JPH09186037A - Manufacture of inductance element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an element of small size and low cost. SOLUTION: A spiral recessed part 5 is formed at the same time when a pillar-shaped inner magnetic material 4 is pushed out from an extrusion molding machine 1 wherein a protruding part 3 is formed inside a rotating nozzle 2. Paste for forming a conductor is spread on the recessed part 5, and a spiral conductor is formed. After that, the inner magnetic material 4 forming the conductor is dipped in ferrite paste, an outer magnetic material is formed, and magnetic path is closed. After the part member obtained in this manner is cut to be a desired length and sintered, an external electrode is arranged on a cut surface, and an inductance element is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a surface mounting inductance element including a magnetic body and a coil-shaped conductor.

[0002]

2. Description of the Related Art Conventionally, the structure of an inductance element used for noise prevention of electronic equipment is most convenient when a conductor is wound around a toroidal magnetic core.

However, in recent years, as the miniaturization of electronic devices has progressed, the demand for miniaturization of the inductance element has become more strict, but in the above structure, the smaller the size, the more difficult the winding becomes. Due to the reason, there are many cases where it is not possible to deal with it.

Further, in order to reduce the size, it is necessary to improve the performance of the element, but by embedding the coil in the magnetic core,
A method of forming a closed magnetic circuit so that the magnetic flux generated by the coil does not leak outside is effective.

From this point of view, it is formed by alternately laminating a magnetic layer composed of a soft magnetic ferrite powder and a binder and a conductive layer composed of a conductive powder and a binder and then integrally sintering the layers. The inductance element that has been used has been put to practical use.

[0006]

However, since the laminated inductance element obtained by this method requires high printing accuracy, it cannot be easily manufactured.
Also, as the number of layers increases, the number of manufacturing steps increases,
There is a problem that the manufacturing cost increases.

An object of the present invention is to solve the above drawbacks and to provide a method for manufacturing a small-sized and low-cost inductance element.

[0008]

The present invention is directed to Ni, Cu,
A spinel soft magnetic ferrite powder composed of Zn and Fe and a mixture containing a binder as a main component were extruded from a rotating nozzle having a convex portion inside to form a columnar internal portion having a spiral concave portion. In the first step of molding the magnetic body, a spiral-shaped conductor is formed by applying a conductor forming paste containing a conductive filler such as Ag and a binder as a main component and an organic solvent as a dispersion medium in the concave portion of the internal magnetic body. A second step of forming,
On the surface of the internal magnetic material obtained in the second step, Ni, C
Third step of forming an external magnetic material and forming a closed magnetic circuit by applying a magnetic material forming paste containing a spinel soft magnetic ferrite composed of u, Zn and Fe as a main component and a binder and an organic solvent as a dispersion medium. And a fourth step of cutting the columnar body composed of the inner magnetic body and the outer magnetic body obtained in the third step to a desired length and sintering the columnar body and attaching an external electrode to the cut surface. And a method of manufacturing an inductance element.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of a rotating nozzle of an extrusion molding machine, and FIG. 2 shows the members of an inductance element produced in each manufacturing process. In the first step, as shown in FIG. 1, the protrusion 3 is formed inside the nozzle 2 of the extrusion molding machine 1.
Since the columnar inner magnetic body 4 is extruded, the spiral concave portion 5 is formed at the same time as shown in FIG.
(A)]. At this time, if the ratio between the extrusion speed and the rotation speed is kept constant, the pitch of the spiral recesses 5 becomes constant.

In the second step, when the conductor forming paste is applied to the position of the recess 5 of the internal magnetic body 4 while rotating the dispenser or the like, the conductor 6 is spirally formed in the recess 5 [FIG. 2 (b)]. ].

Further, in the third step, the external magnetic body 7 can be formed by dipping in the ferrite paste to form a closed magnetic circuit [FIG. 2 (c)]. In addition, in the fourth step, after cutting to a desired length [FIG. 2 (d)] and sintering, an external electrode 8 is provided to obtain an inductance element [FIG.
(E)]. By using this method, the inductance element can be easily manufactured at low cost.

