KR20060089466A - Mobile communication terminal with FPC with improved ground performance - Google Patents

Abstract

The present invention relates to a flexible printed circuit board (FPCB) that connects the upper body and the lower body in a mobile communication terminal having a lower body and an upper body, and more specifically, a ground of an FPCB. The present invention relates to a mobile communication terminal having an improved FPC ratio for improving the transmission / reception sensitivity of the antenna by enhancing the performance and at the same time preventing the performance degradation of the terminal due to electrostatic discharge.

In the present invention, in the mobile communication terminal in which the main board of the lower main body and the sub board of the upper main body are electrically and signally connected by the FPC ratio, the FPC ratio has both ends connected to the ground area of the main board and the subboard. And a ground substrate further connected to the ground, wherein an intermediate portion of the ground substrate is electrically branched to be grounded to an electromagnetic shielding coating layer applied to an inner surface of the case of the lower body. A mobile communication terminal having an FPC ratio with improved performance is provided.

FPC, Ground, Grounding, Static Electricity, Terminal, Mobile Phone, Main Board, Sub Board, Conductive Sheet

Description

Mobile communication terminal having FPCB enhanced ground ability}             

1 is a plan view showing an FPC lead wire structure in a general mobile communication terminal.

2A and 2B show a structure of a conventional general FPC, where FIG. 2A is a plan view of a separated state, and FIG. 2B is a cross-sectional view of a coupled state.

3 is an exploded perspective view showing the structure of the FPC in accordance with a preferred embodiment of the present invention.

Figure 4 is a perspective view showing a state in which the flexible conductive sheet is assembled in the FPC in accordance with the present invention.

5A to 5C are views illustrating a form in which a flexible conductive sheet is assembled to a case of a terminal according to the present invention. FIG. 5A is a plan view illustrating a state in which FPC is assembled before the main board is assembled. It is AA sectional drawing of FIG. 5A, FIG. 5C is sectional drawing which shows the state after a main board is assembled according to FIG. 5B.

<Explanation of symbols for the main parts of the drawings>

10: lower body

10a: Paint layer for EMI shielding

14: main board 14a: connector

20: upper body 24: sub board

30: FPCB 30a, 30b: junction

32: connector 34: connection pin

40,50,60: 1st, 2nd, 3rd layer substrate 40a, 50a, 60a: signal line

42,52,62,72 Insulation coating layer 70Ground substrate

70a: ground copper foil 72: insulation coating layer

80: copper foil exposed part 100: flexible conductive sheet

110: base material 111: first conductive adhesive portion

112: second conductive adhesive portion

The present invention relates to a flexible printed circuit board (FPCB) that connects the upper body and the lower body in a mobile communication terminal having a lower body and an upper body, and more specifically, a ground of an FPCB. The present invention relates to a mobile communication terminal having an improved FPC ratio for improving the transmission / reception sensitivity of the antenna by enhancing the performance and at the same time preventing the performance degradation of the terminal due to electrostatic discharge.

Mobile communication terminals such as mobile phones, portable wireless terminals, PDAs (Personal Digital Assistants), etc., are largely folded and folded terminals (folder type, rotary switch type, rotary type, swivel hinge type) according to the type of opening and closing of the upper body with respect to the lower body. Terminal) and a slide type terminal. The foldable terminal and the slide-type terminal agree with each other in that the upper body opens and closes in a different manner with respect to the lower body, but the upper body relatively moves with respect to the lower body.

As described above, in a mobile communication terminal in which a lower main body and an upper main body are physically divided and connected to each other in a relatively movable manner, electrical and signal connection between the lower main body and the upper main body is generally made by an FPC. .

The FPC is an electrical signal line is printed on a flexible thin plate-like substrate free of warpage and connects the lower body and the upper body to transmit signals and electricity.

