JPH0870195A - Shielding of printed circuit board - Google Patents

Abstract

PURPOSE: To make it possible to mount simply a cover member on a miniaturized printed circuit board and moreover, to bring the cover member into contact with the circuit board stably and firmly as well as to increase the contact area of the cover member to the circuit board to make it possible to obtain a good shielding effect for the printed board. CONSTITUTION: When a shielding cover 22 is incorporated in a housing 44, a force, which is inclined to separate the cover 22 from a printed circuit board 18 by the resilient force of pawl pieces 26 provided in the cover 22, acts, while a force A, which presses the cover 22 to the side of the board 18 by the housing 44, acts in the opposite direction to the above force. Accordingly, the cover 22 is attached on the board 18 by the pressing force of the housing 44 to fulfill a shielding effect for the board 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for shielding a printed circuit board incorporated in a housing of, for example, a small portable telephone.

[0002]

2. Description of the Related Art Normally, in order to avoid the influence of an electric field,
A shield means such as a grounded metal screen, sheet, or enclosure is provided around the device or between the device and the device.

For example, in a small portable telephone, noise is mixed into the radio frequency receiving section by radio waves emitted from logic circuit parts and the like, which causes a reduction in the receiving sensitivity of the radio frequency receiving section. As shown in FIG. 9, a shield case for surrounding and electrostatically shielding the logic circuit parts and the like arranged on the printed circuit board is provided, and the shield case allows the radio frequency receiver to receive the interference radio waves. Is prevented.

The shield case 1 has a printed circuit board 4 on the front surface of which a logic system component 2 such as a CPU is disposed, and a ground layer 3 (see FIG. 10) formed on the back surface, and the front surface of the printed circuit board 4. A shielded sheet metal case frame 6 surrounding the wiring pattern 5 formed on the printed circuit board 4 and fixed to the surface of the printed circuit board 4 by soldering, and a case cover 7 attached to the shielded sheet metal case frame 6. To be done.

The printed circuit board 4 is formed with a plurality of through holes 8 for electrically connecting the wiring pattern 5 formed on the front surface and the ground layer 3 formed on the back surface. The through holes 8 are formed along the outer periphery of the wiring pattern 5 so as to surround the logic components 2 and the like, and are separated by a predetermined distance.

As shown in FIG. 10, the outer peripheral portion 9a of the case cover 7 is formed by bending it inward at a predetermined angle in a substantially L-shaped cross section, and an elastic force is exerted on an end edge portion 9b of the outer peripheral portion 9a. F
Has been granted. Due to the elastic force F, the case cover 7
The case cover 7 is attached to the shield sheet metal case frame 6 by pressing the outer wall surface of the shield sheet metal case frame 6 in the direction of the arrow by the end edge portion 9b.

[0007]

In this case, in the shield case 1 according to the prior art, the outer wall surface of the shield sheet metal case frame 6 is pressed by the end edge portion 9b of the case cover 7 from one direction to cause the case cover 7 to move. And the shield sheet metal case frame 6 are in contact with each other, the contact state between the case cover 7 and the shield sheet metal case frame 6 is weak and the edge 9
There is a disadvantage that the contact state varies depending on the bending angle of b. Further, there is also a disadvantage that the contact area between the case cover 7 and the shield sheet metal case frame 6 is small. Therefore, there is a problem that a desired shield effect cannot be exhibited.

Further, in response to the demand for miniaturization of portable telephones, miniaturization of printed circuit boards incorporated in the housing of the portable telephones is also required. There is an inconvenience that the work of soldering the shield sheet metal case frame is complicated.

The present invention has been made in order to overcome the above-mentioned inconvenience, and a cover member can be easily attached to a miniaturized printed circuit board, and further, the cover member and the printed circuit board can be mounted. It is an object of the present invention to provide a method of shielding a printed circuit board, capable of stably and firmly contacting with each other and increasing a contact area to obtain a good shielding effect.

[0010]

In order to achieve the above-mentioned object, the present invention is to install a circuit component on a wiring pattern formed on one surface, which is assembled in a housing of a mobile radio communication device. A method of shielding a printed circuit board disposed on the other surface of which a ground layer is formed, wherein a cover member to which elastic force is applied is pressed against the printed circuit board by a pressing force of the housing. It is characterized in that the circuit components are held in the housing in opposition to each other and the circuit component is closed by a cover member.

[0011]

In the printed circuit board shielding method according to the present invention described above, when the cover member is incorporated in the housing, the force for separating the cover member from the printed circuit board by the cover member to which the elastic force is applied is applied. On the other hand, a force that presses the cover member toward the printed circuit board acts in a direction opposite to the force that attempts to separate the cover member from the housing. Therefore, the force for separating the cover member from the printed circuit board and the force for pressing the cover member toward the printed circuit board by the housing face each other, so that the cover member and the printed circuit board are stably and firmly bonded. Can be contacted with.

