JPH1187970A - Shield case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inexpensive shield case superior in contact performance in which a required part can be shielded more strictly by making a continuous groove having cross-section recessed downward in a direction perpendicular to the side face in the opening end face of a shield case making contact with the printed contactor of ground potential on a printed board. SOLUTION: A continuous or continual groove 21 is made in the opening end face of a shield case 2, touching the printed contactor on a printed board 1. When the shield case 2 is tightened to the printed board 1 by means of a screw, a force acts in the direction shown by an arrow to deform the leg contact end part of the groove 21 resiliently. Consequently, the fringe part thereof can surely make contact with the printed contactor, and the contact resistance approaches 0. The groove 21 can be made easily in the end face and the cross- section of the groove 21 is selected, while ascertaining the shield effect for different thicknesses, shapes, sizes, or the like, of the shield case 2. For example, a groove having semicircular cross-section or wedge-like cross-section may be employed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield case (shielding box) for a radio device, and more particularly, to an electromagnetic shield for external communication of a small mobile device in mobile communication such as a portable telephone, and an electromagnetic circuit between internal circuit blocks. The present invention relates to a shield case for shielding an object.

[0002]

2. Description of the Related Art In a small transceiver such as a cellular phone, a shield plate for covering the whole and a shield plate for partitioning each block are provided in order to reduce spurious radiation to the outside and mutual interference of signals between internal circuit blocks. An electromagnetically shielded case formed is provided.

FIG. 6 is a structural example of a conventional shield case. (A) is a plan view, (B) is an AA sectional view, and (C) is a BB sectional view. In the figure, 1 is a printed circuit board, 2
Is a shield case. The conventional shield case 2
Generally, ABS resin plated with electroless Ni or the like is used. A portion indicated by a broken line like a block A and a block B in FIG. 6 is, for example, a shield portion for each circuit block for suppressing electromagnetic interference with an internal nearby circuit such as a VCO (voltage controlled oscillator). The area around the mounting holes is also shielded.

[0004]

The shield case having the above-described structure is formed by making the end face of the opening surface of the shield case 2 come into surface contact with the printed conductor of the ground potential provided on the surface of the printed circuit board 1. This is a configuration that provides an effect, and is relatively easy to design and inexpensive. However, in conduction by merely surface contact, a part (0.05) is required due to distortion (warpage) at the intermediate position of the tightening part due to mounting by screwing. A gap of about 0.1 mm is generated, and the contact surface is poor due to oxidation or contamination of the contact surface, and the shielding effect is insufficient. In particular, in a high-frequency circuit such as a mobile phone, it is difficult to prevent the influence of electromagnetic waves leaking from the gap, and the shielding effect is insufficient.

FIG. 7 is a partial sectional view of a conventional shield effect improving structure. This structure is an example of a structure for improving the contact failure. (A) shows a printed conductor of a copper pattern on the printed circuit board 1 by attaching an individual contact body 4 such as a conductive elastic body to an opening end of the conventional shield case 3 on the printed circuit board 1 side and screwing the case. 11 has improved contactability. However, although this structure has good contact properties, it has disadvantages in that it is expensive and the mold used is complicated and expensive.

FIG. 7 (B) shows a conventional shield case 3 in which soldering 5 is performed from outside the contact portion with the printed circuit board 1. However, this method has the drawbacks that the working cost is high, the productivity is low, the work cannot be performed on the partition between the inner blocks, and the appearance is not clean. In the structures (A) and (B), it is necessary to check for unnecessary radiation or the like after assembling.

SUMMARY OF THE INVENTION An object of the present invention is to provide a shield case which solves the above-mentioned conventional drawbacks, is inexpensive, has excellent contact properties, and more strictly shields necessary parts, so that a shielding effect can be reliably obtained. It is in.

[0008]

SUMMARY OF THE INVENTION A shield case of the present invention covers a printed circuit board on which a radio circuit is mounted and partitions the whole mounted circuit and a plurality of circuit blocks to form a thin box for electromagnetically shielding. In the shield case of
A continuous concave groove whose vertical cross-section perpendicular to the side surface is concave downward is provided on the open end surface of the printed circuit board that contacts the printed conductor of the ground potential, and when the shield case is screwed to the printed circuit board, the tightening is performed. The leg portion tip portion of the concave groove is elastically deformed by a force so that an edge portion thereof and a printed conductor of a ground potential of the printed board are sufficiently contacted with each other, and as another means, The concave groove is characterized in that one leg of the groove is removed at an arbitrary interval.

