JPH06252581A - Attaching structure for feed through capacitor - Google Patents

Abstract

PURPOSE:To prevent electromagnetic noise radiated from a wiring pattern of a printed circuit substrate, etc., from penetrating to a signal line by realizing a structure wherein a circuit constitution on a substrate is shielded by a shield case and the printed circuit substrate. CONSTITUTION:A shield case 12 is jointed to a side surface 11a of a printed circuit substrate 11. The shield case 12 has a first shield case part 12a and a second shield case part 12b. The first and second shield case parts 12a, 12b are constituted to enclose built-in parts including the printed circuit substrate 11 excepting a part of a lower surface of the printed circuit substrate 11. A chip type feedthrough capacitor 14 is surface-mounted on an upper surface of the printed circuit substrate 11 to electrically connect first to third outside electrodes 14a to 14c to first to third electrodes 13a to 13c, respectively. A region excepting an area wherein an input/output electrode 17 is formed is enclosed with the shield case 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure for a chip type feedthrough capacitor, and more particularly, to prevent transfer of electromagnetic noise through a signal line in an electronic device in which a printed circuit board is arranged in a shield case. The present invention relates to a feedthrough capacitor mounting structure.

[0002]

2. Description of the Related Art As is well known, in a feedthrough capacitor, an inner conductor is inserted through the center hole of a cylindrical dielectric ceramic having an inner electrode formed on the inner surface of the center hole, and an inner electrode and a dielectric layer are formed on the outer peripheral surface. It has a structure in which ground electrodes facing each other are formed.

The feedthrough capacitor is excellent in noise removal characteristics in a high frequency region and is excellent in input / output separation with respect to an electromagnetic field. Therefore, a method of attaching the feedthrough capacitor to a shield case containing a printed circuit board or the like and electrically connecting the feedthrough capacitor to the outside via an inner conductor of the feedthrough capacitor is often used.

On the other hand, a three-terminal chip type feedthrough capacitor configured as a surface mount type component is known. 6 and 7 are a perspective view showing an example of a conventional chip type feedthrough capacitor and a schematic perspective view showing the shape of internal electrodes.

Referring to FIGS. 6 and 7, chip type feedthrough capacitor 1 is formed of a sintered body 2 made of a dielectric ceramic and having a rectangular planar shape. Inside the sintered body 2, the signal line electrodes 3 and 4 are arranged at different height positions, and the signal line electrodes 3 and 4 have end faces 2a.
To the end face 2b. In addition, the ground electrodes 5 and 6 are arranged on the side surface 2 of the sintered body 2 so as to partially overlap with the signal line electrodes 3 and 4 via the dielectric layer.
It is extended between c and 2d.

In the feedthrough capacitor 1, the signal line electrodes 3 and 4 are electrically connected to the first and second external electrodes 7a and 7b formed so as to cover the end faces 2a and 2b. The ground electrodes 5 and 6 are provided on the side surface 2 of the sintered body 2.
It is electrically connected to the third external electrode 7c formed on c and 2d.

The chip type feedthrough capacitor 1 includes the first to first
By electrically connecting the third external electrodes 7a to 7c to the electrode pads on the printed circuit board, they can be surface-mounted on the printed circuit board.

[0008]

When the conventional through capacitor having the inner conductor inserted through the through hole at the center of the cylindrical dielectric body and the ground electrode formed on the outer peripheral surface is used, the shield case is used as a shield case. Holes had to be formed for mounting feedthrough capacitors. In addition, a certain amount of space is required to connect the feedthrough capacitor to the printed circuit board in the shield case. Therefore, not only is the assembly process complicated, but it also hinders the miniaturization of electronic devices.

On the other hand, in the chip type feedthrough capacitor shown in FIGS. 6 and 7, if the feedthrough capacitor 1 is simply mounted on the printed circuit board, the hot side electrodes, that is, the signal line electrodes 3 and 4 are exposed to the electromagnetic field. On the other hand, since it is spatially exposed, electromagnetic waves radiated through the wiring pattern on the printed circuit board as an antenna may be received by the signal line electrodes 3 and 4, and electromagnetic noise may be conducted to the outside. It was That is, the input / output separation performance in the electromagnetic field is not sufficient, and particularly when used in a high frequency region, good noise removal characteristics cannot be obtained.

