JPH05135949A - Laminated chip inductor and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a higher inductance value by making the kind of conductor patterns necessary to obtain a desired turn as little as possible and by maintaining the number of ferrite sheets. CONSTITUTION:In manufacturing a laminated chip inductor, during its laminating process, it is constituted of the other coil conductor formed by continuity with a part of one conductor coil via a ferrite paste 5 formed so as to coat a part of one conductor coil of a conductor paste 4 formed to a through hole 3 formed in a ferrite green sheet 1 and the through hole, and a unit layer is used which consists of each sheet overlaid with a coil conductor circulating by one turn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated chip inductor and a method for manufacturing the same.

[0002]

2. Description of the Related Art A laminated chip inductor is an electronic component in which a coiled conductor spirally circulates in a laminated magnetic body, and its start end and end are connected to different external electrode terminals.

FIG. 7 is a perspective view schematically showing a step of stacking a ferrite green sheet in a manufacturing process of a conventional multilayer chip inductor, and the manufacturing process will be described with reference to this figure. It is as follows.

In the drawing, one chip element cut and separated from the ferrite green sheet is shown.

That is, a ferrite green sheet 1 obtained by coating a slurry of magnetic ceramics on a base film is prepared, and through holes 3 are formed at predetermined positions on each sheet piece cut into an appropriate size. ,
So that the coil with the desired conductor pattern is formed,
A conductor pattern is printed on each of a plurality of ferrite green sheets by the conductor paste 4, and a ferrite green sheet in which the external outlet of the conductor is exposed at one end of the sheet is prepared. A plurality of green sheets that are not printed with a conductor pattern to be used as the lower and uppermost green sheets. A plurality of printed green sheets 1 and similarly a plurality of cover sheets 2 are laminated in this order, and then pressure-bonded to form a laminated molded body, which is cut into each chip element, separated, and then fired, and then an external electrode. Is applied and baked to obtain a product.

[0006]

However, in the conventional method, when printing a conductor pattern on a ferrite green sheet, what kind of conductor pattern should be prepared and how many conductor patterns should be prepared in order to obtain a desired number of turns. In addition, the printing screen had to be replaced several times due to various conductor patterns. Moreover, as chips are becoming smaller and higher inductance is required, we have to deal with it by increasing the number of turns.
The conventional method has a problem that the chip becomes thick.

Therefore, the object of the present invention is to obtain a higher inductance value by reducing the number of kinds of conductor patterns required to obtain a desired number of turns as much as possible and without particularly increasing the number of ferrite green sheets to be laminated. An object of the present invention is to provide such a multilayer chip inductor and a method for manufacturing the same.

[0008]

As a result of research to achieve the above object, the inventors of the present invention have found that a ferrite green sheet having a through hole as shown in FIG. A part of the coil conductor is formed, a ferrite paste is applied to the through hole part, another coil conductor is formed continuously with a part of the coil conductor, and a coil conductor is formed on the green sheet. If so, a green sheet having a uniform conductor pattern is obtained, and if the plurality of green sheets thus obtained are laminated to form a spiral coil, the above problems can be solved. Found and arrived at the present invention.

Therefore, the present invention is, firstly, a ferrite magnetic body in which through holes are provided at fixed positions, and a spiral coil conductor is formed through the through holes.
The wrapping coil conductor is separated by the interposition of a spot-shaped insulating ferrite layer in the through hole portion to form a coil conductor for one turn. A laminated chip inductor characterized in that a predetermined number of layers are laminated so as to be connected to form an internal coil portion; and secondly, a coiled conductor spirally circulates in a laminated ferrite magnetic body, In a method of manufacturing a multilayer chip inductor having its start end and end connected to different external electrode terminals, a ferrite green sheet on which the coiled conductor is formed is set (a) a conductor pattern based on a desired number of turns, A ferrite green sheet printed with the end of the pattern exposed to one end surface. (B) A predetermined number of ferrite green sheets on which conductor patterns are printed, (c) Ferrite green sheets on which the end portions of the pattern described in (a) above are exposed on the other end surface, and these (a) ) To (c) When the laminate is formed by pressure bonding together with the sheets on which the conductor patterns provided on the upper and lower sides are not printed, the layers are formed on each of the ferrite green sheets (b) above. The conductor pattern is formed by first forming a part of the conductor coil so as to cover the through hole formed in the sheet, then applying a ferrite paste so as to cover the through hole, and further forming a part of the coil conductor. Another coil conductor is continuously formed on the sheet, and as a result, a coil conductor that circulates one turn for each sheet is formed. There is provided a method for producing a laminated chip inductor to.

[0010]

2 is a plan view showing the state of application of the conductor paste and the ferrite paste in the through holes, FIG.
Is a vertical sectional view thereof.

As is apparent from the figure, in the method of the present invention, the ferrite paste 5 is sandwiched at the intersecting portions of the conductors serving as the internal electrodes, in other words, the through holes 3 are formed.
In this area, the conductor of the conductor paste 4 is formed through the ferrite paste 5, and a uniform unit layer in which one turn of the conductor coil is formed on one green sheet is obtained. The number of turns is increased even when the thickness is the same as in the conventional case, so that a multilayer chip inductor having a higher inductance value can be obtained.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited by the following examples.

