JPH11340042A - Laminating inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small laminating inductor with large allowable current and least variation in L value. SOLUTION: With an element body 12 and a pair of external electrodes formed at the end parts of the element body 12 provided, the element body 12 comprises a laminated magnetic body 14, and a plurality of coil conductors 16 are spirally formed inside the magnetic body 14, the coil conductors are formed coaxially and in parallel, while both end parts of the coil conductors 16 are connected to the pair of external electrodes, respectively. Here, the core area formed of the entire or a part of one coil conductor 16 is smaller than the minimum core area formed of other coil conductors 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated inductor having a spiral coil conductor in a magnetic body, and more particularly to a laminated inductor having a coil conductor having a double spiral structure.

[0002]

2. Description of the Related Art In general, a laminated inductor includes a body and a pair of external electrodes formed at both ends of the body. The body is composed of a laminated magnetic body and the magnetic body. It is composed of a spiral coil conductor laminated inside. Both ends of the coil conductor are connected to the pair of external electrodes.

[0003] This laminated inductor is manufactured as follows. That is, a plurality of magnetic sheets on which the coil conductor patterns are printed are laminated, and a laminate in which the coil conductor patterns are spirally connected is formed in the laminated magnetic sheet. Next, this laminated body is cut into chips for each coil conductor pattern, and the obtained chip-shaped laminated body is fired at a high temperature to form external electrodes by baking.

[0004] With the recent miniaturization of electronic devices, the size of multilayer inductors used therein has also been reduced. When reducing the size of the multilayer inductor, not only must the size of the magnetic material be reduced, but also the line width of the coil conductor must be reduced. Then, as the line width of the coil conductor is reduced, the DC electric resistance R _DC of the coil conductor increases, the Q value decreases, and the allowable current value decreases.

In view of this, there has been proposed a multilayer inductor having a double spiral structure in which coil conductors are formed double in the stacking direction as shown in FIG.

In FIG. 1, reference numeral 10 denotes a multilayer inductor. The multilayer inductor 10 includes a body 12 and a pair of external electrodes (not shown) formed outside the body 12.
The element body 12 includes a laminated magnetic body 14 and a magnetic body 14.
Two coil conductors 1 formed in a spiral shape inside
6,16. The coil conductors 16 and 16 are made of the magnetic material 1
4 are formed coaxially in parallel with the laminating direction of the coil conductor 1.
Both ends of 6, 6 are connected to a pair of external electrodes (not shown), respectively.

A multilayer inductor having a double spiral structure
Means that the coil conductor is formed double in the lamination direction
And a single spiral structure having the same L value.
The surface area of the coil conductor is larger than that of
Great effect, DC electric resistance R _DCIs small and Q value is large
This has the advantage that the allowable current value is large.

[0008]

However, in the multilayer inductor having the double spiral structure, the number of layers of the magnetic sheet and the coil conductor pattern is twice as large as that of the single spiral structure having the same L value. There is a problem that lamination misalignment is likely to occur at the stage of laminating the magnetic material sheets on which the conductor patterns are printed, and the variation of the L value tends to increase.

The present invention is compact, has a large allowable current,
It is an object of the present invention to provide a laminated inductor having as small a variation in L value as possible.

[0010]

A laminated inductor according to the present invention has a body and a pair of external electrodes formed at an end of the body, and the body has a laminated magnetic body. Body and
A coil conductor formed in a spiral shape is provided inside the magnetic body, and both ends of the coil conductor are connected to the pair of external electrodes, respectively. Then, the core area formed by a part of the coil conductor was made smaller than the minimum core area formed by the remaining part.

Here, the element may have a plurality of coil conductors, and the plurality of coil conductors may be formed coaxially and in parallel. Further, two or more of the plurality of coil conductors may be formed coaxially in the same spiral plane. Further, the plurality of coil conductors may be connected to each other via a through hole.

[0012]

FIG. 1 is an explanatory view showing an embodiment of the present invention. In the figure, reference numeral 10 denotes a multilayer inductor, and the multilayer inductor 10 includes a body 12 and a body 1
2 comprises a pair of external electrodes (not shown) formed at both ends. The element body 12 includes a laminated magnetic body 14,
It comprises two coil conductors 16, 16 formed in a spiral shape inside the magnetic body 14.

The coil conductors 16 are formed coaxially and coaxially in the direction in which the magnetic bodies 14 are laminated.
Are connected to a pair of external electrodes (not shown). The core area formed by one coil conductor 16 is smaller than the minimum core area formed by another coil conductor 16. Here, the minimum core area refers to a core area formed to be the smallest due to the displacement of the coil conductors 16, 16.

