JPH06267791A - Noise filter block with varistor function - Google Patents

Abstract

PURPOSE:To miniaturize the whole shape of a noise filter block with a varistor function by thinning it and narrowing a pitch between signal paths, to widen the gained range of capacitance, to satisfactorily remove high-frequency noise by the use of a simple structure and at the same time to absorb surge voltage without cracks and the like generated even when a temperature cycling test is executed. CONSTITUTION:A signal electrode 14 is continuously formed in an inner surface electrode 12a in the inner surface of a hole in the surface of the peripheral edge of an insulating board in which a plurality of terminal inserting holes 12 are provided at a predetermined interval. The electrode 14 and a first earth electrode 16 are formed so as to be spaced with a predetermined insulating gap 15. The electrode 16 is electrically connected to a second earth electrode 17 which is formed in the rear surface of the board 11 so as to be spaced from the inner surface electrode 12a with a predetermined insulating gap 18. A chip capacitor 19 and a chip varistor 29 are erected between the signal electrode in the surface of the board and the first earth electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise filter block for removing high frequency noise in a plurality of signal lines. More specifically, the present invention relates to a noise filter block with a varistor function, which is suitable for being built in a connector or the like and is capable of absorbing surge voltage.

[0002]

2. Description of the Related Art In digital equipment such as computers, there is a problem that if electromagnetic waves of high frequency are mixed in a signal line, malfunctions are likely to occur, and that unnecessary electromagnetic waves that may damage other electronic equipment are radiated from wiring. is there. For this reason, a noise filter using a capacitor element for removing high frequency noise is often used in the signal line. As a noise filter block for removing high frequency noise in a plurality of signal lines, a feedthrough capacitor is arranged by soldering in a plurality of mounting holes formed in a metal ground plate or a shield case, or a printed circuit. It is known that a chip capacitor is mounted on a board by soldering.

On the other hand, since a surge voltage may be applied to this kind of signal line in addition to the mixing of high frequency noise, conventionally, high frequency noise can be removed and at the same time, surge voltage can be absorbed. A "filter" is disclosed (JP-A-1-102874). In this filter, an elongated signal line for transmitting an electric signal is provided on one surface of a flat plate made of a dielectric material having capacitive and varistor characteristics, and an earth electrode is provided on almost the other surface of the flat surface. Distributed constant type capacitors and varistors are formed between the electrodes.

[0004]

However, in a noise filter block using the above feedthrough capacitors, when a plurality of feedthrough capacitors are attached to the ground plate,
The noise filter block becomes thicker by the length of the feedthrough capacitor, making it difficult to make it thinner.In addition, the mounting holes must be spaced in accordance with the outer diameter of the feedthrough capacitor, and the narrow pitch of the signal line. However, when the temperature cycle test is carried out with the connector built into the connector, the difference in the coefficient of thermal expansion between the insulating resin of the connector and the ground plate causes stress on the connector pin, which is the terminal. There is a problem that the feedthrough capacitor through which the pin is inserted may be cracked, and the range in which the capacitance of the feedthrough capacitor can be acquired is limited. Further, the noise filter block using the chip capacitor is insufficient in the ability to route the printed pattern on the substrate and the structure of the ground electrode to remove high frequency noise.

Further, the "high frequency and surge absorption filter" disclosed in Japanese Patent Application Laid-Open No. Hei 1-102874 requires not only a role as a capacitor but also a role as a varistor for a dielectric such as a ceramic substrate. In order to obtain the effect of, the structure and composition of the ceramic substrate must be rigorously specified, and the range in which the electrostatic capacitance can be acquired is narrowed like the feedthrough capacitor, improving the noise blocking characteristics. Therefore, there was a problem that a ferrite plate or ferrite beads were required.

An object of the present invention is to provide a noise filter block which has a thin overall shape and can be miniaturized by narrowing a pitch between signal lines and which is free from cracks or the like even when a temperature cycle test is carried out. It is in. Another object of the present invention is to provide a noise filter block with a varistor function, which has a simple structure, has a wide range of capacitance acquisition, can sufficiently remove high frequency noise, and can also absorb surge voltage.