Further, a continuous or partial reinforcing groove for reducing warpage of the shield case when the shield case is screwed to the printed circuit board is provided on the upper surface of the shield case according to claim 1 or 2. It is characterized by providing a plurality.

[0010]

1 is a structural view showing an embodiment of the present invention, in which (A) is a plan view, (B) is a cross-sectional view along AA,
(C) is BB sectional drawing. (D) and (E) are CC
It is sectional drawing and is a partial expanded sectional view which shows the principal part structure of this invention. As shown in the figure, the present invention provides a printed circuit board 1 of a shield case 2 having an opening end face which comes into contact with a printed conductor.
This is a structure in which a continuous or intermittent concave groove 21 is provided as shown in FIG. When the shield case 1 is fastened to the printed circuit board 2 with screws, the force of the arrow is applied as shown in (E), and the leg contacting end of the concave groove 21 to the printed circuit board 1 is elastically deformed and its edge is deformed. The contact with the printed conductor by the portion is ensured, and the contact resistance can be made close to zero. It is easy to provide the concave groove 21 on the end face, and the cross-sectional shape of the groove is selected while confirming the shielding effect by the thickness, shape, size, etc. of the shield case 2.

FIGS. 2, 3 and 4 show another embodiment of the groove showing the main part of the present invention. FIG. 2A shows a concave groove 22 having a semicircular cross section. FIG. 2B shows a groove 23 having a wedge-shaped cross section. By forming the groove so as to approach one side, one of the grooves can be elastically deformed as shown in FIG.

FIG. 3 shows another embodiment, which shows a shape in which one of the legs of the groove is cut off at an arbitrary interval as shown in FIG. FIG. 4 shows a shape in which one notch of FIG. 3 is provided in a partially dispersed manner. These may be selected depending on the desired shielding effect and the degree of contact.

FIG. 5 is a structural view showing a further embodiment of the present invention.
26 is provided. When the shield case 2 provided with a concave groove on the contact end face shown in FIGS. 1 to 4 is fixedly fastened to the printed circuit board 1 with screws, the continuous case 25 or a part of the continuous groove 25 is formed on the upper surface to prevent the warp of the shield case 2. The groove 26 is provided, and the rigidity of the shield case 2 is increased to improve the degree of adhesion between the peripheral opening end surface and the printed circuit board 1.

[0014]

As described above in detail, the following effects can be obtained by implementing the present invention. (1) The contact between the shield case and the printed circuit board is improved only by screwing, and the shield effect is ensured. (2) It is easy to design and can be manufactured at low cost. (3) Since a concave groove can be provided even in a thin shield case, the size of the shield case can be reduced.

[Brief description of the drawings]

FIG. 1 is a structural diagram showing a first embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view showing a second embodiment of the present invention.

FIG. 3 is a partially enlarged sectional view showing another embodiment of the present invention.

FIG. 4 is a partially enlarged perspective view showing another embodiment of the present invention.

FIG. 5 is a structural view showing a further embodiment of the present invention.

FIG. 6 is a structural example diagram of a conventional shield case.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Shield case 3 Shield case 4 Individual contact body 5 Soldering 11 Copper pattern 21, 22, 23 Groove provided on the end surface 25, 26 Groove provided on the upper surface

Claims (3)

[Claims] 1. A thin box-shaped shield case for covering a printed circuit board on which a radio device circuit is mounted and for electromagnetically shielding by partitioning the entire mounted circuit and a plurality of circuit blocks, wherein a ground potential of the printed circuit board is provided. A continuous concave groove whose vertical cross-section perpendicular to the side surface is concave downward is provided on the open end surface that comes into contact with the printed conductor, and when the shield case is screwed to the printed circuit board, the tightening force of the shield case causes the concave groove to be closed. A shield case, wherein a tip portion of a leg portion is elastically deformed so that an edge portion thereof and a printed conductor of a ground potential of the printed circuit board are sufficiently in contact with each other. 2. The shield case according to claim 1, wherein one of the concave grooves is removed at an arbitrary interval. 3. A continuous or partial reinforcing groove for reducing warpage of the shield case when the shield case is screwed to the printed board on the upper surface of the shield case according to claim 1. The shield case according to claim 1, wherein a plurality of the shield cases are provided.