JP2002141645A - Structure and method for bonding of flexible printed- circuit board to connecting terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure and a method for the bonding of a flexible printed- circuit board to a connecting terminal, wherein a conductor resistance around a bonding part to the bonding end part of the interconnection of the flexible printed- circuit board to the connecting terminal is reduced, and a temperature rise in an electrifying operation can be suppressed. SOLUTION: A conductive material 9 such as a copper foil or the like whose width is identical to the conductor width of the interconnection 6 and whose thickness is identical to the film thickness of an overlay 7 is placed on the interconnection 6 which is formed on the terminal part of an FPC 4 in an exposed state. A large current at a capacity used for a series welding operation is applied across an electrode 10a and an electrode 10b. The conductive material 9 and the interconnection 6 are welded by heat energy generated due to the electrifying operation and by a pressurization force. The electrodes 10a, 10b are separated from the conductive material 9, the bonding end of a connecting terminal 1 is placed on the conductive material 9 welded to the interconnection 6 of the FPC 4, the electrodes 10a, 10b are brought into contact from the upper side of the bonding end 3, a large current is made to flow, and the bonding end and the conductive material 9 are welded. The total conductor resistance of the bonding part 8 can be made smaller than that in an ordinary case.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining structure and a joining method between a flexible printed circuit board and a connection terminal, and more particularly, to suppressing a temperature rise in the vicinity of a joint between the flexible printed circuit board and the connection terminal during energization. The present invention relates to a bonding structure and a bonding method that can be performed.

[0002]

2. Description of the Related Art In recent years, wire harnesses used in automobiles and the like have been used as much as
There is a growing movement to substitute rinted circuits (FPC). By such a movement, for example, as shown in FIG.
0 to electrically connect the electronic control unit 301 and the fuse box 302 mounted inside the FPC 40.
When the FPC 400 and the conventional circuit connection wire harness 500 are used together, the connection between the FPC 400 and the circuit connection wire harness 500 is very important.

As an FPC connector used in such a case, a connector as shown in FIG. 4 is known. The connector 100 is mainly used as a wiring connector for meters installed in a console panel of a dashboard of an automobile. Connector 100
Is an FPC 40 in a fitting hole formed in the meter housing 101.
0 is inserted, and the connector 110 is fitted so that the FPC 400 is sandwiched between the connector 110 and an electrical connection. For example, FPC400 is made of polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).
A conductive material 105 in the form of foil is placed on an insulating film 104 made of
Is formed by forming a wiring pattern by printing or the like, and a coverlay 106 is further laminated thereon as a circuit protection member. At the end of the FPC 400 inserted into the fitting hole, the coverlay 106 is laminated. Not conductive material 10
5 is exposed. On the other hand, connector 110
A connection terminal 113 is provided at the tip of the circuit connection wire harness 500 housed in the terminal housing hole 111 formed therein.
Are connected by crimping or the like, and an elastic contact piece 114 is formed on the connection terminal 113. That is, as described above, by fitting the connector 110 into the fitting hole, the connector 100 sandwiches the previously inserted FPC 400 in the fitting hole and exposes the conductive material 10 of the exposed FPC 400.
Since the elastic contact piece 114 of the connection terminal 113 presses and presses the five portions toward the wall surface of the fitting hole and makes contact therewith, the FP
It has a structure that can ensure electrical continuity between the C400 and the circuit connection wire harness 500.

However, in the connector 100 described above, a connector having a fitting hole must be provided in the dashboard 300 or the meter housing 101, and the structure of the connector is completely changed by a slight design change or the like. In some cases, the cost of parts and the like increases, which may lead to an increase in production costs.

[0005] Therefore, in general, in order to connect the FPC 400 and the wiring harness 500 for circuit connection without causing such an increase in cost, for example, as shown in FIG. The female connection terminal 80 used in the wiring harness 500 is replaced with a female connection terminal 60 for an FPC having a similar fitting portion 62 as shown in FIG. Then, it is fitted with another connector housing (not shown) in which the male connection terminal 83 is accommodated, and the circuit connection wire harness 500 is connected.
Electrical connection between the FPC400 and the FPC400 is being studied. In this case, as shown in FIG. 7A, the female connection terminal 80 is joined to the tip of the circuit connection wire harness 500 at the joint end 81 by, for example, crimping. As shown in (1), the joining end 61 of the female connection terminal 60 is directly joined to the copper foil-like wiring 71 formed on the FPC 400, and a reinforcing portion 72 is formed thereon with an adhesive or a curing agent before use. It has been proposed to. In this way, by adopting a connector having a structure capable of fitting and fitting between the connector housing used for the FPC and the connector housing used for the wiring harness for circuit connection, significant design changes and the like can be achieved. Inexpensive connection between the FPC and the wire harness, which does not involve the above, can be realized.

