JPH09326586A - High frequency electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To connect the terminals of an IC to be grounded and electrode of a chip component to a metal base with lower impedance and then shield the electronic elements by connecting a metal conductor formed of a metal plate to a connection pattern formed like an island at the area near the earth terminal or earth electrode. SOLUTION: A metal plate 24 formed of a plate metal conductor is bonded almost to the entire surface of the lower surface of a printed circuit board 21. On the metal plate 24, a pawl piece 25 is formed near the earth terminal of an IC5 and earth electrode 11 of ship component 6 which are located at the comparatively isolated position from a metal case 3 and this pawl piece 25 is projected to the upper surface through a hole of the printed circuit board 21 and is then soldered to a relay pattern 23 at the upper surface. This metal plate 24 is soldered to the metal case 3 at a plurality of points. This connection pattern 23 connects the earth terminal and earth electrode 11 connected to the metal case 3 and is formed like an island by connecting the earth terminal and earth electrode 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency electronic device suitable for application to a tuner for a television, an RF modulator for a VTR and the like.

[0002]

2. Description of the Related Art In recent years, electronic devices of this kind have been frequently used for so-called surface mount type electronic parts for downsizing, and the structure thereof is a predetermined position on a wiring pattern formed on one surface of a printed circuit board. A printed board to which an electronic component such as an IC (integrated circuit) or a leadless type component (hereinafter referred to as a chip component) is soldered is housed in a metal case.

Such conventional high frequency electronic equipment is shown in FIGS. FIG. 5 is a plan view for explaining a mounting state of electronic components on a printed circuit board housed in a metal case, and FIG. 6 is an explanatory view taken along line AA in FIG. That is, as shown in FIGS. 5 and 6, a wiring pattern 2 for connecting electronic components to each other and a ground pattern 4 for connecting to a metal case 3 are formed on one surface (upper surface) of the printed board 1. The surface mount type IC 5 and the chip component 6 are soldered to predetermined positions of the wiring pattern 2 and the earth pattern 4 to form a high frequency electronic circuit.

The general assembly sequence is as follows. First, so-called cream solder is applied to a predetermined position of the wiring pattern 2 and the ground pattern 4 by a transfer method or a printing method, and then the IC 5 and chip parts are applied to the applied position by an automatic mounting device. 6 and the like are temporarily fixed and then heated in a reflow furnace to melt the cream solder and solder it to the printed circuit board 1 to fix the terminals 8 and 9 of the IC 5 and the electrodes 10 and 11 of the chip component 6. It is connected to the wiring pattern 2 or the ground pattern 4. Where IC
The terminals 8 of 5 and the electrodes 10 of the chip component 6 are connected to the wiring pattern 2 for connecting the components. Further, the terminal 9 of the IC 5 and the electrode 11 of the chip component 6 are ground terminals and ground electrodes which are connected to the metal case 3 and are grounded at a high frequency, and are connected to the ground pattern 4. Thereafter, the printed circuit board 1 is housed in a metal case 3 having upper and lower openings, positioned by a projection 12 formed on the metal case 3, and a ground pattern 4 formed on the peripheral edge of the printed circuit board 1 is provided with a wide soldering portion 13. It is fixed to the case 3 by soldering. In this way, the ground terminal 9 and the like of the IC 5 which should be grounded at high frequencies are connected to the ground pattern 4
Is connected to the metal case 3 via. After that, the upper and lower openings are covered with the covers 14 and 15 to complete the assembly of the high-frequency electronic device.

Even when such a surface mount type IC 5 or chip component 6 is used, a component such as the coil 16 which needs to avoid electromagnetic coupling with other components may be used. In such a case, the leaded component is used instead of the leadless chip component so that the electromagnetic coupling is reduced as much as possible by keeping the distance from other components. That is, in this conventional example, the coil 16 is I
Although it is connected to the terminal 8 of the C5 via the wiring pattern 2, it is necessary to avoid electromagnetic coupling with the IC 5 and the chip component 6, so that the component main body can be used for the IC 5 and the chip component 6 by using the leaded component. The height will be higher than that and the distance will be increased accordingly. Such a leaded component is an IC of a surface mount component produced by the above reflow furnace.
After the soldering of the chip 5 and the chip component 6, the surface mounting component was manually soldered to the same surface as the soldered surface.

