JP3288875B2 - Mounting structure of shield case - Google Patents

Abstract

PURPOSE: To provide a shield case attaching structure which can be easily fitted to a circuit board and can easily attach shield cases even when the cases have complicated shapes without unnecessary gaps between an plastic enclosure and the cases. CONSTITUTION: Deep-drawn shield cases 50 formed of thin metal plates are fitted in the recessed sections 2a of a plastic enclosure 2 and the cases 50 are pressed against the enclosure 2 by a circuit board 3 fitted to the enclosure 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield case mounting structure suitable for shielding electromagnetic waves in small electronic devices such as portable radios.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional portable telephone. This portable telephone has a plastic case composed of an upper case 1 and a lower case 2, a circuit board 3 on which a radio circuit is formed,
A shield case 4 attached to the circuit board 3; a circuit board 5 on which circuit parts constituting various functions of the telephone are configured; a rubber switch 7 attached to the circuit board 5; electronic components such as a speaker 8; , An antenna housing 10 for shielding the antenna 9 from electromagnetic waves when the antenna 9 is housed in the housing, and the circuit board 3 and the shield case 4 are screwed into the lower case 2 with screws 12. The circuit board 5 is attached to the upper side of the shield case 4 and covered with the upper case 1, and the upper and lower cases 1 and 2 are fixed using screws 13.

In a radio device such as a mobile phone, it is necessary to shield a radio circuit from the outside in order to prevent electromagnetic interference. Therefore, also in the portable telephone, as shown in FIG. 7, a shield case 4 is mounted on the upper side of the circuit board 3 constituting the radio circuit section, and the lower side of the circuit board 3 is mounted on the lower side of the circuit board 3. Lower case 2 covering the side
The radio circuit portion is shielded from the outside by forming a conductive layer 15 on the inner surface of the substrate by means of electroconductive plating, electroless plating, vapor deposition or the like.

However, the method of conducting the conductive treatment inside the lower case (hereinafter referred to as a plastic casing) 2 not only increases the cost of the conductive treatment itself but also lowers the yield of the production of the plastic casing 2, so that the method as a whole is not good. The cost was very high. In addition, when the product is discarded, the conductive layer 15 cannot be separated from the plastic housing 2, so that there is a problem that the plastic cannot be recycled.

On the other hand, as shown in FIG. 8, in the case where the shield case 17 in which a sheet metal is formed in a box shape is used to cover the lower side of the circuit board 3, the shield case 17 is soldered or screwed. It is necessary to attach the shield case 17 to the circuit board 3 by the above method, so that a large number of man-hours are required to attach the shield case 17. Particularly, in this type of radio, in order to prevent radio wave interference between circuit blocks constituting the radio circuit, Since it is necessary to provide the shield case 17 for each circuit block, mounting the shield case 17 requires even more man-hours. Also, shield case 1
In order to mount the circuit board 3 on which the circuit board 7 is mounted to the plastic housing 2, the shield case 17 and the housing 2
, A clearance is required between them, so that there is a problem that the casing 2 is unnecessarily enlarged.

[0006]

As described above, in the conventional shielding method in which conductive treatment is performed on the inner surface of a plastic casing, the cost of conducting treatment is high, the production yield of the plastic casing is deteriorated, and the recycling of plastics can be prevented. There was a problem that it could not be performed.

[0007] On the other hand, the conventional shielding method performed by attaching a shield case to a circuit board has a problem that it takes a lot of man-hours to attach the shield case, and the plastic housing to which the circuit board is attached becomes large. there were.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and has a structure in which a radio circuit section is covered with a shield case, but the shield case can be easily attached to the circuit board, and the circuit board is attached. Provided is a shield case mounting structure capable of reducing the size of a plastic housing to a necessary minimum size and easily manufacturing a shield case having a complicated shape corresponding to the arrangement of a circuit part to be shielded. With the goal.

[0009]

According to a first aspect of the present invention, there is provided a shield case mounting structure formed of plastic.
With a recess for fitting the shield case
An electronic device provided with a rib for partitioning the fitting recess into a plurality of portions.
By drawing the housing of the device and a thin metal plate
The rib fitting recess is formed and fitted with the rib.
And fitted into the shield case fitting recess.
A sheet metal aperture shield case, and a predetermined circuit part is attached to the housing in a state where the sheet metal aperture seed case fitted into the shield case fitting recess is pressed toward the housing, and a predetermined circuit portion is covered with the sheet metal aperture shield case. And a circuit board.

According to a second aspect of the present invention, there is provided a shield case mounting structure according to the first aspect, wherein the circuit board is provided with the sheet metal aperture.
In the shield case and the rib fitting recess.
A portion facing the tip of the rib with a portion serving as a bottom wall therebetween
Earth putter that can be brought into contact with the bottom wall
Configuration is provided.