[0007]

A configuration of the present invention for achieving the above object will be described with reference to FIG. 1 corresponding to an embodiment. The noise filter block 10 with a varistor function of the present invention includes an insulating substrate 11 having a plurality of terminal insertion holes 12 provided at predetermined intervals, and an inner surface electrode on the inner surface of the hole on the peripheral surface of the substrate 11. 12a, a signal electrode 14 continuously formed on the substrate 12a, a first ground electrode 16 formed on the surface of the substrate 11 with a predetermined insulating gap 15 from the signal electrode 14, and an inner electrode on the inner surface of the hole 12. A second ground electrode 17 formed on the back surface of the substrate 11 with a predetermined insulating gap 18 between the second ground electrode 12a and the first ground electrode 16a.
And a pair of terminal electrodes 19b and 19c provided at both ends of the bare chip 19a are connected to the signal electrode 14 and the first ground electrode 16 respectively.
The chip capacitor 19 provided between the signal electrode 14 on the substrate surface and the first ground electrode 16 so as to be connected to the signal electrode 14 and the pair of terminal electrodes 29b and 29c provided at both ends of the bare chip 29a are connected to the signal electrode 14 respectively. And a chip varistor 29 installed between the signal electrode 14 on the substrate surface and the first ground electrode 16 so as to be respectively connected to the first ground electrode 16.

[0008]

The signal lines P such as connector pins are inserted into the plurality of terminal insertion holes 12, the signal lines P are connected to the signal electrodes 14 on the front surface of the substrate, and the second ground electrode 17 on the rear surface of the substrate is connected. To the ground electrode of the ground shield case. Since the chip capacitor 19 can provide a large electrostatic capacity in a small space, the noise filter block 10 can be made small and thin, and the residual inductance generated on the ground side after being mounted on the connector can be extremely reduced by the block 10. It can be suppressed to a small value, and high-frequency noise of the signal passing through each signal line can be collectively and reliably removed. When a surge voltage is applied to the signal line P, the chip varistor 29 causes the signal electrode 14 and the ground electrode 16,
17 conducts, and a surge current flows through the earth electrodes 16 and 17 to the earth electrode of the shield case, and the signal line P
Protect electronic devices connected to.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 to 4 show a noise filter block 10 with a varistor function according to the first embodiment of the present invention. As shown in FIGS. 1 to 4, a glass epoxy substrate 11 which is an insulating substrate.
As a starting material, a copper clad laminate having thin copper foils attached to both surfaces thereof was used to remove unnecessary portions by etching to form signal electrodes 14, and first and second ground electrodes 16 and 17. That is, four terminal insertion holes 12 were provided at the center of the copper-clad substrate 11, and ten through holes 13 were provided at equal intervals in the vicinity of both edges of the substrate 11. The inner surface of each of the holes 12 and the through holes 13 is plated with copper to form an inner electrode 1.
2a and 13a were formed.

On the surface of the substrate 11, a circular signal electrode 14 centered on the hole 12 and the first ground electrode 1 around the signal electrode 14 are provided.
The resist is printed on the portion 6 at a gap 15 and the second portion is formed on the back surface of the substrate 11 at a gap 18 around the hole 12.
A resist was printed on each of the ground electrodes 17. The copper foil in the gaps 15 and 18 was removed by etching. As a result, the signal electrode 14 is continuously formed on the surface of the peripheral edge of the hole of the substrate 11 with the inner surface electrode 12a of the inner surface of the hole 12, and the first ground electrode 16 is the signal electrode 14
The electrode 14 and the electrode 14 are formed with a predetermined insulating gap 15 therebetween. The second earth electrode 17 is formed on the back surface of the substrate 11.
Surround the inner surface electrode 12a on the inner surface of the hole 12 and
The second ground electrode 17 is formed with a predetermined insulating gap 18 between the inner surface electrode 13 and the inner surface electrode 13 of the through hole 13.
It was electrically connected to the first ground electrode 16 via a.
The signal electrode 14 and the first ground electrode 16 on the surface of the substrate 11
Between the chip electrodes and the chip capacitor 19 for each signal electrode.
And one chip varistor 29 are installed. The chip capacitor 19 is installed by soldering the pair of terminal electrodes 19b and 19c provided at both ends of the bare chip 19a to the signal electrode 14 and the first ground electrode 16, respectively. The chip capacitor 19 is a chip type monolithic ceramic capacitor, and is a bare chip 19a.
Is a sintered body obtained by alternately stacking internal electrodes and barium titanate-based or lead-based dielectric layers and then firing. The terminal electrodes 19b and 19c are formed by applying a conductive paste containing Ag to both end surfaces of the bare chip and then baking it, and the surface of the terminal electrodes is subjected to solder plating.