[0006]

Since such a conventional electronic device is miniaturized, the wiring pattern 2 and the ground pattern 4 are extremely dense, and the IC 5 having a large number of terminals 8 and 9 is used. Since the terminal spacing is also narrow, the wiring pattern 2 and the ground pattern 4 have a narrow line width. Therefore, the ground terminal 9 of the IC 5 and the ground electrode 11 of the chip component 6 which are to be connected to the metal case 3 for grounding are inevitably connected to the metal case 3 through the ground pattern 4 having a narrow line width. There are problems that the ground terminal 9 of the IC 5 and the ground electrode 11 of the chip component 6 cannot be connected to the metal case 3 with sufficiently low impedance, so that predetermined circuit performance cannot be obtained or the stability of operation deteriorates.

Further, since the surface mount type electronic component is used for downsizing, the printed board 1 uses a so-called single-sided copper-clad board having a copper foil for wiring adhered to only one surface thereof. , The coil 16, which needs to eliminate electromagnetic coupling with other components, is mounted on the same surface as the other components, so even if a leaded component is used and the components are separated, Electromagnetic coupling cannot be ignored, and using a shield plate to completely eliminate electromagnetic coupling, providing a shield plate (not shown), etc. on the same surface as the surface on which electronic components are mounted hinders miniaturization. However, there is a problem in that the structure is difficult because the patterns are dense.

[0008]

In order to solve the above problems, a high-frequency electronic device according to the present invention has a metal case and a surface-mounted electronic component mounted on one surface thereof and is housed in the metal case. A printed circuit board and a metal conductor formed of a metal plate joined to the other surface of the printed circuit board and connected to the metal case, and the surface mount electronic component on one surface of the printed circuit board. An island-shaped relay pattern connected to the ground terminal or the ground electrode was provided, and the metal plate was connected to the island-shaped relay pattern near the ground terminal or the ground electrode.

In the high frequency electronic device of the present invention, a metal case, a surface-mounted electronic component on one surface of the printed circuit board, and a printed circuit board housed in the metal case are joined to the other surface of the printed circuit board. And a plate-shaped metal foil or metal plate connected to the metal case, and a leaded electronic component mounted on the other surface and connected to the surface-mounted electronic component, the plate-shaped The metal foil or the metal plate is made to extend so as to surround at least the mounting area of the electronic component with leads.

Further, according to the present invention, a metal case, a printed circuit board having a surface mount electronic component mounted on one surface thereof and housed in the metal case, and the other surface of the printed circuit board are joined and the metal A plate-shaped metal conductor connected to the case, and an electronic component with a lead mounted on the other surface and connected to the surface-mounted electronic component, the one surface of the surface-mounted electronic component An island-shaped relay pattern connected to the terminal is provided, the plate-shaped metal conductor is connected to the island-shaped relay pattern in the vicinity of the terminal, and extends so as to surround at least the mounting area of the leaded electronic component. Let

[0011]

1 to 3 show a first embodiment of a high-frequency electronic device according to the present invention. 1 is a plan view for explaining a mounting state of electronic components on a printed circuit board housed in a metal case, FIG. 2 is an explanatory view taken along line BB in FIG. 1, and FIG. 3 is an opposite surface of FIG. The perspective view seen from is shown. In these figures, a surface mounting type electronic component such as an IC 5 and a chip component 6 is mounted on one surface (upper surface) of a printed circuit board 21, and these terminals 8 and 9 and electrodes 10 and 11 are wiring patterns. It is soldered to 22, the ground pattern 4, and the relay pattern 23. The relay pattern 23 is a pattern for relaying the ground terminal 9 and the ground electrode 11 to be connected to the metal case 3 among these terminals 8 and 9, and the electrodes 10 and 11, and is connected to the ground terminal 9 and the ground electrode 11 in an island shape. Is formed in. Of the ground terminal 9 and the ground electrode 11, those relatively distant from the metal case 3 are soldered to the relay pattern 23, and those near the metal case 3 are soldered to the ground pattern 4.
Further, the terminals 8 and the electrodes 10 are soldered to the chip components 6 or to the wiring pattern 22 or the like connecting the chip components 6 and the IC 5.

