JP2001284125A - Planar magnetic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar magnetic device which is thin and superior in magnetic properties and used for a transformer or the like, utilized in a small electronic apparatus. SOLUTION: A planar magnetic device is equipped with two ferrite magnetic films 11 and 19, each being made through wet method or a method in which ferrite magnetic powder is fixed together with a resin binder and two electroplated plane coils 13 and 18 which are stacked up in the direction of thickness through the intermediary of an insulating layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar magnetic element used for a transformer or a line filter.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and thinner, it has been desired to make coil components thinner.
It is difficult to reduce the thickness of conventional components such as transformers and line filters in which a copper wire is wound around a ferrite sintered body bobbin. Therefore, recently, a stack of green sheets has been developed. For example, Japanese Patent Application Laid-Open No. 4-123405 discloses that a laminated chip is formed by laminating a magnetic material sheet and an internal conductor pattern, two coils are formed in the laminated chip by the internal conductor pattern, and one coil is formed. In the laminated chip common mold choke coil in which the internal conductor patterns constituting the other coil are alternately arranged with the internal conductor patterns constituting the other coil, the inner conductor pattern of the outermost layer constituting one coil and the inner conductor pattern constituting the other coil constitute the same. By reducing the interlayer distance between the inner conductor patterns of the outer layer, a capacitance is generated between the ends of both coils, and by increasing the interlayer distance between the inner conductor patterns of the both coils in the intermediate layer, the A multilayer chip common mold choke coil in which the stray capacitance between both coils in a layer is reduced is disclosed.

Also, a structure suitable for miniaturization and thinning with a planar coil sandwiched between ferrite substrates, for example,
And a first magnetic substrate sandwiching the laminate between a first magnetic substrate and a laminate formed by stacking an insulator layer and a coil pattern in the thickness direction, the laminate being formed on a surface thereof by a thin film forming means. And a coil component comprising at least two magnetic substrates and a coil pattern constituting at least two coils
203737) has been proposed.

[0004]

In the green sheet laminated type, since the coil is formed by a printing method, the DC resistance of the coil is large, and there remains a problem in electrical reliability.
On the other hand, in the case of a type in which a planar coil is formed between ferrite substrates, it is difficult to reduce the thickness because a bulk sintered body is used for the ferrite, and the problem of increased copper loss due to the magnetic flux interlinking the coil. Was left. An object of the present invention is to provide a planar magnetic element which can be reduced in thickness and has excellent electromagnetic characteristics.

[0005]

As a result of intensive studies, the present inventor has found that the above object can be achieved by using the following means, and has completed the present invention.
A first invention of the present invention is a two-layer ferrite magnetic film composed of a ferrite magnetic film formed by a printing method or a green sheet method, and two electroplating layers laminated in the thickness direction with an insulating layer interposed therebetween. A planar magnetic element comprising a planar coil. In this case, the stacked 2
It is preferable that a ferrite magnetic material is interposed between the coil wires of the electroplated planar coils, because the flux linkage between the coils can be reduced and the copper loss can be reduced.

A second invention of the present invention is directed to a two-layer ferrite magnetic film composed of a ferrite magnetic film formed by a printing method or a green sheet method, and a plurality of electric films formed on the same plane therebetween. A planar magnetic element comprising: a plated planar coil.

In this planar magnetic element, it is preferable that a ferrite magnetic material is disposed inside the innermost periphery of each coil and outside the outermost periphery of the entire coil. Further, a ferrite magnetic body may be provided inside the innermost circumference and outside the outermost circumference of the coil, and a ferrite magnetic body and a nonmagnetic insulator may be alternately provided between the other coils. With such a configuration, it is possible to reduce the flux linkage of the coil and reduce the copper loss. Further, the planar magnetic element may be formed on a substrate.

