JPH0318111A - Fitting structure for chip type noise filter - Google Patents

Abstract

PURPOSE:To display proper filter characteristics by connecting signal conductor paths in array arrangements and signal electrodes which are arrayed and arranged between both terminals of the noise filter, and bringing the tongue of a metallic plate terminal fixed to a substrate into contact with a ground electrode in the center of the noise filter. CONSTITUTION:Ground conductors 2a and 2b and signal conductor paths 3a and 3b are arrayed and arranged on the top surface of a substrate 1 opposite in parallel. Three-terminal capacity 10 is arranged in array, signal electrodes A and B are soldered to the conductor paths 3a and 3b respectively, and the connection surface of a ground terminal C is set up. A metallic plate electrode 5 is fitted from above the substrate 1 where the capacitor 10 is mounted and an insert 5c is inserted into slits 4a and 4b of the conductors 2a and 2b and soldered 8. At this time, the tongue piece 5d of the metallic electrode plate is pressed elastically against the ground electrode C of the capacity 10 and connected. The metallic plate electrode 5 can secure wide width and is increased in its plate 1, thickness and a material which is small in inductance is selected to reduce a noise voltage without impeding the noise removing operation of the filter.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a structure for attaching a filter group to a substrate for noise prevention in electronic circuits, particularly digital circuits.

Conventional Technology and Issues One of the methods adopted to counter noise in electronic circuits, especially digital circuits, is to connect the signal conductor and the ground conductor via a noise filter, generally a bypass capacitor, to ground the noise. There is a known method for removing it by letting it escape into a conductor.

As a bypass capacitor, there is, for example, a chip type three-terminal capacitor 10 shown in FIG. 8(a). The three-terminal capacitor 10 has signal electrodes (A), (B) formed at both ends and a ground electrode (C) formed at the center.

FIG. 8(b) shows an equivalent circuit diagram of the chip type three-terminal capacitor 10.

By the way, when a noise filter is placed near a connector and used, one three-terminal capacitor 10 is often connected to each bin of the connector. At this time, the three-terminal capacitors 10 are conventionally arranged on the substrate l1 in an aligned and densely arranged manner as shown in FIG. 9(.).

That is, as shown in FIG. 9(b), the ground conductor 12a.
12b, ground conductor lead-out portion 12c, and signal conductor path 13a. 13b is formed on the upper surface of the substrate 11,
The signal conductor paths 13a and 13b are arranged in parallel and facing each other. The signal conductor 13b is connected on the right side, for example, to a connector (not shown). The ground conductor lead-out portion 12c is the ground electrode (C) of the three-terminal capacitor 10.
The ground conductor 12a. 1
2b is bridged. The ground conductor lead-out portion 12c is connected to the signal conductor path 13a during the assembly process. No solder bridge is generated between the capacitor 13b and the three-terminal capacitor 1.
It has a width sufficient to ensure electrical connection with the ground electrode (C) of 0. The three-terminal capacitor 10 has a signal conductor path L3 between the signal conductor path 13g and the signal electrode (A).
b and the signal electrode (B), and between the ground conductor lead-out portion 12c and the ground electrode (C) through solder.

However, in the above mounting structure, the width of the ground conductor lead-out portion 12c has to be elongated due to the dimensions of the three-terminal capacitor 10, especially the distance between the signal electrodes. In this region, it functions as a so-called coil. Therefore, between the ground electrodes (C) of each three-terminal capacitor 10 and between the ground electrodes (C
) and the ground conductors 12a, 12b, respectively, with inductances L2, L3. L4, L5. LL. L6 is generated, and these inductances L1 to L6 enter in series with the ground electrode (C) of the three-terminal capacitor 10. Figure 9 (a
) is not shown in Fig. 9(c).

For this reason, the noise removal effect of the three-terminal capacitor 10 may be inhibited, and the filter characteristics may not be fully exhibited. In addition, the inductance 1 to L6 is the change in current di/
dt to generate a noise voltage of L·di/dt,
Moreover, this change in current di/dt is caused by the inductance L
Since this affects all three-terminal capacitors 10 through L1 to L6, there is a problem in that so-called common impedance noise is generated.

