JPH05290945A - Connecting method for film type circuit body using laser deposition - Google Patents

Abstract

(57) [Abstract] [Purpose] In a connection method for connecting a film-shaped circuit body and an external connection terminal, a land portion of the film-shaped circuit body and an external connection terminal are not soldered and a welding portion by laser welding is used. The purpose of the present invention is to prevent evaporation and scattering of a nearby insulating substrate and ensure reliable and stable welding. [Structure] A film-shaped circuit body 4 having a land portion 4a and a non-conductor portion 4b provided on a film-shaped substrate 4c is provided on an insulating substrate 1. At the base end of the contact piece 2a of the external connection terminal 2, a connecting portion 2b having a protrusion 2c is formed by bending. Further, the contact piece 3a at the end of the bus bar 3 has
A connecting portion 3 having a protrusion 3c at the base end of the contact piece 3a.
b is formed. On the other hand, the insulating substrate 1 has the protrusion 2
An escape hole 1a is provided corresponding to c and 3c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a connection method for connecting a film-like circuit body of a wiring board used for an electric connection box or the like and an external connection terminal.

[0002]

2. Description of the Related Art In FIG. 8, (A) is a perspective view of a film-shaped circuit body (flexible printed wiring board) a and connection terminals g, and (B) is a sectional view showing a conventional wiring board h using these. It is a figure. The film-shaped circuit body a is formed by forming a plurality of pattern portions c on a film-shaped substrate b via non-conductive portions e, and land portions d having holes f are provided at the end portions of each pattern portion c. . A connector housing i is integrally formed on the upper surface of the insulated wiring board h, and a plurality of connection terminals g are arranged in the housing i so as to penetrate the insulated wiring board h. On the other hand, the film-shaped circuit body a is arranged on the lower surface of the insulated wiring board h, and the end portion g ₁ of the connection terminal g is the land portion d.
Through the hole f and soldered with solder j (Japanese Utility Model Laid-Open No. 61-96718).

In the above-mentioned conventional technique, cracks may be generated due to a corrosive compound between metals in a soldered portion, which is problematic in terms of electrical performance, and further, the number of soldering steps is increased. was there. Also, in order to cover the above drawbacks, connection by laser welding is being considered instead of soldering, but in this case, heat generated in the insulating wiring board near the laser welding location evaporates and scatters to other locations. It has not been actually adopted because it has a bad effect.

Further, as shown in FIG. 9, when two film-shaped circuit bodies a, a are overlapped and a desired land portion d, d is to be laser-welded, a film for supporting the pattern portion c by laser irradiation is formed. Substrate b evaporates at the welding point,
Due to the scattering, the welded portion is often blown or the welded thickness is not uniform as shown in FIG. 10, and the reliability of the weldedness and the stability of the quality are insufficient, and it is difficult to put it into practical use. An insulating coating b'is provided on the entire surface of the pattern portion c of the film-shaped circuit body a except for the land portion d to be welded.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, in which a film-shaped circuit body and external connection terminals are provided on an insulating substrate, and a pattern portion of the film-shaped circuit body is provided. In the connection method for connecting the provided land portion and the external connection terminal, the land portion and the connection terminal, etc. are not soldered, and evaporation and scattering of the insulating substrate near the welded portion due to laser welding are prevented, It is an object of the present invention to provide a method for connecting a film-like circuit body by laser welding, which is electrically connected to the film. Another object is to provide a method for reliably and stably laser-welding the land portions between the film-shaped circuit bodies.

[0006]

In order to achieve the above object, the method for connecting a film-shaped circuit body by laser welding according to the present invention is, as described in claim 1, for connecting a film-shaped circuit body to an external connection. In a connection method of connecting a terminal provided on an insulating substrate and a land portion provided in a pattern portion of a film-shaped circuit body to an external connection terminal, at a base end portion of the external connection terminal and at the land portion. A lower jig for forming a pair of upper and lower abutting jigs by providing a facing connection portion and a protrusion on the connection portion, and forming an escape hole at a position of the insulating substrate corresponding to the protrusion. The convex portion of the upper jig is inserted into the escape hole of the insulating substrate, and the corresponding land portion of the film-shaped circuit body and the protruding portion of the external connection terminal are stacked in this order on the convex portion, and the convex portion of the upper jig is protruded. After pressing down the part to bring the protrusion and the land into contact with each other, the upper jig is Irradiating a laser on the rear surface of the projection and removed by, characterized by welding the projection and the land portion. In addition, the bus bar provided on the insulating substrate in a plane-parallel manner is bent at its end to form an external connection terminal, and the external end of the bus bar on the external connection terminal side is projected so as to face the land section. A connecting portion having a portion is formed (claim 2).