In the present invention, in order to solve the problem of thinning, a ferrite layer is formed by a printing method or a green sheet method, and the coil has a planar structure. The thickness of the ferrite layer is not particularly limited, but is preferably 20 to 60 μm from the viewpoint of achieving both easy formation and excellent characteristics. In the printing method and the green sheet method, a paste in which ferrite magnetic powder is mixed with a binder is used. After forming the film, the film may be fired without the binder, or may be used after solidifying the binder. As a binder for solidifying the binder, an epoxy resin or a polyimide resin is more preferable.

[0009] As for the problems regarding the electromagnetic characteristics, it is necessary to reduce the DC resistance and the flux linkage of the coil. To solve the former problem of reducing the DC resistance, means for forming a planar coil by an electroplating method was used. According to this means, as in the case of the printing method, contamination of impurities from the binder and generation of voids can be suppressed, a coil having a small specific resistance can be achieved, and the coil can be made thicker than by the printing method. A coil having an easy and large cross-sectional area can be obtained, and the DC resistance of the coil can be reduced. With respect to the problem of reducing the coil linkage magnetic flux, in the planar magnetic element of the first invention, it is preferable that a ferrite magnetic material is interposed between the coil wires of the two stacked electroplated planar coils. In the planar magnetic element according to the second aspect of the present invention, it is preferable that the ferrite magnetic material is disposed inside the innermost periphery of each coil and outside the outermost periphery of the entire coil. In addition, a ferrite magnetic material is provided inside the innermost circumference and outside the outermost circumference of the coil, and is achieved by alternately interposing a ferrite magnetic material and a nonmagnetic insulator between the other coils. .

Although the magnetic element of the present invention does not require a substrate, it may be formed on a substrate such as Si or Al ₂ O ₃ .

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 17 shows the pattern of the planar coil.
There is a spiral coil 35 shown in FIG. 18 and a meander coil 36 shown in FIG.
The spiral coil 35 shown in FIG. 17 is preferable because a larger inductance can be obtained. Although the magnetic element of the present invention is composed of two or more coils, these may be arranged with an insulating layer sandwiched in the thickness direction as shown in FIGS. As shown in FIG.

FIG. 1 is a sectional view of a planar magnetic element 10 of an embodiment according to the first invention of the present invention, and FIG. 2 is an exploded perspective view showing its components. This planar magnetic element 10 has a first planar coil 13 formed on a first ferrite layer 11. Ferrite magnetic material 14 between coils
, And a ferrite magnetic body 14 is also provided outside the outermost periphery of the first planar coil 13. First
The polyimide resin layers 15 and 17 are provided as insulating layers on the flat coil 13 of the above. The lead electrode 16 is formed from the terminal 34 of the first flat coil 13 therein. A second planar coil 18 is formed on the polyimide resin layer 17.
Is formed thereon, the second ferrite layer 19 is formed thereon, and the lead electrode 21 of the second planar coil 18 is formed on the terminal 34 through the hole 20.

As shown in FIG. 3 and FIG. 4, between the coil of the first planar coil and the first planar coil 13
Polyimide resin 12 as an insulator outside the outermost layer of
May be provided. FIG. 3 is a cross-sectional view of the planar magnetic element 10, and FIG. 4 is an exploded perspective view of the elements, and other symbols are the same as those in FIGS.

FIGS. 5, 7, and 9 are cross-sectional views of a planar magnetic element 100 according to a second embodiment of the present invention, and FIGS. 6, 8, and 10 are exploded perspective views thereof. In the planar magnetic element 100, two planar coils 22 and 23 are formed on the first ferrite layer 11. The second ferrite layer 19 is formed on the two planar coils 22 and 23, and the lead electrodes 26 and 27 of the respective planar coils 22 and 23 are formed on the terminal 34 through the holes 24 and 25. ing. In the case of the second embodiment, (A) a ferrite magnetic material is provided around the terminal 34 and outside 43 of the planar coils 22 and 23,
(2) An insulator such as a polyimide resin is disposed on the substrate 2 (FIGS. 5 and 6). (B) An insulator such as a polyimide resin is provided on all of the periphery 41 of the terminal 34, the outside 43 of the planar coils 22 and 23, and the space 42 between the planar coils. (FIGS. 7 and 8) (C) A ferrite magnetic material is disposed on all of the periphery 41 of the terminal 34, the outside 43 of the planar coils 22 and 23, and the space 42 between the planar coils (FIG. 9, FIG. 9). FIG. 10).

