JPH1075029A - Connecting structure of flexible printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection structure of a flexible printed board, wherein connecting sections of the flexible printed board can be surely connected without being peeled off and, at the same time, electrically connected in nearly an electrically ideal state and thereby the damage to be caused by poor contact or generation of heat can be reduced as much as possible. SOLUTION: A flexible printed board 1 which is made by stacking a conductor 1B on a cover lay 1A is soldered to be electrically connected to a connected section 3. In a connecting section 1C of the flexible printed board 1, the conductors 1B are adhered to both faces of the cover lay 1A. The conductors 1B on both faces of the cover lay 1A are soldered to be electrically connected to the connected section 3. Preferably, a through-hole 4a is formed in the connecting section 1C of the flexible printed board 1. Solder enters the through- hole 4 and connects the conductors 1B on both faces of the cover lay 1A to the connected section 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for connecting a flexible printed circuit board to a connected portion such as a hard flexible printed circuit board by soldering.

[0002]

2. Description of the Related Art A flexible printed circuit board can be freely deformed and can be conveniently stored in a gap in a case. The flexible printed circuit board is manufactured by bonding and laminating a conductor to a coverlay made of plastic. The flexible printed circuit board having this structure is used, for example, by connecting to a hard printed circuit board 2 on which electronic components are mounted, as shown in the perspective view of FIG. An electronic circuit is mounted on the hard printed board 2, and the flexible printed board 1 is used as a lead wire. When the flexible printed circuit board 1 is used as a lead wire and is built in the case 6, a large number of lead wires can be efficiently processed. Further, as shown in the figure, when the flexible printed circuit board 1 is connected to the printed circuit board 2 by the connector 5, a large number of complicated wirings can be processed more efficiently. However, the connector 5 cannot be used for electrical connection of a portion where a large current flows. This is because the contact resistance is larger than that of soldering, and if a large current is applied, it is heated and damaged or a contact failure occurs. For this reason, it is necessary to use a connector for the connection of the small current and to connect the connection of the large current by soldering.

FIG. 2 is a sectional view of a portion where a connecting portion of a flexible printed circuit board is soldered to a connected portion of the printed circuit board. As shown in this figure, the flexible printed circuit board 1 has a cover lay 1A laminated on the surface of the connected portion 3 of the printed circuit board 2, and a conductor 1B exposed on the upper surface of the cover lay 1A is soldered. 3 is electrically connected.

[0004]

In the connection structure of the flexible printed circuit board shown in FIG. 2, the coverlay 1A is interposed between the connected portion 3 of the printed circuit board 2 and the conductor 1B of the flexible printed circuit board 1. There is a disadvantage that the strength is weakened. Although the amount of solder is increased in order to prevent this adverse effect, this structure has disadvantages that the work time for soldering is long and the amount of solder used is large. In addition, even if the amount of solder is increased, the conductor 1B and the connected portion 3 are not soldered in an ideal state. When flowing, there is a problem that heat is generated by Joule heat.
The contact area between the conductor 1B and the connected portion 3 is small, and the conductor 1B
This is because the coverlay 1 </ b> A is interposed between the connection part 3 and the connection part 3, and the space for connection by soldering is widened. To further complicate matters, this condition is determined to be normal by inspection at the time of shipment, but after using the device for a considerable period of time, adverse effects such as damage to the connecting portion occur. For this reason, there is a drawback that it is extremely difficult to find a connection failure of the connecting portion by inspection at the time of shipment.

The present invention has been developed to solve this drawback. It is an important object of the present invention that the connection portion of the flexible printed circuit board can be connected so as not to be peeled off, and the connection is made in an electrically more ideal state, thereby minimizing damage due to poor contact and heat generation. An object of the present invention is to provide a flexible printed circuit board connecting structure that can be used.

[0006]

According to the connecting structure of the present invention, a flexible printed circuit board 1 in which a conductor 1B is adhered in a laminated state to a cover lay 1A is soldered and electrically connected to a connected portion 3. . Further, in the connection structure of the present invention, the connection portion 1C of the flexible printed circuit board 1 connected to the connection target portion 3 has a laminated structure in which a conductor 1B is adhered to both surfaces of the cover lay 1A, 1B is electrically connected to the connected portion 3 by soldering.