According to a third aspect of the present invention, there is provided a shield case mounting structure according to the second aspect, wherein a portion between the bottom wall of the rib fitting recess and the tip of the rib is located inside the rib fitting recess. The configuration is such that an elastic body is provided.

According to a fourth aspect of the present invention, there is provided the shield case mounting structure according to any one of the first to third aspects, wherein the sheet metal drawing shield case is formed by forming a thin metal sheet in which a metal foil is fixed to a plastic sheet. It is formed by drawing so as to form an inner surface.

According to a fifth aspect of the present invention, there is provided a shield case mounting structure according to any one of the first to third aspects, wherein a plurality of slits are formed in the thin metal plate.

[0014]

According to the first aspect of the present invention, since the shield case is formed by drawing a thin metal plate, a complicated shape can be easily formed. Further, the sheet metal aperture shield case can be attached to a predetermined position of the circuit board only by fitting the sheet metal aperture shield case formed by the drawing process into the plastic casing and attaching the circuit board to the casing. In addition, since the sheet metal aperture shield case is pressed by the circuit board so as to be in close contact with the inner surface of the housing, an unnecessary gap does not occur between the shield case and the housing, and the shield formed by a thin plate. The case itself is reinforced by the housing. rib
Reinforcing ribs are fitted into the fitting recesses, and
The recess divides the circuit board into a plurality of circuit blocks .

According to the second aspect of the present invention, a sheet metal drawing seal is provided.
Since the bottom wall of the rib fitting recess of the case is in contact with the ground pattern of the circuit board, in addition to the function of claim 1, a plurality of circuit blocks formed on the circuit board can be combined with one sheet metal aperture shield case. It can be used to shield each circuit block.

According to the third aspect of the invention, in addition to the function of the second aspect, the bottom wall is elastically attached to the ground pattern by an elastic body provided between the bottom wall of the rib fitting concave portion and the tip of the rib. Can be done.

According to the fourth aspect of the present invention, since the metal sheet formed by fixing the metal foil to the plastic sheet is narrowed, a shield case having a complicated shape can be easily manufactured, and furthermore, it is reinforced by the plastic sheet. Therefore, the strength of the metal foil can be increased.

According to the fifth aspect of the present invention, since a large number of slits are formed in the metal plate, the diaphragm can be easily reduced by that much, so that a sheet metal diaphragm shield case having a complicated shape can be easily manufactured.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. 1 and 2 are views showing a first embodiment. FIG. 2 is an exploded perspective view showing a state in which a circuit board is mounted on a lower case of a portable telephone. FIG. 1 is a view showing a circuit board mounted on a lower case. FIG. 3 is a sectional view taken along line AA of FIG. 2 later.

FIGS. 1 and 2 show a process of incorporating the circuit board 3 into the lower case 2 of the portable telephone shown in FIG. 6, and as shown in FIG. The sheet metal aperture shield case 50 is fitted into the concave portion 2a of the lower case 2, and the sheet metal aperture shield case 50
With the circuit board 3 placed thereon and the shield case 4 placed on the circuit board 3, the shield case 4, the circuit board 3 and the sheet metal aperture shield case 50 are fixed to the lower case 2 using screws 12. . And the circuit board 3
The lower case 2 shown in FIG. 1 incorporating the shield cases 4 and 50 is screwed together with the circuit board 5 to the upper case 1 by screws 13 as shown in FIG.

The circuit board 3 constitutes a radio circuit section in the same manner as in the prior art. As shown in FIG. 1, on both front and back surfaces of the board 3, an earth pattern 31 is provided on the periphery of the circuit board 3 and the radio circuit section is provided. The earth pattern 32 is provided so as to partition each circuit block constituting the above. The circuit board 3 has a hole 3a into which the screw 12 is inserted and a hole 3b into which the screw 13 is inserted.

The shield case 4 is formed of a material obtained by applying electroless Ni plating to plastic. The shield case 4 has two upper and lower concave portions formed with a central partition wall 4a as a bottom wall so as to cover the entire upper surface 3c side of the circuit board 3 and a part of the lower surface side of the circuit board 5. Further, a partition wall 4b is provided in the lower concave portion of the shield case 4 corresponding to the ground pattern 32, and the lower concave portion is partitioned into a plurality of rooms. In the shield case 4, an insertion hole 4d for the screw 12 and an insertion hole 4e for the screw 13 are provided.
Are provided at the portions of the circuit boards 3 and 5 that come into contact with the ground pattern, and a large number of projections 4f are formed to ensure the contact with the ground pattern. The reason why the shield case 4 is formed of plated plastic is that the shape is complicated and that a predetermined strength for holding the circuit boards 3 and 5 is required.

