JP2000216582A - Shield unit and satellite broadcast receiving tuner employing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shield unit excellent in shield effect and heat dissipation effect for IC, or the like, and a tuner for receiving satellite broadcast employing it. SOLUTION: A shield unit comprises a shield frame section 2 for containing a printed board 1 mounting a heating part 4 while shielding electrically, and a shield cover section 3 being fitted to the shield frame section 2 through claw spring parts 3a, 3b. The shield cover section 3 is provided, on the inside of a position for arranging the heating part 4 on the printed board 1, with an inner frame part 2a to be fitted with the claw spring part 3b of the shield cover section 3. The shield cover section 3 is provided integrally with a heat dissipation plate 5 touching the heating part 4 while being coupled with the claw spring part 3a being fitted to the inner frame part 2a at the shield frame section 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield device for a printed circuit board used for a high-frequency component, a high-frequency device, and the like, and a satellite broadcast receiving tuner device using the same.

[0002]

2. Description of the Related Art A conventional shield device will be described with reference to FIG. 4A is a top view, FIG.
(B) is a cross-sectional view taken along a cutting line BB 'in (a). The conventional shield device shown in FIG. 4 includes a printed circuit board 11 on which an IC 14 as a heat-generating component is mounted, and includes a shield frame 12 and a shield cover 13 for electrically shielding the printed circuit board 11. The claw spring 13a provided on the shield lid 13 allows the shield frame 1
2 is fitted. Further, since the IC 14 needs heat radiation, the heat radiation plate 15 is adhered to the heat radiation surface on the upper surface thereof with an adhesive 16 made of a silicon rubber material or the like.

[0005] In addition, there is another conventional shield device as shown in FIG. In FIG. 5, (a) is a top view, and (b) is a cutting line CC ′ of (a).
FIG. The conventional shield device shown in FIG. 5 includes a printed circuit board 11 on which an IC 14 which is a heat-generating component is mounted, and includes a shield frame 12 and a shield cover 13 for electrically shielding the printed circuit board 11. It is configured to be fitted to the shield frame portion 12 by a claw spring portion 13a provided on the shield lid portion 13. And
In the structure shown in FIG. 5, a part of the shield lid 13 is cut and bent downward to form a heat radiating plate 15 '. It is adhered by an adhesive 16 made of a silicon rubber material or the like.

[0004]

However, the above-mentioned prior art has the following problems. In the conventional shield device as shown in FIG. 4, since the heat sink 15 is a separate component from the shield frame 12 and the shield lid 13,
When the heat radiating plate 15 is fixed to the upper surface of the IC 14, not only the alignment is necessary, but if the position is shifted, the contact with the IC 14 becomes insufficient and the heat radiating effect is reduced.

In the conventional shield device as shown in FIG. 5, a part of the shield lid 13 is bent downward to provide a radiator plate 15 ', and the shield lid 13 and the radiator plate 1 are provided.
Since the heat radiating plate 5 'is formed integrally with the heat radiating plate 5', the positioning of the heat radiating plate 15 'is unnecessary. However, since a part of the shield lid 13 is bent downward to form the heat radiating plate 15 ', and a part of the shield lid 13 is extracted, the shielding effect of the shield device itself is reduced. Was.

Further, since the IC 14, which is a heat-generating component having the heat radiating plate 15 'adhered to the upper surface, is disposed in a space which is substantially more sealed with the shield frame 12 and the shield lid 13, the heat radiating plate is provided. The radiant heat from 15 'is trapped inside the space. As a result, the temperature inside the shield device increases with respect to the ambient temperature, and the heat radiation effect of the IC 14 decreases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is a shield device having an excellent shield effect and a heat-dissipating effect for heat-generating components such as ICs, and a satellite broadcast receiving tuner using the same. It is intended to provide a device.

[0008]

According to the first aspect of the present invention, there is provided a shield for accommodating a printed board on which a heat-generating component is mounted and for electrically shielding the printed board. In a shield device composed of a frame portion and a shield lid portion, which is fitted to the shield frame portion by a claw spring portion provided on the shield lid portion, the arrangement of heat-generating components on a printed circuit board in the shield frame portion An inner frame portion that fits with the claw spring portion of the shield lid portion is provided inside from the position, and a claw spring portion that fits the heat dissipating plate that contacts the heat generating component with the inner frame portion of the shield frame portion is provided on the shield lid portion. And are integrally provided.

