JP3033262B2 - Planar inductance components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar inductance component such as a planar inductor and a planar transformer.

[0002]

2. Description of the Related Art In recent years, electronic devices have been reduced in size and thickness, and there has been a demand for even smaller inductors and transformers. At present, a planar inductor and a planar transformer in which a planar coil and a ferromagnetic layer are stacked have been proposed to achieve the above object.

Hereinafter, a conventional planar inductor will be described. FIG. 10A is a plan view showing a configuration of a planar inductor using a conventional spiral conductor coil, and FIG.
FIG. 10B is a sectional view taken along the line BB ′ of FIG.

Referring to FIGS. 10A and 10B, a spiral conductor coil 3 and input / output terminals 4a and 4b are formed on a ferromagnetic layer 1a via an insulator layer 2a. . An insulator layer 2b is formed on the spiral conductor coil 3, and an extraction electrode 6 is extracted from a through hole 5 formed in the insulator layer 2b, and the input / output terminal 4
b. Furthermore, a spiral conductor coil 3
In addition, an insulating layer 2c is formed on the insulating layer 2b so as to cover the extraction electrode 6, and a ferromagnetic layer 1b is formed thereon. For convenience of explanation, FIG.
In FIG. 5A, the ferromagnetic layer 1b is cut away, and only the lower spiral conductor coil 3 and the extraction electrode 6 can be seen.

[0005]

However, in the conventional structure shown in FIGS. 10A and 10B, when the substrate is formed by using a vacuum film forming process, if the base has irregularities, it is formed on the base. Similar irregularities are likely to be formed on the film. In particular, the formation process is very complicated because four layers are formed on the spiral-shaped conductor coil 3. However, the ferromagnetic layers 1a and 1b are particularly liable to have a degraded soft magnetic characteristic when the layers have irregularities. Therefore, flatness is important.

If the ferromagnetic layers 1a and 1b are insulators, the insulator layers 2a and 2b can be omitted and the thickness can be reduced.
In that case, a protrusion is generated in the ferromagnetic layer 1b, which causes the above-described problem.

Further, the distance between the spiral conductor coil 3 and the ferromagnetic layer 1a can be freely controlled, but the distance between the spiral conductor coil 3 and the ferromagnetic layer 1b can be freely controlled since the extraction electrode 6 exists. However, there is a problem that the design of the magnetic circuit is restricted.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a planar inductance component which is small and thin and has no deterioration in soft magnetic characteristics.

[0009]

SUMMARY OF THE INVENTION To achieve this object, the present invention provides an inductor comprising a spiral coil conductor provided on a substrate, and an inductor connected to an outer end and an inner end of the coil conductor. A pair of input / output terminals provided on the substrate, and a ferromagnetic layer provided so as to sandwich the coil conductor from above and below, while protruding an inner end of the coil conductor to the outside of the ferromagnetic layer. The coil conductor located between the inner end and the input / output terminal protrudes outside the ferromagnetic layer, and the inner end of the coil conductor is connected to one of the input / output terminals.

[0010]

According to the present invention, it is possible to obtain a small and thin planar inductance component which is easy to produce.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings, taking a planar inductor as an example of a planar inductance component.

(Embodiment 1) FIG. 1A is a plan view showing a configuration of a planar inductor according to a first embodiment of the present invention, FIG. 1B is a cross-sectional view taken along the line BB 'of FIG. 1A, FIG.
FIG. 2C is a cross-sectional view taken along line CC ′ of FIG.