Further, the contact surface between the cover member and the printed circuit board can be increased by bringing the claw surface or the conductive rubber provided on the cover member into contact with the upper surface portion of the printed circuit board.

As a result, the radio waves radiated from the circuit component blocked by the cover member are shielded.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method for shielding a printed circuit board according to the present invention will be described in detail below with reference to the accompanying drawings, with reference to preferred embodiments in relation to a shield case for carrying out the method.

FIG. 1 is an exploded perspective view of a shield case to which a method of shielding a printed circuit board according to an embodiment of the present invention is applied, FIG. 2A is a plan view of the printed circuit board shown in FIG. 1, and FIG. 1 is a bottom view of the printed circuit board shown in FIG.
3 is a side view of the shield case shown in FIG. 1, FIG.
3A and 3B respectively show partially enlarged perspective views of the shield cover shown in FIG.

The shield case 10 is preferably assembled in a housing of a small mobile radio communication device such as a small portable telephone, and basically, a logic system circuit component such as a CPU is provided on the surface. Circuit parts 14 including 12
The printed circuit board 18 on which the ground layers 16 (see FIG. 2B) are printed and the wiring patterns 20 formed on the printed circuit board 18 are surrounded, and the printed circuit board 18 is provided. It is composed of a shield cover 22 (cover member) attached in a pressed state. The ground layer 16 formed on the back surface of the printed circuit board 18 is formed at a position corresponding to the wiring pattern 20 formed on the front surface, as shown in FIGS. 2A and 2B.

The shield cover 22 is preferably formed of a sheet metal material, and is formed integrally with a substantially rectangular flat surface portion 24a and a frame portion 24b which is bent along the outer peripheral shape of the flat surface portion 24a. On the edge of the frame portion 24b, a claw piece 26 that is divided into a plurality of parts and is bent inward to exhibit elasticity is formed (see FIG. 4). Note that the plurality of claw pieces 26, ... May be formed by bending the base portion thereof into a flat plate shape, or may be formed by bending and bending. Further, guide pieces 32a to 32g (32e to 32g are not shown in the drawing) that perform a positioning function when the shield cover 22 is attached to the outer peripheral portion of the shield cover 22 while being pressed against the printed circuit board 18. Multiple) are provided.

A wiring pattern 20 is formed on the surface of the printed circuit board 18, and a plurality of circuit components 14a to 14c including the logic circuit component 12 are electrically connected to the wiring pattern 20. Further, a plurality of through holes 38, ... Are defined on the printed circuit board 18 at equal intervals along the outer peripheral shape of the wiring pattern 20, and the wiring pattern 20 and the ground are formed through the through holes 38 ,. The layer 16 is electrically connected. Further, the guide piece 3 of the shield cover 22 is provided on the outer peripheral portion of the wiring pattern 20.
A hole 40 and a recess 42 that engage with 2a to 32g are defined.

The shield case 10 to which the printed circuit board shield method according to the embodiment of the present invention is applied is basically constructed as described above. Next, the operation and effect thereof will be described. It will be described based on.

First, a plurality of through holes 38, ... Are formed at equal intervals along the outer peripheral portion of the wiring pattern 20 formed on the printed circuit board 18. In this case, the wiring pattern 20 formed on the front surface of the printed circuit board 18 and the ground layer 16 formed on the back surface are electrically connected by the through holes 38.

Subsequently, the guide piece 3 of the shield cover 22 is inserted into the hole 40 and the recess 42 of the printed circuit board 18.
2a to 32g are engaged with each other to position them. In the thus positioned state, the shield cover 22 is pressed against the printed circuit board 18 by pressing force by the housing 44 of a small portable telephone or the like (see FIG. 3). Therefore, the shield cover 22 and the printed circuit board 18 are attached while being pressed against each other by the pressing force of the housing 44, and the housing 44 is attached.
Retained within.

In this way, when the shield cover 22 is attached to the printed circuit board 18, the shield cover 22 is attached.
Since the plurality of claw pieces 26, ... Provided on the outer peripheral portion of, have elasticity, a force (not shown) for separating the shield cover 22 from the printed circuit board 18 acts. In this case, as shown in FIG. 3, due to the housing 44 in which the shield case 10 is incorporated, a force A larger than the separating force is in the arrow direction (the direction substantially perpendicular to the shield cover 22 and the printed circuit board 18).
Act on. Therefore, the shield case 10 has a force to move the shield cover 22 away from the printed circuit board 18 and the shield cover 2 by the housing 44.
2 and the force A that presses the printed circuit board 18 toward the printed circuit board 18 face each other, so that the shield cover 22
The printed circuit board 18 and the printed circuit board 18 can be stably and firmly contacted with each other.

