JPH07202416A - Method and structure for connecting board and flexible coupling member - Google Patents

Abstract

PURPOSE:To facilitate connection of flexible circuit boards, while protecting a flexible board against damage, when they are connected conductively with the thin parts being set on the same side. CONSTITUTION:In the method for electrically connecting flexible circuit boards 17, 19 having thin parts 21, 23 for conduction provided on flexible bases 20, 22, the end parts of the flexible circuit boards 17, 19 are arranged or superposed such that the thin parts 21, 23 are set on the same side. The thin parts 21, 23 at an end part 17a are then superposed by a flexible coupling member 29 having a thermally fusible conductive part 31 on the surface such that the conductive part 31 touches both thin parts. It is then heated at a temperature higher than the melting point of the conductive part 31 for a predetermined time thus conducting the thin parts 21, 23 through the conductive part 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a board connecting method for electrically connecting flexible circuit boards to each other, a board connecting structure, and a flexible connecting member.

[0002]

2. Description of the Related Art As a conventional board connecting method and board connecting structure, for example, there are those shown in FIGS.
-22473). In this conventional example, the rigid circuit boards 1 and 3 are electrically connected by a flexible circuit board 5. The rigid circuit board 1 has a rigid copper thin portion 7 on its surface as a conductive thin portion, and the flexible circuit board 5 has a flexible copper thin portion 9 on its surface as a conductive thin portion. There is. Then, the flexible side copper thin portion 9 of the flexible circuit board 5 is aligned so as to face the rigid side copper thin portion 7 of the rigid circuit boards 1 and 3, and both are electrically connected by the conductive hot melt 11. is there. Therefore, the rigid circuit boards 1, 3
The connection between the flexible circuit board 5 and the flexible circuit board 5 or the handling thereof can be simplified.

[0003]

However, in recent automobile instrument circuits and the like, since the light bulb socket is directly attached to the flexible circuit board, the direction of the flexible copper thin portion 9 is often limited.

For example, in the connection of the flexible circuit boards 5 with each other, the flexible copper thin portions 9 are not on the same side as in the case of the interconnection of the rigid circuit boards 1, 3 and the flexible circuit board 5 as described above. And are required to be conductively connected to each other.

In response to such a demand, there are a connection method and a connection structure shown in FIG. In FIG. 7, the end portions 5a and 5b of both flexible circuit boards 5 are overlapped with each other,
A conductive wire 13 is bridged between the flexible copper thin portions 9 on a and 5b and fixed by solder 15.

However, when the solder 15 is used, the work is extremely difficult and the workability is significantly impaired. That is, the heat resistance temperature of the flexible circuit board 5 is generally about 150 ° C., and the ends 5a and 5b of the flexible circuit board 5 are destroyed unless the solder 15 having a temperature higher than that is handled very carefully. Because there is a fear.

Therefore, an object of the present invention is to provide a circuit board connecting method, a circuit board connecting structure, and a flexible connecting member which are extremely easy to manufacture and handle.

[0008]

In order to solve the above-mentioned problems, the invention of claim 1 provides a board connecting method for electrically connecting flexible circuit boards having a thin portion for conduction on a flexible base. Ends of the flexible circuit board are arranged or overlapped so that the thin parts are on the same side, and a flexible connecting material having a heat-melting conductive part on the surface is formed on the thin parts of the ends. The conductive parts are overlapped so that they are in contact with both thin parts, and the conductive parts are heated to a temperature equal to or higher than the melting point of the conductive part for a certain period of time so that the thin parts are electrically connected to each other by the conductive parts.

According to a second aspect of the present invention, there is provided a board connection structure for electrically connecting flexible circuit boards, each having a thin portion for conduction provided on a flexible base, wherein the end portions of the flexible circuit board have the thin portions. Are aligned side by side so that they are on the same side, or are overlapped, and the end portions are mutually
A flexible connecting member having a heat-melting conductive portion on its surface is provided, and the thin portions are electrically connected by the conductive portion.

According to a third aspect of the present invention, a heat-resistant flexible film, an adhesive layer provided on the surface of the flexible film, and a heat fusion which is provided on the surface of the adhesive layer and melts at a lower temperature than the flexible film. And a conductive portion.

[0011]

According to the invention of claim 1 of the above-mentioned means, the ends of the flexible circuit board are arranged or overlapped so that the conductive thin portions are on the same side when connecting. Then, a flexible connecting material having a heat-melting conductive portion on its surface is superposed on the thin portions between the end portions so that the conductive portions contact both thin portions. Then, using a hot press or the like, the thin portions are heated to a temperature equal to or higher than the melting point of the conductive portion for a certain period of time to electrically connect the thin portions to each other at the conductive portion. As a result, the flexible circuit boards are electrically connected to each other with the thin portions on the same side.

According to the invention of claim 2, the end portions of the flexible circuit board are arranged such that the thin portions are on the same side.
Alternatively, since they are overlapped with each other, the structure is advantageous when a light bulb socket or the like is directly attached to a flexible circuit board in an automobile instrument circuit or the like.

According to the third aspect of the present invention, when the end portions of the flexible circuit board are arranged so that the thin portions are on the same side and are electrically connected by the flexible connecting member, the heat-fusible conducting portions are provided on both thin portions. Both flexible circuit boards can be conductively connected to each other by the flexible connecting member by aligning them so as to be in contact with each other and heating them. Further, the adhesive layer can increase the fixing strength of the conductive connecting portion.

