimum become the magnetic path neck that controls the magnetic permeability of the entire closed magnetic path. If the magnetic path cross-sectional area at the magnetic path neck is small, the linear change range of the magnetic flux density, that is, the linear region, is narrowed even if the magnetic path cross-sectional area is large in other parts. In the cross-sectional model shown in FIG. 10, a magnetic path neck is formed near corners (b and d) where the magnetic path is bent near both ends of the coil L ′, and this magnetic path neck narrows the linear region. found.
[0008]
In a power supply circuit such as a DC-DC converter, a direct current is usually superimposed on an inductor such as a transformer or a choke coil. For this purpose, it is necessary to secure the linear region as wide as possible. However, the above-mentioned magnetic core type laminated inductor 10 'cannot secure a wide linear region. In addition, magnetic loss concentrates on the magnetic neck, thereby causing a problem of heat generation. As described above, the above-described magnetic core type laminated inductor 10 ′ lacked suitability for use in a power supply circuit (power circuit) such as a DC-DC converter.
[0009]
In order to widen the linear region of the change in the magnetic flux density in the above-described magnetic core type laminated inductor 10 ', it is effective to secure a sufficiently large volume, particularly the thickness, of the magnetic core portion formed by the magnetic material layer 30. Is contrary to the downsizing of the inductor 10 ′, especially the downsizing.
[0010]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a magnetic core type laminated inductor formed by laminating an electrically insulating magnetic material layer and a conductor pattern. Accordingly, it is an object of the present invention to provide a technique capable of securing a wide linear region of a change in magnetic flux density while achieving the above, thereby making it suitable for, for example, an application in which DC superposition is used.
[0011]
[Means for Solving the Problems]
The present invention provides the following means.
A first means is to form a coil in which an electrically insulating magnetic material layer and a conductor pattern are laminated, and the conductor pattern overlaps in a layer direction while sandwiching the magnetic material layer and spirals around. In a magnetic core type laminated inductor in which a layer forms a closed magnetic path that guides a magnetic field from the coil in an annular shape, the inner diameter of the coil is expanded in a tapered shape in the vicinity of openings at both ends of the coil, so that the closed magnet penetrates the coil. The magnetic path cross-sectional area of the road is equalized as a whole.
[0012]
According to the above means, in a magnetic core type laminated inductor formed by laminating an electrically insulating magnetic material layer and a conductor pattern, it is possible to secure a wide linear region of a change in magnetic flux density while achieving downsizing, particularly thinning of the inductor. Can be. Thereby, for example, a thin magnetic core type laminated inductor suitable for an application in which DC superposition is used can be obtained.
[0013]
As an embodiment of the above means, a conductor pattern forming an intermediate winding portion of a coil is patterned so as to draw a relatively small inner diameter with a relatively wide conductor width, while a conductor pattern forming both end winding portions of the coil is formed. A configuration in which the pattern is patterned so as to draw a relatively large inner diameter with a relatively narrow conductor width is preferable. The conductor pattern may be patterned so as to form a rectangular coil by a pattern bent at a right angle.
[0014]
The second means forms a coil in which an electrically insulating magnetic material layer and a conductor pattern are laminated, and the conductor pattern overlaps in a layer direction while sandwiching the magnetic material layer and spirals around. In a magnetic core type laminated inductor in which a layer forms a closed magnetic path that guides a magnetic field from the coil in a ring shape, the magnetic gap is selectively interposed in the magnetic layer, so that the magnetomotive force of the coil is unevenly distributed. It is characterized in that the deviation of the magnetic flux density is equalized.
According to this means, it is possible to eliminate the variation in the saturation of the magnetic flux density caused by the odd number of turns of the coil, thereby achieving the miniaturization of the inductor, especially the thinning, as in the first means. A wide linear region of magnetic flux density change can be secured. In order to arrange electrode terminals at both ends of the inductor chip, it is necessary to draw conductor patterns in opposite directions from both ends of the coil, but this drawing conductor pattern portion makes the number of turns of the coil a non-integer odd number . In the coil having the odd number of turns, the magnetomotive force is unequally distributed and the magnetic flux density in the closed magnetic circuit is biased. According to the above-described means, the magnetic flux density bias can be equalized. Thereby, the line region of the self-made density change can be enlarged. The magnetic gap can be formed by replacing a part of the magnetic layer with a layer having a relatively low magnetic permeability.
