JPH0639508Y2 - Printed circuit board shield structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline of the Invention] The present invention includes an elastic conductive member sandwiched between a rib of a chassis and a printed circuit board, and the conductive member is provided on the printed circuit board. A shield structure for a printed circuit board having a plurality of protrusions fixed to the printed circuit board through holes, which enables shielding of each circuit portion of the printed circuit board and facilitates assembly / disassembly inspection.

[Industrial application field]

The present invention relates to a printed circuit board. In particular, the present invention refers to the shield structure of the printed circuit boards between the circuits as the density of electronic components on the printed circuit boards increases.

[Conventional technology]

As electronic equipment becomes smaller and higher in performance, high-density mounting is progressing. For example, in a mobile device of a wireless communication device, a transmitter and a receiver are housed in a common chassis. FIG. 7 is a diagram for explaining circuit block formation of a mobile device in the chassis. The configuration of this figure will be described below. In addition, the same reference number or symbol is used to represent the same component throughout the drawings. The printed circuit board 3 of this figure is divided into four circuit blocks as an example, and the receiving circuit section 11 of the mobile device is provided on the upper surface thereof.
Electronic components that constitute the transmission circuit unit 12, the signal processing circuit unit 13, and the power supply circuit unit 14 are mounted. The reason why the electronic parts are divided in this way is that the respective circuit parts are shielded so as not to interfere with each other by electromagnetic waves. Before explaining the shield method, a supplementary explanation of FIG. 7 will be given. FIG. 8 is a diagram for supplementarily explaining the circuit block of the mobile device in FIG. In the figure, the reception circuit section 11 and the transmission circuit section need to be shielded from each other because normal calls cannot be made if their frequencies interfere with each other. The control unit 16 included in the signal processing unit 13 controls setting of a wireless channel with a wireless base station (not shown) and control of the handset 10. Further, the local transmission circuit 17 is a circuit having a multi-channel switching function, and the transmission / reception duplexer is a shared machine for performing simultaneous transmission / reception with one antenna 15. Since the signal processing unit 13 composed of these components is composed of a microcomputer, it is susceptible to electromagnetic interference from the receiving circuit unit 11 and the transmitting circuit unit 12, and therefore it is necessary to shield from them. Power circuit section
If 14 is provided in the vicinity of the other circuit section, it is likely to cause electromagnetic interference to the other circuit section, so it is necessary to shield it from now on.

FIG. 9 is a diagram for explaining the shield structure of each circuit section of the mobile device of FIG. In the figure, the mobile device includes a chassis 1 and a printed circuit board 3 built in the chassis 1.
The chassis 1 is electrically conductive, has an integrally molded rib 2 inside, and is manufactured by die casting of aluminum, for example. The rib 2 has a printed circuit board 3 described below on its upper surface.
Are molded so that the ground patterns 6 on the peripheral portions of the respective circuit portions (11, 12, 13, 14) are brought into close contact with each other. Printed circuit board 3
Is an electronic component of each circuit portion (11, 12, 13, 14) mounted on the upper surface thereof, and a printed wiring for connecting the electronic components to each other is provided on the lower surface of each circuit portion (11, 12, 13, 14). A ground pattern 6 is provided on the peripheral edge of 14). When the printed circuit board 3 is placed on the upper surface of the rib 2 of the chassis 1, the screw 4 is inserted into the screw holes 7 of the printed circuit board 3 and the rib 2 and fixed. As a result, the ground pattern 6 of the printed board 3 and the upper surface of the rib 2 of the chassis 1 are brought into close contact with each other.

Next, the shield of the printed circuit board will be described. The printed wiring or the like connecting the electronic components of the respective circuit parts (11, 12, 13, 14) on the lower surface of the printed board 1 serves as an antenna, generates an electromagnetic wave, and the electromagnetic wave travels linearly to an adjacent part. The rib 2 that is in close contact with the earth pattern 6 prevents the propagation of the radio wave. On the other hand, electromagnetic waves directly generated from the electronic components on the upper surface of the printed circuit board 3 are smaller than those in the above-mentioned case, and electromagnetic waves that go upward from the lower surface of the printed circuit board reach other circuit parts by absorption and reflection of the structural material. Less is. However, when such an influence of electromagnetic waves is strong, a shield case (not shown) may be attached to each circuit portion on the upper surface of the printed circuit board 3 to remove the influence. Thus, electromagnetic waves from each of the divided circuit parts are appropriately shielded to achieve high-density mounting of electronic parts, and miniaturization and high performance of electronic devices are achieved.