Referring to FIGS. 1 (a), 1 (b) and 1 (c), a thickness of 1 μm is formed on a 400 μm thick ferrite plate 11a formed by sintering a Ni—Zn—Cu ferrite powder.
A rectangular spiral conductive coil 12 made of a 0 μm aluminum film, and input / output terminals 13 connected to the inner end 15 and the outer end of the spiral conductive coil 12, respectively.
a, 13b are formed. The spiral conductive coil 12 has a ferrite plate 11b formed thereon. The spiral conductive coil 12 located between the inner end 15 and the input / output terminal 13b is formed so as to protrude outside the ferrite plate 11b to form a protruding portion 14. The inner end 15 is connected to the input / output terminal 13b by a gold wire 16. This connection can be easily made by a wire bonding method. In this embodiment, the reason why aluminum is used as the conductor material is to facilitate wire bonding. In order to facilitate wire bonding, the surface may be gold or aluminum. Further, a ferrite plate 11 b having a thickness of 400 μm is in close contact with the spiral conductive coil 12 so as to expose a portion of the protrusion 14 to which the gold wire 16 is connected. For convenience of explanation, in FIG. 1A, the spiral-shaped conductor coil 12 is placed under the ferrite plate 11b.
It is a figure that can be seen.

The reason why the ferrite plates 11a and 11b can take a simple structure in which the spiral-shaped conductor coil 12 is tightly sandwiched between the ferrite plates 11a and 11b is that the projections 14 are formed. Further, since the distance between the ferrite plates 11a and 11b can be minimized, the magnetic resistance is reduced and a large inductance is obtained. In this embodiment, a ferrite plate is used as the ferromagnetic layer. However, it is a matter of course that a similar configuration can be adopted as long as the ferromagnetic layer has at least an insulating surface.

The size of the spiral conductor coil 12 in this embodiment will be described. The line width is 100 μm, the line interval is 10 μm, and the size in the line CC ′ is 3000 μm.
The size on a straight line that is perpendicular to the m, C-C 'line and does not pass through the protrusion 14 is 3000 [mu] m. The width of the protrusion is 320 μm as calculated from the line width and the line interval. That is, the spiral conductor coil of the present invention may have a width along the line CC ′ larger than the width of the protruding portion. Also, the shape is not limited to a square shape, and a similar configuration can be obtained with a circular or elliptical shape.

Although the connection between the inner end 15 and the input / output terminal 13b is made by wire bonding in this embodiment, the characteristics of this embodiment will not be lost even if the connection is made by another method. Is natural.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described.

FIG. 2A is a plan view showing the structure of the planar inductor in the second embodiment, and FIG. 2B is a plan view of FIG.
FIG. 2C is a sectional view taken along the line BB ′ of FIG.
5 is a sectional view taken along line CC ′ of FIG. FIG. 3 is a cross-sectional view showing a configuration of a laminated magnetic film used as a ferromagnetic layer in this embodiment. In FIG. 3, 31 is a CoNbZr layer having an amorphous structure, and 32 is a SiO ₂ layer. As shown in FIG. 3, the CoNbZr layer 31 is always sandwiched between the SiO ₂ layers 32.

The structure of the planar inductor of this embodiment will be described with reference to FIGS. 2A, 2B and 2C. A 2.5 μm thick CoNbZr layer and a 1 μm thick
laminated magnetic film 22a in which m ₂ SiO ₂ layers are alternately laminated.
Are formed. The number of layers is 10 CoNbZr layers,
There are 11 SiO ₂ layers. A conductor coil 23 made of an aluminum film having a thickness of 10 μm is formed on the laminated magnetic film 22a.
And input / output terminals 24a and 24b. The conductor coil 23 has such a shape that a spiral conductor coil is bent in a zigzag manner. The conductor coil 23 has a line width of 10
0 μm. The line spacing is 10 μm between adjacent conductors in which the current flows in the same direction, and 600 μm between adjacent conductors in which the current flows in opposite directions. Like the case of FIG. 1, the conductor coil 23 also has a protruding portion 25 for extracting an electrode. An inner end 26 inside the protrusion 25 is connected to the input / output terminal 2 by a gold wire 27 in the same manner as in the first embodiment.
4b. Further, an insulating layer 28 is formed in a portion of the laminated magnetic film 22a where the conductor coil 23 does not exist, with the same thickness of 10 μm as the conductor coil 23. Further, the laminated magnetic film 22b is formed on the conductor coil 23 so that the gold wire 27 of the protrusion 25 is exposed. The configuration of the laminated magnetic film 22b is the same as that of the laminated magnetic film 22a. For convenience of explanation, FIG. 2A shows only the conductor coil 23 below the laminated magnetic film 22b. The size of the conductor coil 23 is 2460 μm on the line CC ′, and 3400 μm on a straight line perpendicular to the line CC ′ and not passing through the protrusion 25.
m.