Further, since the plurality of bent claw pieces 26 of the shield cover 22 come into contact with the upper surface portion of the printed circuit board 18, as compared with the conventional example shown in FIGS. 9 and 10,
The contact area between the shield cover 22 and the printed circuit board 18 can be increased.

As described above, in the shield case 10 to which the printed circuit board shielding method according to the embodiment of the present invention is applied, the shield effect can be further increased as compared with the shield case 1 according to the conventional example. . As a result, the interfering radio waves from the logic circuit components 12 arranged in the shield case 10 are shielded, the noise mixed in the radio frequency receiver incorporated in the small portable telephone is reduced, and the reception sensitivity is reduced. Can be improved.

Further, since the shield cover 22 and the printed circuit board 18 can be attached to each other without soldering, the miniaturized printed circuit board 18 can be assembled in the housing 44 of a portable telephone or the like. Thus, the shield cover 22 can be easily attached.

Further, since the shield cover 22 is attached to the printed circuit board 18 by the pressing force of the housing 44, it is possible to prevent the shield cover 22 from warping, twisting or floating.

Next, a shield case 50 to which the method for shielding a printed circuit board according to another embodiment of the present invention is applied.
Are shown in FIGS. The same components as those of the embodiment shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

The shield case 50 has a structure in which the conductive rubbers 54a and 54b are attached to the end edge portion of the shield cover 52 instead of the plurality of claw pieces 26 along the end edge portion. Different from The conductive rubbers 54a, 5 are
The point that elasticity is imparted to the shield cover by 4b is the same.

The shapes of the conductive rubbers 54a and 54b are
As shown in FIG. 8A, the shield cover 52 has a thickness substantially the same as that of the shield cover 52 and has a substantially square cross section, or
As shown in FIG. 8B, the edge portion of the shield cover 52 may be formed to fit inside the recess 56. In addition,
Other functions and effects are substantially the same as those of the above-described embodiment, and thus detailed description thereof will be omitted.

[0030]

According to the printed circuit board shield method of the present invention, the following effects can be obtained.

That is, the cover member and the printed circuit board can be brought into a stable and strong contact state by the pressing force of the housing, and the contact area between the cover member and the printed circuit board can be increased. Therefore, the shield effect can be further improved.

Further, since the cover member is attached to the printed circuit board by the pressing force of the housing, it is possible to shield easily without the need for soldering work as in the prior art.

Further, even when the printed circuit board is required to be downsized, such as a portable telephone, the cover member can be easily attached to the printed circuit board for shielding.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a shield case to which a method of shielding a printed circuit board according to an embodiment of the present invention is applied.

2A is a plan view of the printed circuit board shown in FIG. 1, and FIG. 2B is a bottom view of the printed circuit board shown in FIG.

FIG. 3 is a side view showing a state in which the shield case shown in FIG. 1 is incorporated in a housing.

FIG. 4 is a partially enlarged perspective view of the shield cover shown in FIG.

FIG. 5 is an exploded perspective view of a shield case to which a method of shielding a printed circuit board according to another embodiment of the present invention is applied.

FIG. 6 is a side view showing a state in which the shield case shown in FIG. 5 is incorporated in a housing.

7 is a partially enlarged perspective view of the shield cover shown in FIG.

8A and 8B are cross-sectional views showing a conductive rubber provided on an edge portion of the shield cover shown in FIG. 7, respectively.

FIG. 9 is an exploded perspective view of a shield case according to a conventional technique.

FIG. 10 is a side view of the shield case shown in FIG.

[Explanation of symbols]

10, 50 ... Shield case 12 ... Logic circuit component 16 ... Ground layer 18 ... Printed circuit board 20 ... Wiring pattern 22, 52 ... Shield cover 26 ... Claw pieces 32a to 32g ...
Guide piece 40 ... Hole portion 42 ... Recessed portion 44 ... Housing 54a, 54b ...
Conductive rubber

Claims (4)

[Claims] 1. A printed circuit board assembled in a housing of a mobile radio communication device, in which circuit components are arranged on a wiring pattern formed on one surface and an earth layer is formed on the other surface. The cover member and the printed circuit board to which elastic force is applied are pressed against each other by the pressing force of the housing and held in the housing, and the circuit component is closed by the cover member. A method for shielding a printed circuit board, comprising: 2. The shield method according to claim 1, wherein an elastic force is applied to the cover member by a claw piece provided at an edge portion of the cover member and divided into a plurality of pieces and bent inward. A method for shielding a printed circuit board, comprising: 3. The shield method according to claim 1, wherein an elastic force is applied to the cover member by the conductive rubber attached along the edge of the cover member. Shield method. 4. The method of shielding a printed circuit board according to claim 1, wherein the mobile radio communication device comprises a portable telephone.