For example, in the above mobile communication terminals, the lower main body is mainly provided with an input unit such as a key button for dialing or mode selection / execution, and a main board (main PC) for performing the overall functions of the terminal. The main body is mainly provided with an LCD screen and a sub board (sub PC) for driving the LCD screen. Accordingly, the FPC is electrically and signally connected to the main board of the lower body and the sub board of the upper body, and the lower body and the upper body are formed by their unique flexible properties even when the lower body and the upper body make relative opening and closing movements. It is easily bent at the connection of the main body.

FIG. 1 shows an example in which the above-mentioned FPC is applied to a typical folding cell phone (hereinafter, referred to as a "mobile communication terminal").

As shown in FIG. 1, the mobile communication terminal has a lower main body 10 and an upper main body 20 which is rotatably connected to the lower main body 10, and in the lower main body 10. The key buttons 12 and the main board 14 are provided, and the upper main body 20 has an LCD screen 22 (LCD) and a sub board 24 for driving thereof.

Here, the PCC 30 passes through the hinge parts 16 and 26 of the lower main body 10 and the upper main body 20, and both ends thereof have the main board 14 and the sub board 24, respectively. Is connected to. Specifically, it is connected to the main board 14 through a connector 32 provided on one side of the FPC 30, and is connected to the sub board 24 through the connecting pin portion 34 on the other side.

Particularly, the FPC 30 has the joints 30a and 30b at both ends thereof soldered to the main board 14 of the lower main body 10 and the sub board 24 of the upper main body 20, respectively. The ground pattern of the FPCB 30 is connected to the ground patterns of the main board 14 and the sub-board 24 through the junction parts 30a and 30b. Therefore, the ground patterns of the main board 14 and the sub board 24 which are physically separated are connected.

In addition, as described above, when the main board 14 and the sub board 24 are grounded by soldering both bonding portions 30a and 30b of the FPC 30, the static electricity penetrated from the outside (ESD: Electro-Static Discharge (DC) flows through the grounding circuit and disappears, thereby protecting various electrical elements of the main board 14 and the sub-board 24 from electrostatic discharge. In this case, the main board 14 and the sub-board 24 are respectively applied to the inner surface of the case of the lower body 10 and the inner surface of the case of the upper body 20 (Electro-Magetic Interference Shielding; EMI Shielding) It is electrically grounded to the paint layer, which eventually flows through it and disappears. At this time, the role of the electromagnetic wave shielding coating layer, the electromagnetic wave generated from the electrical, electronic components of the main board 14 or the sub-board 24 is blocked from being emitted to the outside, thereby protecting the terminal user from harmful electromagnetic waves It plays a role.

In addition, as described above, the main board 14 and the sub-board 24 are grounded by soldering the joints 30a and 30b of both ends of the FPC 30 to improve the transmission and reception sensitivity of the antenna to some extent. It works. That is, since the main board 14 of the lower main body 10 and the sub board 24 of the upper main body 20 which are physically separated from each other, and the PCC 30 connecting them, are composed of electrical circuits, Unavoidable electromagnetic waves from the air affect the radiation pattern of the antenna. Therefore, the transmission and reception sensitivity is improved by reducing the effect on the antenna by grounding both ends of the ground pattern of the FPC ratio 30.

However, since the ground pattern of the FPC 30 cannot be physically infinitely large, the effect of improving the transmission and reception sensitivity of the antenna remains at a very small level, and it is also difficult to stabilize the circuit from static electricity. That is, the ground (grounding) connection between the main board 14 of the lower main body 10 and the sub board 24 of the upper main body 20 is made only through the above-described ground pattern of the PC C. There is a certain limit to the performance improvement, the static electricity flow is not made smoothly, the damage of the components due to the static electricity or circuit shock occurs, the performance of the terminal is reduced.

In addition, if the soldering of both ends of the FPC 30 is not properly performed or if the soldering portion is dropped during use, the transmission / reception sensitivity may be deteriorated very much and it may be developed into a dangerous state in which it is difficult to protect the circuit from electrostatic discharge.