[0015]
The third means is to form a coil in which an electrically insulating magnetic material layer and a conductor pattern are laminated, and the conductor pattern overlaps in a layer direction while sandwiching the magnetic material layer and spirals around. A magnetic core type laminated inductor in which a layer forms a closed magnetic path that guides a magnetic field from the coil in a ring shape is characterized by having the following constituent means (1) to (4).
(1) The magnetic material layer forms a middle leg of the closed magnetic path inside the coil and forms an outer leg of the closed magnetic path outside the coil.
(2) A portion where the number of superposed conductor patterns becomes n (an integer of 1 or more) layers by connecting the both ends of the coil to the electrode terminals located in opposite directions via the lead conductor pattern portion. And an n + 1 layer.
(3) The width of the outer leg portion into which the magnetic field from the n + 1 layer conductor pattern portion is introduced is made smaller than the width of the outer leg portion into which only the magnetic field from the n layer conductor pattern portion is introduced.
(4) The magnetic permeability of the entire closed magnetic circuit is equalized by the above (3).
[0016]
This third means can also secure a wide linear region of the change in magnetic flux density while achieving downsizing of the inductor, particularly downsizing. Further, in the above-mentioned means, the following embodiment is preferable.
In other words, the pattern area of the I-shaped outer foot that guides the magnetic field from the lead-out conductor pattern section is set to not more than 1/5 of the pattern area of the U-shaped outer foot formed in other portions. The pattern area of the middle foot portion formed inside the coil is substantially equal to the pattern area of the outer foot portion formed outside the coil. The outer peripheral length of the middle foot portion is substantially equal to the boundary length between the U-shaped outer foot portion and the conductor pattern. The width of the lead-out conductor pattern portion is t, the width of the I-shaped outer foot portion along the lead-out conductor pattern portion is w, and the boundary length between the middle foot portion and the lead-out conductor pattern portion is k. Then, (w + t) ≒ k / 2.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a first embodiment of a magnetic core type laminated inductor according to the present invention. In the same figure, (a) is an example of the appearance configuration, (b) is a part of the conductor pattern, (c) is a sectional view taken along the line AA of (b), and (d) is an enlarged view in the thickness direction of (c). Are respectively shown.
[0018]
The magnetic core type laminated inductor 10 shown in FIG. 1 is configured as a chip component for surface mounting. The magnetic core type laminated inductor 10 is formed by alternately laminating an electrically insulating magnetic material layer (soft magnetic material layer) 30 and a conductor pattern 20 by screen printing or the like. The conductor pattern 20 forms a coil L that spirals and overlaps in the layer direction while sandwiching the electrically insulating magnetic layer 30. In the illustrated embodiment, the conductor pattern 20 forms a rectangular coil L while bending at a right angle.
[0019]
The electrically insulating magnetic layer 30 forms a closed magnetic path for guiding the magnetic field from the coil L in an annular shape. Both ends of the coil L are connected to the electrode terminals 11 and 12 located at both ends of the inductor chip via the conductor patterns 21 and 22 for extraction. The electrode terminals 11 and 12 are disposed symmetrically at both ends of the chip.
[0020]
In the magnetic core type laminated inductor 10 of this embodiment, as shown in FIGS. 1C and 1D, the conductor pattern 20 of each layer forming the coil L overlaps in the layer direction to form a spiral coil L. The coil L is formed so that the inner diameter of the coil L expands in a tapered shape near the openings at both ends of the coil. Therefore, as shown in FIG. 3D, the conductor pattern 20 forming the intermediate winding portion of the coil L is patterned so as to draw a relatively small inner diameter A with a relatively wide conductor width, while The conductor pattern 20 forming the winding portion at both ends of L is patterned so as to draw a relatively large inner diameter B by a relatively narrow conductor width.
