JP2584531Y2 - Multilayer ceramic inductor for high frequency - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency multilayer ceramic inductor.

[0002]

2. Description of the Related Art When a sheet method is used, a laminated ceramic inductor is formed by laminating green sheets of a ferrite magnetic material on which coil conductors are formed by using a lamination technique.
The coil is formed by connecting the coil conductors between the layers via the through-hole conductors formed at predetermined positions on the sheet, and the coil conductor is integrated so that the beginning and end thereof are connected to different external electrode terminals, respectively. It is an inductor.

FIG. 2 is an exploded perspective view showing an example of a laminating process of a conventional laminated ceramic inductor by a sheet method. A pattern of, for example, an L-shaped coil conductor 3 formed on a green sheet 1 forms a coil. The cover sheet 2 made up of a plurality of green sheets is stacked on the lower and upper portions of these sheets.

The white arrows in the figure indicate the repetition of the laminated pattern.

[0005] As in the prior art, when the coil conductor is used in a band of several tens of MHz at the most, the connecting portion when the coil conductor is laminated is a through-hole conductor in the above-described sheet method, and a conductor in the slurry build method. This is the printing overlapped portion.

These are usually provided near the external electrodes, that is, near the ends of the chip body, in order to facilitate the connection with the external electrodes.

When used in the above-mentioned frequency band, as shown in the transmission plan view of FIG. 4 (a), the shape of the end of the winding coil conductor drawn out to the external electrode is the width of the coil conductor. However, in order to improve the connection with the external electrode, as shown in FIG. 4B or 4C, the coil conductor terminal is expanded in parallel with the end surface of the chip body to increase the contact area. Some have been enlarged.

[0008]

When used in a high frequency region of the laminated ceramic inductor [devised SUMMARY], must be as high as possible the resonance frequency f ₀ of the inductor, between the coil conductors, through-hole conductor and the outer electrode between such The stray capacitance generated at the time cannot be ignored. That is, the resonance frequency f
₀ is expressed by the following equation, where L is the inductance value and C is the stray capacitance. To increase f ₀ , it is necessary to lower the stray capacitance C because the L value is determined by the product item and remains unchanged. Because there is.

[0009]

(Equation 1) It is generally known that the magnitude of the stray capacitance is proportional to the facing area of the conductor and inversely proportional to the square of the distance.For use in a high-frequency region, the distance between the through-hole conductor and the external electrode in a conventional pattern is known. Because of the close proximity, the stray capacitance has a significant effect.

Further, as shown in FIG. 4A, when the conductor width of the lead-out portion cannot be obtained sufficiently, the connection with the external electrode is deteriorated and the ratio of defective chips is increased. 4 (b) or the like to the (c), will be become shortened effectively the distance between the external electrodes and the coil conductor, the stray capacitance increases, there is a problem that lowering the resonance frequency f ₀ .

Accordingly, an object of the present invention is to secure the connection between the coil conductor and the external electrode terminal and to reduce the stray capacitance generated between the coil conductor and the external electrode in order to maintain the resonance frequency as high as possible. An object of the present invention is to provide a measured high-frequency multilayer ceramic inductor.

[0012]

In order to achieve the above-mentioned object, the present inventor has conducted a study, and the stray capacitance is proportional to the area of the coil conductor facing the external electrode and inversely proportional to the square of the distance between them. For this reason, we first paid attention to the fact that the stray capacitance generated between the connection part of the coil conductor and the external electrode accounts for a large proportion of the elements constituting the stray capacitance between the coil conductor and the external electrode.

The connection portion of the coil conductor has a layer thickness twice or more that of the other coil conductor portions, whether it is a through-hole portion in the sheet method or a printed portion in the slurry build method. Since the area is large, it is only necessary to reduce the layer thickness of the connecting portion. However, in practice, it is difficult and troublesome to print the portion separately.

However, it has been found that the stray capacitance decreases when the position of the entire connection portion is changed and the distance to the external electrode is increased, and the position of the connection portion is minimized at the midpoint of the external electrode opposite thereto. did.

That is, as shown in FIGS. 3A to 3C, the change in the resonance frequency f ₀ depending on the position of the through hole in the chip body was examined, and the results are as shown in Table 1. Table 1 below relates to a prototype example of a 5-turn chip.