An object of the present invention is that the assembling process is not complicated, and even when it is used in a high frequency band, it can exhibit sufficient input / output isolation characteristics with respect to an electromagnetic field and can exhibit a high electromagnetic shield performance. Is to provide a mounting structure.

[0011]

According to the present invention, there are provided first to third electrodes formed on an upper surface for mounting a feedthrough capacitor, input / output electrodes formed on a lower surface, and the first electrode.
A printed circuit board having a through-hole electrode for electrically connecting one of the third electrodes, which is a signal line, to the input / output electrode; and a ground electrode formed inside the printed circuit board, A three-terminal chip type feedthrough capacitor which is surface-mounted on the upper surface of the printed circuit board and has first to third external electrodes connected to the first to third electrodes, respectively, and the printed circuit. A shield case which is arranged so as to surround the printed circuit board, leaving at least a region where the input / output electrodes of the substrate are formed, and which is joined to a side surface of the printed circuit board. This is a structure for mounting a feedthrough capacitor in which a ground electrode is electrically connected to the shield case.

[0012]

In the present invention, the input / output electrodes for external connection are formed on the lower surface of the printed circuit board in which the ground electrode is embedded, and the shield case has the input / output electrodes formed. The printed circuit board is arranged so as to surround at least the area where it is present, and the shield case and the ground electrode in the printed circuit board shield the circuit configuration on the printed circuit board. Moreover, the shield case is fixed by being joined to the printed circuit board.

Therefore, in order to connect the printed circuit board and the outside, a hole for inserting a feedthrough capacitor is opened in the shield case, and the earth electrode on the outer peripheral surface of the feedthrough capacitor is electrically connected to the shield case. It is possible to omit unnecessary work.

Moreover, a three-terminal chip type feedthrough capacitor is mounted on a printed circuit board, and electrodes used as input / output signal lines of the feedthrough capacitor are formed on the lower surface of the printed circuit board. Since it is electrically connected to the electrodes, the three-terminal chip type feedthrough capacitor effectively prevents the transfer of electromagnetic noise through the input / output signal line.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partially cutaway sectional view for explaining a mounting structure of a feedthrough capacitor according to an embodiment of the present invention. In this embodiment, the side surface 11 of the printed circuit board 11 is used.
The shield case 12 is joined to a. The shield case 12 has a first shield case portion 12a and a second shield case portion 12b. The first and second shield case portions 12a and 12b are the printed circuit board 1
1 is formed so as to surround the built-in components including the printed circuit board 11 except for a part of the lower surface thereof. The shield case portions 12a and 12b may be configured as an integral shield case 12, or the shield case 12 may be configured by joining separate shield case portions 12a and 12b.

In the present invention, the shield case 12 only needs to have at least the case portion 12a, and the case portion 12b can be omitted. In addition, the shield case 12
The attachment of b is not limited to joining to the side surface 11a of the substrate 11, but may be attached to the upper surface or the lower surface of the substrate 11.
The attachment to the lower surface may be performed by penetrating the opening end of the case into a through hole newly provided in the substrate 11.

The printed circuit board 11 is made of, for example, a ceramic multi-layer board, and has first to third electrodes 13a to 13a for mounting a chip type feedthrough capacitor 14 described later on the upper surface thereof.
13c is formed. First to third electrodes 13a to 1
The portion where 3c is formed is shown in a plan view in FIG. In FIG. 2A, the first and third electrodes 13a, 1
Below 3c, as shown by the broken line, the through-hole electrode 1
5a and 15b are formed.

A ground electrode 16 is embedded in the printed circuit board 11 at an intermediate height position. The plan view of the ground electrode 16 is shown in FIG. Ground electrode 16
Has a circular opening 16a so as not to be electrically connected to the above-mentioned through-hole electrode 15a. Further, as is apparent from FIG. 1, the side surface of the printed circuit board 11 is joined to the shield case 12, but the shield case portion 12 is electrically conductive to the side surface of the printed circuit board 11 by a conductive adhesive or solder. , The ground electrode 16 is electrically connected to the shield case portion 12a.