Further, in the connecting structure for a flexible printed circuit board according to the second aspect of the present invention, a through hole 4 is provided in a connecting portion 1C formed by bonding and laminating a conductor 1B to both surfaces of a cover lay 1A. The solder penetrates into the through-hole 4 to connect the conductors 1B on both surfaces of the cover lay 1A to connect to the connected portion 3.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below exemplify a connecting structure of a flexible printed circuit board for embodying the technical idea of the present invention, and the present invention does not specify the connecting structure to the following structure.

Further, in this specification, in order to make it easy to understand the claims, the numbers corresponding to the members shown in the embodiments will be referred to as "claims" and "claims". In the column of “means”.
However, the members described in the claims are not limited to the members of the embodiments.

The connecting structure shown in FIG. 3 has two connecting portions 1C of the flexible printed circuit board 1 indicated by the dashed circles.
Are connected to the hard printed circuit board 2 by soldering, and one portion is connected by a connector 5.

As shown in FIG. 4, the flexible printed circuit board 1 has a conductor 1B bonded and laminated on a cover lay 1A. The conductor 1B is adhered to the cover lay 1A as a shape constituting a lead wire. Coverlay 1A
It is a flexible plastic film that can be freely deformed. The cover lay 1A is an insulating layer, which is laminated on both surfaces of the conductor 1B to insulate the surface of the conductor 1B. Connecting part 1C
In the conductor 1B, the cover lay 1A is laminated only on one surface to expose the surface of the conductor 1B.

Further, the connecting portion 1C of the flexible printed board 1 has the conductor 1B bonded to both surfaces of the cover lay 1A covering the conductor 1B. In the figure, coverlay 1
The conductor 1B adhered to the upper surface of A becomes a lead wire, and the conductor 1B adhered to the lower surface of the cover lay 1A becomes a soldered layer which is soldered to and adhered to the connected portion. The conductor 1B on the lower surface serving as a soldering layer is short because it is adhered only to a portion to be soldered.

In order to cover a part of the conductor 1B serving as a soldering layer, a coverlay 1A is further adhered and laminated on the lower surface. The lowermost coverlay 1A shown in FIG. 4 covers the left end of the conductor 1B at the right end. The lowermost cover lay 1A covering the soldering layer is laminated so as not to peel off the soldering layer.

Further, the connecting portion 1C of the flexible printed circuit board 1 shown in FIG. The through-hole 4 is provided to penetrate the conductor 1B and the cover lay 1A on both surfaces.

FIG. 5 shows that the connecting portion 1C having the through hole 4 is
3 shows a cross-sectional shape that is connected by soldering to a connected portion 3 of a printed circuit board 2. As shown in this figure, the connecting portion 1C having the through-holes 4 is such that the conductors 1B laminated on both surfaces of the cover lay 1A can be brought into close contact with the solder, and in addition, the connecting portions 1C Connect the solder that comes into close contact with the top and bottom. As shown by the arrow A in the drawing, the solder connected through the through-hole 4 firmly connects the solder that is in close contact with the upper surface of the connecting portion 1C to the connected portion 3 like an anchor. Therefore, this connection structure has a feature that the solder in the through hole 4 is mechanically and strongly connected in addition to the fact that the conductor 1B is bonded to the solder over a wide area. Further, when soldering, the solder flowing into the through hole 4 enters the gap between the conductor 1B on the lower surface and the connected portion 3, and the conductor 1B on the lower surface can be securely soldered to the connected portion 3. Realize.

Furthermore, the solder that enters the through hole 4 is
The flexible printed circuit board 1 protruding perpendicularly to the connected portion 3 and being pulled in the direction parallel to the surface as shown by the arrow B in the drawing also considerably increases the tensile strength. That is, the connecting portion 1C having the through hole 4 is connected to the connected portion 3 while improving both the tensile strength and the peel strength. Further, the solder filled in the through hole 4 electrically connects the conductor 1B on the upper surface to the connected portion 3 and electrically connects the connected portion 1C to the connected portion 3 with a lower resistance.

However, in the connection structure of the flexible printed circuit board of the present invention, as shown in FIG. 6, the connection portion 1C having no through hole 4 can be connected to the connection target portion 3 by soldering. In the connection structure of this figure, the conductors 1B bonded and laminated on both sides of the cover lay 1A are connected in a state of being in close contact with solder and electrically connected.

