JP2003133678A - Connection structure of flexible board and printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide connection structure capable of connecting a flexible board to printed boards without using new equipment and reducing the area for mounting a connector for their connection. SOLUTION: In the connection structure capable of mutually connecting the printed boards on which electric parts are mounted through the flexible board, the flexible board (2nd flexible board 101) is held between the printed board (1st printed board 2) and an electric part (CSP 4). Thus, the flexible board can be connected to the printed boards without using new equipment, and the area for mounting the connector for their connection can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for connecting a flexible board and a printed wiring board, and in particular, it is possible to connect the flexible board and the printed wiring board without using new equipment, and a connector for connection. The present invention relates to a connection structure between a flexible board and a printed wiring board, which can reduce the area for mounting the circuit board and can improve a portion where it is difficult to route the lower surface and surrounding electric circuits for mounting an IC or a module board. .

[0002]

2. Description of the Related Art Mobile mobile devices typified by mobile phones have become more and more foldable in order to increase the size of a display screen, protect it, and improve portability (for example,
i-mode N503i). Therefore, the structure of the mobile portable device is divided into two parts with the bending part as a joint, and it is common to use a flexible substrate to electrically connect the circuits of each part. There is.

Here, as a conventional method for electrically connecting a flexible substrate and a printed wiring board, there are the following methods. A connecting method using a connecting connector reflow-soldered to a printed wiring board (see FIG. 7, which will be described later). A method of connecting to a printed wiring board by a method different from reflow soldering. For example, a method of applying solder plating or the like to a flexible board and bringing them into close contact with each other by heat and pressure, and a connection method of hand soldering. A connection method in which flexible boards are laminated simultaneously when manufacturing printed boards.

[0004]

However, the conventional connecting methods using a flexible substrate have the following drawbacks. As shown in FIG. 7 of the above-mentioned drawback, in order to mount the first connector 1 for connection, it is necessary to secure an extra mounting area in the first printed wiring board 2. In addition, it is necessary to insert the first flexible board 3 into the first connector 1. Here, 4 is CSP (Chip Size Package), 5
Is a second printed wiring board, 6 is a second connector, and 7 is I
Electrical components such as C (integrated circuit) and module substrate.

In addition to the equipment for soldering various electric components to the first and second printed wiring boards 2 and 5 described above, the first flexible substrate 3 and the first and second printed wiring boards 2 and 5 are used. Different equipment is required for crimping in different ways. In this case, of course, in FIG. 7, the first connector 1 and the second connector 6 are unnecessary.

The above drawback is a special construction method for a manufacturer of a printed wiring board that supplies a printed wiring board to a manufacturer of finished mobile handheld devices, resulting in an increase in cost. The same applies to manufacturers of flexible substrates. To summarize the above-mentioned disadvantages, it is necessary to secure a mounting area and to newly prepare equipment for connection, and it is possible to achieve miniaturization and price reduction, which are the trends of mobile mobile devices. It becomes an obstacle.

[0007] In addition, since mobile mobile devices of recent years are becoming multifunctional and highly functional, in addition to the increase in the number of wires included in the flexible substrate connecting the electric circuits of the two folding parts, In addition to the above-mentioned board, the number of cases in which a sub-board is also provided is increasing, and there is a tendency that the connectors used for electrically connecting these are also large and many are used, and the miniaturization of devices is being hindered. At the same time, as the number of IC electrode pins and the pitch between the electrodes are narrowed as the scale of the IC increases as the equipment becomes more multifunctional and higher in function, the routing density of the electrical wiring when electrically connecting to the printed wiring board side is IC mounted. It is becoming higher on the lower surface and the surrounding area, and it is becoming difficult to route the wiring.

Therefore, an object of the present invention is to connect a flexible board and a printed wiring board without using new equipment, and to reduce the area for mounting a connector for connection, and to further reduce the size of the IC or module board. It is an object of the present invention to provide a connection structure between a flexible board and a printed wiring board, which can improve a portion of the lower surface and surrounding electric circuits where it is difficult to route for mounting.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for connecting a printed wiring board on which electrical parts are mounted,
In a connection structure of a flexible board and a printed wiring board which are mutually connected by a flexible board, the flexible board is sandwiched between the printed wiring board and an electric component.

In this way, for example, as shown in FIG.
As shown in (B) and FIG. 4, the flexible board and the printed wiring board can be connected without using new equipment, and the area for mounting a connector for connection can be reduced. It becomes possible to improve the part where it is difficult to lay out the lower surface and the surrounding electric circuit for the mounting.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the illustrated embodiments. Note that the same reference numerals are given to the parts that have already been described, and duplicate description will be omitted. (1) First Embodiment FIG. 1A is a side sectional view of this embodiment, and FIG. 1B is a plan view. As shown in FIGS. 1A and 1B, the second flexible substrate 101 is provided on the first printed wiring board 2 by C
The structure is sandwiched between the solder connection portions 102 of SP4 to ensure electrical connection. As is apparent from a comparison between FIG. 7 and FIG. 1B, the first flexible substrate 3
(FIG. 7) and the second flexible substrate 101 (FIG.
Although the size of (B) is different, the number of wiring patterns is the same (in this case, four patterns). That is, the first and second
Transmission and reception of electric signals between the printed wiring boards 2 and 5 are ensured. Further, in FIG. 1B, the first connector 1 shown in FIG. 7 is unnecessary. Therefore, it is not necessary to secure an extra mounting area in the first printed wiring board 2 for mounting the first connector 1.

FIG. 2 is an enlarged view of the solder connection portion sandwiched between the first printed wiring board 2 and the CSP 4 shown in FIG. 1 (A). As shown in FIG. 2, the solder 103 passes through the hole 2c provided in the second flexible substrate 101,
The first land 2a of the printed wiring board 2 of 1 is electrically connected, and at the same time, the second land provided on the outer periphery of the hole 2c is provided.
The land 2b is also soldered.

