JPH0831652A - Noise-proof laminated chip inductor - Google Patents

Abstract

PURPOSE:To enable a noise-proof laminated chip inductor to be easily set optimal in impedance by a method wherein a threaded hole and a magnetic body screw screwed into it are provided to a ferrite core main body, and a part of the screw screwed in the ferrite core main body is controlled in length. CONSTITUTION:A threaded hole 31 is bored in a laminated chip inductor of conventional structure fitted with a terminal electrode 4 penetrating through nearly the center of a ferrite main body 1. At the same time, a ferrite screw 32 of the same material with the ferrite main body 1 or a high-permeability magnetic body screw of material different from that of the ferrite main body 1 is screwed into the threaded hole 31 so as to come into close contact with the ferrite main body 1. A groove 34 in which a screw driver is put for carrying out a fine adjustment in impedance is cut in the head of the ferrite screw 32. By this setup, a noise-proof laminated chip inductor is made variable in impedance, so that it can be set optimal in impedance corresponding to the noises of an electronic equipment mounted with it so as to function as a countermeasure against noises.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise suppression multilayer chip inductor, and more particularly to a noise suppression structure in which the impedance of the inductor is variable by varying the effective volume or magnetic path of the closed magnetic circuit structure of laminated ferrite cores. The present invention relates to a multi-layer chip inductor for electric vehicles.

[0002]

2. Description of the Related Art There is a noise countermeasure inductor using a ferrite core as a component for which an EMC countermeasure is taken by adding an appropriate impedance to various lines in an electronic circuit.

The impedance characteristic of the inductor is the sum (R ² + X ² ) ^1/2 of the resistance component (R component) and the reactance component (X component), and it is important to control the high frequency current by the resistance component in order to prevent noise. The larger this value, the greater the absorption effect.

On the other hand, the reactance component is a component that greatly changes the voltage-current distribution on the line, and may cause a resonance phenomenon in some cases to increase the radiation noise level in a specific frequency band. In that sense, the noise suppression inductor has a Q (X /
A bead inductor having a closed magnetic circuit structure or a wire-wound type is used so that R) becomes low.

The bead inductor has a simple structure in which a conductor is simply passed through a ferrite core, and a plate-shaped ferrite in which a resin is mixed and kneaded with a ferrite magnetic powder as shown in a partially broken perspective view of FIG. There is a laminated chip inductor 20 having a structure in which sheets are laminated one above the other to form a closed magnetic circuit, and a conductor paste (printing electrode) corresponding to a winding is laminated inside and simultaneously fired to provide terminal electrodes.

The laminated chip inductor 20 is of a magnetic shield type in which a laminated ferrite sheet is used as a winding core, and as shown in FIG. It has a structure in which it is sealed and terminal electrodes 4 are provided at both ends, and the manufacturing process is as shown in Fig. 4, in which a ferrite sheet that corresponds to the magnetic core and a conductor paste (which becomes the internal electrode) that corresponds to the winding are alternately stacked by printing. Are laminated and co-fired.

That is, in the manufacturing process diagram shown in FIG.
(A) First, for the underlying ferrite sheet 6, (b)
First conductor paste 7 is printed, (c) 1/2 ferrite sheet 8 is laminated, (d) Second 1/2 conductor paste 9 is printed, (e) 1/2 ferrite sheet 10 is laminated Then, (f) the final conductor paste 11 is printed, (g) the upper ferrite sheet 12 is laminated, (h) the laminate is fired, and (i) the finally exposed end faces of the conductor pastes 7 and 11 are printed. The terminal electrode 4 is formed on the substrate to complete the process (when the number of turns is 1).

The multilayer chip inductor 20 described above has a space factor of 100% and a highly efficient design with no space between the winding and the magnetic core, as compared with a conventional bobbin winding and magnetic core fitting method. Can be miniaturized.

Further, since this multilayer chip inductor 20 is a shield type with a completely closed magnetic circuit, it has almost no influence of leakage inductance and has an advantage that the degree of freedom in arranging the substrate is high.

When the target multilayer chip inductor having the above characteristics is mounted as a noise countermeasure, a component having an optimum impedance value specification as a noise countermeasure should be selected according to the noise situation of the electronic equipment to be mounted. However, conventionally, the most preferable specification component has been investigated by soldering components having various specifications several times and performing an evaluation test.