The above-mentioned through-hole electrode 15b is formed so as to reach the upper surface of the ground electrode 16. Also,
A through hole electrode 15c is formed so as to extend downward from the ground electrode 16.

Returning to FIG. 1, on the lower surface of the printed circuit board 11, the input / output electrode 17 and the ground electrode pad 18 are provided.
Are formed at a predetermined distance. Input / output electrode 17
Are electrically connected to the above-mentioned through-hole electrode 15a. On the other hand, the ground electrode pad 18 is electrically connected to the above-mentioned through-hole electrode 15c, and the second shield case portion 12b of the shield case 12 is provided.
Are electrically conductively bonded to the ground electrode pad 18 using solder or the like.

On the upper surface of the printed circuit board 11, the first to third electrodes 13a to 13c described above are respectively provided with the first electrodes.
~ The chip type feedthrough capacitor 14 is surface-mounted so that the third external electrodes 14a to 14c are electrically connected.

This chip type feedthrough capacitor 14 is constructed by using a sintered body 19 having a rectangular planar shape. The sintered body 19 is composed of a plurality of ceramic green sheets 21 to 27 shown in FIG. Are laminated, pressure-bonded in the thickness direction, and then integrally fired.

Referring to FIG. 3, signal line electrodes 24a are formed on the central ceramic green sheet 24 by printing a conductive paste. Further, the ground electrodes 23a and 25a are printed on the upper surfaces of the ceramic green sheets 23 and 25 so as to partially overlap the signal line electrodes 24a after being laminated. Further, on the upper surfaces of the ceramic green sheets 22 and 26,
Shield electrode 2 so as not to reach the outer peripheral edge except for a part
2a and 26a are printed. The shield electrode 2
2a and 26a are drawn out to a position where they overlap the exposed portions of the ground electrodes 23a and 25a on the side surfaces of the sintered body in the thickness direction after lamination.

The above-mentioned plurality of ceramic green sheets 2
Sintered body 19 obtained by laminating 1 to 27 and integrally firing
As shown in FIG. 4, the first to third external electrodes 14a to
The chip type feedthrough capacitor 14 is formed by forming 14c.

Returning to FIG. 1, since the first external electrode 14a of the chip type through capacitor 14 is electrically connected to the first electrode 13a, the first external electrode 14a is
It is electrically connected to the input / output electrode 17. Therefore, it is possible to electrically connect the signal line to the outside by using the input / output electrode 17. On the other hand, the second external electrode 14b is electrically connected to the second electrode 13b, and the second electrode 13b is electrically connected to another circuit pattern on the printed circuit board 11.

Further, the third external electrode 14c is electrically connected to the third electrode 13c, but the third electrode 13c
c is the above-mentioned ground electrode 16 and the through-hole electrode 15
It is electrically connected by b. Also, the ground electrode 1
6 is the first and second shield case portions 12a,
It is electrically connected to 12b. Therefore, in the feedthrough capacitor 14, the above-mentioned shield electrodes 22a,
26a (see FIG. 3) sandwiches the capacitor portion constituted by the signal line electrode 24a and the earth electrodes 23a and 25a, so that even if electromagnetic wave noise is radiated from other circuit portions, Electrode 2
Electromagnetic noise is securely prevented from entering the 4a.

When the structure shown in FIG. 1 is viewed as a whole, the shield case 12 covers the rest of the region except the region where the input / output electrodes 17 for electrical connection with the outside are formed. Since it is surrounded, a sufficient electromagnetic wave shield structure is provided.

Moreover, the chip type feedthrough capacitor 14 is used.
Can be easily surface-mounted on the printed circuit board 11 using, for example, an automatic machine. Furthermore, the printed circuit board 11 and the first shield case portion 12a can be easily joined. Therefore, as compared with the conventional shield structure using the feedthrough capacitor, it can be assembled by an extremely simple process.