According to the first aspect of the present invention, the shield frame portion is provided with an inner frame portion which fits with the claw spring portion of the shield lid portion inside the position where the heat-generating components are arranged on the printed circuit board. The shield lid has a structure in which a radiator plate that contacts the heat-generating component is provided integrally with the claw spring portion that fits with the inner frame of the shield frame. It is easy to match, the heat radiating plate and the shield lid are formed as a single part, and the manufacturing is easy and the cost can be reduced. Further, since the heat-generating component and the heat radiating plate are not hermetically enclosed by the shield frame and the shield lid, radiant heat from the heat radiating plate is less likely to be trapped inside the shield device, and the heat radiating effect of the heat-generating component is improved.

Further, according to the second aspect of the present invention, in the shield device according to the first aspect, the radiator plate contact portion which contacts the upper surface of the radiator plate and aligns the radiator plate in the height direction is a shield. It is configured to be provided on the frame.

According to the second aspect of the present invention, the heat radiating plate abutment portion which is in contact with the upper surface of the heat radiating plate to position the heat radiating plate in the height direction is provided on the shield frame portion. , Without being affected by the elasticity of the claw spring of the shield lid,
The heat radiating plate can be disposed so as to be in close contact with the heat radiating surface on the upper surface of the heat generating component, and the heat radiating effect of the heat generating component can be further improved.

Further, in the invention according to claim 3, in the shield device according to claim 1 or 2, silicon rubber is interposed between the heat radiating plate and the heat generating component. According to the third aspect of the present invention, since the silicone rubber having excellent thermal conductivity and elasticity is interposed between the heat radiating plate and the heat generating component, the adhesion between the heat radiating plate and the heat generating component is improved. And the heat radiation effect of the heat generating component can be further improved.

According to a fourth aspect of the present invention, there is provided a tuner device for receiving satellite broadcasting using the shield device according to the first, second, or third aspect, wherein the printed circuit board includes a plurality of received signals. A front-end circuit block for selecting from the channels and converting to a baseband signal, an A / D converter for analog-to-digital conversion of an output from the front-end circuit block, a circuit for digital demodulation, and an FEC for error correction A heat-generating component mounted on the printed circuit board is a digital modulation IC in the transport circuit block, and a shield is provided between the front-end circuit block and the transport circuit block on the printed circuit board. The inner frame of the frame is placed and the front end circuit block is sealed Covered with the lid portion, a digital modulation I
The configuration is such that the heat radiating plate contacts the heat radiating surface of C.

According to the fourth aspect of the present invention, by using the shield device of the first, second, or third aspect of the present invention,
Since the satellite broadcast receiving tuner device is configured as described above, the shielding effect is obtained by surrounding only the front-end circuit block with the shield lid, and the digital modulation IC in the transport circuit block is shielded. Since it is not surrounded by the lid, it is possible to suppress the radiant heat from the heat radiating plate from being trapped inside the tuner device, and to obtain an excellent heat radiating effect.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. First, a schematic structure of the shield device of the first embodiment is shown in FIG. 1A is a top view of a main part, FIG. 1B is a cross-sectional view of a main part showing a state before the shield lid is attached to a shield frame at a cutting line AA ′ in FIG. (C) is an essential part sectional view showing a state after attaching a shield lid to a shield frame at a cutting line AA 'of (a). However. FIG.
In the cross-sectional views of (b) and (c), the claw spring portion that can be observed in a side view that is not a cross section is also drawn so that the shape of the claw spring portion of the shield lid can be seen.

As shown in FIG. 1, the shield device of the present embodiment comprises a shield frame 2 for housing a printed circuit board 1 therein and electrically shielding the printed circuit board 1 and a shield lid 3. As shown in FIG. 1B, the shield lid 3 is fitted to the shield frame 2 in the direction of arrow X, and
The structure as shown in (c) is obtained. The shield lid 3 is provided with claw springs 3a and 3b for fitting to the shield frame 2. Further, a heat radiating plate 5 that contacts the heat radiating surface on the upper surface of the IC 4 which is a heat generating component mounted on the printed circuit board 1 housed therein is connected to and provided integrally with a part of the claw spring portions 13a. Have been. On the other hand, in the shield frame 2, an inner frame 2 a that fits into the claw spring 13 a of the shield lid 3 is provided inside the printed circuit board 1 from the position where the IC 4 is arranged.

Further, a silicone rubber is provided between the heat radiating surface on the upper surface of the IC 4 and the heat radiating plate 5 integrally connected to the claw spring portion 13a of the shield lid portion 3 in order to make them adhere to each other. Is applied and interposed.
Since silicon rubber is excellent in heat conductivity and has elasticity, the adhesion between the heat radiating plate 5 and the IC 4 serving as a heat-generating component can be enhanced, and the heat radiating effect of the IC 4 can be further improved.

