Shielding case structure of handheld communication apparatus

A handheld communication apparatus includes a metallic insert molding member, a circuit board and a shielding frame. The metallic insert molding member includes a metal plate. An electronic component is mounted on the circuit board. The shielding frame defines opposite first and second openings, wherein the shielding frame is bonded to the metal plate of the metallic insert molding member at the first opening, thereby forming a shielding case. The electronic component on the circuit board is inserted into the second opening of the shielding frame to be shielded by the shielding case.

FIELD OF THE INVENTION

The present invention relates to a shielding case structure, and more particularly to a shielding case structure of a handheld communication apparatus.

BACKGROUND OF THE INVENTION

With increasing development of communication technologies, handheld communication apparatuses such as mobile phones become essential communication products because they are portable and convenient. Recently, a variety of new mobile phones are brought forth and the old ones are weeded out soon. For increasing competitiveness of these mobile phones, the general trends in designing information electronic devices are toward small size, light weightiness and easy portability. Generally, either slim-type injection molding of plastic material or minimization of the electronic components are redered for facilitating fabrication of slim mobile phones.

As known, electrostatic discharge and electromagnetic interference (EMI) are detrimental to the electronic components on the circuit board inside the communication products. For a purpose of minimizing the influence of electrostatic discharge and/or electromagnetic interference (EMI), some important electronic components should be shielded by electrically conductive material, which is referred hereinafter as EMI shielding case.

Conventionally, the EMI shielding case is welded to a ground wire on a printed circuit board (PCB) of the handheld communication apparatus according to the surface mount technology (SMT). Before the EMI shielding case is welded to the ground wire, solder paste has been previously coated onto the circuit board and a steel plate should have been washed. As a consequence, the process of assembling the EMI shielding case is complicated and labor-intensive. Moreover, for maintaining the electronic components which are shielded by the EMI shielding case, the whole EMI shielding case should be detached for inspecting or replacing the shielded electronic components. In addition, the height of the EMI shielding case with respect to the surface of the circuit board is not small enough.

Generally, the conventional EMI shielding cases are classified into two types, i.e. a one-piece structure and a two-piece structure, which are illustrated as follows with reference toFIGS. 1 and 2.

Please refer toFIG. 1, which is a schematic cross-sectional view illustrating a one-piece structure of an EMI shielding case. InFIG. 1, the EMI shielding case11is directly welded to a ground wire121of a printed circuit board12according to the surface mount technology (SMT), thereby shielding the electronic components13. For neat drawings, however, only one electronic component is shown in the drawing. As previously described, since the EMI shielding case should be detached from the printed circuit board12for inspecting or replacing the shielded electronic components, it is time-consuming and labor-intensive to maintain the electronic components shielded by the one-piece EMI shielding case11. In a case that this EMI shielding case11is detached from the printed circuit board12, it fails to be repeatedly used because it is likely distorted. In addition, during the EMI shielding case11is detached from the printed circuit board12, the electronic components next to the EMI shielding case11are possibly collided with the EMI shielding case11.

Please refer toFIG. 2, which is a schematic cross-sectional view illustrating a two-piece structure. InFIG. 2, the two-piece structure comprises a shielding frame21and an EMI shielding case22. Firstly, the shielding frame21is welded to a ground wire231of a printed circuit board23to enclose the electronic components24according to the surface mount technology (SMT). For neat drawings, however, only one electronic component is shown in the drawing. Subsequently, the EMI shielding case22is secured to the shielding frame21and thus the electronic component24is shielded by the EMI shielding case22. In comparison with the one-piece structure, the two-piece structure is advantageous for maintenance because the EMI shielding case22can be separately detached from the shielding frame21. Unfortunately, this EMI shielding case22is still likely distorted and thus fails to be repeatedly used.