On the other hand, a film-like circuit formed by forming a plurality of pattern parts on a film-like substrate, providing a land part at an end or an intermediate part of the pattern, and applying an insulating coating to the entire surface of the pattern part except the land part. According to a third aspect of the present invention, there is provided an escape hole in the film-like substrate in advance so as to face desired land portions to be connected between the film-like circuit bodies. The land portions exposed from the escape holes are irradiated with a laser in a state of being overlapped with each other, and the land portions are welded to each other.
When welding the land portions to each other, it is recommended to attach a copper alloy tip to the upper and lower sides or one of the overlapped land portions and perform laser irradiation (claim 4).

[0008]

Since the escape hole is formed in the projection of the connection portion of the external connection terminal on the insulating substrate supporting the film-shaped circuit body,
When the projection and the land portion of the film-shaped circuit body are irradiated with laser, evaporation and scattering of the insulating substrate near the welded portion due to laser welding are prevented, and the land portion of the film-shaped circuit body and the external connection are used. The projection of the terminal can be reliably electrically connected. Further, when connecting the film-like circuit bodies, the film substrate supporting the pattern portion is provided with an escape hole in advance facing the land portion to be laser-welded, so that the laser is irradiated in a state where the land portions are overlapped with each other. Then, similar to the above, reliable and stable welding can be performed, and the addition of the metal tip improves the electrical stability and mechanical strength of the welded portion.

[0009]

1 is an exploded perspective view of a wiring board assembly A according to the present invention, and FIG. 2 is a sectional view of an external connection terminal 2. That is,
The wiring board assembly A includes a film-shaped circuit body 4 in which a land portion 4a and a non-conductor portion 4b are provided on a film-shaped substrate 4c, an insulating substrate 1 supporting the film-shaped circuit body 4, and an external connection welded to the film-shaped circuit body 4. The terminal 2 and the bus bar 3 are included.

A base end portion of the external connection terminal 2 is bent at a right angle to form a connection portion 2b, and a projection 2c is formed on a surface of the connection portion 2b facing the insulating substrate 1. The end portion of the bus bar 3 is bent at a right angle to form a contact piece 3a that constitutes an external connection terminal, and the bus bar 3 on the base end side of the contact piece 3a has a protrusion 3c similar to the external connection terminal 2. Is formed as a connecting portion 3b having.

The insulating substrate 1 has an insertion hole 1a for the contact piece 2a of the external connection terminal 2 and the contact piece 3a of the bus bar 3.
Is formed and faces the respective insertion holes 1a, the projection 2 is formed.
An escape hole 1b for c and 3c is formed. Also,
An insertion hole 4d is also formed in the land portion 4a of the film-shaped circuit body 4.
Are formed.

An insulating film (not shown) is applied to the entire surface of the film-like circuit body 4 to maintain electrical insulation, but an insulating film is masked at the portions facing the protrusions 2c and 3c. Is not applied, and a window-shaped notch 7 is formed at a portion corresponding to the protrusions 2c and 3c of the film-shaped substrate 4c as shown in FIG. 4 (B).

Next, the assembly of the wiring board assembly A will be described. First, when the external connection terminal 2 is press-molded, the protrusion 2c serving as a welding portion is formed at the same time as the connection portion 2b (see FIG. 2). A protrusion 3c is also formed on the bus bar 3 in the same manner.

Next, as shown in FIG. 3, a pair of abutting jigs including a lower jig 5 and an upper jig 6 are prepared. That is,
Each of the escape holes 1 of the insulating substrate 1 is provided in the die-shaped lower jig 5.
The protrusion 5a is formed corresponding to b, and the insertion hole 5b for the contact piece 2a and the contact piece 3a is formed. On the other hand, the punch-shaped upper jig 6 is also formed with a convex portion 6a corresponding to the projecting portions 2c and 3c.