The other surface (lower surface) of the printed circuit board 21
As shown in FIG. 3, a plate-shaped metal conductor, for example, a metal plate 24 such as an iron plate in this embodiment is joined to almost the entire surface. Then, the metal conductor made of the metal plate 24 may be simply superposed on the printed circuit board or may be adhered thereto.
The plate thickness is preferably 0.1 mm or more. Metal plate 2
4 is an IC 5 located relatively far from the metal case 3.
A claw piece 25 is formed in the vicinity of the ground terminal 9 and the ground electrode 11 of the chip part 6, and the claw piece 25 is inserted into the hole 26 of the printed board 21 and protrudes to the upper surface to be soldered to the relay pattern 23 on the upper surface. There is. The metal plate 24 is solder-connected to the metal case 3 at a plurality of positions on the periphery. Also in this embodiment, the printed circuit board 21 is positioned in the metal case 3 by the projections 12 formed on the metal case 3 together with the metal plate 24 as shown in FIG.

Further, the coil 27 is attached to the lower surface of the printed board 21, and the lead 28 of the coil 27 is inserted through the hole 29 of the printed board 21 to form the wiring pattern 22 on the upper surface.
It is soldered to the terminal 8 of the IC 5 via. A hollow portion 30 is formed on the metal plate 24 in a region where the coil 27 is attached to avoid mutual contact.
It suffices that the metal plate 24 extends at least around the region where the coil 27 is attached to the mounting region of another electronic component where electromagnetic coupling should be avoided, and the printed circuit board 2 is not always required.
1 does not have to extend over the entire lower surface. Further, the claw piece 25 of the metal plate 24 is preferably provided near the ground terminal 9 of the IC 5 or the ground electrode 11 of the chip component 6 to be connected to the metal case 3 and connected to the relay pattern 23. By thus providing the relay pattern 23, the ground terminal 9 and the like can be connected to the metal plate 24 at a distance shorter than the distance to the metal case 3.

With the above structure, the ground terminal 9 of the IC 5 to be connected to the metal case 3 and the like are the relay patterns 23.
Is connected to a wide metal plate 24 at the shortest distance, and the metal plate 24 is connected to the metal case 3 at a plurality of points, so that the current flowing through the metal plate 24 is dispersed and grounded to the metal case 3 with an extremely low impedance. Thus, the metal plate 24 has the same grounding effect as the metal case 3. Further, since the coil 27 is attached to the other surface of the printed board 21 and the metal plate 24 extends around it, even if magnetic lines of force are generated from the coil 27, the coil 27 is shielded by the metal plate 24 and one side of the printed board 21 is covered. It is not electromagnetically coupled to the parts provided on the surface of.

The metal plate 24 described in the first embodiment is used.
Was bonded to almost the entire lower surface of the printed board 21, but the invention is not limited to this. For example,
A wide strip-shaped metal plate extending from the region including the claw pieces 25 to the metal case 3 may be used.

The first embodiment has been described by using the metal plate 24 which is a separate body from the printed board 21 as the plate-shaped metal conductor, but the present invention is not limited to this. As a second embodiment, as shown in FIG. 4, for example, a so-called double-sided copper-clad substrate 31 can be used and the same effect can be obtained. In this case, a copper foil 32 on the lower surface side of the double-sided copper-clad substrate 31 is used as an alternative to the metal plate 24, and the copper foil 32 and the relay pattern 23 are connected by a pin-shaped conductor lead 33 inserted into a hole 26 of the printed circuit board. Etc. Further, instead of the conductor lead 33, the inner wall of the hole 26 may be conductively plated. If the double-sided copper-clad substrate 31 is used, the number of parts is reduced, so that the workability in assembling is superior to that using the metal plate 24.

