JP2001060838A - Composite parts - Google Patents

Abstract

(57) [Problem] To provide a small composite component having a sufficient static electricity suppressing effect and having a small waveform distortion of a high-frequency signal. A composite component (1) has a circuit configuration in which a varistor (2) is electrically connected in series to a parallel circuit (5) including a varistor (3) and an inductor (4). An input / output electrode 10 and a ground electrode 11 are electrically connected to both ends of a series circuit of the varistor 2 and the parallel circuit 5, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite part,
The present invention relates to a composite component having a varistor element.

[0002]

2. Description of the Related Art In recent years, semiconductor devices such as ICs and LSIs have become more vulnerable to static electricity due to higher integration. As a countermeasure against this static electricity, electronic components such as a varistor are used. Apart from this, a composite component 60 having a circuit configuration shown in FIG. 6 has also been proposed. The composite component 60 has a π-type circuit including one inductor 53 and two varistors. In FIG. 6, 50 is an input electrode, 51 is an output electrode, and 52 is a ground electrode.

[0003]

In high-speed signal lines using high-frequency and high-quality (no waveform distortion) signals in devices such as hard disks, applications requiring measures against static electricity are increasing. In such an application, a component that has a high impedance in a signal frequency region in a normal operation state where no static electricity is applied and has a sufficient protective effect on the device against static electricity is required. However, since the varistor has a capacitance component, in a normal operation state in which static electricity is not applied, the impedance becomes small in a high frequency region, and there is a problem that a signal waveform is distorted. Also, reducing the impedance at high frequencies by reducing the capacitance value has the problem of reducing the surge withstand capability of the varistor. Further, the conventional composite component 60 shown in FIG. 6 has a problem that the impedance at a high frequency becomes small in a normal operation state where no static electricity is applied, which also distorts a signal waveform.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a small composite component having a sufficient static electricity suppressing effect and having a small waveform distortion of a high-frequency signal.

[0005]

In order to achieve the above object, a composite part according to the present invention comprises: (a) a parallel circuit comprising a first varistor and an inductor; and (b) an electrically connected parallel circuit. A second varistor connected in series; and (c) an input / output electrode and a ground electrode connected to both ends of a series circuit of the second varistor and the parallel circuit.

Further, the composite component according to the present invention comprises: (d) a laminate formed by stacking a plurality of insulating layers, a plurality of inductor patterns, and a plurality of varistor patterns; and (e) a laminate built in the laminate. An inductor formed by the inductor pattern; (f) a first varistor and a second varistor formed by the varistor pattern, which are built in the laminate; and (g) provided on a surface of the laminate. Provided input / output electrodes and ground electrodes,
(H) The second varistor is electrically connected in series to a parallel circuit including the first varistor and the inductor.

[0007]

According to the above configuration, since the first varistor and the second varistor are connected in series between the input / output electrode and the ground electrode, static electricity is absorbed by these varistors.
Removed. The first varistor and the second varistor connected in parallel to the inductor have low impedance when static electricity is applied and absorb the static electricity. Moreover, in general, the varistor also has a capacitor function.
The varistor and the inductor form an LC parallel resonance circuit to constitute a bandpass filter. The bandpass filter can increase the impedance in a high-frequency region, and can suppress the distortion of the waveform of the high-frequency signal.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a composite part according to the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the composite component 1 has a circuit configuration in which a varistor 2 is electrically connected in series to a parallel circuit 5 including a varistor 3 and an inductor 4. An input / output electrode 10 and a ground electrode 11 are electrically connected to both ends of a series circuit of the varistor 2 and the parallel circuit 5, respectively.

[0010] The composite component 1 having the above circuit configuration
For example, there is one having a configuration as shown in FIGS. As shown in FIG. 2, the composite component 1 has insulating sheets 22, 23, 24, and 25 having inductor patterns 31, 32, 33, and 34 provided on the surface thereof, and varistor patterns 35 and 36 provided on the surface. It is composed of insulating sheets 27 and 29 and insulating sheets 26 and 28 provided with a varistor pattern 37 on the surface.

The inductor patterns 31 to 34 are formed in via holes 40 a and 40 provided in the sheets 22 to 24, respectively.
b, 40c and are electrically connected in series to form a spiral inductor 4. The lead portion 31a of the inductor pattern 31 is exposed on the right side of the sheet 22.

The varistor pattern 35 includes the sheets 27 and 2
9 are formed on the left side, respectively, and one end thereof is exposed on the left side of the sheets 27 and 29. Similarly, the varistor patterns 36 are formed at positions on the right side of the sheets 27 and 29, respectively, and one end thereof is exposed on the right side of the sheets 27 and 29. The varistor patterns 35 and 36 have a wide area varistor pattern 3 with the insulating sheets 26 to 28 interposed therebetween.
7, varistors 2 and 3 are formed respectively. The varistor pattern 37 is electrically connected to one end of the inductor 4 (specifically, the inductor pattern 34) via via holes 40d, 40e, and 40f provided in the sheets 25 to 27, respectively. The varistor 3 and the inductor 4 constitute a parallel circuit 5.

The insulating sheets 21 to 29 are square sheets made of a semiconductor ceramic material having varistor characteristics (for example, a material mainly composed of ZnO ceramic). Patterns 31 to 37 are Pt, Ag, Pd, C
u, Au, Ag-Pd, etc., and formed by a method such as printing.