FIGS. 3A to 3C are shown in FIGS.
This is a step for realizing the connection structure shown in FIG.
In FIG. 3A, cream solder 104 is printed on the first land 2a provided on the first printed wiring board 2, and after mounting the second flexible substrate 101 in FIG. 3B,
The CSP 4 having the solder ball electrodes 4a is mounted, and as shown in FIG.
By reflow heating in (C), the second flexible substrate 101 and the CSP 4 are soldered to the first printed wiring board 2.

The electrical operation of this embodiment will be described below.
As shown in FIGS. 1A and 1B, the second flexible substrate 101 is sandwiched between the first printed wiring board 2 and the solder connection portion 102 of the CSP 4 to obtain an electrical connection. Here, the solder connection portion 102 is composed of the solder ball electrode 4a. The electrical connection in the present invention is intended for any circuit design. For example, the electric signal from the first printed wiring board 2 passing through the solder connection portion 102 is CS
A timely calculation is performed in P4, and an electric signal indicating the calculation result is returned to the first printed wiring board 2 through the connection portion 105 and is also transmitted to the second flexible substrate 101, and the second It is transmitted to the second printed wiring board 5 via the connector 6. Further, for example, an electric signal enters the connection portion 105 from the wiring pattern of the first printed wiring board 2,
The second flexible substrate 1 is not calculated in the CSP 4
It may be transmitted only to the circuit 01.

(2) Second Embodiment As shown in FIG. 4, there are cases where wiring other than the land pattern cannot be routed directly under the CSP 4 due to the wiring pattern of the third printed wiring board 106. In such a case, it is possible to electrically connect to another area of the same substrate (third printed wiring board 106) via the second flexible substrate 101 and the second connector 6 as shown in the figure. That is, the second flexible substrate 101 can be used to form a two-story wiring pattern, and it is possible to avoid the difficulty of routing the wiring described in the prior art (paragraph number 0007). In this case, the second
Instead of using the connector 6, the left and right connection terminals of the second flexible substrate 101 may be electrically connected to the corresponding terminals of the third printed wiring board 106 by, for example, thermocompression bonding.

(3) Third Embodiment As shown in FIG. 5, the first embodiment and the second embodiment may be carried out simultaneously. That is, in FIG. 5, the second flexible printed circuit board 5 and the third printed wiring board 5 are connected by the second flexible substrate 101.
When connecting the printed wiring board 106 and CSP4 of
This corresponds to the first embodiment, and the case where the CSP 4 and the third connector 108 are connected by the third flexible substrate 107 corresponds to the second embodiment. Moreover, by sandwiching the second flexible substrate 101 under all the electrodes of the CSP 4 used as shown in FIG. 5, it is possible to make the soldering conditions uniform and stabilize the soldering quality.

(4) Fourth Embodiment As shown in FIG. 6, the structure for sandwiching and electrically connecting the second flexible substrate 101 is not limited to a component having a solder ball electrode in a CSP or the like and an arbitrary electrode 110. But it's okay. Further, instead of being sandwiched by the electric parts, the mounting board 109 having the electric parts 7 mounted thereon may be connected.

In the above-described embodiment, the case of the CSP mainly including the solder ball electrode has been described, but the present invention can be applied to any member that can withstand the strength at the time of crimping (corresponds to the fourth embodiment). Of course it is.

[0019]

As described above, according to the present invention, the following effects can be exhibited. No mounting area is required to mount the connector. No separate equipment is needed to connect the flexible board. Electrical connection is possible at the cost of conventional member level.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention,
(A) is a side sectional view and (B) is a plan view.

FIG. 2 is a printed wiring board and CSP shown in FIG.
It is an enlarged view of the solder connection part sandwiched between.

3A to 3C are process diagrams for realizing the connection structure of the first embodiment.

FIG. 4 is a plan view of the second embodiment.

FIG. 5 is a plan view of the third embodiment.

FIG. 6 is a plan view of the fourth embodiment.

FIG. 7 is a plan view of a conventional example.

[Explanation of symbols]

1 first connector 2 First printed wiring board 2a First land 2b Second land 2c hole 3 First flexible substrate 4 CSP 4a solder ball electrode 5 Second printed wiring board 6 Second connector 7 electrical components 101 second flexible substrate 102 Solder connection part 103 solder 104 cream solder 105 connection 106 Third printed wiring board 107 third flexible substrate 108 Third Connector 109 mounting board 110 electrodes

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Claims (6)

[Claims] 1. In a connection structure of a flexible board and a printed wiring board, wherein printed wiring boards on which electric parts are mounted are mutually connected by a flexible board, wherein the flexible board is sandwiched between the printed wiring board and the electric parts. A connection structure between a flexible substrate and a printed wiring board, which is characterized in that 2. The connection structure between a flexible board and a printed wiring board according to claim 1, wherein the electrical components, the flexible board and the printed wiring board are electrically connected to each other by soldering. 3. The connection structure between a flexible board and a printed wiring board according to claim 2, wherein the electric component is provided with a solder ball electrode on a connection surface side with the flexible board. 4. The connection structure between a flexible board and a printed wiring board according to claim 1, wherein the electrical components, the flexible board and the printed wiring board are electrically connected to each other by pressure bonding. 5. The flexible board according to claim 1, wherein the electric component, the flexible board, and the printed wiring board are members for mobile portable devices. Printed wiring board connection structure. 6. A flexible board and a print, wherein when the wiring patterns of electric components mounted in the same printed wiring board are laid out, the wiring pattern of the printed wiring board is laid out by the wiring pattern of the flexible board. Wiring board connection structure.