JP2000244128A - Multilayer printed wiring board and mounting structure of chip type three-terminal noise filter using the same - Google Patents

Abstract

(57) [Summary] (With correction) [Problem] When a plurality of noise filters are arranged in order to remove noise, a multilayer printed wiring board and a multilayer printed wiring board capable of fully exhibiting the inherent noise removing effect without impairing the noise removing effect Provided is a mounting structure of a chip-type three-terminal noise filter using the same. A ground conductor to which a ground electrode of a noise filter is connected is connected to a multilayer printed wiring board.
Is connected to the ground conductor 3 formed on the back surface and the inner-layer ground conductor 10 inside the multilayer printed wiring board via a through hole 4 provided near the ground electrode of the noise filter. As a result, the ground electrode of the noise filter is strongly connected to the ground conductor and the inner-layer ground conductor on the back surface of the substrate, and the inductance value that enters the high-frequency current path in series becomes very small, and the noise voltage generated at the ground electrode of the noise filter is reduced. Is suppressed. Therefore, when the noise removing effect of the noise filter increases, the noise removing effect is sufficiently exhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board for reducing electromagnetic radiation noise from a multilayer printed wiring board and a cable, and a mounting structure of a chip type three-terminal noise filter using the same.

[0002]

2. Description of the Related Art Conventionally, as one method for reducing electromagnetic radiation noise generated from a printed wiring board or a cable connected to the printed wiring board, a method is known in which a through-hole is provided between a signal line serving as an electromagnetic radiation noise source and a ground conductor. Insert a noise filter such as a capacitor or distributed constant LC filter,
There is known a method of removing a high-frequency component from a signal conductor path by returning a high-frequency component of a signal flowing in the signal conductor path to the ground.

Usually, a chip type three-terminal noise filter 35 as shown in FIG. 6 is used as a noise filter. FIG.
Is a top view of the chip-type three-terminal noise filter. Signal electrodes 37a and 38b are formed on both sides of the chip-type three-terminal noise filter 35, and a ground electrode 36 is provided at the center of the chip-type three-terminal noise filter 35. Are formed.

The above-described chip type three-terminal noise filter 3
5 to reduce the electromagnetic radiation noise,
When the chip-type three-terminal noise filter 35 is arranged near the connector, one chip-type three-terminal noise filter 35 is often inserted into one signal conductor path extending from the I / O connector. For this reason, the chip-type three-terminal noise filters 35 are closely arranged and arranged near the I / O connector.

FIG. 7 is a plan view showing a state in which the above-mentioned chip type three-terminal noise filter 35 is arranged and arranged. FIG. 8 is a plan view showing a state of the printed wiring board 31 before the chip type three-terminal noise filter 35 is arranged. 7, eight chip-type three-terminal noise filters 35 are arranged on a four-layer printed wiring board 31 with respect to eight signal conductor paths (bus lines) extending from an I / O connector (not shown). Are located. That is, in FIG. 8, the ground conductor 32, the signal conductor path 39a, the signal conductor path 39b, the signal pad 38a, and the signal pad 39b
Are formed on the four-layer printed wiring board 31. The signal conductor paths 39a and 39b are arranged in parallel and the signal conductor paths 39a and 39b are opposed to each other. The right side of FIG. 8 of the signal conductor path 39a is connected to an I / O connector (not shown). In addition, the ground electrodes 36 of the aligned chip-type three-terminal noise filters 35 are electrically connected by the ground conductor 32, and further connected from one end of the aligned chip-type three-terminal noise filters 35 to the other. ing.

FIG. 9 is a sectional view taken along the line XX 'in FIG. 9, reference numeral 40 denotes an inner-layer ground conductor of the four-layer printed wiring board 31, 41 denotes an inner-layer power supply conductor, and 33 denotes a ground conductor formed on the back surface of the four-layer printed wiring board 31.

[0007]

In the above-described mounting structure of the chip-type three-terminal noise filter, the width of the ground conductor to which each ground electrode of the aligned chip-type three-terminal noise filter is connected (the left and right in FIG. 7). Direction length)
Is substantially determined by the width (length in the left-right direction of FIG. 8) of the ground electrode of the chip-type three-terminal noise filter. Therefore, the chip types 3 arranged as shown in FIG.
In the terminal noise filter, the shape of the ground conductor is an elongated line in the vertical direction in FIG.