[0021]
In the above-described magnetic core type laminated inductor, as shown in FIG. 2, the electrically insulating magnetic material layer 30 forms an annular closed magnetic path that goes around the inside and outside of the coil L. As shown in FIG. 3, the area of the coil L varies with the magnetic path position (ab-b-c) by expanding the inner diameter of the coil L in a tapered shape near the openings at both ends of the coil. A small and substantially uniform magnetic path cross-sectional area is obtained over the entire closed magnetic path. In FIG. 3, the solid line indicates the state of the magnetic path cross-sectional area according to the embodiment of the present invention, and the dashed line indicates the state of the magnetic path cross-sectional area of the above-described conventional inductor 10 '.
[0022]
If the variation in the magnetic path is small, high magnetic permeability can be ensured until the entire closed magnetic circuit is saturated, which allows the inductor to be reduced in size and especially thinner, while securing a wide linear region of magnetic flux density change. As a result, it is possible to obtain the magnetic core type laminated inductor 10 which is also suitable for applications in which DC is superimposed and used, such as a DC-DC converter. At the same time, the magnetic loss is distributed throughout the closed magnetic circuit, so that the problem of heat generation due to concentration of the loss can be avoided.
[0023]
In addition to the configuration described above, if the magnetic path cross-sectional area of the inner peripheral magnetic path portion (part a) and the magnetic path cross-sectional area of the outer peripheral magnetic path part (part c) of the coil L are made equal to each other, The magnetic path balance can be further equalized. For this purpose, in FIG. 1 (d), the intermediate winding portion where the inner diameter of the coil L is the smallest (the portion where the inner diameter is A), that is, the position where the magnetic path cross-sectional area inside the coil L is the smallest (the inner diameter A ), The inner and outer magnetic path cross-sectional areas of the coil should be equal. The winding pattern of the coil L is rectangular in the illustrated example, but may be circular or another loop shape.
[0024]
FIG. 4 shows the magnetic portion of the magnetic core type laminated inductor 10 modeled as a bulk (single) E-type magnetic core. The bulk E-shaped magnetic core has outer legs at both ends of the flat plate, and has a shape in which the middle foot stands at the center of the flat plate. In the figure, an E-shaped magnetic core having a square pillar-shaped middle foot as shown in FIG. 2A is modeled as a magnetic core having a square trapezoidal middle foot as shown in FIG. can do. Further, the E-shaped magnetic core having a cylindrical middle foot as shown in FIG. 3C is modeled as an E-shaped magnetic core having a circular trapezoidal middle foot as shown in FIG. can do.
[0025]
In the magnetic core model of (a), when the length (diameter) of one side of the midfoot portion is B and the thickness of the flat plate portion on which the midfoot portion stands is t, the midfoot portion and the flat plate portion are The cross-sectional area A1 at the connected annular portion is A1 = 4 × B × t. In order to balance the magnetic path between the middle foot portion and the flat plate portion, it is necessary to make the cross-sectional area A1 of the annular connection portion equal to the cross-sectional area A2 of the middle foot portion. The cross-sectional area A2 of the midfoot is A2 = B × B. In order to set A1 = A2 from now on, t is determined so that t = B / 4.
[0026]
In order to balance the magnetic path in the magnetic core model of (b), the upper area of the middle foot and the cross-sectional area of the annular portion connected to the base of the middle foot may be equal to each other. . When the length of one side on the upper surface of the middle foot is B, the length of one side at the base of the middle foot is B ', and the thickness of the flat plate on which the middle foot stands is t', The upper area of the middle foot portion is B × B, and the cross-sectional area of the annular portion where the middle foot portion and the flat plate portion are connected is 4 × B ′ × t ′. In order to balance the magnetic path between the middle foot portion and the flat plate portion, t ′ may be determined so that both areas (B × B) are equal to (4 × B ′ × t ′). That is, in this case, t ′ may be determined so that t ′ = (B × B) / (4 × B ′). This conditional expression indicates that by increasing B ′, the magnetic path can be balanced even if t ′ is small. Thereby, t ′ can be reduced and the magnetic core can be reduced in thickness.
[0027]
In the magnetic core model of (c), when the diameter of the midfoot portion is D and the thickness of the flat plate portion on which the midfoot portion stands is t, the thickness of the annular portion where the midfoot portion and the flat plate portion are connected to each other is represented. The cross-sectional area A1 is A1 = π × D × t. Further, the cross-sectional area A2 of the middle foot portion is A2 = (D / 2) × (D / 2) × π. In this case, in order to balance the magnetic path between the middle foot portion and the flat plate portion, t is determined so that t = D / 4.
