Electromagnetic shielding device

This is a continuation application of and claims the priority of patent application Ser. No. 11/743,160, filed on May 2, 2007, which claims the priority benefit of Taiwan patent application serial no. 95117814, filed on May 19, 2006. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification.

1. Field of Invention

The present invention relates to an electromagnetic shielding device, and more particularly to an electromagnetic shielding device using conductive rubber as the frame thereof.

2. Description of the Related Art

One of common problems with an electronic equipment is electromagnetic interference (EMI). A running circuit usually emits electromagnetic radiation, which affects the transmission signals and electric performances of other electronic components. A mobile phone, for example, has a strict requirement on anti electromagnetic interference (anti-EMI), due to a quite fast transmission speed the mobile phone\'s signal has. Therefore, in general, a mobile phone is always equipped with an electromagnetic shielding device on the printed circuit board (PCB) thereof to prevent the electromagnetic radiation from leakage or to avoid an induced in leakage of external electromagnetic radiations, which causes unwanted interferences.

FIG. 1A is a cubic exploded drawing of a conventional electromagnetic shielding device. FIG. 1B is a cubic drawing of the electromagnetic shielding device in FIG. 1A after assembling. Referring to FIGS. 1A and 1B, a conventional electromagnetic shielding device 100 is made of metal material and includes a metallic frame 110 and a metallic cover 120. The metallic frame 110 is fixed on a PCB 130 by using surface mount technology (SMT) and has multiple protrusion portions 112 on the outer surface 110a thereof. The metallic cover 120 has a cover plate 122 and a side wall 124, which joins the periphery region of the cover plate 122 has multiple through holes 126 corresponding to the above-mentioned protrusion portions 112.

To assemble the metallic cover 120 onto the metallic frame 110, the inner surface of the side wall 124 of the metallic cover 120 is fit on with the outer surface 110a of the metallic frame 110, followed by buckling the protrusion portions 112 on the metallic frame 110 in the corresponding through holes 126 of the metallic cover 120, so as to reliably assemble the metallic cover 120 with the metallic frame 110.

Since the metallic cover 120 and the metallic frame 110 are closely interconnected by means of the above-described approach, the metallic cover 120 is unlikely separated from the metallic frame 110. In turn, the metallic cover 120 is accordingly hard to be disassembled from the metallic frame 110 when the electronic components on the PCB 130 need to be maintained. As a usual maintain manner today, some hand tools, such as tweezers, are used to prize the side wall 124 of the metallic cover 120, followed by removing the metallic cover 120 from the metallic frame 110. However, during removing the metallic cover 120 from the metallic frame 110, the side wall 124 of the metallic cover 120 are likely deformed and then the metallic cover 120 is hard to keep its original shape for using repeatedly. Besides, during disassembling the metallic cover 120, the integrity of the outer surface 110a of the metallic frame 110 is further destroyed. For a metallic frame 110 fixed on the PCB 130 by using surface mount technology (SMT), an accidental operation mistake resulting in integrity loss of the metallic frame 110 may further cause assembly troubles after maintaining.

On the other hand, it needs to take account of material cost issue. For a usual electromagnetic shielding device today, the cover and the frame thereof are made of metal. To get better metal conductive efficiency, copper is a preferred choice for the cover and the frame. However, in recent years, the prices of metal material together with most of crude material, particularly the price of copper, has been soaring continuously, which further increases the production cost of an electromagnetic shielding device to impressive extent.

An objective of the present invention is to provide an electromagnetic shielding device, which uses conductive rubber to fabricate the frame thereof, so as to solve the problem of hard disassembly caused by a conventional metallic frame and occurred during maintaining.

To achieve the above-described or other objectives, an embodiment of the present invention provides an electromagnetic shielding device suitable for a PCB. The electromagnetic shielding device includes a cover and a conductive rubber frame. The cover is made of a conductive material and has a through hole and a containing space. The conductive rubber frame is contacted with the through hole of the cover. The conductive rubber frame contacts with the PCB and is electrically connected to the ground end. The electronic component is enclosed by the cover and the conductive rubber frame.

In an embodiment of the present invention, the above-described conductive material is metal.

In an embodiment of the present invention, the cover includes a cover plate and a side wall joining the cover plate, and at least a through hole is disposed in the side wall.

In an embodiment of the present invention, the above-described conductive rubber frame includes a sheath portion and at least a plug portion. The sheath portion encloses the side wall; the plug portion is located in the through hole, while both ends of the plug portion join the sheath portion enclosing the side wall.

In an embodiment of the present invention, the above-described conductive rubber frame further includes at least a positioning portion, which extends towards the PCB. The PCB has at least a positioning hole corresponding to the positioning portion, and the positioning portion resides in the positioning hole, so as to position the cover and the conductive rubber frame on the PCB.

The electromagnetic shielding device of the present invention mainly includes a cover and a conductive rubber frame enclosing the cover. The conductive rubber frame can be directly fabricated on the cover by using a buried injection process, which effectively reduces the component number of the electromagnetic shielding device and simplifies the mounting process flow thereof. Besides, due to the elasticity the conductive rubber material possesses, the problems of disassembly difficulty and low repeatable usage caused by the prior art where the cover and the frame of a conventional electromagnetic shielding device are made of metal can be solved. Furthermore, due to the low costs of the conductive rubber material and the die development, an entire electromagnetic shielding device is expectedly produced in a cost-effective way.