[0006]

In such a case, however, since the pitch between the male connection terminals 83 housed in the connector housing of the circuit connection wire harness is predetermined, for example, as shown in FIG. So, FP
The inter-terminal pitch b of the female connection terminals 60 housed in the C connector housing 404 must also be determined accordingly. Usually, the wiring pattern 40 of the FPC 400
The conductor width a of 2 is determined in consideration of fuse matching of a circuit, voltage drop between circuits, and the like. In many cases, the pitch c between circuits is larger than the pitch b between terminals. For this reason, in the FPC terminal unit 401, it is necessary to narrow down the conductor width a. As a result, the conductor resistance of the wiring pattern 403 in the narrowed portion becomes large, so that the temperature rise during energization locally increases, and it becomes impossible to satisfy the specifications of the standard test of each automobile manufacturer. There's a problem. Further, when there is a possibility that the temperature rise of the narrowed terminal portion 401 may become extremely high, a design is required on the assumption that a vehicle fire or the like will occur.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and reduces the conductor resistance in the vicinity of a junction between a wiring of a flexible printed circuit board and a connection end of a connection terminal, thereby reducing the temperature during energization. An object of the present invention is to provide a bonding structure and a bonding method between a flexible printed circuit board and a connection terminal that can suppress the rise.

[0008]

According to the present invention, there is provided a joint structure between a flexible printed board and a connection terminal, the flexible printed board having a conductive pattern formed on an insulating film, and the flexible printed board. In the terminal portion of the connection structure with a metal connection terminal having a connection end electrically connected to the conductive pattern, a conductive member between the connection end of the connection terminal and the conductive pattern. It is characterized by being joined.

The connection end of the connection terminal, the conductive pattern, and the conductive member can be bonded by, for example, resistance welding, soldering, or ultrasonic welding.

[0010] The conductive member is preferably a copper foil.

[0011] A method of joining a flexible printed circuit board and a connection terminal according to the present invention includes a flexible printed circuit board having a conductive pattern formed on an insulating film; A method of joining with a metal connection terminal having a joint end electrically connected to a pattern, wherein a conductive member is welded on the conductive pattern by series welding, and then the connection terminal is further placed on the conductive member. Are welded by series welding.

Further, according to the present invention, there is provided a method for joining a flexible printed circuit board and a connection terminal to a flexible printed circuit board having a conductive pattern formed on an insulating film and a terminal portion of the flexible printed circuit board. A method of joining with a metal connection terminal having a joint end electrically connected to the conductive pattern, wherein after soldering a conductive member on the conductive pattern by soldering, further on the conductive member The connection end of the connection terminal is brazed by soldering.

Further, according to the present invention, there is provided a method for joining a flexible printed board and a connection terminal, wherein the flexible printed board having a conductive pattern formed on an insulating film, and a terminal portion of the flexible printed board. A method of bonding with a metal connection terminal having a bonding end electrically connected to the conductive pattern, wherein after welding a conductive member on the conductive pattern by ultrasonic welding, further on the conductive member The joint end of the connection terminal is welded by ultrasonic welding.

According to the present invention, before joining the wiring of the flexible printed circuit board (hereinafter referred to as "FPC") and the joining end of the connection terminal, for example, a copper foil is first placed on the wiring of the FPC. And the like, and the joining end of the connection terminal is joined to the joined conducting material. Therefore, even if the wiring width of the FPC is narrowed at the terminal portion, the thickness of the conducting portion is increased by the conducting material. Since the reduction in the cross-sectional area can be suppressed, the conductor resistance at the joint can be reduced, and the rise in temperature around the joint during energization can be suppressed. As a result, it is possible to join the FPC and the connection terminal that can satisfy the standard test specifications of the automobile manufacturers, and it is possible to avoid an extremely high temperature rise due to energization. A design that assumes a vehicle fire or the like due to a rise in the temperature of the joint becomes unnecessary.

[0015] In addition, the flexible printed circuit with high connection reliability while suppressing the production cost is formed by joining the connection ends of the FPC wiring, connection terminals and the conductive material by resistance welding, soldering or ultrasonic welding. Bonding between the substrate and the connection terminal can be realized.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing, in cross section, a part of a joint using a method of joining an FPC and a connection terminal according to an embodiment of the present invention, and FIG. 2 forms the joint of FIG. 9 is a flowchart showing a joining process for the present invention.