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems as described above, and an object of the present invention is to improve the transmission and reception sensitivity of the antenna by enhancing the FPC ratio ground performance, and at the same time can easily dissipate static electricity, the terminal by the electrostatic discharge To prevent performance degradation.

An object of the present invention described above is a mobile communication terminal in which a main board of a lower main body and a sub board of an upper main body are electrically and signally connected by an FPC ratio, wherein the FPC ratio has both ends of the main board and the subboard. It further comprises a ground substrate connected to the ground region of the ground substrate, the middle portion of the ground substrate is electrically connected to ground connected to the EMI shielding paint layer applied to the inner surface of the case of the lower body The ground performance is improved by providing a mobile communication terminal having an improved FPC ratio.

In the present invention described above, the structure in which the middle portion of the ground substrate is branched and connected to the ground for the electromagnetic interference shielding coating layer applied to the inner surface of the case of the lower main body, has a portion of the insulating coating layer on one side of the ground substrate. Removing and forming a copper foil exposed portion to expose the internal ground copper foil, it is preferable to implement by connecting the copper foil exposed portion and the electromagnetic wave interference shielding coating layer with a flexible conductive sheet.

Here, the flexible conductive sheet includes a conductive flexible substrate, the first surface for bonding to the copper foil exposed portion of the ground substrate and the electromagnetic wave shielding paint layer on the inner surface of the lower body of the terminal on one surface of the substrate; It is preferable that it consists of a sheet in which 2 electroconductive adhesive parts were formed.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Prior to describing the present invention in detail, first, the structure of a typical PCC 30 will be described with reference to FIGS. 2A and 2B.

FIG. 2A shows a plan view of the separated state of the FPC 30, and FIG. 2B shows a cross-sectional view of the coupled state.

As shown in FIG. 2A and FIG. 2B, in general, the FPC 30 has a multilayer structure in which circuits are dispersed and printed (patterned) into multiple layers in order to aggregate complex circuits in a small space, and each layer is laminated. Have.

In FIGS. 2A and 2B, the FPC 30 of the three-layer structure is illustrated as an example. The FPC 30 of the three-layer structure includes first, second, and third layer substrates 40, 50, and 60. Has Signal lines 40a, 50a, 60a are printed on the first, second, and third layer substrates 40, 50, 60, respectively, and on the surfaces of the substrates 40, 50, 60, respectively. Insulation coating layers 42, 52 and 62 are formed. Here, the FPC 30 has a three-layer structure, but may be formed of a two-layer structure, or may be formed of four or more layers.

In particular, the FPC 30 may have a form further including one or more ground substrates 70. This is an essential element for the implementation of the present invention described below. The ground substrate 70 is composed of a flexible ground copper foil 70a as a whole, and an insulating coating layer 72 is formed on the surface of the ground copper foil 70a. The ground substrate 70 serves to ground (ground) the main board and the sub board.

In addition, connecting pin parts 40b and 40c are formed at both ends of the first layer substrate 40, respectively, and connecting pin parts 40b of one side are connected to the sub-board of the upper body, and connecting pin parts of the other side ( 40c) is connected to the motherboard of the lower body.

In addition, at each end of each of the first, second, and third layer substrates 40, 50, 60, and the ground substrate 70, at least one joining groove 44 for soldering the sub board and the main board, respectively ( 54, 64, 74 are formed. The joining grooves 44, 54, 64, 74 are portions in which the copper foil is exposed without the insulating coating layers 42, 52, 62, and 72 being formed, and are electrically connected to each other when stacked. Finally, the ground is soldered to the main board and the sub board.

Accordingly, the FPC 30 stacks the first, second, and third layer substrates 40, 50, 60 and the ground substrate 70 described above, and then connects the connection pin portion 40b on one side of the subboard. It is connected to the connector, the connector is mounted on the other connecting pin portion 40c and connected to the connector of the main board, and connected to the sub board and the main board through the joining grooves 44, 54, 64 and 74. Is soldered.