An object of the present invention is to provide a mounting structure that can fully exhibit the filter characteristics of a group of noise filters mounted in high density.

Means for Solving the Problems In order to solve the above problems, a mounting structure for a chip type noise filter according to the present invention is provided in which aligned signal conductor paths are formed facing each other, and the noise filter is connected to the signal conductor paths. The tongue of a metal plate terminal that is arranged to electrically connect the conductor path and the signal electrodes provided at both ends of the noise filter, is electrically connected to the ground conductor, and is fixed to the substrate. is in contact with a ground electrode provided at the center of the noise filter.

Further, a ground auxiliary conductor is formed between the opposing signal conductor paths, such that the noise filter electrically connects the signal conductor path and the signal electrode of the noise filter, and the ground electrode of the noise filter and the ground auxiliary conductor. A chip type noise filter in which the tongue of a metal plate terminal that is arranged in a line so as to be electrically connected to a ground conductor and that is electrically connected to a ground conductor and fixed to a substrate is in contact with the ground auxiliary conductor. The mounting structure may be the same.

In other words, the ground electrode of the noise filter is electrically connected to the ground conductor via the metal plate electrode, and the ground electrode of the noise filter is generated in the metal plate electrode instead of the inductance of the conventional ground extraction part. It will be affected by inductance. The width of the metal plate electrode can be increased independently regardless of the distance between the signal electrodes of the noise filter, and by increasing the thickness of the metal plate or using a material with low inductance for the metal plate, it is possible to increase the width of the metal plate electrode. Since the inductance of the plate electrode can be made small, the value of the inductance L in series with the ground electrode of the noise filter can be made extremely small, so that the noise removal effect is not inhibited, and the noise voltage is also made small.

Embodiments Hereinafter, embodiments of a mounting structure for a chip-type noise filter according to the present invention will be described with reference to the drawings, together with a method for mounting the same. In this example, the eighth chip noise filter is used as a chip type noise filter.
A case will be described in which five three-terminal capacitors 10 are arranged in a row using the chip-type three-terminal capacitor 10 shown in the figure.

First, as shown in FIG. 1, a ground conductor 2a. 2b and signal conductor paths 3a, 3b are formed. The signal conductors 3a and 3b are arranged parallel to each other and formed opposite to each other. Although not shown, for example, the signal conductor path 3a is connected to an electronic circuit element such as an IC on the left side, and the signal conductor path 3b is connected to a connector on the right side.

Ground conductor 2a. 2b has an insertion slit 4a for a metal plate electrode 5 to be attached later. 4b is provided.

Next, as shown in FIG. 2, the three-terminal capacitors 10 are aligned and installed, between the signal conductor path 3a and the signal electrode (A), and between the signal conductor path 3b and the signal electrode (B). are electrically connected using solder or the like, and the three-terminal capacitor 10 is fixed. At this time, the three-terminal capacitor 10 is installed so that the connection surface of the ground electrode (C) faces upward.

On the other hand, as shown in FIG. 3, the metal plate electrode 5 is made of one metal plate and includes an upper surface portion 5a, a side surface portion 5b, and an insertion portion 5c. 5' tongue portions 5d are formed at predetermined positions on the upper surface portion 5a by punching. The height T of the side surface portion 5b is greater than the mounting height of the three-terminal capacitor 10, and the tongue portion 5 is located at the mounting height of the three-terminal capacitor 10.
Make it smaller than the dimension including the depth of d.

The width of the metal plate electrode 5 is considerably wider than the width of the conventional ground conductor lead-out portion 12c shown in FIG. 9, and is usually wider than the length of the three-terminal capacitor 10. Further, the thickness of the metal plate of the metal plate electrode 5 may be increased, or a metal plate made of a material with low inductance may be used.

As shown in FIG. 4, this metal plate electrode 5 is attached from above the substrate 1 on which the three-terminal capacitor IO is mounted.

That is, the insertion part 5C of the metal plate electrode 5 is connected to the ground conductor 2a.
．． The slit 4a provided in 2b. 4b, electrically connected to the ground conductors 2a and 2b by solder 8, and fixed to the substrate 1. At this time, the metal plate electrode 5
The tongue portion 5d is pressed into contact with the ground electrode (C) of the three-terminal capacitor 10 by its own bending elastic force and is electrically connected.