[0011]

However, the conventional multilayer chip inductors for noise suppression have a fixed impedance value, and the method of examining the conventional noise suppression inductors of the optimum specifications described above is limited to the number of inductors of each specification. Therefore, the evaluation can be made only at discrete values, and the optimum value cannot be strictly investigated. as a result,
Actually, only a preferable inductor is selected from among several kinds of inductors prepared for comparison, and it cannot be said that a true optimum impedance is given.

In addition, soldering chip inductors one by one
Repeated removal is very complicated and difficult to examine in detail.

The above problem is caused by the fact that the conventional multilayer chip inductor for noise suppression has a fixed impedance,
If the impedance is continuously varied within a predetermined range, it should be possible to extremely easily set a strictly optimum impedance value as a measure against noise according to each noise situation.

The present invention has been made in view of the above circumstances. The ferrite core body is provided with a screw hole and a magnetic screw screwed to the screw hole, and the impedance is adjusted by adjusting the screwing amount of the screw. A multilayer chip inductor for noise suppression having a variable structure is provided.

[0015]

According to the present invention, plate-like ferrite sheets obtained by mixing and kneading a resin with ferrite magnetic powder are laminated vertically to form a closed magnetic circuit, and a conductor paste corresponding to a winding is laminated inside. In a multilayer chip inductor for noise suppression having a structure in which it is co-fired and provided with a terminal electrode, a screw hole is formed through the substantial center of the ferrite body, and the screw hole has a ferrite screw of the same material as the ferrite body or a different material. Provided is a multilayer chip inductor for noise suppression, characterized in that the impedance is made variable by adjusting the volume of the screwing part area of the screw by screwing a high-permeability magnetic material screw in close contact with each other. By doing so, the above object is achieved.

[0016]

In the multilayer chip inductor for noise suppression according to the present invention, (1) Amount of a ferrite screw made of the same material as the ferrite main body which is screwed into a screw hole formed at the substantially central portion of the ferrite main body. The closed magnetic circuit environment of the internal electrode is changed by appropriately adjusting. That is, the effective volume of the ferrite core forming the closed magnetic circuit changes, and the impedance of the inductor can be continuously adjusted. That is, the effective volume or magnetic path of the ferrite core increases or decreases according to the screwing amount of the screw, but the impedance increases or decreases approximately in proportion to this increase or decrease.

(2) The impedance characteristic can be varied over a wider range by using a high-permeability magnetic material screw different from the material of the ferrite body as the screw. In this case, it is considered that the screw material having a higher magnetic permeability than that of the ferrite body is more effective.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a noise countermeasure multilayer chip inductor according to the present invention will be described in detail with reference to the drawings.
It should be noted that the same members as in the conventional art are designated by the same reference numerals.

FIG. 1 is a perspective view for explaining the structure of a multilayer chip inductor for noise suppression according to the present invention, and FIG. 2 is a partially cutaway perspective view showing the internal structure of the multilayer chip inductor.

1 and 2, in a multilayer chip inductor 30 for noise suppression, a closed magnetic circuit is formed by a ferrite main body 1 in which plate-like ferrite sheets obtained by mixing and mixing a resin with ferrite magnetic powder are laminated one above the other. A conventional laminated chip inductor having a structure in which a conductor paste corresponding to a winding is laminated and simultaneously fired to provide a terminal electrode 4 is further provided with a screw hole 31 passing through substantially the center of the fired laminated ferrite body 1. Installed and the screw hole 3
A ferrite screw 32 made of the same material as the ferrite body 1 or a magnetic material screw having a high magnetic permeability and made of a different material is screwed to the screw 1 so as to be in close contact with each other, so that the impedance can be varied by adjusting the volume of the screwed portion of the screw. It is characterized by what is done.

As a matter of course, the screw hole 31 must be formed so as not to contact the internal electrode 2 corresponding to the winding as shown in FIG. Further, it can be said that it is preferable to align the center axis of the screw hole with the center of the winding axis of the internal electrode 2 from the viewpoint of symmetry.

The principle of variable impedance of this inductor is that the shape of a ferrite core that surrounds the internal electrode 2 that is a winding and forms a closed magnetic circuit, and the effective volume is a portion where a ferrite screw 32 or a magnetic screw is screwed onto the ferrite body 1. It changes by changing the volume of the area Y, which changes the magnetic path and changes the leakage magnetic flux. As a result, the leakage reactance changes.

However, when the entire ferrite screw 32 is completely screwed into the ferrite body 1, the leakage reactance is small and the impedance is small, and when the screw area 32 is small and the ferrite screw 32 is protruded, the leakage reactance is large. The impedance becomes large.

Each member of the multilayer chip inductor 20 for noise suppression will be described in detail below.

