JPH0650311U - Multilayer ceramic inductor - Google Patents

Abstract

(57) [Abstract] [Purpose] A new monolithic ceramic inductor that does not require the development of new materials, obtains an inductance lower than the one-turn inductance by using conventional materials, and at the same time reduces the DC resistance of the coil conductor. Offer of. [Structure] At least two coils internally provided in the laminated body are connected in parallel to external electrode terminals, and the directions of the coils are different from each other, and the coils are negatively magnetically coupled. In other words, two coils are provided. So that the magnetic flux generated in one coil penetrates the other coil in the opposite direction
It is characterized in that the mutual inductance generated between the two coils is negative.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a monolithic ceramic inductor which has an inductance lower than that of one turn.

[0002]

[Prior art]

 In today's demand for miniaturization and thinning of electronic components, a monolithic ceramic inductor, in which a conductor pattern provided inside a magnetic body is laminated so as to form a coil, is drawing attention as an inductor.

As a method for manufacturing this monolithic ceramic inductor, a so-called printing method of alternately screen-printing a conductor paste having a predetermined pattern and a magnetic paste, and a through hole provided at a predetermined position of a magnetic green sheet are used. There is a so-called sheet method in which the coil conductor pattern formed on the sheet is connected.

The advantage of these monolithic ceramic inductors is that a high inductance can be easily obtained by increasing the number of turns (number of turns) of the coil, and the number of turns can be easily increased by repeating the conductor patterns that circulate. Is.

In any of the above methods, a large number of sheets are simultaneously printed in a certain area in the stacking step, so that cutting is performed according to a predetermined chip element size after the stacking is completed.

FIG. 3 shows an example of a laminated exploded perspective view of a chip element body cut by a green sheet method, in which a conductor pattern for a coil printed on a green sheet 2 obtained from a magnetic substance slurry is printed. 3 are sequentially laminated so as to be connected by a through hole 4 provided at a predetermined position on the sheet, and a plurality of cover sheets 1 having no through holes above and below these sheets are stacked and crimped. It is a laminated body.

In any of the above methods, the chip body obtained by cutting the laminated body is fired, and then the external electrode is provided on the end face from which the conductor lead-out portion is led out.

[0008]

[Problems to be solved by the device]

 Generally, a multilayer ceramic inductor is determined by the magnetic permeability of the magnetic material and the number of turns, and the higher the number of turns, the higher the inductance obtained. In addition, it is desired that the direct current resistance of the conductor, which causes copper loss (resistance loss), be lower.

Therefore, when the application of the monolithic ceramic inductor is to be further expanded, it is easier to increase the number of turns as described above for a high-inductance inductor, but the inductance of one turn is for a low-inductance inductor. It exhibits the lowest value, so lower inductance cannot be obtained by changing the number of turns.

Therefore, in order to obtain a material having an inductance lower than that of one turn, it is necessary to develop a new material having a low magnetic permeability. Needless to say, it is difficult to develop a new material, and even if it is possible to develop it, it will be necessary to review all the processes and it will be extremely difficult.

Therefore, the object of the present invention is not to develop a new material, but to use a conventional material to obtain an inductance lower than the inductance of one turn and at the same time reduce the direct current resistance of the conductor. It is to provide a ceramic inductor.

[0012]

[Means for Solving the Problems]

 In order to achieve the above object, the present inventor first advanced the research by focusing on a structure in which a plurality of coils are connected in parallel in a magnetic body.

That is, the mutual inductance generated between two coils is positive or negative depending on in which direction the magnetic flux generated in one coil penetrates the other coil. For example, as shown in FIG. Thus, the magnetic flux φ generated in the coil 1 in which the direction of the current I _{1 is in} the direction of the arrow penetrates the coil 2 in which the direction of the current I ₂ is in the same direction in the direction in which the magnetic flux is added, and the mutual inductance is (+). is there. On the other hand, as shown in FIG. 6B, the magnetic flux φ ₁ generated in the coil 1 in which the direction of the current I _{1 is in} the direction of the arrow and the magnetic flux generated in the coil _{2 in which} the direction of the current I ₂ is opposite to that of I _1. φ ₂ penetrates these coils in opposite directions, and the mutual inductance is (-). Therefore, as shown in FIG. 4 (b) above, if the stacking order in the stack is devised so that the mutual inductance becomes negative as shown in FIG. The inventors have found that the resistance can be reduced and have reached the present invention.

Therefore, according to the present invention, the coil provided in the laminated body obtained by laminating the magnetic green sheets spirally circulates, and the start end and the end thereof are connected to different external electrode terminals, respectively. In the above multilayer ceramic inductor, at least two coils provided internally are connected in parallel to the external electrode terminal, and the magnetic flux generated in one coil of the two coils forming a pair is the other coil. A multilayer ceramic inductor characterized in that it has a coil arrangement in which each coil is configured to penetrate in the direction opposite to the direction in which mutual magnetic flux is added, and the mutual inductance has a negative value. It is a thing. In this case, the pair of coils may have the axes of the coils aligned with each other so that the directions of the currents are opposite to each other, or the coils may be opposed to each other so that the directions of the currents are in the same direction. Further, in the former case, coils having the same diameter and sharing the same axis may be arranged vertically, or a coil having a small diameter may be arranged inside a coil having a large diameter in the same plane.

