JPH07161584A - Chip-type noise filter - Google Patents

Abstract

PURPOSE:To obtain a filter, which has the high mechanical strength and can cope with high-density mounting, by forming a capacitor of a grounding electrode, a conductor and a dielectric substance, which are provided on an insulator substrate. CONSTITUTION:On the surface of an insulator substrate 1, input/output electrodes 2 and 3, a grounding electrode 5, a dielectric substance 7 and a conductor 9 are provided. The input/output electrodes 2 and 3 and the grounding electrode 5 are formed so as to form the thick films by applying paste such as Ag, Ag-Pa or the like on the insulator substrate l with the means of screen printing, and drying the paste. The dielectric substance 7 is formed on the grounding electrode 5. The conductor 9, which electrically connects the input/ output electrodes 2 and 3, are formed on the dielectric substance 7. Thus, the thickness of the insulator substrate does not become the parameter, which determines capacitance. Therefore, the thickness of the insulator substrate can be made sufficiently thick, and the mechanical strength of the filter can be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type noise elimination filter for protecting various high frequency equipment from noise.

[0002]

2. Description of the Related Art One of conventional chip type noise removal filters is disclosed in Japanese Utility Model Laid-Open No. 4-65428. In this filter, a resistor and a ground electrode are provided on the surface of a dielectric substrate so as to intersect with each other across the dielectric substrate, and a capacitor is formed by the resistor, the dielectric substrate and the ground electrode.

By the way, the electrostatic capacity C of the capacitor built in the filter is determined by the following equation. C = εS / d ε: Dielectric constant S: Counter electrode area d: Counter electrode distance Here, the dielectric constant ε is determined by the material of the dielectric substrate used, and the counter electrode area S is also limited by the size of the filter. . Therefore, in order to satisfy the downsizing of the filter and obtain a large electrostatic capacity, it is usual to reduce the distance d between the counter electrodes, that is, to reduce the thickness of the dielectric substrate.

However, if the dielectric substrate is made thin,
There arises a problem that the filter is easily broken by a mechanical load applied when the filter is automatically mounted on a circuit board or the like or a mechanical load applied by a deflection of the circuit board or the like after mounting. Further, when the conventional filter is mounted on a circuit board or the like, the ground electrode provided on substantially the entire back surface of the dielectric substrate faces the circuit board or the like. However, due to high-density mounting of electronic devices in recent years, a signal line is often arranged in an electronic component mounting area on a circuit board, but in a conventional filter, the ground electrode and the signal line are close to each other,
It was difficult to dispose the signal line in the filter mounting area on the circuit board because of concern about short circuit or the like.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a chip-type noise elimination filter which has high mechanical strength and can be used for high-density mounting.

[0006]

In order to solve the above problems, a chip type noise removal filter according to the present invention comprises: (a) two input / output electrodes on the surface of an insulating substrate;
A ground electrode, a conductor that electrically connects the two input / output electrodes, and a dielectric sandwiched between the ground electrode and the conductor are provided, and (b) the ground electrode, the conductor, and the dielectric. It is characterized by forming a capacitor with the body. Here, the conductor functions as a conductor or an inductor when Ag, Ag-Pd, Cu or the like having excellent conductivity is used as the material, and as a resistor when carbon or cermet is used. To do.

With the above structure, a desired capacitance can be obtained by adjusting the thickness of the dielectric by the capacitor composed of the ground electrode, the conductor and the dielectric provided on the surface of the insulator substrate. . On the other hand, the thickness of the insulator substrate is not a parameter that determines the capacitance of the capacitor, and is set to an arbitrary dimension. Therefore, the mechanical strength of the filter is ensured by increasing the thickness of the insulating substrate.

Further, since the ground electrode is not provided on the mounting surface of the filter (or even if it is provided, it occupies only a small area at the edge portion), the circuit board or the like on which the filter is mounted is not provided. A signal line is also arranged in the area.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a chip type noise removal filter according to the present invention will be described below with reference to the accompanying drawings. In the following embodiments, the same parts and the same parts are designated by the same reference numerals. [First Embodiment, FIGS. 1 to 3] As shown in FIGS. 1 and 2, input / output electrodes 2, 3, a ground electrode 5, a dielectric 7 and a conductor 9 are formed on the surface of an insulating substrate 1. It is provided. The insulator substrate 1 is made of a material having high mechanical strength and high heat resistance, such as alumina, polyimide resin, or epoxy resin. The thickness of the insulator substrate 1 is set to a size sufficient to secure the mechanical strength required for the filter.

The input / output electrodes 2 and 3 and the ground electrode 5 are
A thick film may be formed by coating a paste such as Ag or Ag-Pd on the insulating substrate 1 by means of screen printing and drying, or forming a thin film by means such as sputtering, ion plating or vapor deposition. May be. The dielectric 7 is
It is formed from above the ground electrode 5. This dielectric 7
May be formed by applying a paste of a ceramic material such as PZT or BaTiO _{3 to} the insulator substrate 1 by means of screen printing and drying, or by means such as sputtering or vapor deposition.