As shown in FIG. 1 (b), a connection terminal (male or female connection terminal) 1 has a terminal fitting portion (not shown) fitted with a fitting portion (not shown) of a connection terminal of a connection partner. ) And a joint end 3 connected to the FPC 4. FPC4 is made of polyethylene terephthalate (PET) or polyethylene naphthalate (PE).
N) a copper foil is laminated on the insulating film 5 made of
The copper foil is etched to form a wiring 6 made of a conductive pattern.
Is formed, and a cover lay 7 made of a synthetic resin or the like having electrical insulation is put on the insulating film 5 and the wiring 6. In addition, coverlay 7 of FPC4
Is not formed at the portion corresponding to the joint portion 8 and the wiring 6 which should be covered by the coverlay 7 is in a bare and exposed state. The connection end 3 of the connection terminal 1 is brought into contact with the FPC and the connection terminal is attached to the FPC by directly bonding the two.
A conductive material 9 such as a copper foil is laminated on the substrate.

For example, the conductive material 9 is formed on the exposed wiring 6 with the same width as the conductor width of the conductive pattern forming the wiring 6 and the same thickness as the thickness of the cover lay 7. Then, by joining the joining end 3 of the connection terminal 1 on the conductive material 9 formed on the wiring 6,
The bonding structure allows the FPC and the connection terminal to be electrically connected. Thus, the FPC 4 and the connection terminal 1
By newly forming the conductive material 9 between the conductive pattern and the conductive pattern, for example, the conductive width of the conductive pattern of the wiring 6 is 5 mm, and the conductive thickness is 70 mm.
The vertical cross-sectional area of the wiring 6 when it is set to μm is 0.35 mm ^2, and the vertical cross-sectional area of the wiring 6 and the conductive material 9 when the conductive material 9 having a conductor thickness of 50 μm is joined to the wiring 6 is 0.
Since it is 6 mm ² , it can be seen that the conductor resistance can be reduced. Therefore, the joining end 3 of the connection terminal 1
Has a structure in which the conductor width of the wiring 6 is narrowed down to be smaller than that of the main body (not shown) of the FPC 4. Although it is larger than the main body, in the terminal portion joined by the joining structure of this example, even when a large current flows, the conductor resistance is small, so there is little possibility of causing a local temperature rise. And can be used safely.

The connection between the FPC and the connection terminal is as follows.
This is realized by a joining method as described below. First, a sheet or the like forming an insulating film 5 serving as a base of the FPC 4 made of PET, PEN, or the like is processed into a desired shape (S1), and a conductive pattern is formed on the upper surface of the insulating film 5 to form an FPC circuit. The wiring 6 is patterned by a method such as etching, and a coverlay 7 is formed on the insulating film 5 and the wiring 6 excluding a portion to be a terminal portion, and the FPC 4 is manufactured (S2). Next, as shown in FIG. 1A, the conductor width of the wiring 6 and the film of the coverlay 7 are formed on the wiring 6 formed in an exposed state at the terminal portion of the manufactured FPC 4. A conductive material 9 such as a copper foil having the same thickness as that of the conductive material 9 is placed, and for example, electrodes 10a and 10b of a series welding device are brought into contact with the conductive material 9 from above, and a capacity used for series welding between the electrodes 10a and 10b. When a large current is passed through, the heat energy generated and the electrode 10
The copper of the conductive material 9 diffuses into the tin plating layer of the connection terminal 1 due to the pressure applied to the conductive material 9 by a and 10b, and the conductive material 9 and the wiring 6 are diffusion-welded (S3). Thereafter, the electrodes 10a and 10b are separated from the conductive material 9, and as shown in FIG.
4 is placed on a conductive material 9 welded to the wiring 6, electrodes 10 a and 10 b are brought into contact with each other from the upper side of the joint end 3, and a capacity of the capacity used for resistance welding is again applied between these electrodes 10 a and 10 b. A large current is applied to weld the joint end 3 and the conductive material 9 (S4). By forming the joint 8 in this way,
Since the total conductor resistance of the joint 8 can be made smaller than that of a normal one, a vehicle fire or the like due to a temperature rise due to energization can be made less likely to occur, and a highly safe FPC
And the connection terminal can be realized.

In the above-described example, the connection of the FPC wiring, the connection end of the connection terminal, and the conductive material has been described using resistance welding. However, the bonding method is not particularly limited thereto. These may be joined by welding, or may be joined by ultrasonic welding. Further, the material of the conductive material 9 bonded between the wiring 6 and the bonding end 3 is not limited to copper, but may be brass, nickel, aluminum, or the like. Further, the width and the thickness of the conductive material 9 should be at least sufficient to reduce the total resistance value when the conductive material 9 is provided to be smaller than the conductor resistance of the wiring 6 when the conductive material 9 is not provided. Any width may be used as long as it has a practical dimension that does not cause a short circuit or the like between adjacent terminals or around the junction. Different thicknesses may be used.

