JPH07235852A - Pi type filter - Google Patents

Abstract

PURPOSE:To prevent production of a crack due to a difference in a contraction rate and to attain stable manufacture by allowing a 1st layer forming A capacitor part and a 2nd layer forming a ferrite bead part to include a mixture between a dielectric body and a magnetic body. CONSTITUTION:Green sheets 1-7 are formed by coating a slurry of a mixture between a dielectric body and a magnetic body to a polyester base sheet and drying the slurry. After the green sheets 1-7 are formed, a conductive paste is printed onto the green sheets 2,5,6 by the screen print method to form internal electrodes 8-10. Then the three green sheets 1-3 forming a ferrite bead 11 and the four green sheets 5-7 forming a capacitor section 12 are all laminated, baked and a sintered body is obtained. Thus, a capacitor element and an inductor element are laminated and the laminates are stably baked simultaneously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pie filter used for noise removal of electronic equipment.

[0002]

2. Description of the Related Art Conventionally, electronic chip components such as a chip capacitor, a ferrite chip bead, and a T-type EMI filter have been sold as countermeasures against high frequency noise in electronic equipment, but a pie-type chip filter has not been sold. For this reason, when a pie filter is required, a chip capacitor and ferrite chip beads are used in combination.

[0003]

The reason why pie-type chip filters are not generally sold is that they are difficult to manufacture. That is, when the dielectric material forming the chip capacitor and the magnetic material forming the ferrite chip beads are laminated and fired at the same time, a crack occurs due to the difference in contraction between the dielectric material and the magnetic material, and stable manufacturing is performed as it is. It is not possible. Therefore, in order to manufacture a pie-shaped chip filter, it is necessary to bond the chip capacitors and the ferrite chip beads to each other after firing them in independent steps, which results in a problem of increasing man-hours and costs.

In view of the above circumstances, an object of the present invention is to provide a pie filter which can be manufactured at low cost and stably.

[0005]

A pie filter according to the present invention which achieves the above object is provided with a first layer containing a dielectric material and both surfaces of the first layer and at least the first layer. A capacitor part having a plurality of capacitor elements formed of internal electrodes having one surface separated into a plurality of parts; a plurality of second layers containing a magnetic material; and a plurality of second layers sandwiched between the plurality of second layers. A pie-type filter formed by laminating ferrite bead portions having inductor elements formed of internal electrodes with each other and forming a pie-type filter circuit with the plurality of capacitor elements and the inductor element, It is also characterized in that the first layer forming the capacitor portion and the second layer forming the ferrite bead portion contain a mixture of a dielectric substance and a magnetic substance. It is.

In the present invention, a dielectric rich mixture may be used for the capacitor portion and a magnetic rich mixture may be used for the ferrite bead portion.

[0007]

In the pie filter of the present invention, since the first layer forming the capacitor portion and the second layer forming the ferrite bead portion contain the mixture of the dielectric substance and the magnetic substance, the shrinkage occurs. The occurrence of cracks due to the difference in rate is prevented. Therefore, the capacitor part and the ferrite bead part can be fired after being laminated on each other, and there is no need for the conventional process of firing and pasting in separate steps, and the number of steps and cost can be reduced.

It should be noted that when a dielectric material and a magnetic material are mixed, the dielectric constant and the initial magnetic permeability are lowered, but in recent years, the clock signals of personal computers and the like have become faster and faster, and on the other hand, as a measure against noise. The capacitance value of the capacitor used is becoming less than 1000 pF. Therefore, even if the dielectric constant is lowered by mixing the magnetic substance with the dielectric substance, there is no problem in terms of capacitance value. Further, even if the initial magnetic permeability is considered to be a measure against high frequency noise, even if it is slightly lowered, there is a sufficient noise removing effect, and there is no problem in this respect.

[0009]

EXAMPLES Examples of the present invention will be described below. FIG. 1 is a plan view showing an example of laminated sheets arranged in the order of lamination. Here, seven illustrated green sheets 1 to 7 are prepared. The green sheets 1 to 7 are formed by coating a polyester base sheet with a slurry of a mixture of a dielectric material and a magnetic material by a doctor blade method and drying the slurry. The dielectric material used here is
Pb _0.88 La _0.12 Zr is a powder having an average particle size of 0.1 μm, which is obtained by wet-mixing PbO, La ₂ O ₃ , ZrO ₂ , and TiO ₂ and firing at 1150 ° C. for 2 hours and then pulverizing with a wet mill.
_It has a composition of _0.7 Ti _0.3 O _0.08 . Also,
The magnetic material used here is NiO, ZnO, CuO,
Fe ₂ O ₃ was wet-mixed, fired at 1000 ° C. for 2 hours, and then pulverized by a wet mill to obtain a powder having an average particle size of 0.1 μm.
i _0.14 Zn _0.22 Cu _0.06 Fe _0.96 O _1.88 .

