JP2003204151A - Connecting method between printed-wiring board and flexible printed-wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting method between a printed-wiring board and a flexible printed-wiring board that can maintain connection reliability for a long time even if stress is repeatedly applied to the flexible printed-wiring board. <P>SOLUTION: A printed-wiring board 21 and an FPC 22 are mutually connected via an ACF 7. Additionally, at a terminal section 22a of the FPC 22, an ACF 7a is bonded in a spare bonding region 18 at the side of a middle section 22b as compared with a bonding region 16 where the ACF is bonded. Contrarily, the ACF 7a is also bonded to a spare bonding region 17 of the printed-wiring board 21. As a result, the printed-wiring board 21 and the FPC 22 are bonded each other also by the ACF 7a, and a terminal 2a and a terminal 4a are connected mutually. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a printed wiring board built in an electric product or the like and a flexible printed wiring board, and particularly to the connection reliability in the case where a stress is repeatedly applied to the connection portion. The present invention relates to an improved method for connecting a printed wiring board and a flexible printed wiring board.

[0002]

2. Description of the Related Art Conventionally, a printed wiring board in an electric product and a flexible printed wiring board (hereinafter also referred to as an FPC) for connecting the wiring of the printed wiring board to other electric parts are connected via a connector. Was there. However, in recent years, electric products such as personal digital assistants have become thinner. Along with this, the electric components built into such electric products have become thinner, and for example, the electric components mounted on a printed wiring board have also become thinner. For this reason, recently, the connection between the printed wiring board and the FPC is often performed via an anisotropic conductive adhesive film (hereinafter, also referred to as ACF).

FIG. 5 is a plan view showing a printed wiring board, FIG. 6 is a plan view showing a flexible printed wiring board (FPC), and FIG. 7 is a conventional printed wiring board and FP.
FIG. 8 is a plan view showing a connecting method with C, and FIG. 8 is a sectional view taken along line AA ′ shown in FIG. 7. As shown in FIG. 5, a printed wiring board 11 is provided with a substrate 1 and a plurality of terminals 2 provided on the substrate 1. The terminal 2 has a rectangular shape, and each terminal 2 is arranged along the direction orthogonal to the longitudinal direction of the terminal 2 so that the longitudinal directions thereof are parallel to each other.
They are arranged at substantially equal intervals.

Further, as shown in FIG. 6, the FPC 12 is provided with a film 3 having plasticity and insulation,
A plurality of terminals 4 are formed on the film 3. The terminal 4 has a rectangular shape, and the terminals 4 are arranged at substantially equal intervals along a direction orthogonal to the longitudinal direction of the terminal 4 such that the longitudinal directions thereof are parallel to each other. Each terminal 4 is F
It is provided at a position such that when the PC 12 is adhered to the printed wiring board 11, the terminals 2 come into contact with each other. Further, the FPC 12 has an end portion 12a where the terminal 4 is formed.
And the other end (not shown) and an intermediate part 12b connecting the end 12a and the other end.
The width of a is larger than the width of the intermediate portion 12b. Wiring (not shown) for connecting the terminal 4 formed at the end 12a to the terminal formed at the other end is formed in the intermediate portion 12b. Further, an insulating film 5 is attached to a part of the end portion 12a and the entire intermediate portion 12b on the surface of the FPC 12 on the side where the terminals 4 are formed. The region where the insulating film 5 is attached to the end portion 12a is the boundary portion 6.

As shown in FIG. 7, a printed wiring board 11 is provided.
And the FPC 12 are connected by an anisotropic conductive adhesive film (A
CF) 7. The ACF 7 includes conductive particles 14 (see FIG. 8) on the insulating resin film 13 (see FIG. 8).
Are uniformly dispersed, conductivity is obtained in the thickness direction of the ACF 7, and insulation is maintained in the direction parallel to the surface of the ACF 7. Terminal 2 of printed wiring board 11
The ACF 7 is bonded to a part of the FPC 12 and the terminal 4 of the FPC 12. The ACF 7 has its one surface adhered to the surface of the printed wiring board 11 and the other surface adhered to the surface of the FPC 12, thereby adhering the printed wiring board 11 to the FPC 12 and Each terminal 2 is connected to each terminal 4 of the FPC 12, respectively.