Further, the chip varistor 29 is installed by arranging a pair of terminal electrodes 29 provided at both ends of the bare chip 29a.
This is performed by soldering b and 29c to the signal electrode 14 and the first ground electrode 16, respectively. The chip varistor 29 is a chip-type multilayer ceramic varistor, and the bare chip 29a is a sintered body obtained by alternately stacking internal electrodes and zinc oxide based varistor layers and then firing. The terminal electrodes 29b and 29c are the terminal electrodes 19b and 19c.
Is formed similarly to.

A case will be described in which the noise filter block 10 with a varistor function configured as described above is built in, for example, a connector (not shown). Four connector pins P (FIG. 1), which are signal lines, are inserted into the four terminal insertion holes 12, and these connector pins P are used as the inner surface electrode 12a and the second ground electrode 1 on the back surface of the substrate 11.
7 are electrically connected to a ground shield case (not shown) by soldering. The connector pin P is the inner surface electrode 12a, the signal electrode 14 and the chip capacitor 1.
9 or the ground electrode 16, 1 via the chip varistor 29
Connected to 7. Since the chip capacitor 19 can provide a large electrostatic capacity in a small space, the noise filter block 10 can be made small and thin, and the residual inductance generated on the ground side after being mounted on the connector can be extremely reduced by the block 10. It can be suppressed to a small value, and high-frequency noise of the signal passing through each signal line can be collectively and reliably removed. When a surge voltage is applied to the signal line P by the chip varistor 29, the signal electrode 14 and the ground electrode 16,
17 conducts, and a surge current flows through the earth electrodes 16 and 17 to the earth electrode of the shield case, and the signal line P
Protect electronic devices connected to.

5 to 8 show a noise filter block 20 with a varistor function according to a second embodiment of the present invention. 1 to 4
The same reference numerals denote the same components. The characteristic structure of this example is that, instead of providing the through holes 13 of the first embodiment, end face electrodes 21 are formed on both end faces of the insulating substrate 11, and the first ground electrode 16 and the second ground electrode 17 are formed on the inner surface. It is electrically connected via the end face electrode 21 instead of the electrode 13a. In this example, an alumina ceramic substrate was used as the insulating substrate 11. Similar to the first embodiment, four terminal insertion holes 12 were provided at the center of the substrate 11 at equal intervals. Inner electrodes 12a were formed on the inner surfaces of these holes 12 by through-hole printing. The signal electrode 14 and the first ground electrode 16 are Ag or Ag / P on the surface of the substrate 11.
It was formed by screen-printing a conductive paste containing d and the like. That is, the signal electrode 14 is formed in a circular shape on the surface of the peripheral edge of the hole of the substrate 11 so as to be continuous with the inner electrode 12a on the inner surface of the hole 12, and the first ground electrode 16 surrounds the signal electrode 14 and The electrode 14 and the electrode 14 are formed with a predetermined insulating gap 15.

A second ground electrode 17 was formed on the back surface of the substrate 11 by screen printing the same conductive paste as above. Further, the end face of the substrate 11 was coated with a conductive paste to form a baked end face electrode 21. As a result, the second ground electrode 17 is formed so as to surround the inner surface electrode 12a on the inner surface of the hole 12 and to leave a predetermined insulating gap 18 from the electrode 12a, and the second ground electrode 17 is provided with the first surface electrode 21 via the end surface electrode 21.
It was electrically connected to the ground electrode 16. A chip capacitor 19 and a chip varistor 29 were provided between the signal electrode 14 and the first ground electrode 16 on the surface of the substrate 11 as in the first embodiment. This noise filter block 2
The use method and characteristics of 0 are the same as those in the first embodiment, and thus the repeated description will be omitted.

Although the glass epoxy substrate and the alumina ceramics substrate are shown as the insulating substrate in the above example, other substrates may be used as long as they are heat resistant and have high mechanical strength. Further, the shape of the signal electrode is not limited to a circular shape, but may be another shape such as a square shape or an elliptical shape.
Further, one chip capacitor and one chip capacitor are provided for each signal electrode, but this number is an example, and two chip capacitors are provided according to the frequency range to be removed.
One or more pieces may be provided, or the capacitance may be changed according to the frequency range to be removed. Two or more chip varistors may be provided depending on the surge withstand capability required. Furthermore, the number of terminal insertion holes or the number of through holes is an example, and is not limited to the above example.