Here, as the binder mixed with the soft magnetic ferrite powder for forming the inner magnetic body, various polyolefins, copolymers, waxes, etc. can be used, and are used in the conductor forming paste and the outer magnetic body forming paste. As the binder, a cellulose derivative, polyvinyl butyral,
Although an acrylic resin or the like can be used, it is appropriately selected in consideration of the particle size of powder, surface property, degreasing property and the like.

(Examples) Examples of the present invention will be described in detail below. The raw material for extrusion molding in the first step was spinel Ni-Cu-Zn ferrite powder (average particle size 0.5μ).
m) 90 wt%, ethylene-vinyl acetate copolymer (vinyl acetate content 14%) 5 wt%, paraffin wax (melting point 60 ° C) 4 wt%, dioctyl phthalate 1 wt% as a binder at 130 ° C with a pressure kneader The one kneaded for time was used. Extrusion molding is 0.3 × 0.
This was performed with a rotating nozzle having a convex portion with a shape of 3 mm, and an internal magnetic body having a spiral concave portion with a pitch of 1 mm was obtained.

As the conductor forming paste in the second step,
70 wt% Ag powder (average particle size 0.6 μm), 3 wt% ethyl cellulose as a binder, 12 wt% xylene solvent
%, Toluene 14 wt%, and stearic acid 1 wt% were kneaded and dispersed by a spiral mixer and a roll mill, and were applied to the spiral recesses of the internal magnetic body with a dispenser to form a conductor.

The ferrite paste used for forming the closed magnetic circuit in the third step is 60 wt% of spinel Ni-Cu-Zn ferrite powder (average particle diameter 0.5 μm), 5 wt% of polyvinyl butyral binder, and 20 wt% of methyl isobutyl ketone solvent. , 15 wt% of toluene was kneaded and dispersed by a spiral mixer and a bead mill, and the molded body prepared in the second step was dipped into this ferrite paste and dried to provide an external magnetic body.

The molded body produced in the third step was cut into a length of 5 mm, debindered, and then sintered at 900 ° C.
On the two exposed end faces of the conductor of the obtained sintered body, A
A conductive paste containing g as a main component was applied and baked at 500 ° C. to provide an external electrode, thereby manufacturing an inductance element.

The inductance element obtained by such a method could be manufactured in about 1/3 the time of the toroidal type having the same characteristics and about 2/3 of the time of the laminated type.

[0018]

According to the present invention, an inductance element can be easily manufactured at low cost, which is industrially beneficial.

[Brief description of the drawings]

1A and 1B are views showing a structure of a rotating nozzle of an extrusion molding machine, FIG. 1A is a perspective view of the nozzle, FIG. 1B is a plan view, and FIG. 1C is a sectional view.

FIG. 2 is a front view showing a member of an inductance element manufactured in each step of the manufacturing method of the present invention.

[Explanation of symbols]

 1 Extrusion Machine 2 Nozzle 3 Convex 4 Internal Magnetic Material 5 Recess 6 Conductor 7 External Magnetic Material 8 External Electrode

Claims (1)

[Claims] 1. A mixture of a spinel soft magnetic ferrite powder made of Ni, Cu, Zn, and Fe and a binder as a main component is extruded from a rotating nozzle having a convex portion on the inside to form a mixture. First step of molding a columnar inner magnetic body having a spiral recess, and a conductor forming paste containing a conductive filler such as Ag and a binder as main components in the recess of the inner magnetic body and an organic solvent as a dispersion medium. Is applied to form a spiral conductor, and a spinel soft magnetic ferrite composed of Ni, Cu, Zn, Fe and a binder are mainly formed on the surface of the internal magnetic body obtained in the second step. A third step of applying a magnetic material forming paste having a component of an organic solvent as a dispersion medium to form an external magnetic material to form a closed magnetic circuit, and an internal magnetic material and an external magnetic material obtained in the third step. Cut the columnar body to the desired length A method of manufacturing an inductance element, comprising a fourth step of attaching an external electrode to a cut surface after sintering.