[0016]

[Table 1]

As can be seen from the results in Table 1, prototype B is
The through hole is more preferable than the conventional example (prototype A) in which the through hole is located on the side of the external electrode, and the prototype C in which the position of the through hole is provided at the midpoint between the external electrodes is more preferable because the stray capacitance is smaller. .

Conventionally, it has been known to enlarge the contact area by extending the ends of the coil conductor parallel to both sides of the chip body end face in order to ensure the connection between the coil conductor and the external electrode terminals.

However, when the contact area was obtained in such a manner, studies were conducted on the point that an increase in stray capacitance generated between the coil conductor and the external electrode was unavoidable, and the direction in which the coil conductor end was pulled out was reversed. It has been found that increasing the contact area can avoid an increase in stray capacitance.

Accordingly, the present invention provides a chip body obtained by laminating a ceramic and an internal coil conductor, wherein the laminated ceramic forms a skeleton of the chip body,
The coil conductor between the ceramic layers is connected through the connection portion of the coil conductor formed on the ceramic to form a coil orbiting the chip body, and the start end and the end are connected to different external electrode terminals, respectively. Wherein the position of the connection portion of the coil conductor, preferably the position of the through hole, is a midpoint between external electrodes formed to face the end surface of the chip body, and the coil conductor is drawn out. It is an object of the present invention to provide a high-frequency multilayer ceramic inductor characterized in that an end is drawn only in a direction away from a coil winding portion in parallel with the end face.

[0021]

The operation and effect of the present invention are as follows. First, since the distance between the coil conductor connection portion, for example, the through-hole conductor and the external electrode is long, the stray capacitance between them is small. That is, it is pulled out from the coil winding part in a direction far from the coil winding part, so that the contact area with the external electrode is large and the connection between the coil conductor and the external electrode is ensured.

As a result, the stray capacitance was reduced, and the connection between the coil conductor and the external electrode was ensured.

[0023]

FIG. 1 shows a through-hole provided at a midpoint between external electrodes and a lead-out end of a coil conductor bent in a direction away from a coil winding portion used in this embodiment. FIG. 2 is an exploded perspective view of the laminated body, which will be described below with reference to these figures. (1) the SiO _2, Al ₂ O ₃ as a main component, BaO, C
Raw materials to which aO or the like was used as an auxiliary component and to which B ₂ O ₃ was further added were mixed in a ball mill for 15 hours and then dried. (2) The obtained mixture was melted at a high temperature of 1500 ° C. or higher, cooled and pulverized, and further pulverized with a ball mill and dried. (3) A binder 10 to 15 with respect to the obtained material powder.
% By weight, 20% by weight of toluene, 20% by weight of ethanol and 40% by weight of butanol.
Mix for 5 hours. (4) The obtained slurry was formed into a long sheet having a thickness of 30 to 80 μm by using the dokuda blade method. (5) Next, when a through hole is provided at a required position of a green sheet piece cut to an appropriate size, as shown in FIG. 1, a midpoint between external electrodes provided on an end face of the chip body after cutting, as shown in FIG. The pattern of the coil conductor 3 corresponding to the position of the through hole 4 was formed by using an Ag paste by a screen printing method. In addition, the shape of the drawn-out end 6 to the external electrode was provided so as to be bent in a direction away from the coil winding portion. (6) Obtained green sheet 1 with coil conductor printed
Were laminated in a predetermined number, and a plurality of sheets on which no coil conductor was printed were overlaid on the upper and lower sides of the printed sheet as a cover sheet ² and pressed under a pressure of 0.5 t / cm ² to obtain a laminate. (7) The obtained laminate was cut according to chip dimensions to obtain individual chip bodies, which were subjected to a binder removal treatment at 500 ° C for 1 hour, and then fired at 900 ° C for 1 hour. (8) The end face of the obtained sintered body is polished, and an Ag paste is applied to the end face by an immersion method to form an external electrode.
, And baked at 800 ° C for 10 minutes to obtain a multilayer ceramic inductor.

The results of examining the performance of the obtained five-turn chip prototype, such as the resonance frequency f _0, are shown in Table 2.

[0025]

Comparative Example 1 FIG. 5 is an exploded perspective view of a laminate used in this comparative example, in which a through hole is provided at a midpoint between external electrodes and a coil conductor lead-out end has the same width as the coil conductor width. This will be described below with reference to this.

As shown in FIG. 5, a five-turn chip prototype was prepared according to the procedure described in the embodiment except that the shape of the coil conductor lead-out end 6 was made the same as the coil conductor width, and the performance was shown. 2 is shown.