A conductor 9 for electrically connecting the input / output electrodes 2 and 3 is formed on the dielectric 7. When Ag, Ag-Pd, Cu or the like having excellent conductivity is used as the material of the conductor 9, it functions as a conductor or an inductor. When carbon, cermet or the like is used as the material of the conductor 9, it functions as a resistor. For example, when the conductor 9 is made to function as a resistor, a thick film may be formed by applying carbon paste or the like to the insulating substrate 1 by means of screen printing, or may be formed of W, Ni-Cr alloy or the like. A thin film may be formed on the insulating substrate 1 by means of sputtering or vapor deposition. The resistance value of the resistor is usually several tens of Ω
It is set within the range of several 10 KΩ. The insulating substrate 1 is integrally fired together with the input / output electrodes 2 and 3, the ground electrode 5, the dielectric 7 and the conductor 9 provided on the surface thereof.

FIG. 3 is an electrical equivalent circuit diagram of the chip type noise elimination filter thus obtained. (A) is a conductor 9
Shows the case where the conductor 9 functions as a conducting wire, (B) shows the case where the conductor 9 functions as a resistor, and (C) shows the case where the conductor 9 functions as an inductor. Ground electrode 5
The dielectric 7 and the conductor 9 form a capacitor having a capacitance C. Since the thickness of the insulating substrate 1 is not a parameter that determines the capacitance C, the insulating substrate 1 can be made sufficiently thick to secure the mechanical strength of the filter.

Further, since the obtained filter does not have the ground electrode 5 provided on the lower surface of the insulating substrate 1, that is, the mounting surface (or, even if it is provided, it only occupies a small area at the edge portion). The signal line can be arranged in the filter mounting area on the circuit board, and high density mounting can be achieved. [Second Embodiment, FIGS. 4 and 5] The chip type noise removal filter of the second embodiment is similar to the filter of the first embodiment,
Input / output electrodes 2, 3, a ground electrode 5, a dielectric 7 and a conductor 9 are provided on the surface of an insulator substrate 1. However,
A conductor 9, a dielectric 7, and a ground electrode 5 are stacked in this order on the upper surface of the insulator substrate 1, and the conductor 9, the dielectric 7 and the ground electrode 5 form a capacitor. This filter has the same effects as the filter of the first embodiment. [Third Embodiment, FIGS. 6 and 7] The chip type noise removal filter of the third embodiment has input / output electrodes 22, 23, a ground electrode 25, a dielectric 27 and a conductor 29 on the surface of an insulator substrate 21. It is provided. The thickness of the insulator substrate 21 is set to a size sufficient to secure the mechanical strength required for the filter.

The input / output electrodes 22 and 23 are provided at the left and right corners of the insulating substrate 21, and the electrodes 22 and 23 are electrically connected via a conductor 29. The ground electrode 25 is provided at the center of the insulator substrate 21. A dielectric 27 and a conductor 29 are stacked in this order on the ground electrode 25, and the conductor 29, the dielectric 27, and the ground electrode 2 are formed.
And 5 form a capacitor. This filter is the first
The same effect as the filter of the embodiment is obtained. [Other Embodiments] The chip-type noise elimination filter according to the present invention is not limited to the above-mentioned embodiments, but can be variously modified within the scope of the gist thereof.

A plurality of conductors may be provided on one insulating substrate to form a chip type noise filter array. Further, in the above-described embodiment, the insulating substrate, the dielectric, the conductor, the input / output electrode, and the ground electrode are integrally fired, but the present invention is not limited to this. Alternatively, a dielectric or a conductor may be formed and fired.

Further, if at least the conductor is covered with an insulating film such as polyimide, the conductor can be protected from the influence of external impact, humidity, etc., and the reliability of the filter is improved.

[0017]

As is apparent from the above description, according to the present invention, since the capacitor having the capacitance C composed of the ground electrode, the conductor and the dielectric is formed on the surface of the insulator substrate, The thickness of the insulating substrate is no longer a parameter that determines the capacitance C. Therefore, the mechanical strength of the filter can be ensured by sufficiently increasing the thickness of the insulating substrate.

In addition, since the obtained filter has no ground electrode on the lower surface of the insulating substrate, that is, on the mounting surface (or even if it is provided, it occupies only a small area at the edge portion), the circuit is The signal line can also be arranged in the filter mounting area on the substrate, and high density mounting can be achieved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a chip type noise removal filter according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

3A and 3B are electrical equivalent circuit diagrams of the chip-type noise elimination filter shown in FIG. 1, where FIG. 3A is a case where a conductor functions as a conductor, and FIG. 3B is a case where a conductor functions as a resistor. , (C) when the conductor functions as an inductor.

FIG. 4 is a perspective view showing a second embodiment of the chip noise elimination filter according to the present invention.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is a perspective view showing a third embodiment of the chip type noise removal filter according to the present invention.

7 is a sectional view taken along line VII-VII of FIG.

[Explanation of symbols]

 1 ... Insulator substrate 2, 3 ... I / O electrode 5 ... Ground electrode 7 ... Dielectric 9 ... Conductor 21 ... Insulator substrate 22, 23 ... Input / output electrode 25 ... Ground electrode 27 ... Dielectric 29 ... Conductor

Claims (1)

[Claims] 1. An insulator substrate is sandwiched between two input / output electrodes, a ground electrode, a conductor electrically connecting the two input / output electrodes, and the ground electrode and the conductor on a surface of the insulator substrate. A chip-type noise removal filter, comprising: a dielectric, and a capacitor formed of the ground electrode, the conductor, and the dielectric.