JPH04257110A - Laminated chip l-type filter - Google Patents

Abstract

PURPOSE:To present a small-sized laminated chip L-type filter which satisfactorily eliminate EMI and is provided with the surge absorbing capability. CONSTITUTION:One element of a laminated chip inductor where ferrite sheets on which band-shaped conductor lines are formed are laminated and one element of a laminated chip capacitor where varister sheets on which counter electrodes are formed are laminated are laminated and unified to constitute the laminated chip L-type filter.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer chip L-type filter that is composed of an inductor and a capacitor and is used as an EMI filter, and more particularly to a multilayer chip L-type filter that removes EMI and has a surge absorption ability.

0002

2. Description of the Related Art Conventionally, individual multilayer chip inductors and multilayer chip varistors have been known. Also, as an L-type filter for removing EMI from laminated chip components, ■
One element of a multilayer chip coil and one element of a multilayer chip capacitor are laminated and mounted on one chip, and then fired simultaneously and integrated. ■One element of a chip inductor and one element of a multilayer capacitor are combined and bonded or embedded into one. There were some that were integrated into a chip. These multilayer chip L-type filters form an L-type equivalent circuit by combining one chip inductor element and one multilayer capacitor element, and are used as EMI removal filters.

0003

However, the conventional multilayer chip L-type filters described above are each a combination of one chip inductor element and one multilayer capacitor element, and do not have a surge absorption effect. Therefore,
When inputting data from a keyboard, etc. in electronic devices such as word processors and personal computers that use the above-mentioned conventional multilayer chip L-type filter, static electricity from the human body cannot be prevented from entering, which can damage ICs, LSIs, etc. There was a risk.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a multilayer chip L-type filter that is small in size, effectively removes EMI, and has surge absorption ability. .

[0005]

[Means for Solving the Problems] A multilayer chip L-type filter according to the present invention includes a multilayer chip inductor element formed by stacking ferrite sheets on which strip-shaped conductor lines are formed, and a varistor sheet having a counter electrode. A ferrite sheet on which no band-shaped conductor line is formed is interposed on the surface of the multilayer chip inductor facing the multilayer chip capacitor, so that the multilayer chip inductor and the multilayer chip capacitor are connected to each other. is characterized by being laminated and integrated. Further, the multilayer chip inductor is characterized in that a varistor sheet on which a counter electrode is not formed is interposed on a surface of the multilayer chip inductor that faces the multilayer chip capacitor.

[0006]

[Function] In the multilayer chip L-type filter according to the present invention configured as described above, the inductance value of the inductor can be changed by changing the number of turns of the strip conductor line, the material of the ferrite sheet, etc., so that a desired value can be obtained. You can easily select items and make them smaller. As for the capacitor, the capacitance can be changed by changing the material and thickness of the varistor sheet, and the area of the opposing electrodes, so a desired capacitor can be easily selected and the capacitor can be made smaller. In addition, a ferrite sheet or a varistor sheet on which no strip conductor line is formed is interposed between the inductor and the capacitor, which improves the adhesion of the layers and reduces leakage of magnetic flux, increasing inductance and making it possible to downsize. In addition, the packaging density can be increased, and the influence of parasitic inductance, stray capacitance, etc. can be reduced, resulting in a highly reliable filter with good frequency characteristics and less variation in attenuation characteristics. Also, if a surge voltage occurs,
It is absorbed by the varistor element as a capacitor, eliminating the risk of damaging ICs, LSIs, etc. due to high voltage.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. In the figure, reference numeral 1 denotes a multilayer chip L-type filter, in which a multilayer chip inductor 2 and a multilayer chip capacitor 3 are laminated and integrated, the outer shape is a rectangular parallelepiped, and electrodes are formed on the surface. The multilayer chip inductor 2 is shown in Figure 3.
As shown in FIG. 2, ferrite sheets 2d, 2e and ferrite sheets 2a, 2b, 2c, 2f on which band-shaped conductor lines 4a, 4b are formed, respectively, are laminated and integrated. The multilayer chip capacitor 3 is formed by laminating and integrating varistor sheets 3a and 3b and varistor sheets 3c to 3e on which opposing first and second electrodes 7a and 7b are formed, respectively. The multilayer chip inductor 2 is laminated and integrated with the multilayer chip capacitor 3 via a ferrite sheet 2f having no electrode on the surface facing the multilayer chip capacitor 3.

[0008] The ferrite sheets 2a to 2f are Mn-Z
It is molded from powder of magnetic material such as n-type ferrite and Ni-Zn-type ferrite. Ferrite sheets 2a, 2b, 2
ferrite sheets 2d and 2e on which band-shaped conductor lines 4a and 4b are formed, and a ferrite sheet 2f interposed between the ferrite sheet 2e and the varistor sheet 3a are laminated and integrated to form one multilayer chip inductor element. is forming. The strip-shaped conductor line 4a is a ferrite sheet 2
The sheet 2d is bent along three sides of the sheet 2d in a roughly U-shape on the surface of d to form an inductor, and one end thereof is connected to the extraction electrode 6a formed along the left edge in FIG. A through hole 5 is provided at the other connected and slightly short end. On the ferrite sheet 2e adjacent to the ferrite sheet 2d, a band-shaped conductor line 4b is bent in the same manner as the band-shaped conductor line 4a. One end of the strip-shaped conductor line 4b is located near a position facing the through hole 5, and the other end is connected to a lead electrode 6b formed along the right edge in FIG. The ferrite sheets 2d, 2e, on which the band-shaped conductor lines 4a, 4b are formed, are sequentially overlapped to form the band-shaped conductor line 4a.
, 4b, . . . , it is possible to form an inductor with a large number of turns and a desired inductance. A multilayer chip capacitor 3 is laminated via a ferrite sheet 2f on which neither a strip conductor line nor an extraction electrode is formed. There may be a plurality of layers of ferrite sheets or varistor sheets without electrodes in order to improve adhesion and reduce leakage of magnetic flux.