The lower case 2 is formed with a recess (shield case fitting recess) 2a having a size and shape capable of covering the lower surface 3d of the circuit board 3. The lower case 2 is provided with ribs 2b for partitioning the recess 2a into a plurality of rooms, corresponding to the ground pattern 32. Also,
The lower case 2 is provided with a boss 2d having a screw hole into which the screw 12 is screwed and a boss 2e having a hole for inserting the screw 13 and being inserted into the hole 3b of the circuit board 3. ing.

The sheet metal aperture shield case 50 is formed by applying a drawing process to a thin metal plate (for example, a metal plate obtained by applying a nickel plate to a copper plate of about 0.1 mm). This shield case 50 is formed in a shape and a size that can be fitted into the concave portion 2 a of the lower case 2.
Further, a concave portion (a rib fitting concave portion) 50a that can be fitted into the rib 2b of the lower case 2 and a concave portion 50b that can be fitted with the boss 2d are formed. The shield case 50 has a hole 50d into which the screw 12 is inserted and a hole 50e into which the boss 2e is fitted.

With the above configuration, the sheet metal aperture shield case 50 is fitted into the recess 2a of the lower case 2, and the opening side peripheral edge 50f of the shield case 50 is formed.
When the circuit board 3 is mounted on the circuit board 3 and the shield case 4 is further mounted on the circuit board 3 and the screw 12 is screwed into the lower case 2, the sheet metal aperture shield case 50 becomes the lower surface 3 of the circuit board 3.
It is in a state of being attached to the circuit board 3 so as to cover the d side. In this case, the peripheral edge 50f of the sheet metal aperture shield case 50 and the bottom wall 50g of the concave portion 50a are grounded by the circuit board 3 pressing the shield case 50.
32, the lower surface side of the circuit board 3 is reliably shielded from the outside by the shield case 50, and a portion 50h of the shield case 50 that serves as a side wall of the recess 50a serves as a partition wall. Therefore, the radio wave interference between the respective circuit blocks constituting the wireless circuit section is also prevented. Further, since the entire outer wall surface of the shield case 50 is pressed against the inner wall surface of the lower case 2 by the circuit board 3, no unnecessary gap is generated between the shield case 50 and the lower case 2. The strength of the shield case 50 formed of a thin sheet metal is increased by being held by the lower case 2.

FIG. 3 is a diagram showing a second embodiment of the present invention. In the sheet metal aperture shield case 50A in this example, a metal foil (in this example, nickel-plated copper foil) 52 is pasted on a plastic sheet (in this example, a polyester sheet having a thickness of about 0.1 mm) 51. Is used as a metal thin plate, and the thin plate is formed by drawing with the metal foil side as the inner surface. In this example, since the extremely thin metal foil 52 is drawn, a shield case having a complicated shape can be easily manufactured, and since the metal foil 52 is reinforced with the plastic sheet 51, the metal foil is not easily damaged by the drawing. Other configurations, actions,
The effects are the same as in the first embodiment.

FIG. 4 is a view showing a third embodiment of the present invention. This embodiment is different from the second embodiment in that the shield case 50 is used.
This shows a case where an elastic body 61 such as a sponge is inserted between the bottom wall 50g of the concave portion 50a of A and the tip of the rib 2b of the lower case 2. In this example, even if the elasticity of the shield case 50A is insufficient or the circuit board 3 is warped, the concave portion bottom wall 50e is grounded by the elastic force of the elastic body 61. The pattern 32 can be securely brought into close contact with the pattern 32. Other configurations, operations, and effects are the same as those of the second embodiment. In this embodiment, the rib 2b has a thickness of 0.6 to 0.8 mm.

FIGS. 5A and 5B show a fourth embodiment of the present invention. FIG. 5A is a perspective view of a metal plate, FIG. 5B is an enlarged view of a circle B in FIG. FIG. 4 is a partially enlarged perspective view of a metal plate in a state where processing is performed. This example shows a case where a metal plate 55 having a large number of slits 55a is used as a metal plate for manufacturing a sheet metal aperture shield case. If a large number of slits 55a having such a size as not to affect the shielding effect are formed on the metal plate 55, the portions where the metal plate is elongated by the drawing work have the slits 55a opened as shown in FIG. As a result, the elongation of the metal plate itself can be eased, so that drawing of a complicated shape can be easily performed.

The present invention is not limited to the above embodiment. For example, the sheet metal aperture shield case 50 may be one without the concave portion 50a, that is, one without a partition wall. Even when a partition wall is provided, if the strength of the partition wall is sufficient, the lower case may be used. Rib 2b on 2 side
May not be provided. Further, the upper surface 3c side of the circuit board 3 is covered with a shield case 4 formed by applying metal plating to plastic, but the upper surface 3c side of the circuit board 3 is simply covered with the same plastic casing as the lower case 2. In the case of the configuration, the upper surface 3c side can be covered with the sheet metal aperture shield case configured as in the above embodiment.