[0017]

As described above, according to the present invention,
Since a metal plate is joined to the lower surface of the printed circuit board and this metal plate is connected in the vicinity to the ground terminal of the electronic component mounted on the upper surface of the printed circuit board, and the metal plate is soldered to the metal case, the grounding of the electronic component is performed. Terminals can be grounded to the metal case with low impedance, improving circuit performance and stability. Further, since the metal case is grounded via the metal plate on the lower surface, it is not necessary to provide a wide ground pattern on the upper surface, and the size can be reduced accordingly.

Also, an electronic component that avoids electromagnetic coupling is mounted on a surface different from the surface on which other electronic components are mounted, and a plate-shaped metal foil or metal plate bonded to the printed circuit board around the surface is extended. Therefore, it can be shielded by this metal foil or metal plate. In this case, as the plate-shaped metal foil, a copper foil on the lower surface side of the printed circuit board, which has copper foil adhered on both sides, may be used.

Furthermore, by connecting the plate-shaped metal conductor to the ground terminal of the electronic component and extending it around the mounting region of the electronic component that avoids electromagnetic coupling, good grounding and shielding can be achieved at the same time. In this case as well, as the metal conductor, either a metal plate separate from the printed board or a copper foil attached to the lower surface side of the printed board may be used.

[Brief description of drawings]

FIG. 1 is a plan view for explaining a first embodiment of a high-frequency electronic device of the present invention.

FIG. 2 is a sectional view taken along line BB in FIG.

FIG. 3 is a perspective view of the high-frequency electronic device according to the first embodiment of the present invention.

FIG. 4 is a sectional view for explaining a second embodiment of the high-frequency electronic device of the present invention.

FIG. 5 is a plan view for explaining a mounting state of electronic components on a printed circuit board housed in a metal case of a conventional high-frequency electronic device.

6 is a vertical cross-sectional view taken along the line AA in FIG.

[Explanation of symbols]

 1.21 Printed circuit board 2.22 Wiring pattern 3 Metal case 4 Ground pattern 5 IC 6 Chip parts 8 Terminal 9 Ground terminal 10 Electrode 11 Ground electrode 12 Protrusion 13 Soldering part 14 15. Cover 16 27. Coil 23 Relay pattern 24 Metal plate 25 Claw piece 26.29 Hole 28 Lead 30 Hollow-out part 31 Double-sided copper-clad substrate 32 Copper foil 33 Conductor lead

Claims (6)

[Claims] 1. A metal case, a printed circuit board having a surface-mounted electronic component mounted on one surface thereof and housed in the metal case, and bonded to the other surface of the printed circuit board and connected to the metal case. And an island-shaped relay pattern connected to the ground terminal or the ground electrode of the surface-mounted electronic component is provided on one surface of the printed circuit board. A high-frequency electronic device, wherein the formed metal conductor is connected to the island-shaped relay pattern near the ground terminal or the ground electrode. 2. A metal case, a printed circuit board having surface-mounted electronic components mounted on one surface thereof and housed in the metal case, and bonded to the other surface of the printed circuit board and connected to the metal case. A plate-shaped metal foil or a metal plate, and a leaded electronic component mounted on the other surface of the printed circuit board and connected to the surface-mounted electronic component, the plate-shaped metal foil or the metal plate Is extended so as to surround at least a mounting area of the electronic component with leads. 3. A metal case, a printed circuit board having a surface-mounted electronic component mounted on one surface thereof and housed in the metal case, and bonded to the other surface of the printed circuit board and connected to the metal case. Plate-shaped metal conductor and a leaded electronic component mounted on the other surface of the printed board and connected to the surface-mounted electronic component, and the surface-mounted one surface of the printed board. An island-shaped relay pattern connected to a ground terminal or an earth electrode of an electronic component is provided, and the plate-shaped metal conductor is connected to the island-shaped relay pattern near the ground terminal or the air electrode and at least the lead is provided. A high-frequency electronic device characterized in that it extends so as to surround a mounting area of electronic parts. 4. The high-frequency electronic device according to claim 3, wherein the plate-shaped metal conductor is a copper foil attached to the printed circuit board. 5. The high-frequency electronic device according to claim 3, wherein the plate-shaped metal conductor is a metal plate. 6. The high-frequency electronic device according to claim 5, wherein the metal plate is formed with a claw piece that inserts the printed circuit board, and the claw piece is connected to the relay pattern.