However, this conventional connection method has the following problems. In the case where the bonded body of the printed wiring board 11 and the FPC 12 shown in FIG. 7 is arranged in a working part of an electric product or the like, the stress 8 is repeatedly applied to the FPC 12 as shown in FIG. At this time, the stress 8 is repeatedly applied to the joint portion between the printed wiring board 11 and the FPC 12, and the ACF 7 is peeled off from the printed wiring board 11 or the FPC 12, or the AC is removed.
There is a possibility that F7 may cause fatigue damage and the FPC 12 may be separated from the printed wiring board 11 to disconnect the terminals 2 and 4. Therefore, the printed wiring board 11
The connection reliability between the FPC 12 and the FPC 12 becomes low.

In Japanese Patent Laid-Open No. 11-109397, for the purpose of preventing the flexible printed wiring board from peeling off from the printed wiring board when an external force acts on the bonded portion between the flexible printed wiring board and the printed wiring board. A technique is disclosed in which adhesive portions are provided on both sides of a printed wiring board and a terminal formation region of the flexible printed wiring board in a direction orthogonal to the longitudinal direction of the flexible printed wiring board.

[0008]

However, the above-mentioned conventional technique has the following problems. As described above, in JP-A-11-109397, the adhesive portions are provided on both sides of the printed wiring board and the terminal formation region of the flexible printed wiring board in the direction orthogonal to the longitudinal direction of the flexible printed wiring board. Therefore, the stress is dispersed and the stress applied to the adhesive portion between the flexible printed wiring board and the printed wiring board is reduced, so that the adhesive portion can be reinforced to some extent, but is repeatedly applied to the FPC 12 shown in FIG. At least part of the stress 8 is caused by the printed wiring board 11 and the FPC.
It cannot be prevented from being applied to the bonding portion with 12. Therefore, when the stress 8 is repeatedly applied to the FPC 12, the stress 8 is repeatedly applied to the adhesive portion,
Eventually, the ACF 7 causes fatigue failure, the FPC 12 is peeled off from the printed wiring board 11,
The terminal 2 and the terminal 4 of the flexible printed wiring board 12 are disconnected.

The present invention has been made in view of the above problems, and a flexible printed wiring board and a flexible printed wiring board can maintain connection reliability for a long period of time even when stress is repeatedly applied to the flexible printed wiring board. An object is to provide a method of connecting to a printed wiring board.

[0010]

A method of connecting a printed wiring board and a flexible printed wiring board according to the present invention comprises:
The first terminal formed on the surface of one end of the flexible printed wiring board and the second terminal formed on the surface of the printed wiring board are electrically connected to each other by bonding an anisotropic conductive adhesive film to each other. Along with the connection, the flexible printed wiring board and the printed wiring board are adhered to each other in another area that is displaced from the connection area to the other end side of the flexible printed wiring board.

In the present invention, the flexible printed wiring board and the printed wiring board are adhered to each other in the other area to preliminarily adhere the flexible wiring board and the printed wiring board. As a result, the flexible printed wiring board is fixed to the printed wiring board at this pre-bonded portion. As a result, the stress applied to the flexible printed wiring board causes the adhesive portions of the first and second preliminary adhesive regions (hereinafter referred to as the preliminary adhesive portions).
Therefore, it is possible to prevent the stress from being applied to the connection portion between the first terminal and the second terminal. As a result, it is possible to prevent the anisotropic conductive adhesive film from causing fatigue damage at this connection portion, and it is possible to prevent the flexible printed wiring board from peeling off from the printed wiring board.
Thereby, the connection reliability between the printed wiring board and the flexible printed wiring board can be improved.

Further, the first terminal and the second terminal are
An anisotropic conductive adhesive film is bonded between the flexible printed wiring board and the printed wiring board, and the first terminal and the second terminal are extended to the other area. Electrical connection is preferable.
As a result, the contact area between the first terminal and the second terminal is increased, and the contact resistance value between both terminals is reduced.

Further, when viewed from a direction perpendicular to the surface of the printed wiring board, the side edge of the anisotropic conductive adhesive film for adhering the flexible printed wiring board and the printed wiring board in the other area is It may be along a side edge of the flexible printed wiring board. As a result, it is possible to prevent the adhesive surface of the anisotropic conductive adhesive film from being exposed and the exposed portion from adhering to another electric component or the like.