In addition to the conventional one-piece structure and two-piece structure, a new approach for assembling the EMI shielding case is illustrated with reference toFIG. 3. The EMI shielding case31is referred as a contact-type EMI shielding case and comprises a shielding case main body311, a metallic frame312and an elastic sheet313. The metallic frame312and the elastic sheet313are substantially a one-piece structure by punching a metallic part. Firstly, the elastic sheet313is placed on a ground wire321of a printed circuit board32to enclose the electronic components33. For neat drawings, however, only one electronic component is shown in the drawing. Then, the shielding case main body311and the metallic frame312are secured to the printed circuit board32by for example screwing or other fastening means. Due to the restoring force generated from the compressed elastic sheet313, a firm attachment between the EMI shielding case31and the printed circuit board32is rendered. Moreover, the electronic components33can be mounted on several regions of the printed circuit board32, which are partitioned by the metallic frame312. Since the electronic components shielded by different regions are not interfered with each other, the overall EMI shielding effect is enhanced.

This approach is also advantageous when the maintenance of the shielded electronic components is required. Under this circumstance, the shielding case main body311is directly detached from the printed circuit board32by loosening the screws. Although the new approach for assembling the EMI shielding case is very convenient, there are still some disadvantages. For example, the width of the ground wire321should be at least 1.0 mm, which is much larger than that required for the one-piece structure or two-piece structure (e.g. 0.5 mm). That is to say, this approach for assembling the EMI shielding case will occupy much area of the printed circuit board32.

In views of the above-described disadvantages resulted from the conventional method, the applicant keeps on carving unflaggingly to develop a shielding case structure of a handheld communication apparatus according to the present invention through wholehearted experience and research.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a shielding case structure of a handheld communication apparatus for minimizing the influence of electrostatic discharge and/or electromagnetic interference (EMI), in which the shielding case has reduced height and is advantageous for maintenance.

In accordance with an aspect of the present invention, there is provided a handheld communication apparatus. The handheld communication apparatus comprises a metallic insert molding member, a circuit board and a shielding frame. The metallic insert molding member includes a metal plate. An electronic component is mounted on the circuit board. The shielding frame defines opposite first and second openings, wherein the shielding frame is bonded to the metal plate of the metallic insert molding member at the first opening, thereby forming a shielding case. The electronic component on the circuit board is inserted into the second opening of the shielding frame to be shielded by the shielding case.

In an embodiment, the electronic component is a high frequency generating IC module.

Preferably, the shielding frame is made of metallic material.

Preferably, the handheld communication apparatus is a mobile phone.

Preferably, the handheld communication apparatus is a personal digital assistant.

In an embodiment, the electronic component is mounted on the circuit board via a surface mount technology.

In an embodiment, the shielding frame has a higher level than the electronic component with respect to the circuit board.

In an embodiment, the shielding frame is bonded to the metal plate of the metallic insert molding member by an arc welding process or a laser spot welding process.

In an embodiment, the circuit board further comprises a ground wire thereon.

In an embodiment, the shielding frame further comprises a plurality of elastic sheets in the vicinity of the second opening of the shielding frame to be in contact with the ground wire.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Exemplary handheld communication apparatuses of the present invention include but are not limited to mobile phones or personal digital assistants (PDAs).

Please refer toFIGS. 4(a),4(b),4(c) and5.FIG. 4(a) is a schematic top view illustrating the reverse side of a metallic insert molding member used in a handheld communication apparatus according to a preferred embodiment of the present invention.FIG. 4(b) is a schematic top view illustrating a shielding frame used in the handheld communication apparatus of the present invention from the second opening of the shielding frame.FIG. 4(c) is a schematic top view of the assembly of the metallic insert molding member ofFIG. 4(a) and the shielding frame ofFIG. 4(b).FIG. 5is a schematic exploded view of a handheld communication apparatus according to a preferred embodiment of the present invention.

Please refer toFIGS. 4(a) and5. The metallic insert molding member41is produced by a metallic insert molding operation. The metallic insert molding member41includes a plastic frame411and a metal plate412. The periphery of the metal plate412is embedded into the plastic frame411.