Next, the insulating substrate 1 is placed so that the insertion holes 1a thereof correspond to the insertion holes 5b of the lower jig 5, respectively. Thereafter, the film-shaped circuit body 4 is placed on the insulating substrate 1 so that the insertion holes 4d are located on the corresponding insertion holes 1a, and the external connection terminals 2 are placed in the respective insertion holes 1a and 5b.
The contact piece 2a of 1 and the contact piece 3a of the bus bar 3 are inserted.

Next, the tip of the projection 6a of the upper jig 6 is applied to the back side of the projection 2c of the connection 2b of the external connection terminal 2 and the projection 3c of the connection 3b of the bus bar 3, and the projection 2c. , 3c
The upper jig 6 is pressed down so that the above contacts the land portion 4a of the film-shaped circuit body 4.

Next, as shown in FIG. 4B, the upper jig 6 is removed, and the projection 2c of the connection portion 2b of the external connection terminal 2 is removed.
The laser irradiation L is performed toward the back side of the film, and the protrusion 2c and the corresponding land 4a of the film-shaped circuit body 4 are laser-welded. The protrusions 3c of the bus bar 3 and the lands 4a are laser-welded in exactly the same manner.

The escape holes 1b of the insulating substrate 1 are provided to prevent the components evaporated from the insulating substrate 1 during laser irradiation from adversely affecting the laser-welded portion. Further, each convex portion 5a of the lower jig 5 is preferably made of a material such as a ceramic having heat resistance in order to prevent welding with the film-shaped circuit body 4 during laser irradiation.

FIG. 5 shows a laser welding method for two film-like circuit bodies, (A) is a perspective view of the film-like circuit bodies,
(B) is a sectional view of a welded portion. Each of the two film-shaped circuit bodies 8 and 8'is formed by arranging a plurality of pattern portions 8b on a film-shaped substrate 8a, and a land portion 8c is provided at the end of each pattern portion 8b and the pattern portion b is formed. An insulating coating 8d is applied over the entire surface. The above is
Although the basic structure is the same as that of the film-shaped circuit body 4 of FIG. 1, in this embodiment, the land portion 8c is formed in a round shape, and the escape hole is formed in the film-shaped substrate 8a facing the round land portion 8c. 9 and an escape hole 10 are provided in the insulating coating 8d, and the upper and lower surfaces of the land portion 8c to be welded are previously released.

Therefore, as shown in FIG. 4B, laser light is emitted in a state where the land portions 8c and 8c of the two film-shaped circuit bodies 8 and 8'are overlapped with each other as in the case of FIG. 4B. Then, since the film-shaped substrate 8c and the insulating coating do not exist in that portion, both are fixed by welding, and stable and reliable connection can be performed.

FIG. 6 (A) shows land portions 8c,
Laser irradiation L is performed by setting copper alloy chips 11 and 11 above and below 8c. In this case, the welded portions (lands 8c, 8
In order to prevent the egress of c) and to supplement the penetration, the welding cross-sectional area becomes large and the strength is improved, and the film-shaped circuit body 8
Even if the tensile force F acts on the welded portion, the force does not reach the welded portion, so that the stability and reliability of the electrical connection are improved.
It should be noted that the chip 11 may be only one of the upper and lower sides.

FIG. 7 shows an example of connection between a film-shaped circuit body and a flexible flat circuit (FFC). FIG. 7A is a perspective view of an essential part and FIG. 7B is a sectional view of a welded part thereof.
Since each conductor portion 12a of the FFC 12 is protected by the resin coating layer 12b, the resin coating layer 12b at a desired portion such as an end portion or an intermediate portion is peeled off to expose the exposed conductor portion 1
2c and the land portion 8c of the film-shaped circuit body 8 may be overlapped and laser irradiation L may be performed as described above.

[0023]

As described above, according to the present invention,
The film-shaped circuit body and the external connection terminal are provided on the insulating substrate, and when connecting the land portion and the external connection terminal provided on the pattern portion of the film-shaped circuit body, the land portion and the external connection terminal are soldered. It is possible to securely electrically connect the film-shaped circuit body and the external connection terminal without attaching them and by preventing evaporation and scattering of the insulating substrate near the welded portion due to laser welding. Further, desired land portions between the film-shaped circuit bodies can be connected to each other in a reliable and stable state.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a wiring board assembly according to the present invention.

2 is a vertical cross-sectional view of the external connection terminal of FIG.

FIG. 3 is an exploded perspective view showing a process of assembling the wiring board assembly.

4A is an enlarged perspective view of a welded portion of an external connection terminal, and FIG. 4B is a vertical cross-sectional view taken along line CC of FIG.

FIG. 5A is a perspective view of an essential part of a film-shaped circuit body 8, 8 ′ showing another embodiment of the present invention, and FIG. 5B is a sectional view of a laser welding part thereof.

6A is a sectional view showing a laser welding method showing an improved example of FIG. 5, and FIG. 6B is a sectional view showing the welding state.

FIG. 7A is a perspective view of essential parts of a film-shaped circuit body 8 and a flexible flat circuit 12 showing another embodiment of the present invention, and FIG. 7B is a sectional view showing a welded portion thereof.

FIG. 8A is a perspective view of an essential part showing a conventional film-shaped circuit body, and FIG. 8B is a vertical sectional view of a wiring board using the film-shaped circuit body of FIG.

FIG. 9 is a perspective view of a main part for showing a conventional method for connecting two film-shaped circuit bodies, and FIG. 9B is an explanatory view of the welding process.

10 is a cross-sectional view showing the welding process of FIG.

[Explanation of symbols]

 A wiring board assembly 1 insulating substrate 1b escape hole 2 external connection terminals 2a, 3a contact pieces 2b, 3b connecting portions 2c, 3c projecting portion 3 bus bar 4 film-like circuit body 4a land portion 4b non-conductor portion 4c film-like substrate 5 Lower jig 6 Upper jig 8,8 'Film-like circuit body 8a Film-like substrate 8b Pattern part 8c Land part 8d Insulation coating 9,10 Escape hole 11 Chip 12 Flexible flat circuit

Claims (4)

[Claims] 1. A connection method, wherein a film-shaped circuit body and an external connection terminal are provided on an insulating substrate, and a land portion provided in a pattern portion of the film-shaped circuit body is connected to an external connection terminal. At the base end of the connecting terminal, a connecting portion facing the land is provided and a protruding portion is provided at the connecting portion, and an escape hole is formed at a location of the insulating substrate corresponding to the protruding portion. The convex portions of the lower jig forming the pair of abutting jigs are inserted into the escape holes of the insulating substrate, and the corresponding land portions of the film-shaped circuit body and the external connection terminals are formed on the convex portions. After pressing down the convex portion of the upper jig in a state of being laminated in the order of the protruding portion to bring the protruding portion and the land portion into contact with each other, the upper jig is removed and a laser is irradiated to the back surface of the protruding portion, Contact of film-like circuit body by laser welding, characterized in that the protrusion and the land are welded Method. 2. An external connection terminal is formed by bending an end portion of a bus bar provided on the insulating substrate in a plane-parallel manner, and an end portion of the bus bar on the external connection terminal side is projected so as to face the land portion. 2. The method for connecting a film-shaped circuit body by laser welding according to claim 1, wherein a connection portion having a portion is formed. 3. A film-shaped circuit in which a plurality of pattern portions are formed on a film-shaped substrate, a land portion is provided at an end or an intermediate portion of the pattern, and an insulating coating is applied to the entire surface of the pattern portion excluding the land portions. In the method of connecting the bodies to each other, an escape hole is provided in advance on the film-shaped substrate so as to face desired lands to be connected between the film-shaped circuit bodies,
A method for connecting film-shaped circuit bodies by laser welding, which comprises irradiating a laser in a state where lands exposed from the escape holes are overlapped with each other to weld the lands. 4. The method for connecting a film-like circuit body by laser welding according to claim 3, wherein a copper alloy tip is attached to the upper and lower sides or one of the overlapped land portions to irradiate a laser.