[0021]

As described above, according to the present invention,
Before joining the wiring of the FPC and the joining end of the connection terminal,
In order to join the conductive material first on the wiring of the FPC and join the joining end of the connection terminal on the joined conductive material,
Even when the wiring of C is narrowed down at the terminal portion, the conductor resistance of the joint can be reduced, and the temperature rise around the joint during energization can be suppressed. As a result, it is possible to join the FPC and the connection terminal that can satisfy the standard test specifications of the automobile manufacturers, and it is possible to avoid an extremely high temperature rise due to energization. A design that assumes the occurrence of a vehicle fire or the like due to joining becomes unnecessary. In addition, the connection between the wiring end of the FPC, the connection end of the connection terminal, and the conductive material is performed by resistance welding, soldering, ultrasonic welding, or the like, so that the connection with a flexible printed circuit board with high connection reliability while suppressing production costs. Bonding with the terminal can be realized.

[Brief description of the drawings]

FIG. 1 is a side view showing a cross section of a part showing a joint portion using a joining method of an FPC and a connection terminal according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a joining process for forming the joint shown in FIG. 1;

FIG. 3 FP used for dashboards of automobiles and the like
It is an upper perspective view which shows C and a wire harness.

FIG. 4 is a partial side sectional view for explaining a conventional FPC connection connector.

FIG. 5 is a side view showing a terminal structure of a conventional connection terminal and a connection structure between the connection terminal, a wire harness, and an FPC.

FIG. 6 is a cross-sectional view illustrating narrowing of a wiring pattern in an FPC terminal unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Connection terminal, 2 ... Terminal body part, 3 ... Joint end part, 4 ... F
PC, 5: insulating film, 6: wiring, 7: coverlay,
8 ... joint, 10 ... electrode.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) H05K 3/34 507 H05K 3/34 507C F term (Reference) 5E051 KA01 KB05 LA02 LA04 LB06 5E085 BB09 BB11 CC03 DD01 DD03 DD04 EE15 HH01 HH13 JJ03 JJ06 5E319 AB01 AC03 BB02 CC02 CC12

Claims (9)

[Claims] A flexible printed circuit board having a conductive pattern formed on an insulating film; and a metal end having a joint end electrically connected to the conductive pattern at a terminal portion of the flexible printed circuit board. A joint structure between a flexible printed circuit board and a connection terminal, wherein a conductive member is joined between a joint end of the connection terminal and the conductive pattern. 2. The flexible printed circuit board and connection terminal according to claim 1, wherein the connection end of the connection terminal, the conductive pattern, and the conductive member are connected by resistance welding. And joining structure. 3. The flexible printed circuit board and the connection terminal according to claim 1, wherein the connection end of the connection terminal, the conductive pattern, and the conductive member are connected by soldering. And joining structure. 4. The connection with a flexible printed circuit board according to claim 1, wherein the connection end of the connection terminal, the conductive pattern, and the conductive member are bonded by ultrasonic welding. Connection structure with terminal. 5. The joint structure between a flexible printed circuit board and connection terminals according to claim 1, wherein the conductive member is a copper foil. 6. A flexible printed circuit board having a conductive pattern formed on an insulating film, and a metal end having a joining end electrically connected to the conductive pattern at a terminal portion of the flexible printed circuit board. A method of joining with a connection terminal, wherein after welding a conductive member on the conductive pattern by series welding, a joint end of the connection terminal is further welded on the conductive member by series welding. A method of joining a flexible printed circuit board and a connection terminal. 7. A flexible printed circuit board having a conductive pattern formed on an insulating film, and a metal end having a joining end electrically connected to the conductive pattern at a terminal portion of the flexible printed circuit board. A method of joining with a connection terminal, comprising: after soldering a conductive member on the conductive pattern by soldering; and further brazing the connection end of the connection terminal onto the conductive member by soldering. Bonding method between the flexible printed circuit board and the connection terminal. 8. A flexible printed circuit board having a conductive pattern formed on an insulating film, and a metal end having a joining end electrically connected to the conductive pattern at a terminal portion of the flexible printed circuit board. A method of joining with a connection terminal, wherein after welding a conductive member on the conductive pattern by ultrasonic welding, further welding an end of the connection terminal on the conductive member by ultrasonic welding. Bonding method between the flexible printed circuit board and the connection terminal. 9. The method according to claim 6, wherein the conductive member is a copper foil.