Please refer toFIGS. 4(b) and5. The shielding frame42is used for enclosing the important electronic components of the handheld communication apparatus to reduce the influence of electrostatic discharge and/or electromagnetic interference (EMI) on the important electronic components of the printed circuit board44. The shielding frame42is made of metallic material, and comprises a plurality of elastic sheets421, a first opening422and a second opening423. At the first opening422, the shielding frame42is bonded to the metal plate412of the metallic insert molding member41by an arc welding process or a laser spot welding process. Please also refer toFIGS. 4(c) and6(b). The metal plate412and the shielding frame42are bonded together to form a shielding case43. Whereas, in the vicinity of the second opening423, the elastic sheets421of the shielding frame42are bonded to the ground wire442of the printed circuit board44. Due to the restoring force generated from the compressed elastic sheets421, a firm attachment between the shielding frame42and the printed circuit board44is rendered.

Nowadays, since the communication apparatuses are developed toward miniaturization and modulization, many functions are integrated into a single IC module. In the above embodiments, the important electronic components to be shielded by the shielding case43and mounted on the printed circuit board44are for example IC modules441, as is shown inFIG. 5. For neat drawings, however, only an IC module is shown in the drawing and the other electronic components are omitted. An example of the IC module441is a high frequency generating IC module such as a baseband processor IC module, a power amplifier IC module, a transceiver IC module, a power management controller IC module or a memory IC module.

The process for assembling the handheld communication apparatus will be illustrated as follows in more details. Firstly, a printed circuit board44having an IC module441mounted thereon is provided, and the metal plate412and the shielding frame42are bonded together to form a shielding case43. Then, the IC module441is inserted into the second opening443of the shielding frame42to be shielded by the shielding case43, and the elastic sheets421of the shielding frame42are bonded to the ground wire442of the printed circuit board44. Afterward, the shielding case43is secured to the printed circuit board44by for example screwing or other fastening means. Due to the restoring force generated from the compressed elastic sheet421, a firm attachment between the shielding case43and the printed circuit board44is rendered. In such manner, since the IC module441is fully shielded by the shielding case43, the influence of electromagnetic interference (EMI) is minimized.

Please refer toFIGS. 6(a) and6(b), which are schematic cross-sectional views illustrating the packaging structures of the conventional handheld communication apparatus (having the contact-type EMI shielding case) and the handheld communication apparatus of the present invention, respectively. In the conventional handheld communication apparatus ofFIG. 6(a), the shielding cover311is also bonded onto a metallic insert molding member34. The distance between the electronic component33and the shielding cover311is h, and the height of the shielding cover311with respect to the circuit board32is h1. Likewise, in the present handheld communication apparatus ofFIG. 6(b), the distance between the electronic component441and the metal plate412of the metallic insert molding member41is also h. Under this circumstance, the height of the metal plate412with respect to the circuit board44is h2. In comparison with the shielding cover311, the height of the shielding case43is reduced by (h1−h2), for example in the range of from 0.15 to 0.20 mm. That is, the thickness of the handheld communication apparatus of the present invention is reduced.

The improved shielding case structure provided by the present invention, when comparing with other previous conventional technologies, has following advantages:

1. The handheld communication apparatus of the present invention has reduced thickness, as is described inFIGS. 6(a) and6(b).

2. Since the shielding case43is secured to the printed circuit board44by for example screwing or other fastening means without the need of using the surface mount technology, the assembling process of the present invention is simplified and labor-saving when compared with the conventional two-piece structure.

3. Like the conventional contact-type EMI shielding case, the shielding case43can be directly detached from the printed circuit board44by loosening the screws and thus the present invention is advantageous for inspecting or replacing the shielded electronic components.

4. Since the shielding case43is secured to the printed circuit board44by for example screwing or other fastening means without the need of using the surface mount technology, the costs associated with the surface mount technology are eliminated.

From the above description, by securing the shielding case43to the printed circuit board, the importance electronic components are shielded by the shielding case. In addition, since the height of the shielding case with respect to the circuit board is lowered, the thickness of the handheld communication apparatus of the present invention is reduced to meet the requirement of miniaturization. Moreover, the shielding case can be directly detached from the printed circuit board by loosening the screws and thus the present invention is advantageous for inspecting or replacing the shielded electronic components.