The parts explained above are shown in FIGS. 1 (a), (b),
The configuration is basically the same as the configuration of (c). FIG.
The difference from the configurations of (a), (b) and (c) is that the conductor coil 23 is bent in a zigzag manner. This is designed for the purpose of improving the high frequency characteristics, particularly the high frequency characteristics of a planar inductor using a laminated magnetic film. For comparison, the spiral-shaped conductor coil 1 shown in FIG.
A planar inductor formed with a spiral-shaped conductor coil having the same shape as that of No. 2 was produced. FIG. 4 shows the configuration of this inductor. 4A is a plan view showing the structure, FIG. 4B is a cross-sectional view taken along line BB 'of FIG. 4A, and FIG. 4C is a line CC' of FIG. 4A. FIG. FIG.
In (a), (b) and (c), 43 is a spiral conductor coil. Reference numerals indicating other configurations are shown in FIG.
The same ones as in (a), (b) and (c) were used.

Hereinafter, the inductor configured as shown in FIG. 2 is referred to as an inductor (2), and the inductor configured as illustrated in FIG. 4 is referred to as an inductor (4).

The operation of the inductor (2) will be described below with reference to FIG. FIG. 5 is a schematic diagram of a magnetic circuit formed in the cross section shown in FIG. The operation of the inductor (4) will be described with reference to FIG. FIG. 6 shows FIG.
It is a schematic diagram of the magnetic circuit formed in the cross section shown in (c).

In FIG. 6, the magnetic flux flow 61 circulates around the entire conductor 62, and the magnetic flux flow 61 intersects perpendicularly with the multilayer magnetic film 63 at the center of the multilayer magnetic film 63. When the magnetic flux interlinks vertically, the CoNbZr layer in the laminated magnetic film 63 has metallic conductivity, so that an overcurrent occurs and a power loss occurs,
The high frequency characteristics of the inductor deteriorate.

On the other hand, in FIG. 5, since the direction of the current flowing through the conducting wire 52 is alternated, the flow 51 of the magnetic flux is subdivided. Therefore, the area of the portion where the magnetic flux flow 51 interlinks perpendicularly to the laminated magnetic film 53 is reduced, and the high-frequency characteristics are improved. That is, the inductor 2 of this embodiment has excellent frequency characteristics as compared to the inductor 4 created for comparison.

A similar effect can be obtained with a meander-type conductor coil generally known (for example, IEEE Tr., MAG-2).
0, pp1804-1806, 1984), since the meander type coil is a one-turn coil, a large inductance cannot be obtained. On the other hand, the conductor coil 23 of the present embodiment can obtain an inductance twice the number of turns.

Assuming that the length of the magnetic flux flowing through the laminated magnetic film 53 attenuating to 1 / e, that is, the characteristic length is λ, λ = √
(Μr · g · tm / 2) (for example, IEEJ Magnetics Research Group MA
G-89-164). Here, μr is the relative magnetic permeability of the laminated magnetic film 53, g is the gap between the laminated magnetic films 53, and tm is CoN.
This is the total thickness of the bZr layer. μr = 1500, g = 10μ
When m and tm = 25 μm are substituted, λ = 430 μm. In the inductor (2), the total width of the conductive wires 52 adjacent to each other and in which the current flows in the same direction is 210 μm, which is sufficiently smaller than λ. Therefore, the magnetic flux density of the magnetic flux linking to the conducting wire 52 is small, and the loss due to the proximity effect can be suppressed to be small. As described above, it is important to reduce the distance between adjacent conductors in which the direction of current flow is the same.
The same is true for inductor (4). Also,
Since λ is 430 μm, the portion where the laminated magnetic films 22a and 22b are effectively working as the magnetic core is limited to the vicinity of the adjacent conductive wire having the same current direction. Therefore, the ratio of the area where the laminated magnetic films 22a and 22b function as the magnetic core to the entire area of the inductor (2) is larger than that of the inductor (4).