As shown in FIG. 2, the above-described sheets 21 to 29 are sequentially stacked and pressed, and then integrally fired to form a laminate 41 shown in FIG. The laminated body 41 includes an inductor portion 42 having the inductor 4 built therein.
Are arranged at the upper part, and the varistor part 43 containing the varistors 2 and 3 is arranged at the lower part. On the left and right end surfaces of the laminate 41, an input / output electrode 10 and a ground electrode 11 made of Ag or the like are formed, respectively. A varistor pattern 35 is electrically connected to the input / output electrode 10, and the ground electrode 1
1, a lead portion 31a of the inductor pattern 31 and a varistor pattern 36 are electrically connected.

In the composite component 1 having the above structure, the varistors 2 and 3 are connected in series between the input / output electrode 10 and the ground electrode 11, so that when the static electricity is applied, the varistors 2 and 3 absorb the static electricity. Can be removed.
Usually, if an inductor is provided between the signal line and GND, the effect of suppressing static electricity becomes insufficient. However, in the case of the present invention, since the varistor 3 is connected in parallel with the inductor 4, the varistor 3 has a low impedance when static electricity is applied, and a current due to the static electricity flows through the varistor 3.
Therefore, static electricity is sufficiently suppressed.

In addition, since the varistor generally has a capacitor function during normal operation in which static electricity is not applied,
The varistor 3 and the inductor 4 form an LC parallel resonance circuit, and form a bandpass filter. The bandpass filter can increase the impedance in the high frequency region, and the composite component 1 can suppress the distortion of the waveform of the high frequency signal. Specifically, the varistor patterns 35 to
37, the capacitance of the varistor 3 can be changed by changing the facing area and spacing, and the inductor patterns 31 to 3 can be changed.
The resonance frequency of the LC parallel resonance circuit is adjusted to the signal frequency band by changing the number of turns or the shape of the coil 4 to change the inductance of the inductor 4. By the way, composite part 1
Is shown in FIG. 5 (see the solid line 47).
For comparison, the impedance characteristics of the varistor are also shown (see dotted line 48). As can be seen from FIG.
The impedance of the composite component 1 increases in the high frequency range.

Further, since the composite component 1 has the two varistors 2 and 3 and the one inductor 4 incorporated in one laminated body 41, the mounting space can be reduced and the number of components can be reduced.

The composite component according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the invention. Although the composite component of the above embodiment has been described as a preferred example in which two varistors and one inductor are incorporated in one laminate, the composite component is configured by mounting a varistor and an inductor of a discrete component on a circuit board. It may be.

Further, a magnetic material such as ferrite is used as the material of the insulating sheets 21 to 25 of the inductor section 42 of the above-described embodiment, and the insulating sheet 2 of the varistor section 43 is used.
Co-firing may be performed with a semiconductor ceramic material having varistor characteristics, which is a material of Nos. 6 to 29.

As means for electrically connecting the inductor and the varistor built in the laminate, a relay electrode is formed on the surface of the laminate in addition to the via hole, and the ends of the inductor and the varistor are connected to the relay electrode. The structure which draws out each and electrically connects may be sufficient.

Further, in the above embodiment, the insulating sheets on which the inductor patterns and the varistor patterns are respectively formed are stacked and then integrally fired.
It is not necessarily limited to this. As the insulating sheet, a pre-fired one may be used. Further, a composite component may be created by a manufacturing method described below. After an insulating layer is formed from a paste-like insulating material by a method such as printing, a paste-like conductive material is applied to the surface of the insulating layer to form an arbitrary pattern. Next, a paste-like insulating material is applied from above the pattern to form an insulating layer in which the pattern is embedded. Similarly, a composite part having a laminated structure can be obtained by successively applying layers.

[0022]

As is apparent from the above description, according to the present invention, the first varistor and the second varistor are connected in series between the input / output electrode and the ground electrode. Absorbed and removed by the varistor. The first varistor connected in parallel to the inductor has a low impedance when static electricity is applied, and a current due to the static electricity flows through the first varistor and hardly flows through the inductor. Therefore, static electricity is sufficiently suppressed. In addition, since the varistor generally also has a capacitor function, an LC parallel resonance circuit is formed by the first varistor and the inductor to form a band-pass filter. The bandpass filter can increase the impedance in a high-frequency region, and can suppress the distortion of the waveform of the high-frequency signal. Furthermore, by incorporating two varistors and one inductor in one laminate, a composite component having a small mounting space and a small number of components can be obtained.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing one embodiment of a composite component according to the present invention.

FIG. 2 is an exploded perspective view showing the configuration of an embodiment of the composite component according to the present invention.

FIG. 3 is an external perspective view of the composite component shown in FIG. 2;

FIG. 4 is a schematic sectional view of the composite component shown in FIG.

5 is a graph showing impedance characteristics of the composite component shown in FIG.

FIG. 6 is an electric circuit diagram of a conventional composite part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Composite component 2, 3 ... Varistor 4 ... Inductor 5 ... Parallel circuit 10 ... Input / output electrode 11 ... Ground electrode 21-29 ... Insulating sheet 31-34 ... Inductor pattern 35-37 ... Varistor pattern 41 ... Laminate

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takaaki Oi 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto F-term in Murata Manufacturing Co., Ltd. (Reference) 5J024 AA09 BA11 DA21 DA29 DA35

Claims (2)

[Claims] 1. A parallel circuit comprising a first varistor and an inductor; a second varistor electrically connected to the parallel circuit in series; and both ends of a series circuit of the second varistor and the parallel circuit. A composite component comprising: an input / output electrode and a ground electrode connected to the component. 2. A laminated body formed by stacking a plurality of insulating layers, a plurality of inductor patterns, and a plurality of varistor patterns; an inductor built in the laminated body and formed by the inductor pattern; A first varistor and a second varistor formed by the varistor pattern, and an input / output electrode and a ground electrode provided on the surface of the multilayer body; the first varistor and the inductor Wherein the second varistor is electrically connected in series to a parallel circuit comprising: