JP2000294332A - Jointed body of flexible wiring body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a jointed body of flexible wiring bodies free from deformation caused by heating for jointing flexible wiring bodies. SOLUTION: In a jointed body of flexible wiring bodies 1, flexible wiring bodies 2, 3 are jointed by ultrasonic welding. The flexible wiring bodies 2, 3 are layered products of base films 23, 33, conductors 22, 32, and cover films 21, 31, and provided with exposed parts 2a, 3a where parts of the base films are removed. Making the conductor abut on each other and superimposing the exposed parts together, an ultrasonic welding tip is applied to the cover film side for providing ultrasonic welding to the conductors and the exposed parts. Since ultrasonic welding is not accompanied by heat, it does not cause deformation or destruction. Thereby, reliability of the jointed parts, strength against bending, and workability are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a flexible wiring body such as a flexible flat cable and a flexible printed circuit. In particular, the present invention relates to a joined body formed by joining flexible wiring bodies.

[0002]

2. Description of the Related Art The above-mentioned flexible wiring body is, for example,
A laminate including a flexible resin base film, a substantially strip-shaped conductor that forms a conductive pattern by laying on the base film, and a cover film further bonded on the conductor. It is configured as a body.

In some cases, a single flexible wiring body is formed by joining a plurality of such flexible wiring bodies in a plane direction. For example, there is a case where an end of a flexible wiring body is configured as a connection part with a connector. In this case, the conductive pattern of the connecting portion is formed by arranging a plurality of conductors of a predetermined width and length at predetermined intervals, and these are determined to predetermined values, and have high precision. Must be formed. On the other hand, in a flexible wiring body that is a portion other than the connection portion, the conductor usually does not need to have such high precision, and preferably has a width and an interval corresponding to the conductive pattern. In addition to it,
It is difficult in practice to form a conductive pattern with high accuracy over the entire flexible wiring body. Therefore, the connecting portion and other portions are configured as a plurality of flexible wiring bodies having different specifications, and these are joined together to form one flexible wiring body.

[0004] Conventional joining methods for joining conductors of a flexible wiring body include a method using an anisotropic conductive film and a method of soldering. In the former method, the insulating film on one side of a part of the flexible wiring body is removed in advance to expose one surface of the conductor. An anisotropic conductive film is interposed between the exposed one surface of the conductor and the corresponding one surface of the counterpart conductor. In this state,
The anisotropic conductive film and the flexible wiring body are heated to connect the anisotropic conductive film and the conductor.

In the latter method, the insulating films on both sides of a part of the flexible wiring body are removed in advance to expose the entire periphery of the conductor. The exposed conductors are connected to each other via the solder that has been melted by heating. After the connection, the exposed conductor is covered again with an insulating film.

[0006]

However, these conventional joining methods have the following problems. That is, since any of the above-described methods involves heating during bonding, the heating may cause shrinkage or breakage of the insulating film. As a result, high-precision bonding cannot be performed. In any of the above methods, an intervening material exists between the conductors to be joined, for example, an anisotropic conductive film in the former method and a solder in the latter method. As a result, there is a concern that instability occurs in the joining state, and, for example, the conductor connection resistance value at the joining portion varies depending on the joining state.

Further, none of the above-mentioned methods has good workability of joining. In addition, the joint was weak against bending, and was insufficient compared with the non-joint. Then, an object of the present invention is to solve the above-mentioned technical problem and to provide a joined body of a flexible wiring body which is less likely to be deformed by heating during joining.

[0008]

In order to achieve this object, a bonded body of a flexible wiring body according to claim 1 is provided.
A pair of flexible wiring bodies having a pair of insulating films and a conductor sandwiched between these insulating films to form a conductive pattern are formed by removing a part of one insulating film and forming a conductive pattern with the other insulating film. The body and each having an exposed portion that is left, while the exposed portions are overlapped with each other to bring the conductors of the exposed portion into contact with each other,
At the joint where the exposed portions of the insulating films are respectively arranged on both sides sandwiching the conductors, in the joint where the flexible wirings are joined to each other, in the joint, the conductor of one flexible wiring and the other And the conductor of the flexible wiring body is ultrasonically welded to each other by high-frequency vibration acting over the exposed portion of the insulating film.

According to this configuration, if ultrasonic welding is used,
Since no heating is involved, there is no risk of deformation or breakage of the insulating film or the like due to heating. The joined body of the flexible wiring body according to claim 2 is the joined body of the flexible wiring body according to claim 1, wherein, at the joint portion, one of the flexible wiring bodies is located at a portion adjacent to the ultrasonically welded conductor. The insulating film at the exposed portion of the body and the insulating film at the exposed portion of the other flexible wiring body are ultrasonically welded to each other.

According to this configuration, since the insulating films can be collectively ultrasonically welded together with the conductor at the joint, there is no need to separately join the insulating films. The joined body of the flexible wiring body according to the third aspect is the second aspect.
In the joined body of the flexible wiring body according to the above, at the joint, at a portion between the ultrasonically welded conductor and the ultrasonically welded insulating film, the insulating film of one flexible wiring body and the other The flexible wiring body is characterized in that the interior surrounded by the insulating film and the conductor that is ultrasonically welded is filled with an adhesive applied to the insulating film.

[0011] According to this configuration, since the generation of the gap is prevented by the adhesive, the bonding portion is more firmly bonded than when there is a gap.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described.
This will be described in detail with reference to the accompanying drawings. FIG. 1 is a front sectional view of a joined body of a flexible wiring body according to an embodiment of the present invention. FIG. 2 is a side sectional view of the joined body of the flexible wiring body shown in FIG. The flexible wiring body 1 includes a plurality of flexible wiring bodies 2 and 3 as joining pieces.
Are joined together. Each flexible wiring body 2, 3
The exposed portion 2 exposing the conductors 22 and 32
a and 3a are respectively formed. Exposed parts 2a, 3a
These are superimposed on each other and joined by ultrasonic welding, so that the conductors 22 and 32 of the flexible wiring bodies 2 and 3 can conduct with each other.

The flexible wiring body 3 has a base film 33, a conductor 32 made of strip-shaped metal foil, and a cover film 31. The conductor 32 is sandwiched between the base film 33 and the cover film 31. And a laminate obtained by laminating them. The base film 33 and the cover film 31 are, for example, sheet members made of resin and have flexibility and insulating properties. The conductor 32 is formed on the base film 33 to form a conductive pattern. The conductive pattern is also formed on the above-mentioned exposed portion 3a.

In the exposed portion 3a, a part of the base film 33 as one insulating film is removed, and the cover film 31 and the conductor 32 as the other insulating film are left. Flexible wiring body 3 having exposed portion 3a
Is manufactured, for example, as follows.

A base film 33 is prepared. An adhesive (not shown) is applied to the upper surface, and is covered with release paper (not shown) thereon. A cut is made in the exposed portion of the base film 33 covered with the release paper. The release paper is removed leaving the portion to be exposed, and the adhesive is exposed on the base film 33. A conductor 32 is laid and adhered on this according to the conductive pattern. Further, a cover film 31 covers and adheres thereon. A hot melt adhesive (not shown) is applied to the lower surface (the surface on the base film side) of the cover film 31. The laminate composed of the base film 33, the conductor 32, the cover film 31, and the like is integrally joined by a known heating laminating apparatus. From the bonded laminate, the base film 3 at the above-mentioned cut portion
When 3 is removed, the trace of the removal becomes the exposed portion 3a.

The flexible wiring body 2 is also configured in the same manner as the flexible wiring body 3, and has the same base film 23, conductor 22, and cover film 2 as those described above.
1 and an exposed portion 2a is formed at the end.
The exposed part 2a of the flexible wiring body 2 and the exposed part 3a of the flexible wiring body 3 constitute a joint part 4.

At the joint 4, the conductors 22, 32 of the exposed portions 2a, 3a are brought into contact with each other while the conductors 22, 32 are in contact with each other.
The cover films 21 and 31 of the exposed portions 2a and 3a are respectively arranged on both sides sandwiching each other. At the joint 4, the conductors 22 and 32 and the cover film 21,
31 are joined together by ultrasonic welding.
That is, as shown in FIG. 2, in portions where the conductors 22 and 32 are present, the cover film 21 of the exposed portion 2 a of the flexible wiring body 2, the conductor 22, the conductor 32 of the exposed portion 3 a of the flexible wiring body 3, and The cover film 31
In this order, the conductors 22 and 32 are joined by ultrasonic welding in a state where the opposing surfaces 22a and 32a are along each other. Also, in the portion without the conductor adjacent to the portion where the conductors are welded, the facing surfaces 21a and 31a of the cover films 21 and 31 of the exposed portions 2a and 3a of the flexible wiring bodies 2 and 3 are connected to each other. Overlap and are joined by ultrasonic welding.

At the joint 4, the conductors 22, 3
2 and the cover films 21, 31
Is welded to the portion to be welded, the inside surrounded by the cover films 21 and 31 and the conductors 22 and 32 is filled with the hot melt adhesive 5 applied to the cover films 21 and 31. . Since the hot melt adhesive 5 is interposed between the conductor and the cover film and joined to each other, the hot melt adhesive 5 surrounds the ultrasonically welded portions of the conductors 22 and 32. As a result, the conductor 2
2, 32 are more securely joined.

Next, a joining method will be described. As shown in FIG. 3, a pair of flexible wiring bodies 2 and 3 having exposed portions 2a and 3a are prepared. The exposed portions 2a and 3a of both flexible wiring bodies 2 and 3 are overlapped with each other, and this is used as a work (see arrows). In particular, in the case of the work, the conductors 22, 3
The two conductors are brought into contact with each other so that the conductors extend in parallel with each other, and the conductors 22 and 32 are arranged inside, and the cover films 21 and 31 are arranged outside. This work is set between the anvil 51 of the ultrasonic welding machine 50 and the welding tip 52 (see FIG. 4).

A known ultrasonic welding machine 50 can be used. For example, the ultrasonic welding machine 50 generates an anvil 51 that supports the workpiece from below, a welding tip 52 that sandwiches the workpiece between the anvil 51, and a predetermined static pressure and a predetermined high-frequency vibration on the welding tip 52. And an actuator 53. The anvil 51 is fixed so that the anvil 51 and the welding tip 52 do not slip on the contact surface in contact with the workpiece. During ultrasonic welding,
The anvil 51 and the welding tip 52 are brought into contact with the back surfaces of the work cover films 21 and 31 (surfaces opposite to the side where the conductor is provided) so that the cover films 21 and 31 cover the conductors 22 and 32. Then, the work is sandwiched between the welding tip 52 and the anvil 51.

The actuator 53 vertically displaces the welding tip 52 by air pressure supplied from the outside. As a result, a static pressure acts on the work in the direction in which the work is held (vertical direction). Also, the actuator 53
Includes a vibrator that generates high-frequency vibration by high frequency from a drive circuit. The high frequency vibration is transmitted from the vibrator to the welding tip 52 via the horn 54, and acts in a direction (horizontal direction) orthogonal to the direction in which the work is held. Here, the above-mentioned static pressure and the magnitude and frequency of the high-frequency vibration are set so that the insulating films and the conductors at the exposed portions can be simultaneously ultrasonically welded.

As described above, the work is subjected to high frequency vibration in the horizontal direction while being pressed in the vertical direction, and the opposing surfaces of the exposed portions 2a and 3a of the work are ultrasonically welded to each other. At this time, the high frequency vibration acts on the contact surfaces 21a and 31a of the conductors 22 and 32 via the cover films 21 and 31 as well as the contact surfaces 21a and 31a of the cover films 21 and 31. As a result, the molecules and atoms on the contact surface come closer to each other, and the bonding is achieved.

As described above, according to the present embodiment, since heating is not performed at the time of joining by ultrasonic welding, shrinkage or breakage of an insulating film such as a cover film or a base film may occur due to heating. There is no. Therefore, the conductive pattern of the flexible wiring body can be bonded with high precision and easily, and the present invention can be applied to a case where the distance between the conductors is small and a case where the width of the conductor is narrow.

In particular, at the joint portion 4, the cover films 21, 3
1 can be ultrasonically welded together with the conductors 22 and 32, so that it is not necessary to separately join the cover films 21 and 31 together. As a result, heating for separate joining can be prevented, and deformation and breakage due to heating can be reliably prevented. This is because when a hot melt adhesive is used for joining the cover films, the joining involves heating.

Further, at the joint 4, the conductors 22,
32 and the cover films 21 and 3
Since the hot melt adhesive 5 is filled between the part 1 and the part to which the part 1 is welded, the occurrence of a gap in the joint part 4 is prevented. It is more firmly joined than when there is a gap. Also,
In the case of ultrasonic welding, the conductors 22 and 32 can be directly joined to each other, so that the conductor connection resistance value at the joint 4 is more stable than in the case of soldering or the joining method using an anisotropic conductive film. Therefore, a highly reliable joint can be easily obtained.

In addition, the ultrasonically welded joint portion 4 is strong against bending and can be hardly damaged. In particular, since the cover films 21 and 31 are arranged so as to surround the conductors 22 and 32 at the joint 4, the conductors are less likely to peel off from each other, so that the joint 4 can be further strengthened against bending.

Further, since the joint 4 is strong against bending, it is not necessary to pay attention so as not to break the joint among the flexible non-joined portions. For example, when the flexible wiring body 1 is manufactured or transported. Easier to handle. In addition, in the case of ultrasonic welding, the work is much easier and workability is remarkably improved as compared with the case of soldering. That is, the cover films and the conductors can be simultaneously ultrasonically welded together. In addition, at the time of ultrasonic welding, it is sufficient to apply high-frequency vibration through the cover film, so it is not necessary to remove both parts of the insulating film before welding, and without re-covering the conductor after welding. Only Further, since the cover film can support the conductor at the exposed portion, the conductors 22 and 32 are hardly displaced at the joint 4.

Further, as described above, since there is no risk of breakage at the time of joining, the production yield of the flexible wiring body is improved, and it is not necessary to strictly pay attention at the time of joining. Therefore, the flexible wiring body 1 as a joined body can be obtained at low cost. In addition, in the joint part 4, the conductors 22, 32
Are arranged in parallel with each other, but are not limited thereto. For example, they may extend in directions crossing each other in plan view. Also, conductors 22 and 32 having different widths and thicknesses may be joined.

In the above-described embodiment, a flexible wiring body in which a strip-shaped conductor is laid on a base film has been described. However, the present invention is not limited to this. In short, the present invention can be applied as long as the flexible wiring body has an insulating film and a conductor.
In addition, various design changes can be made without changing the gist of the present invention.

[0030]

According to the first aspect of the present invention, since there is no fear of deformation or breakage due to heating by ultrasonic welding, high precision and easy joining can be achieved. According to the second aspect of the present invention, the insulating films are also ultrasonically welded to each other, thereby eliminating the need for joining with heating, and making it possible to more reliably avoid deformation and breakage due to heating.

According to the third aspect of the present invention, the joint is firmly joined with the gap prevented by the adhesive.

[Brief description of the drawings]

FIG. 1 is a sectional view of a joined body of a flexible wiring body according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the joined body of the flexible wiring body shown in FIG. 1, showing a cross section different from FIG.

FIG. 3 is a perspective view of a flexible wiring body for explaining an outline of a joining method.

FIG. 4 is a schematic configuration diagram of an ultrasonic welding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible wiring body (joined body) 2, 3 Flexible wiring body 2a, 3a Exposed part 4 Joint part 5 Adhesive 23, 33 Base film (insulating film) 22, 32 Conductor 21, 31 Cover film (insulating film)

Continued on the front page (72) Inventor Tadakatsu Isobe 1-114, Nishisuehiro-cho, Yokkaichi-shi, Mie F-term in Sumitomo Wiring Systems Co., Ltd. (Reference) 5E077 BB32 CC02 DD03 DD04 JJ30 5E085 BB09 CC03 DD04 FF11 HH11 JJ50

Claims (3)

[Claims] 1. A pair of flexible wiring bodies having a pair of insulating films and a conductor forming a conductive pattern sandwiched between these insulating films, wherein one of the insulating films is partially removed and the other is a flexible wiring body. The insulating film and the conductor have respective exposed portions left, and the exposed portions are overlapped with each other so that the conductors of the exposed portion are in contact with each other, and the exposed portions are formed on both sides sandwiching the conductors. In the joint where the insulating films are respectively arranged, in the joint where the flexible wiring bodies are joined to each other, in the joint, the conductor of one flexible wiring body and the conductor of the other flexible wiring body are: A joined body of flexible wiring bodies, characterized in that they are ultrasonically welded to each other by high-frequency vibration acting through an insulating film on an exposed portion. 2. The joined body of flexible wiring bodies according to claim 1, wherein the joint portion is a portion adjacent to the ultrasonically welded conductor, and an insulating film at an exposed portion of one of the flexible wiring bodies; A joined body of flexible wiring bodies, wherein an exposed portion of the other flexible wiring body and the insulating film are ultrasonically welded to each other. 3. The joined body of a flexible wiring body according to claim 2, wherein the joint is a portion between one of the ultrasonically welded conductor and the ultrasonically welded insulating film, and one of the flexible joints. A flexible wiring body, characterized in that the inside surrounded by the insulating film of the wiring body, the insulating film of the other flexible wiring body, and the conductor that is ultrasonically welded is filled with an adhesive applied to the insulating film. Conjugate.