3, 4 and 5a to 5c, a preferred embodiment of the present invention will be described.

In FIG. 3, the FPC 30 is formed by stacking the first to third layer substrates 40, 50, and 60 and the ground substrate 70 described with reference to FIGS. 2A and 2B. 70 is shown in an upward direction. In this way, the one end of the finished PCC 30 is formed with the above-described connection pin portion 40b (part number '34' in FIG. 1), and the other end of the connector 32 at the connection pin portion 40c in FIG. 2A. Has a mounted form. In addition, the grooves 44, 54, 64 and 74 for joining the first to third layer substrates 40, 50 and 60 and the ground substrate 70 are respectively joined portions 30a and 30b for soldering. ) Is achieved.

The present invention has a structure in which the copper foil exposed portion 80 is formed such that the inner ground copper foil 70a is exposed by removing a portion of the insulating coating layer 72 on one side of the ground substrate 70 of the FPC 30 as described above. Have And it has a structure which connected the flexible electroconductive sheet 100 adhering to the said copper foil exposed part 80. As shown in FIG. Therefore, in the present invention, by attaching the flexible conductive sheet 100 to the ground substrate 70, the ground circuit of the FPC 30 is bifurcated.

The flexible conductive sheet 100 is specifically, for bonding to a flexible substrate 110 made of a fiber or resin impregnated or contained with a conductive material, the copper foil exposed portion 80 of the FPC 30 The first conductive bonding portion 111 and the second conductive bonding portion 112 for bonding to the electromagnetic wave shielding coating layer on the inner surface of the lower main body of the terminal are formed. The flexible conductive sheet 100 is literally 'flexible' so that it is free to bend and 'conductive' to allow electricity.

The above-mentioned flexible conductive sheet 100 and the conductive adhesive parts 111 and 112 are well known in the art. Examples thereof include Korean Utility Model Registration Nos. 20-183237, 20-240355, 20-288899, 20-328855, Korean Patent No. 10-429282, and Korean Patent Publication No. 10- There are those disclosed in 2003-14349 and Patent Publication No. 10-2004-20948.

As shown in FIG. 4, the FPC 30 and the flexible conductive sheet 100 of the present invention made as described above are ground copper foils exposed through the copper foil exposed portion 80 of the FPC 30. Electrical connection to 70a).

5A through 5C illustrate the FPC 30 assembled to the case of the lower main body 10 and the upper main body 20 of the terminal through the flexible conductive sheet 100. Specifically, FIG. 5A is a plan view showing a state in which only the PCC 30 is assembled before the main board 14 is assembled. FIG. 5B is a cross-sectional view taken along line AA of FIG. 5A, and FIG. 5C. A cross-sectional view showing the state after the main board 14 is assembled according to 5b is shown.

As shown in FIGS. 5A to 5C, the second conductive adhesive portion of the flexible conductive sheet 100 having the first conductive adhesive portion 111 adhered to the copper foil exposed portion 80 of the FPC 30 described above ( With the 112 facing down, the lead is passed through the hinge portions of the lower body 10 and the upper body 20. Then, the one side connecting pin portion 34 of the FPC 30 is connected to the sub board 24, and the one side bonding portion 30b is soldered and connected.

Subsequently, as illustrated in FIGS. 5A and 5B, an electromagnetic interference (EMI) shielding paint layer coated with the second conductive adhesive part 112 of the flexible conductive sheet 100 on the inner surface of the case of the lower main body 10. Attach it to (10a) and ground it.

Subsequently, as shown in FIG. 5C, the main board 14 is mounted on the case of the lower main body 10, and then the connector 320 of the FPC 30 is connected to the connector 14a of the main board 14. Connect. Then, when the main board 14 side junctions 30a (see FIGS. 1 and 5a) of the FPCB 30 are soldered and connected to the main board 14, the electrical connection of the FPCB 30 is completed.