First, a ferrite sheet (6 in FIG. 4,
Nos. 8, 10, 12) are sheet-shaped products obtained by mixing and kneading a binder resin and a solvent with a general ferrite powder as an oxide magnetic material. Since the above ferrite has relatively large resistance and low high frequency loss,
In particular, it is widely used as a magnetic core material for high frequencies, and nickel cobalt ferrite, nickel zinc ferrite,
There are types such as manganese-zinc-based ferrites, but nickel-zinc-based ferrites in particular have high resistivity, so that electrodes can be directly attached.

Further, the conductor paste 7 which becomes the internal electrodes 2,
9 is an electrode material powder containing silver or a silver-palladium alloy as a main component mixed and kneaded with a resin and a solvent.

The terminal electrode 4 is formed by applying Ag paste or Ag-Pd paste (comprising Ag-Pd alloy powder, glass, vehicle, etc.), drying at about 150 ° C., and then firing at 600 to 800 ° C. . A solder layer is formed by printing or applying solder dip or paste solder on this, or by applying solder plating to facilitate conductive connection.

Next, the screw hole 31 which is the essential part of the present invention.
The manufacturing process of the ferrite screw 32 and the magnetic screw will be outlined.

First, the screw holes 31 are formed after firing the ferrite sheet. When the screw holes 31 are formed, a female screw is tapped after forming a through hole having a slightly smaller diameter.

Next, a ferrite screw 32 as a male screw
Is separately processed and fired, but the screw thread may be formed at the time of press working, or a male screw may be cut with a die after baking. At this time, it is desirable that a groove 34 for inserting a driver at the time of fine adjustment is provided on the zenith surface so that a small driver can finely adjust the impedance.

Although the ferrite screw 32 is made of the same material as the ferrite body 1, a magnetic screw made of a different magnetic material having a high magnetic permeability may be used. For example, different kinds of ferrites or the same kind of ferrites having different composition ratios, or completely different materials such as Fe-based or Co-based amorphous alloys may be used.

Needless to say, the female screw of the screw hole 31 on the ferrite core side and the male screw of the ferrite screw 32 should be screwed so as to be in close contact with each other so that no gap can be formed on the boundary surface.

In the multilayer chip inductor 20 for noise suppression having the above-described structure, the impedance can be finely adjusted within a predetermined range by turning the ferrite screw 32 with a driver, so that the noise condition of the electronic equipment to be mounted can be adjusted. It is obvious that an optimum impedance value can be given as a noise countermeasure.

The shape of the multilayer chip inductor according to the present invention is generally a rectangular parallelepiped, but may be, for example, a cylinder, and the shape is not particularly limited.

[0035]

Since the multilayer chip inductor for noise suppression according to the present invention has a variable impedance as described above, it is necessary to provide an optimum impedance value as a noise suppression according to the noise situation of the electronic equipment to be mounted. Therefore, it has an excellent effect that the time required for the optimum value evaluation test can be significantly shortened.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a structure of a multilayer chip inductor for noise suppression according to the present invention.

FIG. 2 is a partially cutaway perspective view showing an internal structure of the inductor.

FIG. 3 is a partially cutaway perspective view showing the internal structure of a conventional multilayer chip inductor.

FIG. 4 is a manufacturing process diagram for explaining a ferrite sheet laminating process of a laminated chip inductor.

[Explanation of symbols]

1 ferrite main body 2 internal electrode 4 terminal electrode 6 base ferrite sheet 7 first conductor paste 8, 10 1/2 ferrite sheet 9 second 1/2 conductor paste 11 last conductor paste 12 upper ferrite sheet 20, 30 (For Noise Countermeasure) Multilayer Chip Inductor 31 Screw Hole 32 Ferrite Screw (Magnetic Material Screw) 34 Groove Y Ferrite Screw Screw Part Area

Claims (1)

[Claims] 1. A closed magnetic circuit is formed by vertically stacking plate-like ferrite sheets obtained by mixing and mixing a resin with ferrite magnetic powder to form a closed magnetic circuit, and a conductor paste corresponding to a winding is laminated inside and simultaneously fired to provide a terminal electrode. In a multilayer chip inductor for noise suppression with a different structure, a screw hole that passes through the approximate center of the ferrite body is drilled, and a ferrite screw of the same material as the ferrite body or a magnetic material screw of a different magnetic material with a high permeability is formed in the screw hole. A multilayer chip inductor for noise suppression, characterized in that the impedance is made variable by adjusting the volume of the screwed part area of the screw by screwing so as to closely engage.