In this embodiment, as shown in FIG.
A printed circuit board 1 selects a plurality of channels of a received signal from a plurality of channels and converts the signal into a baseband signal, and an A / D converter that performs an analog / digital conversion of an output from the front end circuit block 1a. , A circuit for performing digital demodulation, and a transport circuit block 1b including an FEC circuit for performing error correction.

That is, in this embodiment, the printed circuit board 1
Is a digital modulation IC in the transport circuit block 1b, and an inner frame of the shield frame portion 2 between the front end circuit block 1a and the transport circuit block 1b of the printed circuit board 1. The front end circuit block 1a is covered with a shield cover 2a, and a heat radiating plate 5
Are configured to be in contact with each other.

Therefore, in this embodiment, the shielding effect can be obtained by surrounding only the front end circuit block 1a with the shield lid 3, and the digital modulation IC 4 in the transport circuit block 1b is attached to the shield lid 3. Since it is not surrounded, radiant heat from the heat radiating plate 5 is suppressed from being trapped inside the tuner device, and an excellent heat radiating effect can be obtained.

Here, a tuner device for receiving satellite broadcasting will be described. The front end circuit converts the frequency of an RF signal (for example, 950 MHz to 215 MHz) with a first local signal (for example, 1429.5 MHz to 2629.5 MHz), and converts the RF signal to an IF signal (for example, 479.5 MH).
z), and then perform frequency conversion to output a baseband signal. Therefore, in the front-end circuit, the signal frequency in the circuit is high, and the above-described signal leakage or unnecessary radiation causes interference waves to other devices and circuits. Therefore, in the case of the tuner device as in the present embodiment, it is necessary to sufficiently shield the front end circuit block 1a.

On the other hand, the transport circuit performs A / D conversion and digital demodulation of the baseband signal output from the front end circuit, and then performs error correction. Here, the digital demodulation IC used for digital demodulation has a signal of about several tens of MHz, but performs high-speed data processing, so that the power consumption of the IC is high and the amount of heat generated is large. Therefore, in the case of the tuner device as in the present embodiment, in the transport circuit block 1b, it is more effective to enhance the heat radiation effect of the digital demodulation IC than to provide a shield.

The heat radiation of the semiconductor heat-generating components will be further described. Generally, an IC or the like which consumes a large amount of power generates a large amount of heat and the temperature of the components themselves rises. When the temperature of the component itself rises, the junction temperature of the PN junction surface rises.
If the temperature exceeds ℃, problems such as an increase in leakage current will occur,
There is a possibility that problems such as destruction and malfunction of semiconductor parts such as ICs may be caused. Therefore, in general, a heat radiating plate made of a metal having good thermal conductivity is brought into contact with a heat-generating component such as an IC to suppress a rise in temperature of the heat-generating component itself.

Therefore, in this embodiment, the front-end circuit block 1a is arranged in a space region surrounded by the shield frame 2 and the shield lid 3 as described above, and is surrounded by the shield lid 3. By disposing the transport circuit block 1b in a space area where there is no space, a good shielding effect of the front end circuit block 1a can be obtained, and the radiation heat from the radiator plate 5 is suppressed from being trapped inside the tuner device. Is obtained.

Next, a second embodiment will be described with reference to a sectional view of a main part of FIG. Note that, in the cross-sectional view of FIG. 3, the shape of the claw spring portion of the shield lid can be understood.
The claw spring portion that can be observed in a side view that is not a cross section is also depicted.

The second embodiment is different from the first embodiment in that it comes into contact with the upper surface of a heat radiating plate 5 provided integrally with the claw spring 3a of the shield lid 3, and
Heat sink abutment 2 for positioning the heat sink 5 in the height direction
b is provided on the shield frame 2, and the other points are the same as those in the first embodiment.

That is, in the second embodiment, the first
In addition to the embodiment, as shown in FIG. 3, a heat radiating plate contact portion 2 b is provided so as to be connected to a part of the outer frame portion 2 c of the shield frame portion 2, and is provided on the upper surface of the heat radiating plate 5. The height position of the heat radiating plate 5 is configured to be kept constant by contact.

According to the present embodiment, the heat radiating plate 5 can be arranged so as to be in close contact with the heat radiating surface of the IC 4 which is a heat generating component, without being affected by the elasticity of the claw spring portion 3a of the shield lid 2.
The heat radiation effect of the IC 4 can be further improved.