By the above method, the noise filter mounting structure shown in FIG. 5 is formed. Signal conductor path 3a. A three-terminal capacitor 10 is placed on top of the three-terminal capacitor 10 via solder 8, and the metal plate electrode 5 is attached to the ground conductors 2a and 2b via solder 8 to cover the three-terminal capacitor 10. It has a structure in which it is in contact with the ground electrode (C).

Therefore, the ground electrode (C) of the three-terminal capacitor IO will be electrically connected to the metal plate electrode 5 via the tongue portion 5d, and will be affected by the inductance generated in the metal plate electrode 5. Therefore, the equivalent circuit of the present invention is the same as the equivalent circuit shown in FIG. Since a material having a small inductance can be used for the inductance, the inductances L1 to L6 can have small numerical values, and the noise removal effect of the filter is not inhibited, and the noise voltage is also small.

6 and 7 show other embodiments of the present invention.

In the connection structure shown in FIGS. 6 and 7, the ground conductor 22a
．． 22b and signal conductor paths 23a, 23b,
A ground auxiliary conductor 22c is formed on the upper surface of the substrate 21, and the tongue portion 26 of the metal plate electrode 26 is attached to the ground auxiliary conductor 22c.
It is the one that touches a. The width of the ground auxiliary conductor 22c is approximately equal to the width of the conventional ground lead-out portion 12c shown in FIG. Although not shown in FIG. 6, the three-terminal capacitors IO are installed in an aligned manner, between the signal conductor path 23a and the signal electrode (A), and between the signal conductor path 23b and the signal electrode (B). The three-terminal capacitor 10 is electrically connected using solder or the like, and the three-terminal capacitor 10 is fixed. At this time, the ground electrode (C
) is attached so that the connection surface is on the lower side, unlike the previous embodiment.

On the other hand, the metal plate electrode 26 includes an upper surface portion 26a, a side surface portion 26b, and an insertion portion 26c. On the upper surface part 26a,
Five tongues 26d are formed by punching at predetermined positions moved to the right from the position of the tongues 5d in the previous embodiment. The length of the tongue portion 26d is longer than that of the tongue portion 5d of the embodiment described above so as to be in contact with the ground auxiliary conductor 22c. The height of the side surface portion 26b is greater than the mounting height T' of the three-terminal capacitor 10 and smaller than the depth of the tongue portion 26d.

The width of the metal plate electrode 26 is considerably wider than the width of the conventional ground conductor lead-out portion 12C shown in FIG. 9, and is usually wider than the length of the three-terminal capacitor IO. This metal plate electrode 26 is attached from above the substrate 2l on which the three-terminal capacitor 10 is mounted.

That is, the insertion part 26c of the metal plate electrode 26 is inserted into the slit provided in the ground conductors 22a, 22b, and the ground conductors 22a, 22b are electrically connected by soldering. 22b and fixed to the substrate 21. At this time, the tongue portion 26d of the metal plate electrode 26 is pressed against the ground auxiliary conductor 22c by its own bending elastic force, and is electrically connected.

In this way, the ground auxiliary conductor 22c and the signal conductor path 23a
．． A three-terminal capacitor 10 is placed on the ground conductor 23b via solder, and the metal plate electrode 26 is connected to the ground conductor 22a.
, 22b via solder to cover the three-terminal capacitor 10, and the tongue portion 26d is in contact with the ground auxiliary conductor 23c.

Therefore, the ground electrode (C) of the three-terminal capacitor 10 is connected to the metal plate 'rFt. electrically connected to pole 26 and further connected to ground conductor 22a. 22b, and will be affected by the inductance generated in the metal plate electrode 26. Therefore, the equivalent circuit of the present invention is the same as the equivalent circuit shown in FIG. 9(c), but since the metal plate electrode 26 can ensure a small inductance, the inductances L1 to L6 can have small values, The noise removal effect of the filter is not inhibited, and the noise voltage is also reduced.