[0028]
In the magnetic core model of (d), the diameter at the upper surface of the middle foot is D, the diameter at the base of the middle foot is D ', and the thickness of the flat plate on which the middle foot stands is t'. In this case, the upper area of the middle foot portion is A2 = (D / 2) × (D / 2) × π, and the cross-sectional area of the annular portion where the middle foot portion and the flat plate portion are connected is π × D ′ × t '. In this case, in order to balance the magnetic path between the middle foot portion and the flat plate portion, t may be determined so that t = (D × D) / (4 × D ′). This conditional expression shows that, as in the case of (b), by increasing D ′, the magnetic path balance can be achieved even when t ′ is small. Thereby, t ′ can be reduced and the magnetic core can be reduced in thickness.
[0029]
FIG. 5 shows a second embodiment of the magnetic core type laminated inductor according to the present invention. In a multilayer inductor configured as a chip component for surface mounting, the electrode terminals 11 and 12 are disposed at both ends of the chip in a position symmetrical state so that troublesome direction determination is not required when mounting the substrate. It is desirable (FIG. 1). Therefore, as shown in FIG. 5A, both ends of the coil L are drawn out in opposite directions via the lead-out conductor pattern portions 21 and 22, respectively. When such a terminal lead-out structure is formed, the number of turns of the coil L is not a simple integer, but an odd number of turns such as n × １ ／ (n is an integer).
[0030]
In this case, the number of layers of the conductor pattern 20 forming the coil L differs depending on the location as shown in FIG. That is, a portion where the conductor pattern overlaps n layers and a portion where n + 1 layers overlap are generated. If the portion where the conductor pattern 20 overlaps n + 1 layers corresponds to 1/4 turn, the number of coil turns is n + 1/4. The magnetomotive force differs between a portion where the conductor pattern 20 overlaps the n + 1 layer and a portion where the conductor pattern 20 overlaps the n layer.
[0031]
In the magnetic path A on the side where the lead-out conductor pattern portions 21 and 22 are located, the conductor pattern is superimposed by one extra layer and the number of turns of the coil L is partially increased. Is larger than the magnetic path B of the portion. This difference in the magnetomotive force causes a reduction in the magnetic path balance, thus impairing the linearity of the magnetic flux density change. Even if the magnetic path cross-sectional area of the entire closed magnetic path is uniform, if there is a bias in the magnetomotive force, the portion with a large magnetomotive force will be magnetically saturated first, causing the same problem as the magnetic neck described above. Let it.
[0032]
Therefore, in this embodiment, as shown in FIG. 5, the magnetic gap 31 is selectively interposed in the magnetic path A on the side where the magnetomotive force increases. This magnetic gap 31 can be formed by a nonmagnetic electric insulating layer (magnetic permeability μ ≒ 1) or an electrically insulating magnetic layer (soft magnetic layer) having a relatively low magnetic permeability. Specifically, it can be formed by replacing a part of the electrically insulating magnetic layer 30 formed in a specific layer with a layer having a low magnetic permeability. By providing such a magnetic gap 31, it is possible to compensate for unequal distribution of magnetomotive force due to a difference in the number of partial turns of the coil L, and to obtain a good magnetic balance.
[0033]
FIG. 6 shows a more specific embodiment of the magnetic gap 31. Although the magnetic gap 31 shown in FIG. 5 is provided only in a portion corresponding to one outer leg of the E-shaped magnetic core, in order to balance the magnetic path of the entire core, as shown in FIG. It is better to provide the magnetic gap 31 in a pattern shape that straddles both the outer leg and the middle leg of the E-shaped magnetic core.
[0034]
FIG. 7 shows a third embodiment of the magnetic core type laminated inductor according to the present invention. The uneven distribution of the magnetomotive force due to the partial difference in the number of turns of the coil L can be compensated by the area ratio of the portion corresponding to the pair of outer legs of the E-shaped magnetic core as shown in FIG. That is, in FIG. 3, the outer leg width t1 on the side (magnetic path A side) on which the conductor patterns are overlapped by n + 1 layers due to the formation of the lead-out conductor pattern portions 21 and 22 is only n layers. It is formed narrower than the outer leg width t2 on the overlapping side (magnetic path B side). That is, the width t1 of the outer leg portion into which the magnetic field from the n + 1 layer conductor pattern portion is introduced is made smaller than the width t2 of the outer leg portion into which only the magnetic field from the n layer conductor pattern portion is introduced. I have. Thereby, even if a positional deviation of the magnetic flux density occurs due to the uneven distribution of the magnetomotive force, the deviation can be compensated to obtain a good magnetic balance.