[0016]

As described above, the present invention has the following excellent effects. (a) Since a chip capacitor is used as the capacitor element instead of the conventional feedthrough capacitor, the pitch between signal lines can be narrowed, and the noise filter block can be made smaller and thinner, and the filter connector incorporating this can be made smaller. Is possible. (b) Even if a load is applied to the terminals such as connector pins after mounting on a connector, etc., the chip capacitor, which is a capacitor element, and the chip varistor, which is a surge absorbing element, are not directly loaded. There is nothing to do. Moreover, even if a temperature cycle test is performed, no cracks or the like occur.

(C) Since a chip capacitor is mounted, the capacitance acquisition range is wider than that of a conventional feedthrough capacitor, and high-frequency noise can be sufficiently removed. By combining a chip capacitor for high frequency and low frequency, it is possible to take measures against noise in a wide frequency range. (d) First and second on the front and back of the insulating substrate, respectively.
Since a ground electrode is provided and both ground electrodes are electrically connected by the end face of the board or through holes, when installed in a ground shield case such as a connector, the shield effect is high and the residual inductance generated on the ground side is suppressed. And is excellent in high frequency removal effect. (e) Since a chip varistor is installed, when a surge voltage is applied to the signal line, a surge current is passed through the earth electrode of the shield case to protect the electronic equipment connected to the signal line. (f) In particular, since the filter block of the present invention performs noise removal and surge absorption by dedicated chip electronic components,
It is easy to design and manufacture to obtain a desired effect, and can reliably perform both functions without making a complicated structure.

[Brief description of drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 2 of a noise filter block with a varistor function according to a first embodiment of the present invention.

FIG. 2 is a plan view thereof.

FIG. 3 is an external perspective view thereof.

FIG. 4 is an inverted perspective view of the same.

5 is a sectional view taken along line BB of FIG. 6 of the noise filter block with a varistor function according to the second embodiment of the present invention.

FIG. 6 is a plan view thereof.

FIG. 7 is an external perspective view thereof.

FIG. 8 is an inverted perspective view of the same.

[Explanation of symbols]

 P Connector pin (Signal line) 10, 20 Noise filter block with varistor function 11 Insulating substrate 12 Terminal insertion hole 12a, 13a Inner surface electrode 13 Through hole 14 Signal electrode 15,18 Insulation gap 16 First earth electrode 17 Second Ground electrode 19 Chip capacitor 19a Bare chip 19b, 19c Terminal electrode 21 End surface electrode 29 Chip varistor 29a Bare chip 29b, 29c Terminal electrode

Claims (3)

[Claims] 1. An insulative substrate (11) having a plurality of terminal insertion holes (12) provided at predetermined intervals, and an inner surface of the hole (12) on a surface of a hole periphery of the substrate (11). A signal electrode (14) continuously formed on the inner surface electrode (12a) of the electrode, and a predetermined insulating gap (15) from the signal electrode (14) formed on the surface of the substrate (11). A predetermined insulation gap (1) is formed between the first ground electrode (16) and the inner electrode (12a) on the inner surface of the hole (12).
A second ground electrode (17) which is formed on the back surface of the substrate (11) by opening 8) and is electrically connected to the first ground electrode (16).
And a pair of terminal electrodes (19b, 19b) provided on both ends of the bare chip (19a).
19c) is connected to the signal electrode (14) and the first ground electrode (16) respectively, and the signal electrode (14) and the first ground electrode (16) on the surface of the substrate (11) are connected to each other. Between the chip capacitor (19) and the pair of terminal electrodes (29b, 29b) provided on both ends of the bare chip (29a).
29c) is connected to the signal electrode (14) and the first ground electrode (16) respectively, and the signal electrode (14) and the first ground electrode (16) on the surface of the substrate (11) are connected to each other. A noise filter block with a varistor function that includes a chip varistor (29) installed between the two. 2. A plurality of through holes (1) in an insulating substrate (11).
3) is provided, and the first ground electrode (16) and the second ground electrode (1
The noise filter block with a varistor function according to claim 1, wherein 7) is electrically connected through an inner electrode (13a) of the through hole (13). 3. An end surface electrode (21) is formed on an end surface of an insulating substrate (11), and a first ground electrode (16) and a second ground electrode (17) are electrically connected via the end surface electrode (21). Claim 1 connected to
Noise filter block with varistor function described.