Further, the adhesion of the other area can be performed by using a thermoplastic tape. As a result, a tape having high adhesive strength can be used, and the strength of the pre-bonded portion can be further improved.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. First, a first embodiment of the present invention will be described. FIG. 1 is a plan view showing a method of connecting a printed wiring board and an FPC according to this embodiment. Note that among the constituent elements shown in FIG. 1, the same constituent elements as those shown in FIG. 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, in this embodiment,
The terminals 2a of the printed wiring board 21 and the terminals 4a of the flexible printed wiring board (FPC) 22 are connected to each other. In the printed wiring board 21, the board 1 is provided, and a plurality of terminals 2 a are provided on the board 1. The terminals 2a have a rectangular shape, and the terminals 2a are arranged at substantially equal intervals along a direction orthogonal to the longitudinal direction such that their longitudinal directions are parallel to each other. Terminal 2a
7 is longer than the length of the terminal 2 shown in FIG. 7 in the longitudinal direction.

Further, the FPC 22 is provided with a film 3a having plasticity and insulating properties, and a plurality of terminals 4a are formed on the surface of the film 3a. Each terminal 4a has a rectangular shape and is arranged at substantially equal intervals along a direction orthogonal to the longitudinal direction so that the longitudinal directions thereof are parallel to each other. The length of the terminal 4a in the longitudinal direction is
The terminal 4a is longer than the longitudinal length of the terminal 4 shown in FIG. 7, and each terminal 4a is provided at a position where each terminal 4a abuts when the FPC 22 is bonded to the printed wiring board 21. Further, the FPC 22 includes an end portion 22a on which the terminal 4a is formed, the other end portion (not shown), and an intermediate portion 22b that connects the other end portion and the end portion 22. The width of 22a is larger than the width of the intermediate portion 22b. Further, the terminal 4a of the FPC 22 of this embodiment is
Since the length in the longitudinal direction is longer than that of the terminal 4 of the conventional FPC 12 shown in FIG. 7, the length of the end portion 22a is equal to that of the end portion 12a (see FIG.
(See) is longer than the length. Furthermore, in the intermediate portion 22b, the terminal 4a formed at the end portion 22a is
Wiring (not shown) connected to a terminal formed at the other end of C22 is formed. Further, the end 22a on the surface of the FPC 22 on the side where the terminals 4a are formed
The insulating film 5 is adhered to a part of the above and the entire intermediate portion 22b. The region where the insulating film 5 is attached to the end portion 22a is the boundary portion 6.

The printed wiring board 21 and the FPC 22 are
It is connected via the ACF 7. Further, in the terminal portion 22a of the FPC 22, the other area deviated to the intermediate portion 22b side from the adhesion area 16 to which the ACF 7 is adhered is a preliminary adhesion area 18, and the preliminary adhesion area 18 is provided.
ACF 7a is adhered to. ACF7a is AC
It is arranged parallel to F7. Also, ACF7a
Is also adhered to the surface of the printed wiring board 21, and the area on the surface of the printed wiring board 21 to which the ACF 7a is adhered is the preliminary adhesion area 17. In this way, the printed wiring board 21 and the FPC 22 are also bonded by the ACF 7a, and the terminals 2a and 4a are connected to each other. The ACFs 7 and 7a are adhered to the printed wiring board 21 and the FPC 22 by pressure bonding, for example. A portion where the preliminary bonding area 17 of the printed wiring board 21 and the preliminary bonding area 18 of the FPC 22 are bonded to each other by the ACF 7a is the printed wiring board 21 and the FP.
It becomes a pre-bonded part with C22.

As described above, according to the method of connecting the printed wiring board 21 and the FPC 22 according to this embodiment, the lengths of the terminals 2a of the printed wiring board 21 and the terminals 4a of the FPC 22 in the longitudinal direction are longer than those in the conventional case. Then, the printed wiring board 21 and the FPC 22 are bonded by the ACF 7,
The ACF7 is located closer to the intermediate portion 22b of the FPC 22 than the ACF7.
a is provided, and the printed wiring board 21 and the FPC 22 are also bonded by this ACF 7a. As a result, the printed wiring board 21 and the FPC 22 have two ACFs (ACFs).
7 and 7a), the bonding strength is higher than that of the conventional bonding method shown in FIG.
Moreover, the contact resistance value between the terminals 2a and 4a can be reduced. Furthermore, when the stress 8 (see FIG. 7) is repeatedly applied to the FPC 22, the stress 8 is ACF.
It is applied to the pre-bonded portion between the printed wiring board 21 and the FPC 22 by 7a. Therefore, the stress 8 is not applied to the bonded portion between the printed wiring board 21 and the FPC 22 by the ACF 7. As a result, it is possible to prevent the ACF 7 from causing fatigue damage, and it is possible to prevent the FPC 22 from being separated from the printed wiring board 21 at the bonded portion.
Although the stress 8 is applied to the pre-bonded portion, even if the FPC 22 is peeled off from the printed wiring board 21 at this pre-bonded portion, the contact portion is formed by the ACF 7 bonded portion between the printed wiring board 21 and the FPC 22. The connection between 2a and terminal 4a is ensured. Therefore, the joined body of the printed wiring board 21 and the FPC 22 of this embodiment has high connection reliability.