The ground conductor having such an elongated shape comes to have a function as a coil, and an inductance is generated. As a result, the inductance is connected in series to the path of the high-frequency current to be removed by the chip-type three-terminal noise filter. Therefore,
The inductance of the chip-type three-terminal noise filter is impaired by the inductance, and the noise-reduction effect inherent to the chip-type three-terminal noise filter is not exhibited. Further, there is a problem that a noise voltage is generated on the ground electrode of the chip-type three-terminal noise filter due to the inductance of the ground conductor.

In order to solve the problem of the occurrence of inductance due to the mounting structure of the chip-type three-terminal noise filter described above, an auxiliary ground conductor is formed on the back side of the substrate facing the chip-type three-terminal noise filter arranged in line. Japanese Patent No. 26769 discloses a mounting structure in which a through-hole is provided in the vicinity of a ground electrode of a three-terminal noise filter to electrically connect a ground conductor and an auxiliary ground conductor, thereby reducing inductance that enters a high-frequency current path in series.
No. 21 has proposed. However, this mounting structure is applied to a double-sided printed wiring board.

The present invention relates to a multilayer printed wiring board capable of sufficiently exhibiting the original noise removing effect without impairing the noise removing effect of the chip type three-terminal noise filter, and a chip type three-terminal noise filter using the same. It is intended to provide a mounting structure.

[0011]

In order to solve the above-mentioned problems, a multilayer printed wiring board according to the present invention has an elongated ground conductor and signal conductor paths opposed to each other with the ground conductor interposed therebetween. A chip-type three-terminal noise filter having signal electrodes formed at both ends and a ground electrode formed at the center so as to electrically connect the signal electrode, the signal conductor path, the ground electrode, and the ground conductor. A multilayer printed wiring board that is arranged and mounted,
A multilayer printed wiring board having a functional element that acts to cancel an inductance generated by a ground conductor and a through hole that electrically connects the ground conductor and the functional element. At this time, the functional element is an inner-layer ground conductor formed inside the multilayer printed wiring board. The functional element is a ground conductor formed on the back surface of the multilayer printed wiring board.

Further, the mounting structure of the chip type three-terminal noise filter of the present invention is characterized in that the both ends are formed on a multilayer printed wiring board in which a long and narrow ground conductor and signal conductor paths opposed to each other across the ground conductor are formed. Chip-type three-terminal noise filter in which a signal electrode is formed in a portion and a ground electrode is formed in a central portion so as to electrically connect the signal electrode, the signal conductor path, the ground electrode, and the ground conductor. A mounting structure of a three-terminal type noise filter, wherein the ground conductor is provided on an inner-layer ground conductor formed inside the printed wiring board acting to cancel the inductance generated by the ground conductor, and on an opposite mounting surface of the chip-type three-terminal noise filter. A plurality of multi-layered printed wiring boards having through holes for electrically connecting formed ground conductors A mounting structure of a chip-type three-terminal noise filter is implemented is.

That is, a signal conductor formed on both sides of a chip type noise filter and a signal conductor formed on a ground conductor formed on a multilayer printed wiring board and a signal conductor path formed to face each other with the ground conductor interposed therebetween. A plurality of chip-type three-terminal noise filters are arranged and arranged so as to electrically connect the conductor path and electrically connect the ground electrode of the chip-type three-terminal noise filter to the ground conductor. And the inner layer ground conductor formed inside the multilayer printed wiring board is electrically connected by through holes provided near the ground electrode.

The ground electrode of the chip-type three-terminal noise filter is formed on the back surface of the multilayer printed wiring board, not in the conventional structure in which the ground electrode is connected only to the substrate surface on which the chip-type three-terminal noise filter is mounted. The ground conductor and the inner-layer ground conductor formed inside the multilayer printed wiring board are electrically connected to each other through through holes provided near the ground electrode. With such a mounting structure of the chip-type three-terminal noise filter in the multilayer printed wiring board, the ground electrode of the chip-type three-terminal noise filter is strongly connected to the ground conductor and the inner-layer ground conductor on the back surface of the substrate. Thereby, the value of the inductance that enters the high-frequency current path in series can be made very small.

[0015]

Next, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, FIG.
An example in which eight three-terminal chip type noise filters 5 shown in FIG. FIG. 4 is a plan view of the chip-type three-terminal noise filter 5.
, Signal electrodes 7a and 7b are formed on both sides, and a ground electrode 6 is formed at the center of the chip type three-terminal noise filter 5.