The results of measuring the inductances of the inductor (2) and the inductor (4) will be described below. The inductance of the inductor (2) at 100 kHz was 2.0 μH, which was about 20 times that in the air-core state. On the other hand, the inductance of the inductor (4) at 100 kHz is 2.4 μH, which is about 1 compared to the air-core state.
It was 5 times. This indicates that the area of the laminated magnetic films 22a and 22b acting as a magnetic core is larger in the inductor 2 than in the inductor 4, as described above.

FIG. 9 shows the frequency characteristics of the inductances of the inductors (2) and (4). In addition,
In FIG. 9, the inductance of the inductor (2) at 100 kHz is normalized as 1 and shown. FIG.
As is clear from FIG. 5, the inductance of the inductor (4) decreases as the frequency increases, but the inductance of the inductor (2) shows a flat characteristic up to about 10 MHz. As is evident from the results, the inductor (2) according to the present embodiment shows a better frequency characteristic than the inductor 4 prepared for comparison.

As described above, the conductor coil 23 of the present embodiment
As described above, when the spiral conductor coil is formed into a zigzag planar coil, a planar inductor having good frequency characteristics can be obtained.

In this embodiment, a laminated magnetic film of CoNbZr and SiO ₂ is used as a laminated magnetic film. However, a laminated magnetic film made of a composite metal and an insulating layer having excellent soft magnetic properties can be used. Naturally, it can be used for an inductor.

(Embodiment 3) Hereinafter, a third embodiment of the present invention will be described.

FIG. 8A is a plan view showing the structure of a planar inductor according to the third embodiment, and FIG. 8B is a plan view of FIG.
8C is a sectional view taken along the line BB 'of FIG. 8, and FIG.
5 is a sectional view taken along line CC ′ of FIG. FIG. 8 (a),
In (b) and (c), 21 is a substrate, 22a and 22b are laminated magnetic films, 23 is a conductor coil, 24a and 24b are input / output terminals, 25 is a projection, 26 is an inner end, 27 is a gold wire, and 28 is a gold wire. It is an insulating layer.

The parts explained above are shown in FIGS.
The configuration is basically the same as the configuration of (c). FIG.
The difference from (a), (b) and (c) is that the laminated magnetic film 22
a and 22b are not formed so as to sandwich the entire conductor coil 23. That is, the laminated magnetic films 22a, 22
2b is formed in a zigzag shape with a width of 250 μm above and below an adjacent conductor having the same direction of current flow in the conductor coil 23 so as to sandwich the conductor. This laminated magnetic film 22
Assuming that the widths of a and 22b are W _m , the number of turns of the conductor coil 23 is N _s , and the width of the conductor is W _c , FIGS.
It is necessary to design meet the condition _{N s · W c <W m} <(N s +1) · W c in the configuration of (c). In this embodiment, since N _s = 2 and W _c = 100 μm, 200 μm <
The W _m can be selected in the range of W _m <300μm.

Hereinafter, an inductor configured as shown in FIGS. 8A, 8B and 8C is referred to as an inductor (8).

The operation of the inductor (8) will be described below with reference to FIG. FIG. 7 is a schematic diagram of a magnetic circuit formed in the cross section shown in FIG. In FIG. 7, 71
Is a flow of magnetic flux, 72 is a conducting wire, and 73 is a laminated magnetic film.
Since λ = 430 μm and W _m = 250 μm, the flow 71 of the magnetic flux flows in the laminated magnetic film 73 in parallel to the laminated magnetic film 73 and has a small amount of components that interlink vertically. Further, the area where the flow of the magnetic flux 71 intersects perpendicularly with respect to the laminated magnetic film 73 is reduced as compared with FIG. 5, and the frequency characteristic is further improved as compared with the configuration of FIG. Also, the laminated magnetic films 22a, 22a
Since b is elongated, shape anisotropy occurs in the longitudinal direction.
Therefore, the longitudinal direction becomes the axis of easy magnetization, and is shifted by 90 degrees from the direction of excitation. Therefore, the speed of the magnetization response is increased, and the high-frequency characteristics are improved.