[0013]

FIG. 4, FIG. 5 and FIG. 6 are perspective views schematically showing the lamination process of the ferrite green sheets in this embodiment in a disassembled state, and FIG. 1 also shows the basics of coil conductor formation in the lamination process. FIG. 6 is a perspective view showing a procedure for producing a unit layer consisting of

In general, a ferrite green sheet on which a large number of conductor patterns are printed at the same time is obtained, and these are laminated and pressure-bonded, and then cut into individual chip elements. In the figure, one cut chip element is shown. ..

Hereinafter, the present invention will be described in detail with reference to FIGS. 4 to 6 and FIG.

Ferrite powder, which is a magnetic material, is mixed with a binder containing polyvinyl butyral as a main component to form a slurry, and a ferrite green sheet is formed by a doctor blade method. As for the Ag powder as the internal conductor material, a conductor paste was prepared by using ethyl cellulose as a binder and mainly α-terpineol and butyl carbitol acetate as a solvent. Separately, ferrite paste was similarly prepared from ferrite powder.

As shown in FIG. 1, the unit layer is first prepared. That is, a part of the conductor coil is formed on the ferrite green sheet 1 so as to cover the through hole 3, and the ferrite paste 5 is applied to the through hole part so as to cover the through hole. By applying another continuous coil conductor, a one-turn winding conductor coil is formed on the sheet. A plurality of unit layers thus obtained are prepared according to a desired number of turns.

Next, as shown in FIG. 4, first, a cover sheet 2 composed of a plurality of ferrite green sheets on which no conductor pattern is printed is laminated (FIG. 4 (e)), and the external outlet is exposed. A green sheet 1 (FIG. 2 (d)), a plurality of the unit layers (FIG. 2 (c), 7 sheets in the figure), another green sheet 1 with an external outlet exposed (FIG. 2 (b)). Finally, the top cover sheet 2
(The same figure (a)) is laminated in order and pressure-bonded to form a laminated body 6
After obtaining (Fig. 5), the laminated body was cut according to the conventional method and then baked at 1,000 ° C in the atmosphere, and subsequently, the conductor paste to be the external electrode 7 was applied to both end surfaces of the chip where the external outlet was exposed. After baking at 700 ° C. in the atmosphere, the multilayer chip inductor shown in FIG. 6 is obtained.

[0019]

As described above, in the multilayer chip inductor manufactured by the method of the present invention, the number of turns per ferrite sheet is increased when the same inductance value as that of the conventional one is obtained, so that the number of turns is increased. Even if it is the same, it can be configured with a small number of sheets, and the thickness of the chip can be reduced accordingly, which can contribute to miniaturization.

Further, as described with reference to FIG. 1, in the inductor of the present invention, the conductor pattern is standardized except for a part. Therefore, there are other problems in the design of the conductor pattern that occur in the conventional method. Problems such as screen replacement during pattern printing are simplified.

[Brief description of drawings]

FIG. 1 is a perspective view showing a procedure for manufacturing a unit layer that is a basis for forming a coil conductor in a lamination process of ferrite green sheets in the present invention.

FIG. 2 is a plan view showing a coating state of a conductor paste and a ferrite paste in a through hole portion of the unit layer shown in FIG.

FIG. 3 is a vertical cross-sectional view of the vicinity of a through hole portion in FIG.

FIG. 4 is a perspective view schematically disassembling and showing a lamination process of a ferrite green sheet according to an embodiment of the present invention.

FIG. 5 is a perspective view showing a laminated body obtained by laminating various sheets of FIG.

6 is a perspective view showing a laminated chip inductor obtained by forming external electrodes by pressure bonding the laminated body of FIG.

FIG. 7 is a perspective view schematically showing a lamination process of ferrite green sheets by a conventional manufacturing method in an exploded manner.

[Explanation of symbols]

 1 ... Ferrite green sheet 2 ... Cover sheet 3 ... Through hole 4 ... Conductor paste 5 ... Ferrite paste 6 ... Laminated body 7 ... External electrode

Claims (2)

[Claims] 1. A ferrite magnetic body having a through hole at a fixed position, and a winding coil conductor formed through the through hole, wherein the winding coil conductor has a spot-shaped insulation in the through hole portion. The internal coil portion is formed by stacking a predetermined number of ferrite magnetic unit sheets, which are separated by the interposition of the ferrite layer for use and serve as coil conductors for one turn, so as to be connected to the upper and lower unit sheets at the through holes. Is a multilayer chip inductor. 2. A method for manufacturing a laminated chip inductor, wherein a coiled conductor spirally circulates in a laminated ferrite magnetic body, and its start end and end are connected to different external electrode terminals, respectively. (B) a ferrite green sheet on which a conductor pattern is set based on a desired number of turns, and the end portion of the pattern is exposed to one end face, and printed (b) a conductor pattern A predetermined number of ferrite green sheets on which (a) is printed, (c) a ferrite green sheet on which the end portion of the pattern described in (a) is exposed on the other end face, and these (a) to (c) sheets When a laminated body is formed by pressure bonding with a sheet on which the conductor patterns provided on the upper side and the lower side are not printed, the above (b) The conductor pattern formed on each sheet of the ferrite green sheet of No. 1 first forms a part of the conductor coil so as to cover the through hole formed in the sheet, and then the ferrite paste is formed so as to cover the through hole. A multilayer chip inductor characterized by being applied and further forming another coil conductor on a part of this coil conductor, and as a result, forming a coil conductor that circulates by one turn for each sheet. Production method.