In the above embodiment, as the chip type feedthrough capacitor, the one in which the shield electrodes 22a and 26a are arranged in the sintered body 19 is used, but as shown in FIG.
A chip type feedthrough capacitor 34 in which a third electrode 34c also serving as a shield electrode is formed on the outer peripheral surface of the sintered body 19 may be used. In the chip type feedthrough capacitor 34, the sintered body 39
Inside, only the signal line electrode 24a and the ground electrodes 23a and 25a shown in FIG. 3 are formed. That is, the shield electrodes 22a and 26a are not formed, but instead of these, the third external electrode 34c is formed so as to wind around the outer periphery of the sintered body 39 so as to also serve as the shield electrode.

Further, as shown in FIG.
The second external electrodes 44a and 44b are formed on the one main surface 49a of the sintered body 49, and the internal through-hole electrodes form the signal line electrodes electrically connected to the external electrodes 44a and 44b. You may use the feedthrough capacitor 44 embedded in. In this case, the signal line electrode is completely embedded inside the sintered body 49 and is formed so as not to reach the end surface and side surface of the sintered body 49.

A ground electrode is formed similarly to the case shown in FIG. 3, and the ground electrode is electrically connected to the shield electrode 45 formed on the outer peripheral side surface of the sintered body 49. . Similarly, the shield electrode 45 is electrically connected to the third external electrode 44c formed on the upper surface. Therefore, by reversing the upper surface and the lower surface of the chip type feedthrough capacitor 44 from the state shown in FIG. 5B, the chip type feedthrough capacitor 14 in the structure shown in FIG.
Can be used instead of, and the same effect can be obtained. In each of the above embodiments, the feedthrough capacitor itself has a shield structure, but it is also possible to use one without a shield structure.

[0032]

As described above, according to the present invention, since the circuit configuration on the board is shielded by the shield case and the printed circuit board, the electromagnetic wave radiated from the wiring pattern of the printed circuit board or the like. It is possible to reliably prevent noise from entering the signal line.

Moreover, in the conventional cylindrical feedthrough capacitor, complicated work such as making a hole in the shield case or electrically connecting the ground electrode to the shield case after inserting the shield case into the shield case is required. On the other hand, in the present invention, it suffices to mount the chip type feedthrough capacitor on the printed circuit board, and it is possible to assemble very easily.

Further, since the shield case is attached to the printed circuit board, the printed circuit board and the shield case can be easily assembled. Therefore,
According to the present invention, it is possible to provide a mounting structure for a feedthrough capacitor, which is easy to assemble, has an excellent effect of removing electromagnetic noise, and is compatible with downsizing of equipment.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view showing a mounting structure of a feedthrough capacitor according to an embodiment.

2A to 2C are plan views showing the electrode structure of the printed circuit board in FIG. 1, respectively.

FIG. 3 is a perspective view for explaining a ceramic green sheet used to manufacture the chip type through capacitor used in the examples and electrodes formed thereon.

FIG. 4 is a perspective view showing a chip type feedthrough capacitor used in an embodiment.

5A and 5B are perspective views showing modified examples of the chip type feedthrough capacitor used in the present invention.

FIG. 6 is a perspective view showing an example of a conventional chip type feedthrough capacitor.

7 is a schematic perspective view for explaining the shape of internal electrodes of the chip type through capacitor shown in FIG.

[Explanation of symbols]

 11 ... Printed circuit board 12 ... Shield case 13a-13c ... 1st-3rd electrode 14 ... Chip type feedthrough capacitor 14a-14c ... 1st-3rd external electrode 16 ... Ground electrode 17 ... Input / output electrode

Claims (1)

[Claims] 1. A first to third electrode formed on an upper surface for mounting a feedthrough capacitor, an input / output electrode formed on a lower surface, and a signal among the first to third electrodes. A printed circuit board having a through-hole electrode for electrically connecting one electrode to be a line and the input / output electrode, and a ground electrode formed inside, and surface mounting on the upper surface of the printed circuit board. And a three-terminal type chip type feedthrough capacitor having first to third external electrodes connected to each of the first to third electrodes, and an input / output electrode of the printed circuit board. A shield case that is arranged so as to surround the printed circuit board and that is bonded to the printed circuit board, leaving at least the area where the ground electrode of the printed circuit board is present. Mounting structure for feedthrough capacitors electrically connected to the source.