FIGS. 11, 13 and 15 are sectional views of a planar magnetic element 101 of another embodiment, and FIGS. 12, 14 and 16 are exploded perspective views thereof. The planar magnetic element 10 has two planar coils 28 and 29 formed concentrically on a first ferrite layer 11. These two planar coils 28,
29, a second ferrite layer 19 is formed.
4 through the holes 30, 31 above each planar coil 2
8, 29 lead electrodes 32, 33 are formed.
In this type of planar magnetic element, (A) a ferrite magnetic material is disposed around a terminal 45 and outside 46 of the planar coils 28 and 29, and an insulator such as a polyimide resin is disposed between the planar coils 44. (FIGS. 11 and 12) (B) Insulator, for example, a polyimide resin is disposed on all of the periphery 45 of the terminal 34, the outside 46 of the plane coils 28 and 29, and the space 44 between the plane coils (FIGS. 13 and 14). (C) The periphery 45 of the terminal 34 and the outside 4 of the coils 28 and 29
6 and the one in which the ferrite magnetic material is provided in all of the spaces 44 between the coils (FIGS. 15 and 16).

In the thin magnetic element according to the present invention, first,
Since the second ferrite layers 11 and 19 are close to each other and oppose each other, a large amount of magnetic flux is generated across the ferrite layers. Reduce the coupling. In the planar magnetic element according to the first invention, the stacked 2
Preferably, a ferrite magnetic material is interposed between the coil wires of the electroplated planar coils. In the planar magnetic element according to the second aspect of the invention, the ferrite magnetic material is disposed inside the innermost circumference of each coil and outside the outermost circumference of the entire coil. Preferably, a ferrite magnetic material is provided. In addition, ferrite magnetic material is arranged inside the innermost circumference and outside the outermost circumference of the coil, and ferrite magnetic material and non-magnetic material insulator are alternately interposed between the other coils. The magnetic reluctance of the portion is reduced to reduce the magnetic flux across the coil, and to improve the magnetic coupling between the coils.

It is to be noted that a polyimide resin layer may be provided on the first ferrite layer for smoothing the first ferrite layer according to the first and second inventions.

Although the magnetic element of the present invention has four or more terminals, it is more preferable that the terminals are at the ends. In the case of a spiral coil, of a pair of terminals of each coil,
One of them requires a separate extraction electrode as shown in FIGS. At this time, if the electrode thickness is large, it is difficult to backfill for flattening. On the other hand, if only the thickness direction is reduced,
The cross-sectional area is reduced, the DC resistance at this portion is increased, and the loss is increased. Therefore, it is preferable that the extraction electrode is made wider than the coil width of the other portion to reduce the thickness.

Next, the present invention will be described in more detail with reference to examples.