[Problems to be solved by the device]

However, the following problems occur due to the dimensional accuracy of the ribs 2, the manufacturing precision, and the flexibility of the material of the printed circuit board 3. First
FIG. 10 is a diagram illustrating a state where the printed circuit board is attached to the rib. In the figure, the distance between the holes 7 for fixing the screws 4 of the rib 2 is displaced in a direction smaller than that of the printed circuit board 3. In this case, when the printed circuit board 3 is fastened to the ribs 2 with the screws 4, the flexibility of the material of the printed circuit board 3 causes the central portion to be lifted and warpage occurs. Therefore, the adhesion between the surface of the ground pattern 6 of the printed circuit board 3 and the surface of the rib 2 is lost. If this adhesion is lost, electromagnetic waves will leak from the gap between the ground pattern 6 and the rib 2, and the shield of each circuit part (11, 12, 13, 14) cannot be maintained. For example, the main cause of the central portion of the printed circuit board 3 being lifted is due to the dimensional accuracy of the manufacturing, but conversely to the above, if the distance between the screw holes 7 of the rib 2 is larger than that of the printed circuit board 3, the mounting becomes impossible and the yield is increased. It becomes worse and you have to re-drill. Therefore, in order to eliminate this yield, etc., and to eliminate the lifting at the center, it is necessary to improve the accuracy of the die-cast ribs and the holes in the printed circuit board, which leads to high manufacturing costs. I have a problem.

Therefore, in consideration of the above problems, the present invention has good adhesion,
It is another object of the present invention to provide a shield structure with low cost.

[Means for Solving the Problems]

FIG. 1 is a partial sectional view showing the principle configuration of the present invention. The present invention has a conductive member 5. The conductive member 5 is sandwiched between the rib 2 formed integrally with the chassis 1 and the printed circuit board 3 and has conductivity and elasticity. Further, the conductive member has a plurality of protrusions 9 fixed to the printed circuit board 3 through holes 8 formed in the printed circuit board 3.

[Action]

In FIG. 1, since the conductive member 5 between the rib 2 and the printed circuit board 3 has conductivity, it shields the circuits mounted on the printed circuit board 3 together with the rib 2 from each other. Even if the printed circuit board 3 is lifted up due to the screwing at the central portion between the rib 2 and the printed circuit board 3, the conductive member 5 that is sandwiched and compressed between the ribs 2 and the printed circuit board 3 has elasticity and expands so that the rib 2 and the printed circuit board 3 are printed. The gap that should be formed between the circuit board and the circuit board is filled to prevent incomplete shielding between the circuits. Further, since the conductive member 5 is fixed to the printed circuit board 3 by the protrusion 9 formed on the conductive member 5, the assembly / disassembly inspection is facilitated.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a view for explaining the shield structure which is the first embodiment of the present invention. In this figure, a component different from that shown in FIG. 9 is a conductive member 5. The conductive member 5 is a commercially available conductive and elastic member, and is a conductive rubber that can be easily molded. The conductive member 5 has a circular cross section, is processed according to the shape of the rib 2 or the ground pattern 6, and is provided with a plurality of protrusions 9. Furthermore, the component different from that of FIG. 9 is the conductive member 5.
A plurality of holes 8 provided in the ground pattern 6 of the printed circuit board 3 in order to fix the
Further, a rib groove 10 is provided on the upper surface of the rib 2 of the chassis 1 for closely contacting the conductive member 5. FIG. 4A is a partial sectional view showing fixing of the conductive member of FIG. 2 to a printed circuit board. In this figure, the projecting portion 9 has a pillar portion 9-1 formed on the conductive member 5, and has a stepped portion at the tip thereof and a tapered tip portion 9-2. The hole 8 of the printed circuit board 3 has the pillar portion 9-1.
Has the same shape as. When the tip portion 9-2 abuts against the hole 8 and is pushed in, the tip portion 9-2 contracts due to its elasticity, passes through the hole 8, and returns to its original shape after passing. Since the dimension of the stepped portion of the tip portion 9-2 is larger than that of the hole 8, the projecting portion 9 cannot be removed unless it is inserted into the printed circuit board 3 and a force of the same degree as when pushing is applied. In this way, the conductive member 5 is fixed to the printed board 3. FIG. 4B is a partial sectional view showing the close contact with the conductive member rib of FIG. In the figure, a rib groove 10 matching the shape of the conductive member 5 is provided on the upper surface of the rib 2. The conductive member 5 is brought into contact with the rib groove 10 and when tightened with the screw 4, a compressive force is applied by the printed circuit board 3 and the rib 2, and the conductive member 5 is brought into close contact with the ground pattern 6 and the rib 2 of the printed circuit board 3.