It should be noted that the mounting structure of the chip-type noise filter according to the present invention is not limited to the above-mentioned embodiment, and can be variously modified within the scope of the gist. As a method for attaching the metal plate electrode 5 to the substrate 1, in addition to the soldering method of the embodiment, a screwing method may be used. In that case, holes for screws are provided in the substrate 1, and holes for screws are also provided in the metal plate electrode 5.

Further, even if a conventional ground conductor lead-out portion 12c shown in FIG. 9 is additionally provided on the upper surface of the substrate 1 shown in FIG. 1, the noise removal effect and noise voltage of the filter can be improved compared to the conventional one. Similarly, the ground auxiliary conductor 2 of the board 21 shown in FIG.
2c is extended to form a ground conductor 22a. Even if the filter is connected to 22b, the noise removal effect and noise voltage of the filter are improved compared to the conventional filter.

Effects of the Invention According to the present invention, the width of the metal plate electrode can be increased independently regardless of the distance between the signal electrodes of the noise filter, and the thickness of the metal plate can be increased or the metal plate can be made of a material with low inductance. Therefore, the inductance of the metal plate electrode becomes extremely small. And this metal plate! Since the ground electrode of the noise filter is electrically connected to the pole, the value of the inductance L in series with the ground electrode of the noise filter is also extremely small, and does not inhibit the noise removal action of the noise filter.

Furthermore, the noise voltage L·di/dt caused by the change in current di/dt can be practically ignored since the value of the inductance L is extremely small, and the problem of common impedance noise is also solved.

As a result, a mounting structure for a chip-type noise filter is provided in which the original filter characteristics of the noise filter can be sufficiently exhibited.

Further, since the wide metal plate electrode covers the noise filter, the noise filter is shielded by the metal plate electrode, thereby preventing the influence of external noise.

[Brief explanation of the drawing]

1 and 2 are plan views illustrating the mounting structure of a chip-type noise filter according to an embodiment of the present invention, FIG. 3 is a perspective view of a metal plate electrode, and FIG. 4 is a metal plate shown in FIG. 3. A plan view after the electrodes are attached to the substrate, and FIG. 5 is a sectional view taken along line xx' in FIG. 4. FIG. 6 is a plan view showing another embodiment, and FIG. 7 is a sectional view taken along line XX' in FIG. FIG. 8(a) is a perspective view showing the external appearance of the chip type noise filter used in the example, and FIG. 8(b) is its equivalent circuit diagram. FIGS. 9(a) and 9(b) are plan views illustrating the mounting structure of a conventional chip-type noise filter, and FIG. 9(c) is an equivalent circuit diagram thereof. 1... Substrate, 2g. 2b...Ground conductor, 3a.
3b...Signal conductor path, 5...Metal plate electrode, 5d.
...Tongue, 10... Chip type noise filter (chip type three-terminal capacitor), 21-... Board, 228.22
b...Ground conductor, 22c...Ground auxiliary conductor, 23a, 23b...Signal conductor path, 26...Metal plate electrode, 26d...Tongue, (A), (B)... Signal electrode, (C)...Ground electrode.

Claims (2)

[Claims] 1. In the mounting structure of a chip-type noise filter that electrically connects a ground conductor and a signal conductor path formed on the surface of a substrate, the signal conductor paths arranged in alignment are formed facing each other,
The noise filter is arranged in alignment so as to electrically connect the signal conductor path and signal electrodes provided at both ends of the noise filter, and is electrically connected to a ground conductor,
A mounting structure for a chip-type noise filter, characterized in that a tongue portion of a metal plate terminal fixed to a substrate is in contact with a ground electrode provided at the center of the noise filter. 2. In the mounting structure of a chip-type noise filter that electrically connects a ground conductor and a signal conductor path formed on the surface of a substrate, the signal conductor paths arranged in alignment face both sides of the ground auxiliary conductor. formed such that the noise filter electrically connects the signal conductor path and signal electrodes provided at both ends of the noise filter, and a ground electrode provided at the center of the noise filter and the ground auxiliary conductor. and are arranged in such a way that they are electrically connected to each other, and the tongue portion of the metal plate terminal that is electrically connected to the ground conductor and fixed to the substrate is in contact with the ground auxiliary conductor. Mounting structure of chip type noise filter.