FIG. 1 is a plan view showing a mounting structure of a chip type three-terminal noise filter of the present invention. FIG. 1 shows a state in which eight chip-type three-terminal noise filters 5 are arranged and arranged in the vicinity of an I / O connector (not shown) on a four-layer printed wiring board 1. In FIG. 1, eight chip-type three-terminal noise filters 5 are arranged on a four-layer printed wiring board 1 for eight signal conductor paths (bus lines) extending from an I / O connector (not shown). Have been. That is, the ground conductor 2, the signal conductor 9a, the signal conductor 9b, the signal pad 8a, and the signal pad 8b are four-layer printed wiring boards 1 in FIG. Is formed on. Further, the signal conductor paths 9a and 9b are aligned in parallel, and the signal conductor paths 9a and 9b
Are formed facing each other. 1, the right side of the signal conductor path 9a is connected to an I / O connector (not shown), and the left side of the signal conductor path 9a is connected to the signal pad 8a of the chip type three-terminal noise filter 5 in FIG. The right side of the signal conductor path 9b is connected to the signal pad 8b of the chip type three-terminal noise filter 5, and the left side of the signal conductor path 9b is connected to another electronic circuit element (not shown). The ground conductor 2 is soldered to and electrically connected to each ground electrode 6 of the aligned three-terminal noise filter 5. Further, the ground conductor 2 is connected from end to end of the eight chip-type three-terminal noise filters 5 arranged in a line. Chip type 3
Of the two signal electrodes formed on the terminal noise filter 5, the signal electrode 7a is electrically connected to the signal pad 8a by soldering, and the other signal electrode 7b of the chip type three-terminal noise filter 5 is connected to the signal pad. 8b and are electrically connected by soldering.

When the eight chip-type three-terminal noise filters 5 are aligned, the chip-type three-terminal noise filters 5
Ground conductor 2 to which each ground electrode 6 is connected
Is a through conductor provided in the vicinity of the ground conductor 6 formed on the inner layer ground conductor 10 of the four-layer printed wiring board 1 and the back surface of the four-layer printed wiring board 1 and the ground electrode 6 of the chip type three-terminal noise filter 5. It is electrically connected via the hole 4. Therefore, the ground electrode 6 of the chip-type three-terminal noise filter 5 is immediately connected to the inner-layer ground conductor 10 and the ground conductor 3 on the back surface of the four-layer printed wiring board. As a result, the effect of the inductance generated on the ground conductor 2 is almost eliminated, and the inductance generated on the ground conductor 2 is replaced by the inductance of the inner ground layer 10 and the inductance of the ground conductor 3 on the back surface of the four-layer printed wiring board 1. Of the parallel circuit. However, since the inner-layer ground conductor 10 and the ground conductor 3 have a large conductor area, the inductance can be reduced. Therefore, the ground conductor 3 and the inner-layer ground conductor 10 function to cancel the inductance generated in the ground conductor 2. Element. Therefore, the noise voltage generated on the ground electrode 6 of the chip-type three-terminal noise filter 5 is reduced, and the high-frequency noise removal effect of the chip-type three-terminal noise filter 5 is not hindered.

As another embodiment of the present invention, a case where a certain electronic circuit element is mounted on the back surface of the four-layer printed wiring board 1 will be considered. FIG. 4 shows a mounting structure of the chip-type three-terminal noise filter 5 shown in FIG. 1 in which a surface-mount type IC is mounted on the back surface of the four-layer printed circuit board 1 immediately below the aligned chip-type three-terminal noise filter 5. FIG. 4 is a vertical cross-sectional view showing a state in which In FIG. 5, a signal conductor path 14a and a signal conductor path 14b are formed on the back surface of the four-layer printed wiring board 1, and the lead electrodes 13a and 13b of the IC 12 are connected. For this reason, FIG.
The ground conductor 3 formed on the back surface of the four-layer printed wiring board 1 is not provided as shown in FIG. Therefore, the ground conductor 2 is electrically connected only to the inner-layer ground conductor 10 inside the four-layer printed wiring board 1 via the through hole 4. In this case, the value of the inductance can be reduced by the inner-layer ground conductor 10, though not as much as in the previous embodiment. Accordingly, the noise voltage generated on the ground electrode 6 of the chip-type three-terminal noise filter 5 is reduced, and the function of removing high-frequency noise of the chip-type three-terminal noise filter 5 is not hindered.