Here, as the above mixture, the above-mentioned dielectric material and magnetic material are calcined and then pulverized to obtain 6
The mixture was mixed at a weight ratio of 0:40, and a binder was further added and pulverized. In addition to the above-mentioned dielectric and magnetic material, it is preferable to add an improving agent for preventing the reaction between the dielectric and magnetic material and lowering the sintering temperature to the mixture. Here, experiments were carried out both with and without addition of the following improving agents. As the improving agent, CdO,
ZnO and B ₂ O ₃ were mixed at a molar ratio of 1: 1: 1, and 90
The powder was fired at 0 ° C. for 1 hour and then milled to obtain a powder having an average particle diameter of 0.1 μm. When the improver was added, the weight ratio of dielectric: magnetic substance: improver was 40: 60: 1.5.

After forming the green sheets 1 to 7 as described above, a conductive paste is printed on each of the green sheets 2, 5 and 6 by a screen printing method so as to have the illustrated shape, whereby the internal electrodes 8 and 9a, 9b and 10 were formed. Of these internal electrodes 8, 9a, 9b and 10, the internal electrode 2 is surrounded by a magnetic material to form an inductor element, and the internal electrodes 9a, 9b and 10 form two capacitor elements with a dielectric material sandwiched therebetween. To do.

The three green sheets 1 to 3 forming the ferrite bead portion 11 and the four green sheets 5 forming the capacitor portion 12 are formed as described above.
7 to 7 were all stacked and fired for about 1 hour to obtain a sintered body. The firing temperature is 10 when the mixture containing no modifier is used.
30 ° C., 950 ° C. in the case of a mixture added with a modifier.

FIG. 2 is an external perspective view of the pie-type chip filter in this embodiment, and FIG. 3 is an equivalent circuit diagram of the pie-type filter circuit. After obtaining the sintered body as described above, the internal electrodes 8, 9a, 9b, 1
The sintered body was barrel-polished so that 0 was exposed, and the internal electrodes 8, 9a, 9b, and 10 were exposed to the exposed portions, respectively.
An electrode 1 connected with the internal electrode 8 and the internal electrode 9a is obtained by applying a conductive paste containing Ag as a main component.
3, the electrode 1 connected to the internal electrode 8 and the internal electrode 9b
4, electrodes 15a, 15 connected to the internal electrode 11
b was formed.

Contrasting this with the equivalent circuit shown in FIG.
The capacitor element 16 includes the internal electrode 9a and the internal electrode 10, and the dielectric material sandwiched between the internal electrodes 9a and 10.
Is formed, a capacitor element 17 is formed by the internal electrode 9b and the internal electrode 10, and a dielectric material sandwiched between the internal electrodes 9a and 10, and the two capacitor elements 16 and 17 are connected to each other. The inductor element 18 is formed by the internal electrode 8 and the magnetic material surrounding the internal electrode 8, and thus a pie filter circuit is configured as a whole.

When the characteristics of the pie-type chip filter manufactured as described above were examined, it was satisfactory, and no cracks or the like were found when disassembled and observed. In addition, in the above-mentioned embodiment, the mixture of the same composition is used for all of the green sheets 1 to 7, but the mixture of the magnetic substance rich is used for the green sheets 1 to 3 constituting the ferrite bead portion 11, A dielectric rich mixture may be used for the green sheets 4 to 7 forming the capacitor portion 12.

FIG. 4 is a plan view showing another example of laminated sheets arranged in the order of lamination. The same components as those of the seat shown in FIG. 1 are designated by the reference numerals shown in FIG. 1, and only different points will be described. In the example shown in FIG. 4, the internal electrode 9c is formed on the sheet 5. This internal electrode 9c is shown in FIG.
The inner electrode 10 of the sheet 6 in the completed state as shown in FIG.
Connected with and used as ground. in this case,
The two capacitors 16 and 17 are separated as the ground by the internal electrode 9c, and the crosstalk between the capacitors 16 and 17 is reduced.

[0017]

As described above, according to the present invention,
The occurrence of cracks due to the difference in contraction rate between the dielectric material and the magnetic material is prevented, and the capacitor element and the inductor element can be stacked on each other and stably fired at the same time, which reduces the number of steps and cost.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of laminated sheets arranged in the order of lamination.

FIG. 2 is an external perspective view of a pie-type chip filter.

FIG. 3 is an equivalent circuit diagram of a pie filter circuit.

FIG. 4 is a plan view showing another example of laminated sheets arranged in the order of lamination.

[Explanation of symbols]

 1, 2, ..., 7 Green sheet 8, 9a, 9b, 9c, 10 Internal electrode 11 Ferrite bead portion 12 Capacitor portion 13, 14, 15a, 15b Electrode 16, 17 Capacitor element 18 Inductor element

Claims (1)

[Claims] 1. A plurality of first layers including a dielectric material and a plurality of internal electrodes formed on both surfaces of the first layer and having at least one surface of the first layer separated into a plurality of internal electrodes. A capacitor part having a capacitor element, and a ferrite bead part having an inductor element formed of a plurality of second layers containing a magnetic material and internal electrodes sandwiched by the plurality of second layers are laminated on each other. And a pie-type filter formed by forming a pie-type filter circuit with the plurality of capacitor elements and the inductor element, the first layer forming the capacitor section and the ferrite bead section being formed. The pi-shaped filter, wherein the second layer contains a mixture of a dielectric substance and a magnetic substance.