JPH0650312U - High Frequency Multilayer Ceramic Inductor - Google Patents

Abstract

(57) [Abstract] [Purpose] 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. Providing high frequency monolithic ceramic inductors. When the through hole 4 is provided on the green sheet 1, the through hole 4 is positioned so as to be a midpoint between the external electrodes provided on the end surface of the chip body after cutting.
It is characterized in that a pattern of the coil conductor 3 corresponding to the position of is formed by printing, and the shape of the lead-out end portion 6 to the external electrode is bent in a direction away from the coil winding portion.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a high frequency monolithic ceramic inductor.

[0002]

[Prior art]

 When using the sheet method, a laminated ceramic inductor uses a lamination technique to laminate a green sheet of a ferrite magnetic material on which a coil conductor is formed, and through a through-hole conductor formed at a predetermined position of the sheet. Is an inductor in which coil conductors between layers are connected to form a coil, and the starting end and the terminating end of the coil conductor are connected to different external electrode terminals, respectively.

FIG. 2 is a laminated layer exploded perspective view showing an example of a lamination process of a conventional laminated ceramic inductor by a sheet method. For example, an L-shaped coil conductor 3 pattern formed on the green sheet 1 is a coil. The sheets are connected by the through-hole conductors of the through-holes 4 as they are formed, and the cover sheet 2 composed of a plurality of green sheets is superposed on the lower and upper portions of these sheets.

In addition, the outline arrows in the figure indicate the repetition of the laminated pattern.

When the coil conductor is used in the band of at most several 10 MHz as in the prior art, the connecting portion when the coil conductors are laminated is the through-hole conductor in the sheet method as described above, and in the slurry build method. It is the printed overlap portion of the conductor.

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

Further, when used in a band of the above-mentioned frequency, as shown in the transmission plan view of FIG. 4A, the shape of the lead-out end of the circulating coil conductor to the external electrode is the width of the coil conductor. Although it is formed with the same width as the above, in order to improve the connection with the external electrode, the coil conductor end is expanded in parallel with the end surface of the chip body to improve the contact area, as shown in FIG. Some are larger.

[0008]

[Problems to be solved by the device]

 When the monolithic ceramic inductor is used in the high frequency range, the resonance frequency f of the inductor is₀Is required to be as high as possible, and stray capacitance generated between coil conductors, between through-hole conductors and external electrodes, etc. cannot be ignored. That is, the resonance frequency f₀Is represented by the following formula, where L is the inductance value and C is the stray capacitance: ₀ This is because the floating capacitance C needs to be lowered because the L value is determined by the product item and is invariable in order to increase.

[0009]

[Equation 1] It is generally known that the size 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 the high frequency region, the distance between the through-hole conductor and the external electrode in the conventional pattern is Is close to each other, stray capacitance has a great influence.

Further, as shown in FIG. 4A, when the conductor width of the lead-out portion cannot be sufficiently obtained, the connection with the external electrode is deteriorated and the ratio of defective chips increases. In the case of 4 (b) or (c), the distance between the external electrode and the coil conductor is effectively shortened, the stray capacitance is increased, and the resonance frequency f ₀ is lowered. .

Therefore, an object of the present invention is to ensure 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. The purpose is to provide a measured high frequency monolithic ceramic inductor.

[0012]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present inventor conducted stray capacitance in proportion to the facing area of the coil conductor and the external electrode and in inverse proportion to the square of the distance between them. We paid attention to the fact that the stray capacitance generated between the connection part of the coil conductor and the external electrode occupies a large proportion among the elements that constitute the stray capacitance between the electrodes.

The connecting portion of the coil conductor has a layer thickness that is at least twice as large as that of other coil conductor portions regardless of whether it is a through-hole portion in the sheet method or a printed overlapping portion in the slurry build method. Since the area is large, it is only necessary to reduce the layer thickness of this connection part, but in practice it is difficult and time-consuming to print that part separately.

However, it has been found that if the position of the entire connecting portion is changed to increase the distance from the external electrode, the stray capacitance decreases, and the position of the connecting portion becomes minimum at the midpoint of the facing external electrode. did.