(Embodiment 1) Embodiment 1 is a planar magnetic element 10 shown in FIGS. Fe ₂ O ₃ / Z on Si substrate
nO / CuO / NiO = 49/23/12/16 (mo
1%) A paste containing a ferrite magnetic powder having a composition is applied as a first ferrite layer 11 by a screen printing method,
Subsequently, firing was performed at 950 ° C. in the atmosphere. The film thickness after firing is 4
0 μm. Next, Cu 0.5 μm was formed as a plating base on the first ferrite layer 11 by a sputtering method. After applying a photoresist on this plating base,
A resist frame of a spiral coil having a line width of 40 μm / line interval of 40 μm, thickness of 50 μm, and 7 turns was formed by photoetching. Next, after depositing Cu in the resist frame by an electroplating method, the resist frame was peeled off, and a plating underlayer between the coils was removed by chemical etching to obtain a first planar coil 13. Next, in Example 1A, a paste in which a ferrite powder was dispersed in a polyimide resin was buried between the coils by a printing method and thermally cured to form a coil-to-coil ferrite 14. (Corresponding to FIGS. 1 and 2) In Example 1B, a polyimide resin 15 was embedded instead of the ferrite 14. (Corresponding to FIG. 3 and FIG. 4) After a polyimide resin 15 was applied on the planar coil by 5 μm, a lead electrode 16 was formed in the same manner as the first planar coil 13. After the polyimide resin 17 was applied again and cured, a second planar coil 18 was formed in the same manner as the first planar coil 13.
Next, a second ferrite layer 19 having a pattern in which holes 20 were formed on the terminals of the second planar coil 18 was printed and applied.
The ferrite composition of the second ferrite layer 19 was the same as that of the first ferrite layer 11, and was thermoset using a polyimide paste. The thickness after curing is 80 μm. Second
The extraction electrode 21 of the planar coil 18 was formed from the hole 20.

The manufactured element was separated from the substrate by treating it in an atmosphere of 90 ° C. and 95% RH for 15 hours to obtain a magnetic element having two planar coils in the thickness direction.

(Embodiment 2) As Embodiment 2, FIGS.
0 shows a case where planar coils are arranged close to each other on the same plane. The means for forming the first ferrite layer 11 on the Si substrate is the same as in the first embodiment. On top of that, two spiral coils (plane coils 22, 2
3) was arranged as shown in FIGS. The shapes of the individual planar coils 22 and 23 and the coil forming method are described in Example 1.
Is the same as The second on the two planar coils 22 and 23
The ferrite layer 19 is formed in the same manner as in the first embodiment, and the lead electrodes 26,
27 was created. In Examples 2A, 2B and 2C, (A) a ferrite magnetic material was provided around the electrode 34 and outside 43 of the coils 22 and 23, and an insulator such as a polyimide resin was provided between the coils 42. (Corresponding to FIG. 5 and FIG. 6) (B) Peripheral 41 of electrode 34 and outer 4 of coils 22 and 23
3 and an insulator, for example, a polyimide resin, is disposed between all of the coils 42 (corresponding to FIGS. 7 and 8). (C) Periphery 41 of electrode 34, outside 4 of coils 22, 23
3 and FIGS. 7 and 8 in which the ferrite magnetic material was disposed in all of the spaces 42 between the coils (Example 3). A planar coil was formed on the same plane as shown in FIGS. The case where they are arranged close to each other will be described.
The means for forming the first ferrite layer 11 on the Si substrate is the same as in the first embodiment. Further, as shown in FIGS. 11 to 16, two spiral coils (the planar coil 28,
29) was arranged. The individual coil shapes and coil forming methods are the same as in the first embodiment. A second ferrite layer 19 was formed on the planar coils 28 and 29 in the same manner as in Example 1, and lead electrodes 32 and 33 were formed from holes 30 and 31 opened on the terminal 34. As examples 3A, 3B and 3C, (A) the circumference 45 of the electrodes 30 and 31 and the coils 28 and 29
A ferrite magnetic substance is disposed on the outer side 46 of the coil, and an insulator such as a polyimide resin is disposed between the coils 44 (corresponding to FIG. 11 and FIG. 12). (B) The periphery 45 of the electrodes 31 and 32, the coils 28 and 29 Insulator, for example, a polyimide resin is provided on all of the outer side 46 and between the coils 44 (corresponding to FIGS. 13 and 14). (C) The periphery 45 of the electrodes 31 and 32, the outer side 46 of the coils 28 and 29, and the coil A ferrite magnetic body was provided in all of the gaps 44 (corresponding to FIGS. 15 and 16).