The above embodiment shows a specific example in which a flexible printed board is connected to a connected portion of a hard printed board. The present invention does not specify a connected portion that connects the connecting portions of the flexible printed circuit board to a rigid printed circuit board. The connection portion of the flexible printed circuit board may be a connected portion other than the printed circuit board, for example, any part that connects the flexible printed circuit board by soldering, such as a battery electrode or a metal plate.

[0019]

The connecting structure of the present invention has a feature that the connecting portion of the flexible printed circuit board can be connected to the connected portion so as not to be peeled off without fail. That is, the connection structure of the present invention
This is because conductors are adhered to both sides of the coverlay at the connecting portion of the flexible printed circuit board, and the conductors on both surfaces are connected to the connected portion by soldering. In particular, the conductor laminated on the lower surface of the coverlay is soldered to the connected portion in a state close to directly contacting the connected portion. For this reason, the gap between the conductor on the lower surface of the coverlay and the portion to be connected is significantly reduced, and the molten solder flowing during this time connects the conductor to the portion to be connected extremely strongly. This synergizes with soldering both sides of the cover lay to the connected portion with a large area, thereby significantly improving the connection strength of the flexible printed circuit board.

Further, the connection structure of the present invention also realizes a feature that the connection portion of the flexible printed circuit board can be electrically connected to the connection portion in a more ideal state. For this reason, there is a feature that damage due to poor contact between the flexible printed circuit board and the connected portion and heat generation can be minimized. This feature is realized because the connecting portion of the flexible printed circuit board can be soldered to the connected portion with a larger area, and the conductor laminated on the lower surface of the connecting portion can be very close to the connected portion. The conductors laminated on both sides of the coverlay
By providing on both the front and back surfaces, the solder is soldered in about twice the area, and the contact area is doubled to minimize the contact resistance with the solder. 5 and FIG. 6 are connected to the solder. In the conventional connection structure, a narrow area is connected to solder as shown by a thick line in FIG. Furthermore, since the connection structure of the present invention can connect the conductor provided on the lower surface of the coverlay to the connected portion with an extremely thin solder layer, the thickness of the solder layer can be reduced, and the electrical resistance of the solder layer can be extremely reduced. . Together with these, the connection structure of the present invention has a feature that the electric resistance of the connection portion between the flexible printed board and the connected portion can be extremely reduced.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a battery pack for connecting a flexible printed circuit board to a connected portion.

FIG. 2 is a cross-sectional view showing a conventional connection structure between a flexible printed circuit board and a connected portion.

FIG. 3 is a plan view showing a connection structure according to the embodiment of the present invention.

FIG. 4 is a plan view, a cross-sectional view, and a bottom view showing a connecting portion of a flexible printed circuit board used in the connecting structure according to the embodiment of the present invention.

FIG. 5 is a sectional view showing a connection structure according to an embodiment of the present invention.

FIG. 6 is a sectional view showing a connection structure according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Flexible printed circuit board 1A ... Cover lay 1B ... Conductor 1C ... Connection part 2 ... Printed circuit board 3 ... Connection part 4 ... Through-hole 5 ... Connector 6 ... Case

Claims (2)

[Claims] 1. A flexible printed circuit board (1) formed by bonding a conductor (1B) to a coverlay (1A) in a laminated state, and a flexible printed circuit board formed by soldering and electrically connected to a connected portion (3). In the connection structure of (1), the flexible printed circuit board (1) connected to the connected portion (3)
The connection part (1C) has a laminated structure in which the conductor (1B) is adhered to both sides of the coverlay (1A), and the conductor (1B) on both sides of the coverlay (1A)
Characterized by being soldered and electrically connected to the connected portion (3). 2. A through hole (4) is provided in a connecting portion (1C) formed by bonding and laminating a conductor (1B) to both surfaces of a coverlay (1A), and a solder hole is provided in the through hole (4). Is invaded by coverlay (1
2. The connection structure for a flexible printed circuit board according to claim 1, wherein the connection structure is configured such that A) a conductor (1B) is connected to both surfaces to be connected to a connected portion (3).