[0015]

[Action]

 When two coils are electrically connected in parallel, the mutual inductance is positive or negative depending on the direction in which the magnetic flux generated in one coil penetrates the other coil, as shown in Fig. 4 (b). As shown in the drawing, when the coils have different directions of currents, the magnetic coupling is negative, that is, the mutual inductance is negative, so that the inductance can be reduced.

Therefore, an inductance lower than the inductance of one turn can be obtained only by changing the coil conductor pattern.

Regarding the direct current resistance of the conductor, the combined direct current resistance can be made smaller than the direct current resistance of the individual coils because they are connected in parallel.

[0018]

Embodiment 1 FIG. 1 is a stacking exploded perspective view showing a stacking order of a stack body in which coils of the same diameter are connected in parallel with the same winding core in this embodiment. This will be explained below.

(1) A slurry prepared from Ni—Cu—Zn-based ferrite powder was formed on a magnetic green sheet by a doctor blade method.

(2) A through hole was opened at a predetermined position of the obtained magnetic substance green sheet having a thickness of 50 μm, and a conductor pattern for a coil was printed with a conductor paste containing Ag as a main component.

(3) Next, the layers are laminated so that the first coil is formed in the order shown on the right side of FIG. That is, a cover sheet 1 consisting of three magnetic green sheets is placed, and a predetermined conductor pattern 3 is connected by a through hole 4 between a pair of upper and lower green sheets each having a conductor lead-out portion. In this way, the sheet group sandwiching the multiple stacked green sheets is stacked.

(4) Next, the second coil shown on the left side of the figure is formed in the same order, but the direction in which the coil is wound is different from that in the case of the above sheet group, and thus the direction of current flow is reversed. The sheet groups in which the respective conductor patterns are arranged are stacked so that they face each other.

(5) Finally, the cover sheet 1 composed of four magnetic green sheets is stacked to obtain a laminated body.

In the actual laminating step, a large number of conductor patterns are simultaneously printed on the green sheet.

(6) After thermocompression bonding of the obtained laminated body, firing is performed through cutting into a chip element body, and an electrode paste is applied to the end surface of the fired body having a conductor lead-out portion and baked to provide an external electrode. .

Through the above steps, the magnetic coupling between the right side coil and the left side coil in FIG. 1 has a negative value, so that the mutual inductance becomes negative and an inductance lower than one turn can be obtained.

[0027]

[Embodiment 2] FIG. 2 is an exploded perspective view showing a stacking order of a stack body in which coils having different core diameters are connected in parallel in the present embodiment. The description will be given below.

As shown in the figure, when the outer first coil and the inner second coil are formed between the upper cover sheet 1 and the lower cover sheet 1 similar to the case of the first embodiment, the directions of the coils are opposite to each other. The green sheets 2 connected by the respective through holes 4 were laminated so as to face in opposite directions.

According to the procedure of Example 1, the obtained laminated body was cut into a chip inductor element body, which was fired and then external electrodes were provided on the end faces thereof.

Through the above steps, a laminated ceramic inductor having an inductance lower than one turn was obtained.

In each of the above-mentioned first and second embodiments, an example in which the winding cores are the same is shown. However, in the case where the coils are arranged on the left and right, the magnetic flux generated in the first coil is the same even if the current directions of the coils are the same. Since it is in the opposite direction when passing through the second coil, the same effect as in the case of the above embodiment can be obtained.

Therefore, the material of the ferrite magnetic material, the sheet thickness, the number of cover sheets arranged above and below, the shape of the coil conductor pattern, the size of the through holes, etc. can be arbitrarily set so as to obtain a desired inductance. Needless to say, the lamination process is easy not only by the sheet method but also by the printing method.

[0033]

[Effect of device]

 As described above, according to the present invention, the conventional material is used, and only the change of the conductor pattern for the coil is used, so that the minimum inductance (minimum number of turns is 1) obtained so far is obtained. It is possible to provide a monolithic ceramic inductor that acquires low inductance and also reduces direct current resistance, which is a cause of ohmic loss.

[Brief description of drawings]

FIG. 1 is a stacking exploded perspective view showing a stacking order of a stack used in an embodiment of the present invention, in which coils having the same winding core and having the same diameter are connected in parallel.

FIG. 2 is a stacking exploded perspective view showing a stacking order of a stack used in another embodiment of the present invention, in which coils having the same core and different coil diameters are connected in parallel.

FIG. 3 is a laminated exploded perspective view showing a lamination process by a sheet method in a conventional laminated ceramic inductor.

FIG. 4 is a diagram for explaining a mutual inductance of two coils, FIG. 4A is a schematic diagram when the mutual inductance is (+), and FIG. is there.

[Explanation of symbols]

1 Cover Sheet 2 Green Sheet 3 Conductor Pattern 4 Through Hole 5 Coil 1 6 Coil 2 I ₁ Coil 1 Current I ₂ Coil 2 Current φ Magnetic Flux φ ₁ Coil 1 Magnetic Flux φ ₂ Coil 2 Magnetic Flux

Claims (1)

[Scope of utility model registration request] 1. A laminated ceramic inductor in which a coil provided in a laminated body obtained by laminating magnetic green sheets spirally circulates, and a start end and an end thereof are connected to different external electrode terminals, respectively. At least two of the coils installed inside are connected in parallel to the external electrode terminal, and of the two coils forming a pair, the magnetic flux generated in one coil is opposite to the other coil. A monolithic ceramic inductor having a coil arrangement which is configured to penetrate in a direction and has a negative mutual inductance.