Embodiment 1 (1A, 1B), Embodiment 2 (2
A, 2B, 2C), Example 3 (3A, 3B, 3C) (the magnetic element of the present invention) and a conventional example were compared in terms of electromagnetic characteristics and thickness. Comparative Example 1 was obtained by winding a sintered ferrite core, Comparative Example 2 was obtained by using a bulk ferrite substrate (sintered ferrite substrate) instead of the ferrite magnetic film of Example 1, and Comparative Example 3 was obtained by The planar coil of the first embodiment is formed by a printing method.

Table 1 shows the results of comparison of the coupling coefficient, quality factor Q value (5 MHz), coil DC resistance, and element thickness.
From these results, it can be seen that the magnetic element of the present invention has a smaller element thickness and a smaller coil DC resistance than the conventional one. Further, it is understood that the Q value is at the same level as that of the conventional product, and the copper loss is small.

[0025]

[Table 1]

[0026]

According to the present invention, it is possible to obtain a planar magnetic element which is excellent in thinning, has a small DC resistance value of the coil, is highly reliable, and has excellent electromagnetic characteristics.

[Brief description of the drawings]

FIG. 1 is a sectional view of Example 1A of the first invention.

FIG. 2 is an exploded perspective view of Embodiment 1A of the first invention.

FIG. 3 is a sectional view of another embodiment 1B of the first invention.

FIG. 4 is an exploded perspective view of another embodiment 1B of the first invention.

FIG. 5 is a sectional view of Example 2A of the second invention.

FIG. 6 is an exploded perspective view of Embodiment 2A of the second invention.

FIG. 7 is a sectional view of Embodiment 2B of the second invention.

FIG. 8 is an exploded perspective view of Embodiment 2B of the second invention.

FIG. 9 is a sectional view of Example 2C of the second invention.

FIG. 10 is an exploded perspective view of Embodiment 2C of the second invention.

FIG. 11 is a sectional view of Example 3A of the second invention.

FIG. 12 is an exploded perspective view of Embodiment 3A of the second invention.

FIG. 13 is a sectional view of Example 3B of the second invention.

FIG. 14 is an exploded perspective view of Embodiment 3B of the second invention.

FIG. 15 is a sectional view of Example 3C of the second invention.

FIG. 16 is an exploded perspective view of Embodiment 3C of the second invention.

FIG. 17 is a plan view showing a pattern of a planar coil.

FIG. 18 is a plan view showing a pattern of a planar coil.

[Explanation of symbols]

 10, 100, 101 Planar magnetic element 11 First ferrite layer 12 Polyimide resin 13 First planar coil 14 Ferrite magnetic material between coils 16 Leader electrode 17 Polyimide resin 18 Second planar coil 19 Second ferrite layer 20 hole 21 extraction electrode 22, 23, 28, 29 plane coil 24, 25, 30, 31 hole 26, 27, 32, 33 extraction electrode 28, 29 plane coil 34 terminal 35 spiral coil 36 meander coil 41, 45 terminal Around 42,44 between plane coils 43,46 outside of plane coil

Claims (6)

[Claims] 1. A two-layer ferrite magnetic film comprising a ferrite magnetic film formed by a printing method or a green sheet method, and two electroplated planar coils laminated therebetween in the thickness direction via an insulating layer. A planar magnetic element comprising: 2. The planar magnetic element according to claim 1, wherein a ferrite magnetic material is interposed between the coil wires of the two electroplated planar coils. 3. A ferrite magnetic film comprising a ferrite magnetic film formed by a printing method or a green sheet method, and a plurality of electroplated planar coils formed on the same plane therebetween. Characteristic planar magnetic element. 4. The planar magnetic element according to claim 3, wherein a ferrite magnetic material is provided inside the innermost periphery of each coil and outside the outermost periphery of the entire coil. 5. A ferrite magnetic material is disposed inside the innermost circumference and outside the outermost circumference of the coil, and a ferrite magnetic material and a nonmagnetic insulator are alternately interposed between the other coils. The planar magnetic element according to claim 3, wherein: 6. The planar magnetic element according to claim 1, wherein said planar magnetic element is formed on a substrate.