Next, a second embodiment of the present invention will be described. FIG. 2 is a printed wiring board and an FPC according to this embodiment.
FIG. 3 is a plan view showing a method of connecting with, and FIG.
It is a -A 'sectional view. Note that, of the constituent elements shown in FIGS. 2 and 3, the same constituent elements as those shown in FIGS. 7 and 8 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIGS. 2 and 3, in this embodiment, as compared with the conventional connection method shown in FIGS. 7 and 8, the end portion 10 of the printed wiring board 11 and the root portion 9 of the FPC 12 are compared. That is, the middle portion 12b of the FPC 12 and the portion near the end portion 12a are bonded via the ACF 7b. As a result, the terminal 2 of the printed wiring board 11 and the FP
The terminal 4 of C12 is connected to each other. Other than the above, the connection method of the present embodiment is the same as the above-described conventional connection method.

In this embodiment, the printed wiring board 1
By adhering the end portion 10 of No. 1 and the root portion 9 of the FPC 12 with the ACF 7b, a pre-bonded portion is formed between the end portion 10 of the printed wiring board 11 and the root portion 9 of the FPC 12 and is applied to the FPC 12. The stress is applied to this pre-bonded portion. As a result, it is possible to prevent the stress from being applied to the bonding portion between the printed wiring board 11 and the FPC 12 by the ACF 7, and improve the connection reliability between the printed wiring board 11 and the FPC 12. Also, in comparison with the first embodiment described above,
A smaller amount of ACF can form the prebonded portion. Further, the printed wiring board 11 and the FPC 12
As the conventional printed wiring board and the FPC, the same one can be used. Therefore, compared with the first embodiment described above, the printed wiring board and the FPC can be more simply and easily.
The connection reliability between and can be improved.

Next, a third embodiment of the present invention will be described. FIG. 4 is a printed wiring board and an FPC according to this embodiment.
It is a top view which shows the connection method with. Note that among the constituent elements shown in FIG. 4, the same constituent elements as those shown in FIG. 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 4, in this embodiment,
The printed wiring board 11 and the FPC 12 are bonded by the ACF 7c. The side edge of the ACF 7c is FPC1.
The second end portion 12a is formed in a shape along a side edge of a region other than the adhesion region 16 and a part of a side edge of the intermediate portion 12b. In this embodiment, the FPC1
The insulating film 5 is not attached to the area of the surface of No. 2 where the ACF 7c is adhered. The connection method of this embodiment other than the above is the same as the conventional connection method shown in FIG.

In this embodiment, by the ACF 7c,
By forming a pre-bonded portion between the printed wiring board 11 and the FPC 12, the stress applied to the FPC 12 is
It is possible to prevent the ACF 7 from being applied to the bonding portion between the printed wiring board 11 and the FPC 12, and improve the connection reliability between the printed wiring board 11 and the FPC 12. Further, as described above, by making the shape of the ACF 7c such that the side edge is along the side edge of the FPC 12, it is possible to prevent the adhesive surface of the ACF from being exposed,
It is possible to prevent the exposed portion of the ACF from adhering to another electric component or the like.

In the first to third embodiments described above, the pre-adhesion region is formed by the anisotropic conductive adhesive films (ACF 7a, 7b and 7c), but the present invention is not limited to this. Alternatively, the pre-bonded area may be formed by a thermoplastic reinforcing tape. This makes it possible to further increase the adhesive strength in the preliminary adhesive area. In addition, in the above-mentioned first to third embodiments, 1
Although the example in which the pre-bonded region is formed by one sheet of ACF is shown, in the present invention, the pre-bonded region may be formed by two or more sheets of ACF and / or thermoplastic reinforcing tape. When the preliminary bonding area is formed by two or more ACFs, bonding between the printed wiring board and the FPC is performed by a total of three or more ACFs. In addition to the board, a conductor, a solder resist, silk or the like may be arranged in the pre-bonded area on the surface of the printed wiring board.