[0027]

COMPARATIVE EXAMPLE 2 FIG. 6 shows a lamination of the laminated body used in this comparative example, in which a through hole is provided at a midpoint between external electrodes and a coil conductor lead-out end is extended in parallel with the end surface of the chip body. It is a perspective view and it demonstrates below also with reference to this.

As shown in FIG. 6, a five-turn chip prototype was prepared according to the procedure described in the embodiment except that the shape of the coil conductor lead-out end 6 was expanded in parallel with the end surface of the chip body, and its performance was evaluated. Are shown in Table 2.

[0029]

Comparative Example 3 FIG. 7 is an exploded perspective view of a laminated body used in this comparative example, in which a through hole is provided at a midpoint between external electrodes and a coil conductor lead-out end is bent toward a coil winding side. This will be described below with reference to this.

As shown in FIG. 7, a 5-turn chip prototype was prepared in accordance with the procedure described in the embodiment except that the shape of the coil conductor lead-out end 6 was bent to the coil winding side, and the performance was shown. 2 is shown.

[0031]

[Table 2]

FIGS. 8 (a), 8 (b), 8 (c) and 8 (d) are transmission plan views of the respective laminates produced in Comparative Examples 1 to 3 and Example. ) Shows the same shape as the coil conductor width at the leading end of the coil conductor, FIG. 2B shows the shape expanded to the full width of the chip, FIG. 2C shows the shape bent to the coil winding side, and FIG. FIG. 4D shows a coil bent in a direction opposite to the coil winding side.

As can be seen from the results in Table 2 above, by setting the shape of the coil conductor leading end to the shape shown in FIG. 8D, it is possible to obtain a high resonance frequency f ₀ and secure connection to the external electrode. Was confirmed to be compatible.

[0034]

[Effects of the Invention] As described above, according to the present invention,
Higher resonance frequency f _0, and connecting the inner conductor coil and the outer electrode can provide a reliable high-frequency multilayer ceramic inductor.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of the present invention, in which a through hole is provided at a midpoint between external electrodes, and a coil conductor lead-out end is bent in a direction away from a coil winding portion. FIG. 4 is an exploded perspective view of a stacked body.

FIG. 2 is an exploded perspective view of a multilayer body in a conventional multilayer ceramic inductor in which a position of a through hole is provided on an external electrode side of a coil conductor.

FIGS. 3A and 3B are transmission plan views for explaining positions of through holes in a chip element body, where FIG. 3A is a view on the external electrode side of a coil, and FIG. 3B is a view of FIG. (C) shows a case where the distance from the external electrodes is 1/4 of the coil length, and FIG.

4 (a) to 4 (c) are transmission plan views of a laminate showing the shape of a conventional coil conductor leading end.

FIG. 5: A through hole is provided at a midpoint between external electrodes,
It is a lamination exploded perspective view of the laminated body whose coil conductor lead-out end is the same as the coil conductor width.

FIG. 6: A through hole is provided at a midpoint between external electrodes,
FIG. 4 is an exploded perspective view of a laminate in which a coil conductor lead-out end is extended in parallel with an end surface of a chip body.

FIG. 7: A through hole is provided at a midpoint between external electrodes,
FIG. 4 is an exploded perspective view of a laminate in which a coil conductor lead-out end is bent toward a coil winding side.

8 (a) to 8 (d) are transmission plan views of the respective laminates shown in FIGS. 5, 6, 7 and 1. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Green sheet 2 Cover sheet 3 Coil conductor 4 Through hole 5 Chip body 6 Pull-out end 7 External electrode

Claims (2)

(57) [Scope of request for utility model registration] In a chip body obtained by laminating ceramic and an internal coil conductor, a skeleton of the chip body is formed by the laminated ceramic, and the chip body is connected via a connection portion of the coil conductor formed on the ceramic. A high-frequency laminated ceramic inductor having a coil that connects the coil conductors between the ceramic layers to form a coil that circulates in the chip body, and has a start end and an end connected to different external electrode terminals, respectively; Is located at the midpoint between the external electrodes formed facing the end face of the chip body, and the coil conductor lead-out end is parallel to the end face and only in a direction away from the coil winding portion. A high frequency multilayer ceramic inductor which is drawn out. 2. The high frequency multilayer ceramic inductor according to claim 1, wherein said connection portion is a through-hole conductor.