In this embodiment, eight chip types 3
Although the mounting structure in which the terminal noise filters 5 are arranged has been described, the present invention can naturally be applied to all mounting structures in which a plurality of chip-type three-terminal noise filters 5 are arranged. Further, in the present embodiment, the four-layer printed wiring board 1 is used as the substrate on which the chip-type three-terminal noise filters 5 are arranged and arranged. However, the mounting structure of the present invention can be applied to a multilayer printed wiring board having six or more layers. Needless to say.

In addition, as the functional element acting to cancel the inductance generated by the ground conductor, an inner-layer ground conductor having the same shape and size as the ground conductor is provided, but is not limited to this shape. However, the shape is not limited as long as the above action occurs. For example, a bent-shaped pattern is conceivable so that an inductance of the same size can be obtained in a smaller area, and such a configuration may be adopted.

[0021]

As described above, according to the present invention, when a plurality of chip-type three-terminal noise filters are arranged on a multilayer printed wiring board, the ground conductor for connecting the ground electrode of the chip-type three-terminal noise filter is formed. A chip type three-terminal noise filter is mounted by using a multilayer printed wiring board having a through hole for electrically connecting a ground conductor formed on the back surface of the multilayer printed wiring board and an inner ground conductor inside the multilayer printed wiring board. The inductance of the ground conductor on the reduced surface is reduced. As a result, the noise removal effect of the chip-type three-terminal noise filter increases, and the noise voltage generated at the ground electrode of the chip-type three-terminal noise filter is removed, thereby impairing the high-frequency noise removal effect of the chip-type three-terminal noise filter. Thus, the original high-frequency noise removal effect is sufficiently exhibited.

[Brief description of the drawings]

FIG. 1 is a structural plan view of an embodiment of the present invention, showing a state where chip type three-terminal noise filters are arranged and arranged on a four-layer printed wiring board.

FIG. 2 is a plan view showing the four-layer printed wiring board in the embodiment shown in FIG. 1 before a chip type three-terminal noise filter is arranged.

FIG. 3 is a vertical sectional view taken along line XX ′ of FIG. 1;

FIG. 4 is a plan view of the chip-type three-terminal noise filter in the embodiment shown in FIG.

FIG. 5 is a vertical sectional view of a four-layer printed wiring board according to another embodiment of the present invention.

FIG. 6 is a plan view of a conventional chip-type three-terminal noise filter.

FIG. 7 is a structural plan view of a conventional example, showing a state in which a chip type three-terminal noise filter is arranged and arranged on a four-layer printed wiring board.

FIG. 8 is a plan view showing a state before a chip type three-terminal noise filter is arranged and arranged on a four-layer printed wiring board in a conventional example.

FIG. 9 is a vertical sectional view of XX ′ in FIG. 7 in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Four-layer printed wiring board 2 Ground conductor 3 Ground conductor 4 Through hole 5 Chip type three terminal noise filter 6 Ground electrode 7a, 7b Signal electrode 8a, 8b Signal pad 9a, 9b Signal conductor path 10 Inner layer ground conductor 11 Inner layer power conductor 12 IC 13a, 13b Lead electrode 14a, 14b Signal conductor path 31 Four-layer printed wiring board 32 Ground conductor 33 Ground conductor 34 Through hole 35 Chip-type three-terminal noise filter 36 Ground electrode 37a, 37b Signal electrode 38a, 38b Signal pad 39a, 39b Signal conductor path 40 Inner layer ground conductor 41 Inner layer power conductor

Claims (4)

[Claims] 1. A multilayer printed wiring board having an elongated ground conductor and a signal conductor path opposed to the ground conductor sandwiching the ground conductor formed on an upper surface thereof, so as to cancel an inductance generated by the ground conductor. A multilayer printed wiring board having a functioning element that functions and a through hole for electrically connecting the ground conductor and the functioning element. 2. The multilayer printed wiring board according to claim 1, wherein the functional element is an inner-layer ground conductor formed inside the multilayer printed wiring board. 3. The multilayer printed wiring board according to claim 1, wherein the functional element is a ground conductor formed on a back surface of the multilayer printed wiring board. 4. A chip-type three-terminal noise filter having a signal electrode formed at both ends and a ground electrode formed at the center on the multilayer printed wiring board according to claim 1. A chip-type three-terminal noise filter for electrically connecting each of the signal electrode and the signal conductor path, and the ground electrode and the ground conductor.