[0035]
FIG. 8 is a dimensional relationship diagram of a magnetic core type laminated inductor in which the conductor pattern 20 and the electrically insulating magnetic layer 30 are both formed in a rectangular shape. In the figure, in order to achieve the above-mentioned magnetic path balance, the dimensions of each part may be set as follows.
(1) The area s22 of the I-shaped outer leg pattern formed on the side of the lead-out conductor pattern portions 21 and 22 is 1/1 of the area s21 of the U-shaped outer leg pattern formed on the other portions. 5 or less.
(2) The area s1 of a certain midfoot pattern formed inside the coil L, and the total pattern area s2 of the I-shaped and U-shaped outer feet formed outside the coil L (= s21 + s22) And are approximately equal.
(3) The outer peripheral length (2 × j + 2 × k) of the middle foot portion is substantially equal to the boundary length (2 × u + n + 2 × p) between the U-shaped outer foot portion and the conductor pattern.
(4) The width of the lead-out conductor pattern portions 21 and 22 is denoted by t, the width of the I-shaped outer foot portion along the lead-out conductor pattern portions 21 and 22 is denoted by w, and (W + t) ≒ k / 2, where k is the boundary length between the midfoot portions. As a result, the magnetic path cross-sectional area at the middle foot can be effectively transmitted to the I-shaped outer foot, and a good magnetic path balance can be obtained.
[0036]
In the dimension diagram of FIG. 8, the dimensions (x, y, u, t, w, m) of each part can be optimized by determining so as to satisfy the following expressions (1), (2), and (3). .
2u + n = y (1)
t + u + m = x (2)
(M−2w) (n−2w) = (xy−mn−2wu) (3)
Thereby, the width w of the I-shaped outer leg can be optimized by determining so as to satisfy the above equations (1), (2), and (3).
[0037]
As described above, the present invention has been described based on the typical embodiments. However, the present invention can have various aspects other than those described above. For example, the pattern shape of the coil L may be a circular pattern or a rectangular pattern having a circular arc at the corner.
[0038]
【The invention's effect】
According to the present invention, in a magnetic core type laminated inductor formed by laminating an electrically insulating magnetic material layer and a conductor pattern, a linear region of a change in magnetic flux density is secured widely while achieving downsizing, particularly thinning, of the inductor. Thereby, for example, a thin magnetic core type laminated inductor suitable for an application in which DC superposition is used can be obtained.
[Brief description of the drawings]
FIG. 1 is a view showing a first embodiment of a magnetic core type laminated inductor according to the present invention.
FIG. 2 is a diagram showing a cross-sectional state of a magnetic core type laminated inductor according to the present invention.
FIG. 3 is a graph showing a magnetic path cross-sectional area state of the magnetic core type laminated inductor according to the present invention.
FIG. 4 is a diagram showing a magnetic portion of a magnetic core type laminated inductor modeled on a bulk E-type magnetic core;
FIG. 5 is a view showing a second embodiment of the magnetic core type laminated inductor according to the present invention.
FIG. 6 is a diagram showing a more specific embodiment of a magnetic gap forming one of the main parts of the present invention.
FIG. 7 is a view showing a third embodiment of the magnetic core type laminated inductor according to the present invention.
FIG. 8 is a dimensional relation diagram of the magnetic core type laminated inductor according to the present invention.
FIG. 9 is a diagram showing a configuration of a magnetic core type laminated inductor studied prior to the present invention.
10 is a diagram showing a cross-sectional state of the magnetic core type laminated inductor shown in FIG.