As shown in FIG. 3, the multilayer chip capacitor 3 has varistor sheets 3a to 3e sequentially laminated and integrated to form one multilayer chip inductor element. Opposed first and second electrodes 7a and 7b are formed on the varistor sheets 3a and 3b, respectively. An extraction electrode 8a is formed along the edge of one side connected to the opposing first electrode 7a of the varistor sheet 3a, and extraction electrodes 9a and 9b are connected to the opposing second electrode 7b of the varistor sheet 3b at two locations.
It is formed so as to extend to the end at a position away from a.

The varistor sheets 3a to 3e are made of zinc oxide (ZnO) or tin oxide (SnO2) having non-linear resistance.
), barium titanate (BaTiO3), and strontium titanate (SrTiO3). One element each of the multilayer chip inductor 2 and the multilayer chip capacitor 3 is formed into a rectangular parallelepiped block that is laminated and integrated, and external electrodes 10a, 10
b and 11 are formed as shown in FIG. In this way, a multilayer chip L-type filter having the equivalent circuit shown in FIG. 2 is obtained. Forming of the sheet is not particularly limited, and may be performed by any forming method such as a powder press method, an extrusion method, a casting method, or a sheet method. Formation of the electrode is not particularly limited, and may be performed by any method such as coating, printing, plating, or sputtering.

A plurality of inductors 2 of this laminated chip L-type filter may be connected to the strip conductor lines 4a and 4b so as to form an inductor of a desired value. By sequentially connecting the ferrite sheets on which strip-shaped conductor lines are formed in this manner through through holes to establish conduction, a desired value can be obtained and the device can be made smaller. Furthermore, by stacking the capacitor 3 while changing the material, thickness, counter electrode area, etc. of the varistor sheets, a desired capacitance can be obtained and the capacitor 3 can be made smaller. This multilayer chip L-type filter is composed of one inductor element and one capacitor element, and it effectively removes EMI, and since the capacitor is composed of a varistor, even if abnormal voltages such as surge voltages are loaded, the varistor's The linear resistance rapidly reduces the resistance of the capacitor, allowing current to flow through the connected ground and preventing abnormal voltage from being applied to ICs, LSIs, etc.

FIG. 4 is a perspective view showing another example of forming an external electrode, in which a band-shaped external electrode 11a connected to the extraction electrodes 9a and 9b of FIG. It is formed in a ring shape. By doing so, the influence of parasitic inductance etc. is reduced. Figure 5
3 is a circuit diagram showing an equivalent circuit when the extraction electrode 8a of FIG. 3 is formed on the right side. When the output impedance is high, a filter with such an equivalent circuit is formed and used.

As described above, the multilayer chip L-type filter according to the present invention, which is composed of one multilayer chip inductor and one multilayer chip capacitor, is less affected by parasitic inductance, distributed capacitance, etc., and has less variation in attenuation characteristics. This results in a highly reliable EMI filter with good frequency characteristics. Furthermore, when a surge voltage occurs, it is absorbed by the varistor. Therefore, the laminated chip L according to the present invention
The type filter not only removes EMI well, but also absorbs surge voltage well and protects ICs and LSIs due to high voltage.
etc., there is no risk of damage.

[0014] In the above embodiment, an example has been described in which a sheet having no electrode is interposed on the surface of the multilayer chip inductor facing the capacitor, but the sheet may be interposed on the surface facing the inductor of the multilayer chip capacitor. Further, a ferrite sheet and a varistor sheet without electrodes may be interposed on the inductor side and the capacitor side, respectively. Furthermore, although the ferrite sheet and varistor sheet have been described as being molded from powder, they are not limited to those molded from powder, and thick or thin films may be used. In addition, the present invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the scope of the invention.

[0015]

[Effects of the Invention] The multilayer chip L-type filter according to the present invention allows selection of inductors and capacitors relatively easily, various combinations are possible, is small and surface-mounted, and has low parasitic inductance and stray inductance. It is less affected by capacitance, etc., and has high-performance noise removal ability and surge absorption ability with less variation in attenuation characteristics.

[0016]

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a multilayer chip L-type filter according to the present invention.

FIG. 2 is an equivalent circuit diagram thereof.

FIG. 3 is an exploded perspective view showing the configuration of a part thereof.

FIG. 4 is a perspective view showing another embodiment of the external electrode of the present invention.

FIG. 5 is an equivalent circuit diagram of another embodiment of the present invention.

[Explanation of symbols]

1. Multilayer chip L-type filter. 2. Multilayer chip inductor. 2a-2f Ferrite sheet. 3. Multilayer chip capacitor. 3a-3e Barista seat. 4a, 4b　Strip conductor line. 7a Opposing first electrode. 7b Opposing second electrode.

Claims (2)

[Claims] Claim 1: Consists of one multilayer chip inductor element made of laminated ferrite sheets on which band-shaped conductor lines are formed, and one multilayer chip capacitor element made of laminated varistor sheets on which counter electrodes are formed, and this laminated The multilayer chip inductor and the multilayer chip capacitor are laminated and integrated by interposing a ferrite sheet on which a strip conductor line is not formed on the surface of the multilayer chip inductor facing the chip capacitor. Multilayer chip L-type filter. 2. The multilayer chip L-type filter according to claim 1, wherein a varistor sheet on which a counter electrode is not formed is interposed on a surface of the multilayer chip inductor facing the multilayer chip capacitor.