Here, the ground pattern (not shown) formed on the main board 14 is the electromagnetic wave interference (EMI) shielding coating layer 10a applied to the inner surface of the case of the lower main body 10 in the same manner as a general mobile communication terminal. Is connected to the ground through the rib portion (10b).

According to the present invention made as described above, the main board 14 of the lower main body 10 and the sub board 24 of the upper main body 20 which are physically separated from each other are joined portions 30a and 30b of the PCC 30. In addition to being grounded by soldering, the ground function is further enhanced by being grounded through the flexible conductive sheet 100 in the middle of the FPC.

That is, in the related art, the ground (grounding) connection between the main board 14 of the lower body 10 and the main board 24 of the upper body 20 is made only through the ground pattern of the FPC 30 described above. there was. Therefore, there is a certain limit to the ground performance of the FPCB 30 only, the static electricity flow was not made smoothly.

However, in the present invention, part of the insulating coating layer 72 on one side of the ground substrate 70 of the FPCB 30 is removed to expose the inner ground copper foil 70a, thereby exposing the exposed copper foil 80. The flexible conductive sheet 100 is adhered to the structure, and the flexible conductive sheet 100 is attached to the coating layer 10a for shielding electromagnetic interference (EMI) applied to the inner surface of the case of the terminal to connect the ground (ground). Has

Therefore, the ground is reinforced through the ground of the flexible conductive sheet 100, so that the static electricity generated in the process of using the terminal does not flow out through only the ground pattern of the FPCB 30, but is flexible. By flowing through and disappearing through the conductive conductive sheet 100, it is possible to effectively prevent damage to circuit components and generation of circuit shock by static electricity.

In addition, when the ground of the FPCB 30 is reinforced as described above, the electromagnetic wave generated from the FPCB 30 and the electrical components of the main board 14 and the sub-board 24 is reduced, thereby improving the transmission and reception sensitivity of the antenna. You can do it. When the ground is reinforced as in the present invention, it has been confirmed that the transmission and reception sensitivity is improved by about 4 dB in the 800 to 900 MHz band.

In the foregoing description, specific embodiments of the present invention shown in the accompanying drawings have been described in detail, but this is only an example and the protection scope of the present invention is not limited thereto. In addition, the embodiments of the present invention as described above can be variously modified and equivalent other embodiments by those of ordinary skill in the art within the technical spirit of the present invention, such modifications and equivalent other embodiments are It goes without saying that it belongs to the appended claims of the invention.

As described above, in the present invention, the ground connection between the main board of the lower main body and the sub board of the upper main body, which are physically separated from each other, has a structure in which a flexible conductive sheet is further connected in the middle of the FPC. Therefore, the ground function of the FPC is further enhanced, so that the transmission and reception sensitivity of the antenna can be improved and the performance degradation of the terminal due to the electrostatic discharge can be prevented.

Claims (3)

In the mobile communication terminal in which the main board of the lower body and the sub-board of the upper body are electrically and signally connected by FPC, The FPC ratio may further include a ground substrate having both ends connected to ground regions of the main board and the sub board. And a middle portion of the ground substrate electrically connected to a ground layer of the EMI shielding coating layer applied to an inner surface of the case of the lower body to improve ground performance. The method of claim 1, Branching the middle portion of the ground substrate to ground connection to the electromagnetic interference shielding coating layer applied to the inner surface of the lower body, Removing a portion of the insulating coating layer on one side of the ground substrate to form a copper foil exposed portion to expose the inner ground copper foil, and the copper foil exposed portion and the electromagnetic wave interference shielding coating layer is connected to the flexible conductive sheet. A mobile communication terminal having an FPC ratio with improved ground performance. The method of claim 2, The flexible conductive sheet, A conductive flexible substrate, wherein one surface of the substrate is provided with first and second conductive adhesive portions for adhering the copper foil exposed portion of the ground substrate and the electromagnetic wave shielding coating layer on the inner surface of the lower main body of the terminal; A mobile communication terminal having an FPC ratio with improved ground performance.

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