Next, the shield function of the conductive member will be described. FIG. 6 is a diagram showing a shield of a conductive member. In the figure, when a gap is formed in the central portion between the screws 4 and the conductive member 5, the conductive member 5 is deformed according to the shape and fills the gap. Further, the elastic property of the conductive member 5 prevents the screw from loosening, and it is possible to prevent the adhesiveness from being broken due to the loosening of the screw in the past. In this way, the rib 2 and the ground pattern 6 of the printed circuit board 3 are brought into close contact with each other via the elastic conductive member 5. Since this conductive member 5 has conductivity, each circuit portion (11, 1
2, 13 and 14) to shield electromagnetic waves that try to pass through the gap. Therefore, since the problem of the shield can be solved in this way, in the die-cast manufacturing of the rib 2, it is sufficient to manufacture the ribs 7 so that the distance between the holes 7 is slightly smaller than that of the printed board 3, and high precision is required. That will disappear. Furthermore, the protruding portion 9 of the conductive member 5 facilitates attachment of the conductive member 5 and speeds up assembly. Further, the wireless communication device may be required to remove the printed circuit board 3 on which the electronic component is mounted from the chassis 1 due to a periodic inspection, a failure, or the like. In this case, since the conductive member 5 is fixed to the printed circuit board 3, when the printed circuit board 3 is inspected and then returned to the chassis after repair, the conductive member 5 removed in the conventional manner along the groove of the rib 2. It is possible to omit the step of fitting and returning. Further, the management step of preventing the removed conductive member 5 from being lost can be omitted. This makes it easier to disassemble and inspect a large number of wireless communication devices, resulting in a significant reduction in man-hours.

FIG. 3 is a diagram showing a shield structure according to a second embodiment of the present invention. In this figure, a component different from that shown in FIG. 2 is a conductive member 5 '. The conductive member 5'is the same as the conductive member 5 of FIG. 2 except that it is a sheet. Further, since the conductive member 5 has a sheet shape, the upper surface of the rib 2 is brought into close contact with the conductive member 5 and is therefore flat. FIG. 5A is a partial sectional view showing fixing of the conductive member of FIG. 3 to a printed circuit board,
And FIG. 5B is a partial cross-sectional view showing the adhesion of the rib to the conductive member of FIG. Conductive member 5'in FIG. 5A
The fixing to the printed circuit board 3 is exactly the same as in the case of FIG. 4A. In FIG. 5B, the conductive member 5'is in the form of a sheet, but the conductive member 5'is in close contact with the rib 2 with the same effect as in FIG. 4B. Compared with FIG. 2, it is advantageous in that the groove of the rib 2 can be omitted. Since the effect of the shield according to the present embodiment and the effect of assembling in terms of manufacturing overlap with those of the first embodiment, the description thereof will be omitted.

[Effect of device]

As described in detail above, according to the present invention, an elastic conductive member sandwiched between the rib and the printed circuit board is provided, and the conductive member is further provided with a hole provided in the printed circuit board. Since the plurality of protrusions fixed to the printed circuit board are provided, the circuit portions sectioned on the printed circuit board are mutually shielded and the assembly / disassembly inspection of the wireless communication device is facilitated.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing the principle structure of the present invention, FIG. 2 is a view showing a shield structure which is a first embodiment of the present invention, and FIG. 3 is a shield which is a second embodiment of the present invention. FIG. 4A is a partial cross-sectional view showing the fixing of the conductive member of FIG. 2 to the printed circuit board, and FIG. 4B is a partial cross-sectional view showing the adhesion of the conductive member of FIG. 2 to the ribs. 5A is a partial cross-sectional view showing the fixing of the conductive member of FIG. 3 to the printed circuit board, FIG. 5B is a partial cross-sectional view showing the adhesion of the conductive member of FIG. 3 to the rib, and FIG. FIG. 7 is a diagram showing a shield of a flexible member, FIG. 7 is a diagram for explaining circuit block formation of a mobile device in a chassis, FIG. 8 is a diagram for additionally explaining the circuit block formation of FIG. 7, and FIG. 9 is FIG. FIG. 10 is a diagram showing a shield structure of each circuit portion of the mobile device, and FIG. 10 is a diagram showing a state in which a printed circuit board is attached to a rib. In the figure, 1 ... Chassis, 2 ... Rib, 3 ... Printed circuit board, 5 ... Conductive member, 8 ... Printed circuit board hole for fixing the conductive member, 9 ... Projection part.

Claims (1)

[Scope of utility model registration request] 1. A shield structure for a printed circuit board, wherein a printed circuit board (3) is closely adhered to the upper surface of a rib (2) formed integrally with a chassis (1) to shield the rib (2) and the printed circuit board (1). 3) is provided with a conductive member (5) sandwiched between them and having elasticity, and further, the conductive member (5) is provided with the print through a hole (8) provided in the printed board (3). A shield structure for a printed circuit board, comprising a plurality of protrusions (9) fixed to the substrate (3).