[0030]

As described above, in the shield case mounting structure according to the first aspect, since the shield case is formed by drawing a thin metal plate, a shield having a complicated shape can be easily manufactured. it can. Further, the sheet metal aperture shield case can be attached to a predetermined position of the circuit board simply by fitting the sheet metal aperture shield case into a plastic housing and attaching the circuit board to the housing, so that the sheet metal aperture shield case can be easily attached. In addition, since the sheet metal aperture shield case is pressed by the circuit board so as to be in close contact with the inner wall surface of the housing, an unnecessary gap does not occur between the sheet metal aperture shield case and the housing, and the shield case itself formed of a thin plate Is reinforced by the housing. In addition, each material can be recycled by separating the sheet metal aperture shield case from the plastic housing. Also, the rib fitting recess is used for reinforcement.
Since the ribs of the
Make sure that the board is
Can be placed.

According to the second aspect of the present invention, since the rib fitting recess into which the rib of the housing is fitted serves as a partition wall, in addition to the effect of the first aspect, a plurality of circuit blocks formed on the circuit board can be combined into one. This has the effect of being able to shield with a sheet metal aperture shield case .

According to the third aspect of the invention, in addition to the effect of the first aspect, the bottom wall is elastically provided on the ground pattern of the circuit board by an elastic body provided between the bottom wall of the rib fitting concave portion and the tip of the rib. This has the effect that it can be closely adhered.

According to the fourth aspect of the present invention, since the metal plate formed by fixing the metal foil to the plastic sheet is narrowed, a shield case having a complicated shape can be easily manufactured.
Further, since the plastic sheet is reinforced, the strength of the metal foil is increased.

According to the fifth aspect of the present invention, since a large number of slits are formed in the metal plate, the diaphragm can be easily drawn, so that a sheet metal diaphragm shield case having a complicated shape can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 2;

FIG. 2 is an exploded perspective view of a main part of the portable telephone according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

FIG. 4 is a sectional view showing a third embodiment of the present invention.

FIG. 5 is a diagram showing a fourth embodiment of the present invention.

FIG. 6 is an exploded perspective view of a conventional portable telephone.

FIG. 7 is a sectional view of a conventional shield structure.

FIG. 8 is a cross-sectional view of another conventional shield structure.

[Explanation of symbols]

Reference Signs List 2 plastic housing 2a shield case fitting recess 2b rib 3 circuit board 32 ground pattern 50, 50A sheet metal aperture shield case 50a rib fitting recess 50g bottom wall 51 plastic sheet 52 metal foil 55 metal plate 55a slit 61 elastic body

Continuation of the front page (56) References JP-A-4-215500 (JP, A) JP-A-8-13873 (JP, A) JP-A-57-91600 (JP, A) JP-A-5-191077 (JP) JP-A-8-102592 (JP, A) JP-A-5-235576 (JP, A) JP-A 62-111789 (JP, U) JP-A 58-182494 (JP, U) 3-36198 (JP, U) JP-A 1-140897 (JP, U) JP-A 60-146726 (JP, U) JP-A 58-133989 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H05K 9/00

Claims (5)

(57) [Claims] 1. A shield case made of plastic.
With a recess for fitting the case, and
A case of an electronic device provided with ribs for partitioning a number of parts, and formed by performing a drawing process on a thin metal plate;
A rib fitting recess into which the rib is fitted is formed, and
Sheet metal diaphragm seal to be fitted into the recess for fitting the case
And a circuit board in which a predetermined circuit portion is attached to the housing in a state where the sheet metal aperture seed case fitted into the shield case fitting recess is pressed toward the housing, and a predetermined circuit portion is covered by the sheet metal aperture shield case. A mounting structure for a shield case, comprising: 2. The circuit board according to claim 1, wherein said sheet metal aperture shield case is provided on said circuit board.
Part which is the bottom wall of the rib fitting recess
With the bottom wall in a portion facing the tip of the rib
Is provided with an earth pattern that can be contacted
Mounting structure of the shield case according to claim 1, characterized in that there. 3. The rib body according to claim 2, wherein an elastic body is provided in the rib fitting concave portion and between a portion serving as a bottom wall of the rib fitting concave portion and a tip of the rib. Mounting structure of the shield case. 4. The sheet metal drawing shield case is formed by drawing a thin metal sheet in which a metal foil is fixed to a plastic sheet so that the metal foil becomes an inner surface. Item 4. A structure for mounting a shield case according to any one of Items 1 to 3. 5. The mounting structure for a shield case according to claim 1, wherein a number of slits are formed in the thin metal plate.