Next, the result of measuring the inductance of the inductor (8) will be described. 10 of the inductor (8)
The inductance at 0 kHz was 1.7 μH, which was 15% smaller than that of the inductor (2). FIG. 9 shows the frequency characteristics of the inductor (8). In FIG. 9, the inductance at 100 kHz of the inductor 2 is standardized as 1. As is clear from FIG. 9, the inductor (8) according to the present embodiment has better frequency characteristics than the inductor (2) and shows a flat characteristic up to about 30 kHz. As is clear from this result, the inductor (8) according to the present embodiment has higher frequency characteristics than the inductor (2).

As described above, when the laminated magnetic films 22a and 22b are formed only above and below the conductors which are adjacent and have the same current flowing direction as in the present embodiment, a planar inductor having excellent frequency characteristics can be obtained. .

In the first, second, and third embodiments, only the planar inductor is formed. However, the configuration of the planar coil pattern and the ferromagnetic layer according to the present invention is based on a planar primary coil and a secondary coil. It goes without saying that the present invention is also effective when producing a planar transformer sandwiched between ferromagnetic layers.

[0039]

As described above, according to the present invention, it is possible to realize a planar inductor and a planar transformer which are easy to produce and have excellent high-frequency characteristics by protruding a part of the spiral conductor coil into a slender shape.

[Brief description of the drawings]

FIG. 1A is a plan view showing a configuration of a planar inductor according to a first embodiment of the present invention, and FIGS. 1B and 1C are cross-sectional views of the planar inductor.

2A is a plan view showing a configuration of a planar inductor according to a second embodiment of the present invention, and FIGS. 2B and 2C are cross-sectional views of the planar inductor.

FIG. 3 is a sectional view showing a configuration of a laminated magnetic film used as a ferromagnetic layer in a second embodiment of the present invention.

4A is a plan view showing a configuration of a planar inductor prepared for comparison in a second embodiment of the present invention. FIGS. 4B and 4C are cross-sectional views of the planar inductor.

FIG. 5 is a schematic diagram of a magnetic circuit formed in the first embodiment of the present invention.

FIG. 6 is a schematic diagram of a magnetic circuit formed in a second embodiment of the present invention.

FIG. 7 is a schematic diagram of a magnetic circuit formed in a third embodiment of the present invention.

8A is a plan view showing a configuration of a planar inductor according to a third embodiment of the present invention, and FIGS. 8B and 8C are cross-sectional views of the planar inductor.

FIG. 9 is a characteristic diagram showing a change in inductance according to the frequency of the planar inductor in the second and third embodiments of the present invention.

10A is a plan view showing a configuration of a conventional planar inductor, and FIG. 10B is a sectional view of the planar inductor.

[Explanation of symbols]

 11a, 11b Ferrite plate 12 Spiral conductor coil 13a, 13b I / O terminal 14 Projection 15 Inner end 16 Gold wire

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01F 17/00 H01F 17/04 H01F 27/00 H01F 27/29

Claims (4)

(57) [Claims] 1. An inductance comprising a spiral coil conductor provided on a base, a pair of input / output terminals provided on the substrate so as to be connected to an outer end and an inner end of the coil conductor, respectively, A ferromagnetic layer provided so as to sandwich the conductor from above and below, and a coil conductor positioned between the inner end and the input / output terminal while projecting an inner end of the coil conductor to the outside of the ferromagnetic layer. A planar inductance component characterized by projecting outside a ferromagnetic layer and connecting an inner end of a coil conductor to one of input / output terminals. 2. The planar inductance component according to claim 1, wherein the coil conductor has a zigzag shape. 3. The planar inductance according to claim 2, wherein a distance between adjacent conductors having the same current flowing direction is smaller than a distance between adjacent conductors having opposite current flowing directions. parts. 4. A laminated magnetic film comprising a ferromagnetic material layer and an insulator layer stacked on each other, wherein the laminated magnetic film has the same current flowing direction and is formed only above and below adjacent conductors. Planar inductance components.