[0029]

As described above, according to the first aspect of the present invention, the claw spring portion of the shield lid is fitted into the shield frame inside the position of the heat-generating component on the printed circuit board. An inner frame is provided, and a heat radiating plate in contact with the heat-generating component is provided on the shield lid and connected integrally with a claw spring that fits into the inner frame of the shield frame. The positioning between the plate and the heat-generating component is easy, and the heat-radiating plate and the shield lid are formed as a single component, so that the production is easy and the cost can be reduced. Furthermore, since the heat-generating component and the heat sink are not hermetically sealed by the shield frame and the shield lid, radiant heat from the heat sink is less likely to be trapped inside the shield device,
The heat radiation effect of the heat-generating component is improved.

Further, according to the second aspect of the present invention,
The radiator plate abuts on the upper surface of the radiator plate and aligns in the height direction of the radiator plate.This structure is provided on the shield frame, so it is not affected by the elasticity of the claw spring of the shield lid. Further, the heat radiating plate can be disposed so as to be in close contact with the heat radiating surface on the upper surface of the heat generating component, and the heat radiating effect of the heat generating component can be further improved.

Further, according to the third aspect of the present invention,
Silicon rubber with excellent thermal conductivity and elasticity is interposed between the heat radiating plate and the heat generating component, so that the adhesion between the heat radiating plate and the heat generating component is enhanced, and the heat radiating effect of the heat generating component is further improved. be able to.

Further, according to the invention described in claim 4,
Since the satellite broadcast receiving tuner device is configured using the shield device according to the first, second, or third aspect of the present invention,
By enclosing only the front-end circuit block with the shield lid, the shielding effect is obtained, and since the digital modulation IC in the transport circuit block is not surrounded by the shield lid, the radiant heat from the heat sink is reduced inside the tuner device. An excellent heat dissipation effect can be obtained by suppressing dents.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic structure of a shield device or a satellite broadcast receiving tuner device according to a first embodiment of the present invention;
(A) is a top view of a main part, and (b) and (c) are cross-sectional views of the main part along a cutting line AA 'in (a).

FIG. 2 is a principal block diagram conceptually showing an arrangement block of the printed circuit board 1 shown in FIG.

FIG. 3 is a sectional view of a main part showing a schematic structure of a shield device or a tuner device for receiving satellite broadcasting according to a second embodiment.

4A and 4B are diagrams showing a schematic structure of a conventional shield device, wherein FIG. 4A is a top view of a main part, and FIG.
It is principal part sectional drawing in B '.

5A and 5B are diagrams showing a schematic structure of a conventional shield device, in which FIG. 5A is a top view of a main part, and FIG. 5B is a cut line C- in FIG.
It is principal part sectional drawing in C '.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed circuit board 1a Front end circuit block 1b Transport circuit block 2 Shield frame part 2a Inner frame part 3 Shield lid part 3a, 3b Claw spring part 4 IC (heat generating component) 5 Heat radiating plate 6 Adhesive

Claims (4)

[Claims] 1. A printed circuit board on which a heat-generating component is mounted is housed inside, and a shield frame part and a shield lid part for electrically shielding the printed circuit board are provided, and a claw spring part provided on the shield lid part is provided. In the shield device configured to be fitted to the shield frame portion, the shield frame portion is fitted inside the position where the heat-generating component is arranged on the printed circuit board with the claw spring portion of the shield lid portion. A frame portion is provided, and a heat sink in contact with the heat-generating component is provided integrally with the claw spring portion fitted to the inner frame portion of the shield frame portion on the shield lid portion. Shield device. 2. The shield frame portion according to claim 1, wherein a heat radiating plate abutting portion that is in contact with the upper surface of the heat radiating plate to position the heat radiating plate in a height direction is provided on the shield frame portion. Shield device. 3. A silicon rubber is interposed between said heat radiating plate and said heat generating component.
The shield device according to claim 1. 4. A tuner device for satellite broadcast reception using the shield device according to claim 1, 2 or 3, wherein the printed circuit board selects from a plurality of channels of a received signal and performs baseband operation. A front-end circuit block for converting the signal to a signal, an A / D converter for converting the output from the front-end circuit block from analog to digital, a circuit for performing digital demodulation, and a transport circuit block including an FEC circuit for performing error correction; Wherein the heat-generating component mounted on the printed circuit board is a digital modulation IC in the transport circuit block, and the inside of the shield frame portion is provided between the front-end circuit block and the transport circuit block of the printed circuit board. A frame portion is arranged, and the front end circuit block is the shield lid portion. A tuner device for receiving satellite broadcasting, wherein the tuner device is configured to be covered with the heat sink and to contact the heat sink of the digital modulation IC.