That is, as shown in FIGS. 3A to 3C, as a result of examining the change of the resonance frequency f ₀ depending on the position of the through hole in the chip body, it is as shown in Table 1. Table 1 below relates to a prototype of a 5-turn chip.

[0016]

[Table 1]

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

Conventionally, in order to ensure the connection between the coil conductor and the external electrode terminal, it is known to expand the end portion of the coil conductor parallel to both sides of the end surface of the chip body to increase the contact area.

However, when the contact area was acquired in this way, research was conducted on the fact that an increase in stray capacitance generated between the coil conductor and the external electrode was unavoidable, and the drawing direction of the coil conductor end was reversed. It was found that the increase of stray capacitance can be avoided if the contact area is secured by using this method.

In view of the above, the present invention provides a chip body obtained by laminating a ceramic and an internal coil conductor, in which a skeleton of the chip body is formed by the laminated ceramics, and a coil conductor formed on the ceramic is formed. A high frequency monolithic ceramic inductor in which coil conductors between the ceramic layers are connected via a connecting portion to form a coil that circulates in the chip body, and the start end and the end are connected to different external electrode terminals respectively. The connecting portion of the coil conductor, preferably the position of the through hole, is the midpoint between the external electrodes formed facing the end face of the chip element body, and the coil conductor lead-out end is parallel to the end face. In addition, the present invention provides a high frequency monolithic ceramic inductor which is drawn out in a direction away from the coil winding portion.

[0021]

[Action]

 The effect of the present invention is that, firstly, since the distance between the coil conductor connecting portion, for example, the through-hole conductor and the external electrode is long, the stray capacitance between them is small, and secondly, the coil conductor lead-out end is the coil. It was pulled out in a direction away from the winding part, and the contact area with the external electrode was wide, ensuring the connection between the coil conductor and the external electrode.

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

[0023]

【Example】

FIG. 1 shows a laminated body used in this embodiment, in which the position of the through hole is provided at the midpoint between the external electrodes and the coil conductor lead-out end is bent in a direction away from the coil winding part. FIG. 3 is an exploded perspective view of a stack, which will be described below with reference to these. (1) Raw materials containing SiO ₂ and Al ₂ O ₃ as main components, BaO and CaO as auxiliary components, and further added B ₂ O ₃ 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, pulverized, further pulverized with a ball mill, and then dried. (3) To the obtained material powder, 10 to 15% by weight of a binder, 20% by weight of toluene, 20% by weight of ethanol and 40% by weight of butanol were added and mixed in a ball mill for 15 hours. (4) The obtained slurry was made into a long sheet having a film thickness of 30 to 80 μm by using the docker blade method. (5) Next, when a through hole is provided at a required position of a green sheet piece cut into an appropriate size, as shown in FIG. 1, between the external electrodes provided on the end surface of the chip body after cutting. Positioning was made so as to be at a midpoint, and a pattern of the coil conductor 3 corresponding to the position of the through hole 4 was formed using Ag paste by screen printing. In addition, the shape of the lead-out end 6 to the external electrode was provided so as to be bent in a direction away from the coil winding portion. (6) A predetermined number of the obtained green sheets 1 on which the coil conductor has been printed are laminated, and a plurality of sheets on which no coil conductor is printed are further stacked as the cover sheet 2 on the upper and lower sides of the printed sheet to form 0.5 t. A pressure was applied at a pressure of / cm ² to obtain a laminate. (7) The obtained laminated body was cut according to the chip size to obtain individual chip bodies, which were subjected to a binder removal treatment at 500 ° C. for 1 hour and then baked at 900 ° C. for 1 hour. (8) The end surface of the obtained sintered body was polished, and Ag paste was applied thereto by an immersion method to form an external electrode. The external electrode was dried at 150 ° C for 15 minutes, and then baked at 800 ° C for 10 minutes. A multilayer ceramic inductor was obtained.

The results of examining the resonance frequency f _{0 and} other properties of the obtained 5-turn chip prototype are shown in Table 2.

[0025]

Comparative Example 1 FIG. 5 is a laminated 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 has the same width as the coil conductor width. However, this will be described below with reference to this also.