FIG. 2 is an explanatory view showing another embodiment of the present invention. The basic configuration is the multilayer inductor 10 shown in FIG.
, Except that two parallel coil conductors 16, 16 are formed coaxially in the same spiral plane. The laminated inductor 10 has two coils in the same spiral plane.
Since the two parallel coil conductors 16 and 16 are formed coaxially, the surface area of the coil conductors 16 and 16 increases, and the allowable current value of the multilayer inductor increases due to the skin effect.

FIG. 3 is an explanatory view showing another embodiment of the present invention. The basic configuration is the same as that of the laminated inductor shown in FIG. 1, but the core area formed by one turn of one coil conductor 16 is different from the core area formed by another part of one coil conductor 16 and the other coil conductors. 16 is smaller than the core area formed. For this reason, even if a lamination shift occurs, the core area formed by one turn of one coil conductor 16 is smaller, so that there is no variation in the L value due to lamination displacement.

[0016]

EXAMPLE 1 The radius up to the center of the line was the same and the width was 100 μm and 1
Two types of magnetic sheets on which a 20 μm coil conductor pattern is printed are prepared, and these magnetic sheets are alternately laminated in a double spiral structure by five layers (see FIG. 1).
The obtained laminate was fired and the external electrodes were baked to produce a multilayer inductor. Then, the absolute value (L value: nH) and the resonance frequency (f ₀ ) of the inductance of the multilayer inductor were determined, and the variation (CV value) of the L value was determined.

COMPARATIVE EXAMPLE 1 A magnetic sheet having the same radius up to the center of the line as in Example 1 and printed with a coil conductor pattern having a width of 120 μm was prepared. (See FIG. 4), the obtained laminate was fired, and the external electrodes were baked to produce a multilayer inductor. Then, the L value and the resonance frequency (f ₀ ) of the laminated inductor were determined, and the variation (CV value) of the L value was determined.

From the results shown in Table 1, it can be seen that the variation of the L value of the laminated inductor of Example 1 is smaller than that of the laminated inductor of Comparative Example 1. This is presumably because the number of coil conductor patterns that affect the L value of the multilayer inductor of Example 1 is half the number of coil conductor patterns that affect the L value of the multilayer inductor of Comparative Example 1.

Further, when the sectional state of the multilayer inductor having an inductance close to each average value was observed, the sectional state was similar to that of FIG. That is, in Example 1, it can be said that the stacking deviation itself is small, and even if the stacking deviation occurs, the influence on the L value is small. In addition, the resonance frequency (f ₀ ) also shifted to the high frequency side.

Second Embodiment In the first embodiment, one of the coil conductor patterns is made thin. In the second embodiment, however, the coil conductor pattern is divided into a plurality of pieces as shown in FIG. In this case, the number of divisions is not limited as long as the line width of the divided coil conductor pattern is at least 50 μm. Further, as a result, in addition to the effect of the first embodiment, the line width is substantially the same as that of the first comparative example, so that an increase in the DC electric resistance R _DC can be suppressed. Here, the coil conductor pattern having a width of 50 μm was formed by a coil conductor pattern divided into two. The results were as shown in Table 1.

Embodiment 3 In Embodiment 1, a wide coil conductor pattern and a narrow coil conductor pattern are stacked alternately. In Embodiment 3, as shown in FIG. A multilayer inductor was formed by combining only one coil conductor pattern having a wide width and a coil conductor pattern having a small width.
The results were as shown in Table 1. In this case, the core area is determined only by one wide coil conductor pattern.
The variation of the L value becomes smaller.

[0022]

[Table 1]

[0023]

According to the present invention, the variation of the L value caused by the displacement of the coil conductor pattern depends on the number of turns of the coil conductor having a small core area. Since the coil conductor pattern is part of the entire coil conductor pattern,
There is an effect that it is possible to provide a small-sized multilayer inductor having a small variation in value, a large allowable current value, and the like.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a multilayer inductor according to an embodiment of the present invention.

FIG. 2 is a partial sectional view of a laminated inductor according to another embodiment of the present invention.

FIG. 3 is a partial sectional view of a laminated inductor according to another embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of an example of a conventional multilayer inductor having a double spiral structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Multilayer inductor 12 Element body 14 Magnetic body 16 Coil conductor

Claims (4)

[Claims] 1. An element comprising: a body; and a pair of external electrodes formed at end portions of the body, wherein the body has a laminated magnetic body and a spiral shape inside the magnetic body. A coil area formed by a part of the coil conductor in a laminated inductor connected to the pair of external electrodes. Characterized in that it is smaller than the minimum core area required. 2. The multilayer inductor according to claim 1, wherein the element body has a plurality of coil conductors, and the plurality of coil conductors are formed coaxially and in parallel. 3. The multilayer inductor according to claim 1, wherein two or more coil conductors are formed coaxially in the same spiral plane. 4. The plurality of coil conductors are connected to each other via a through hole.
The multilayer inductor according to any one of the above.