[0027]

As described in detail above, according to the present invention,
When connecting the printed wiring board and the flexible printed wiring board, a stress was applied to the FPC by providing a preliminary bonding area on the intermediate side of the FPC with respect to the conventional bonding area, in addition to the conventional bonding area. In this case, this stress can be prevented from being applied to the adhesive region, and the FPC can be prevented from peeling off from the printed wiring board in the adhesive region. As a result, the connection reliability between the printed wiring board and the flexible printed wiring board can be maintained for a long period of time.

[Brief description of drawings]

FIG. 1 is a plan view showing a method of connecting a printed wiring board and an FPC according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a method for connecting a printed wiring board and an FPC according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along the line A-A ′ shown in FIG.

FIG. 4 is a plan view showing a method of connecting a printed wiring board and an FPC according to a third embodiment of the present invention.

FIG. 5 is a plan view showing a printed wiring board.

FIG. 6 is a plan view showing a flexible printed wiring board (FPC).

FIG. 7 is a plan view showing a conventional method for connecting a printed wiring board and an FPC.

8 is a cross-sectional view taken along the line A-A ′ shown in FIG.

[Explanation of symbols]

1; Substrate 2, 2a, 4, 4a; Terminal 3, 3a; Film 5; Insulating film 6; Boundary 7, 7a, 7b, 7c; Anisotropic conductive adhesive film (AC
F) 8; Stress 9; Root portion 10 of FPC 12; End portions 11 and 21 of printed wiring board 11; Printed wiring boards 12 and 22; Flexible printed wiring boards (FPC) 12a and 22a; End portions 12b and 22b; Intermediate portion 13; Insulating resin film 14; Conductive particles 15 and 16; Adhesion regions 17 and 18; Pre-adhesion region

Claims (7)

[Claims] 1. An anisotropic conductive adhesive film is bonded between the first terminal formed on the surface of one end of the flexible printed wiring board and the second terminal formed on the surface of the printed wiring board. By connecting electrically,
A flexible printed wiring board and a flexible printed wiring board, wherein the flexible printed wiring board and the flexible printed wiring board are bonded to each other in a region other than the connection region, which is displaced to the other end side of the flexible printed wiring board. How to connect with. 2. The first terminal and the second terminal extend to the other area, and the other area is provided between the flexible printed wiring board and the printed wiring board to form an anisotropic conductive adhesive film. The method for connecting a printed wiring board and a flexible printed wiring board according to claim 1, wherein the first terminal and the second terminal are electrically connected to each other while being bonded. 3. The second terminal is connected to the first terminal in the connection area.
Characterized in that the flexible printed wiring board and the printed wiring board are adhered to each other by adhering another anisotropic conductive adhesive film to the other region in parallel with the anisotropic conductive adhesive film for connecting terminals. The method for connecting a printed wiring board according to claim 1 and a flexible printed wiring board. 4. The side edge of the anisotropic conductive adhesive film for adhering the flexible printed wiring board and the printed wiring board in the other area when viewed from a direction perpendicular to the surface of the printed wiring board, The method for connecting a printed wiring board and a flexible printed wiring board according to claim 2 or 3, wherein the flexible printed wiring board is provided along a side edge of the flexible printed wiring board. 5. The method of connecting a printed wiring board and a flexible printed wiring board according to claim 1, wherein the other area is bonded by a thermoplastic tape. 6. A side edge of a thermoplastic tape for adhering the flexible printed wiring board and the printed wiring board in the other area when viewed from a direction perpendicular to a surface of the printed wiring board has a side edge of the flexible printed board. The method for connecting a printed wiring board and a flexible printed wiring board according to claim 5, wherein the method is provided along a side edge of the wiring board. 7. The width of the one end portion of the flexible printed wiring board is larger than the width of the flexible printed wiring board on the other end portion side, and the other region is the one end portion and other portions. The method for connecting a printed wiring board and a flexible printed wiring board according to any one of claims 1 to 6, which is a region that extends over a part of the end side.