As shown in FIG. 5, except that the shape of the coil conductor lead-out end 6 was made the same as the coil conductor width, a 5-turn chip prototype was created according to the procedure described in the example, and its performance was evaluated. The results are shown in Table 2.

[0027]

[Comparative Example 2] FIG. 6 shows a laminated assembly 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 spread in parallel with an end face of a chip body. FIG. 3 is a perspective view, which will be described below with reference to FIG.

As shown in FIG. 6, a 5-turn chip prototype was prepared in accordance with the procedure described in the example except that the shape of the coil conductor lead-out end 6 was expanded in parallel with the end surface of the chip element body, and its performance was obtained. Is shown in Table 2.

[0029]

COMPARATIVE EXAMPLE 3 FIG. 7 is a laminated 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 the coil winding side. However, this will be described below with reference to this also.

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

[0031]

[Table 2]

FIGS. 8A, 8B, 8C, and 8D are transmission plan views of the laminates prepared in Comparative Examples 1 to 3 and Example, and FIG. (a) shows the shape of the coil conductor lead-out end that is the same as the coil conductor width, (b) shows the chip width expanded to the full width, (c) shows the coil winding bent, Also, FIG. 3D shows a case where the coil winding is bent in the opposite direction.

As can be seen from the results in Table 2 above, by making the shape of the coil conductor lead-out end into the shape shown in FIG. 8D, a high resonance frequency f ₀ and reliable connection to the external electrode can be obtained. It was confirmed that both can be achieved.

[0034]

[Effect of device]

As described above, according to the present invention, it is possible to provide a high frequency monolithic ceramic inductor having a high resonance frequency f ₀ and a reliable connection between the inner conductor coil and the outer electrode.

[Submission date] December 18, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

[0016]

[Table 1]

[Brief description of drawings]

FIG. 1 is a perspective view showing a through hole according to an embodiment of the present invention, in which a through hole is provided at a midpoint between external electrodes, and a coil conductor leading end is bent in a direction away from a coil winding portion. FIG. 3 is an exploded perspective view of the laminated body.

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

FIG. 3 is a transparent plan view for explaining the positions of through holes in the chip body, where FIG. 3 (a) is on the external electrode side of the coil, and FIG. 3 (b) is FIG. 3 (a). In this case, the distance from the external electrode is 1/4 of the coil length, and the case (c) in FIG.

4A to 4C are transparent plan views of a laminated body showing the shape of a conventional coil conductor lead-out end.

FIG. 5 is a through hole provided at a midpoint between external electrodes,
FIG. 9 is a laminated exploded perspective view of a laminated body in which the coil conductor lead-out end has the same width as the coil conductor width.

FIG. 6 is a through hole provided at a midpoint between external electrodes,
FIG. 5 is a stacking exploded perspective view of a stack in which the coil conductor lead-out end is spread in parallel to the end face of the chip body.

FIG. 7 is a through-hole provided at a midpoint between external electrodes,
FIG. 7 is a laminated exploded perspective view of a laminated body in which the coil conductor lead-out end is bent toward the coil winding side.

8A to 8D are transmission plan views of the respective laminates shown in FIGS. 5, 6, 7 and 1. FIG.

[Explanation of symbols]

 1 Green Sheet 2 Cover Sheet 3 Coil Conductor 4 Through Hole 5 Chip Element 6 Lead-out End 7 External Electrode

Claims (2)

[Scope of utility model registration request] 1. A chip element body obtained by laminating a ceramic and an internal coil conductor, wherein a skeleton of the chip element body is formed by the laminated ceramics, and a connecting portion of the coil conductor formed on the ceramic is interposed. A high frequency monolithic ceramic inductor in which coil conductors between the ceramic layers are connected to each other to form a coil that circulates in a chip element body, and a start end and an end thereof are connected to different external electrode terminals, respectively. Is the midpoint between the external electrodes formed facing the end face of the chip body, and / or the coil conductor lead-out end is parallel to the end face and is away from the coil winding portion. Is a high frequency monolithic ceramic inductor. 2. The high frequency multilayer ceramic inductor according to claim 1, wherein the connecting portion is a through-hole conductor.