11 is a graph showing a state of a magnetic path cross-sectional area of the magnetic core type multilayer inductor shown in FIG. 9;
[Explanation of symbols]
10 Magnetic core type laminated inductor (the present invention)
10 'core type multilayer inductor (conventional)
11, 12 electrode terminals 30 electrically insulating magnetic layer (soft magnetic layer)
20 Conductor Patterns 21, 22 Leader Conductor Pattern Part 31 Magnetic Gap L Coil (The Present Invention)
L 'coil (conventional)
A Magnetic path B Magnetic path

Claims (11)

An electrically insulating magnetic material layer and a conductor pattern are laminated, and the conductor pattern overlaps in a layer direction while sandwiching the magnetic material layer to form a coil that helically circulates. In a magnetic core type laminated inductor that forms a closed magnetic circuit that guides a magnetic field in an annular shape, the inner diameter of the coil is expanded in a tapered shape near the openings at both ends of the coil, so that the magnetic path cross-sectional area of the closed magnetic circuit penetrating the coil A magnetic core type multilayer inductor characterized by equalizing as a whole. 2. The conductor pattern according to claim 1, wherein a conductor pattern forming an intermediate winding portion of the coil is patterned so as to draw a relatively small inner diameter with a relatively wide conductor width, while forming a winding portion at both ends of the coil. Is a magnetic core type multilayer inductor characterized by being patterned so as to draw a relatively large inner diameter by a relatively narrow conductor width. 3. The magnetic core type multilayer inductor according to claim 1, wherein the conductor pattern forms a rectangular coil by a pattern bent at a right angle. An electrically insulating magnetic material layer and a conductor pattern are laminated, and the conductor pattern overlaps in a layer direction while sandwiching the magnetic material layer to form a coil that helically circulates. In a magnetic core type laminated inductor that forms a closed magnetic path that guides a magnetic field in a ring shape, a magnetic gap is selectively interposed in the magnetic material layer to evenly distribute the magnetic flux density caused by uneven distribution of the magnetomotive force of the coil. A magnetic core type multilayer inductor characterized in that it is made into a core. 5. The magnetic core type inductor according to claim 4, wherein the magnetic gap is formed by replacing a part of the magnetic layer with a layer having a relatively low magnetic permeability. 6. The magnetic core according to claim 4, wherein the coil has a non-integer odd number of turns by connecting both ends of the coil to electrode terminals located in opposite directions through a lead conductor pattern portion. Type multilayer inductor. An electrically insulating magnetic layer and a conductor pattern are laminated, and the conductor pattern overlaps in a layer direction while sandwiching the magnetic layer to form a coil that spirals around, and the magnetic layer is formed from the coil. A magnetic core type laminated inductor which forms a closed magnetic path for guiding a magnetic field in an annular shape, comprising the following constituent means (1) to (4).
(1) The magnetic layer forms a middle leg of the closed magnetic path inside the coil and forms an outer leg of the closed magnetic path outside the coil.
(2) A portion in which the number of superposed conductor patterns is n (an integer of 1 or more) layers by connecting the both ends of the coil to electrode terminals located in opposite directions via a lead conductor pattern portion. And an n + 1 layer.
(3) The width of the outer leg portion into which the magnetic field from the n + 1 layer conductor pattern portion is introduced is made smaller than the width of the outer leg portion into which only the magnetic field from the n layer conductor pattern portion is introduced.
(4) The magnetic permeability of the entire closed magnetic circuit is equalized by the above (3). 8. The pattern area of the I-shaped outer foot portion for guiding a magnetic field from the lead conductor pattern portion according to claim 7, wherein the pattern area of the U-shaped outer foot portion formed in other portions is equal to or less than 1/5. A magnetic core type multilayer inductor characterized by the following. 9. The magnetic core type laminated inductor according to claim 7, wherein a pattern area of a middle foot portion formed inside the coil and a pattern area of an outer foot portion formed outside the coil are substantially equal. . 10. The magnetic core type laminated inductor according to claim 9, wherein an outer peripheral length of the middle foot portion and a boundary length between the U-shaped outer foot portion and the conductor pattern are substantially the same. The width | variety of the said conductor pattern part for a drawer in any one of Claims 7-10, set to t, the width | variety of the I-shaped outer leg | foot part along this conductor pattern part for a extract | drawing is set to w, and the said middle foot part and the said drawer A magnetic core type laminated inductor, wherein (w + t) ≒ k / 2, where k is a boundary length between conductor pattern portions.

Images