[0014]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view showing the principal part of a substrate connecting structure according to an embodiment of the present invention. The pair of flexible circuit boards 17 and 19 are respectively the flexible base 2
Copper thin portions 21 and 23 which are thin portions for conduction on the surface of 0 and 22
Is provided. Also, both flexible circuit boards 17,
The cover lay 2 is provided on the surface except the ends 17a and 19a of 19
5, 27 are provided. Flexible circuit board 1
The end portions 17a and 19a of the wires 7 and 19 are overlapped with each other, and the thin copper portions 21 and 23 are electrically connected by the flexible connecting member 29. That is, the flexible connecting material 29 is coated over both coverlays 25 and 27 of both flexible circuit boards 17 and 19, and the conductive hot melt 31 serves as a heat-melting conductive portion and both copper thin portions 21 and 23.
Is connected.

The structure before the flexible connecting member 29 is connected is as shown in FIG. That is, a heat resistant flexible film 33 is used as a base, and an adhesive layer, for example, an insulating hot melt 35 is provided on the surface thereof. The insulating hot melt 35 is set to 50 μm or less,
In this embodiment, it is, for example, 10 μm. Further, a conductive hot melt 31 is provided on the surface of the insulating hot melt 35 as the heat melting conductive portion 3 that melts at a lower temperature than the flexible film. A plurality of conductive hot melts 31 are provided on the surface of the insulating hot melt 35 at predetermined intervals. Hot melt 35,31
Various types such as EVA type, acrylic type, polyester type, and epoxy type can be selected, and can be appropriately selected depending on the conditions such as heat resistance and adhesive strength. It is also possible to use a hardening type hot melt to which a cross-linking agent is added. Further, the hot melt 31 is formed on the flexible film 33 by printing or an appropriate method. If the thickness is thin, the conductivity will be poor, and if it is thick, it will spread to the left and right when melted and crushed, making it impossible to handle high pitches. Therefore 10μ
m to 50 μm is desirable. In this example, 2
It is 0 μm. The resistivity of the hot melt 37 is preferably 10 ^-1 Ωcm or less.

Next, the board connecting method will be described with reference to FIG.

First, as shown in FIG. 3A, the end portions 17a and 19a of the flexible circuit boards 17 and 19 are aligned side by side so that the thin copper portions 21 and 23 are on the same side. Then, as shown in FIG. 3B, the ends 17a and 19a are overlapped. The cross section in the superposed state is as shown in FIG. Next, as shown in FIG. 3C, the flexible connecting member 29 is superposed on the end portions 17a and 19a. At this time, the conductive portions 31 are overlapped so as to contact the thin copper portions 21 and 23 and bridge the thin copper portions 21 and 23. Next, using hot press, insulating hot melt 3
5. Hold at a temperature not lower than the melting point of the conductive hot melt 31 for 10 seconds or more with an appropriate pressure to bond the conductive hot melt 31. For example, the temperature by hot pressing is kept at about 150 ° C. which is the heat resistant temperature of the flexible circuit boards 17 and 19, and for example, 1M for 10 seconds.
It is pressed at Pa. In the case of the type to which the cross-linking agent is added, it is pressed at 150 ° C. for 20 seconds with a force of 1 MPa. As a result, the insulating hot melt 35 is melted, and the thin copper parts 21 and 23 are electrically connected. The insulating hot melt 35 is adhered to the end portions 17a and 19a of the flexible circuit boards 17 and 19 while insulating to maintain the connection strength.

As described above, both flexible circuit boards 1
Flexible connecting material 2 using hot melt 7 and 19
Since the conductive connection is made at 9, the connection is extremely easy, and the structure and method are extremely advantageous for automatic production. Further, since the solder is not used, the flexible circuit boards 17 and 19 are not damaged. Furthermore, since the thin copper parts 21 and 23 are connected so as to face the same side, it is extremely advantageous when the light bulb socket is directly attached to the flexible circuit board in recent automobile instrument circuits and the like.

FIG. 4 shows another embodiment. In this embodiment, the end portions 17a and 19a are arranged flush with each other without overlapping the flexible circuit boards 17 and 19. Also in this case, the thin copper portions 21 and 23 are electrically connected by the flexible connecting member 29.

[0021]

As is apparent from the above, according to the invention of claim 1, the connecting work is extremely easy when the end portions of the flexible circuit board are electrically connected so that the thin portions are on the same side. This is a very advantageous method for automation.
Further, since the thin portions of the flexible circuit board are electrically connected so that they are on the same side, it is advantageous when a light bulb socket or the like is directly attached to an automobile instrument circuit or the like. Furthermore, since no solder is used, the flexible circuit board is not damaged.

According to the second aspect of the invention, the connection of the flexible circuit board has a very simple structure. Further, the structure is advantageous when a light bulb socket or the like is directly attached to an automobile instrument circuit or the like. Furthermore, since no solder is used, the flexible circuit board is not damaged.

According to the third aspect of the invention, when the thin portions of the flexible circuit board are arranged and connected so that the thin portions thereof are on the same side, the conductive portions are melted at a temperature lower than that of the flexible film to facilitate the conductive connection. it can. In this case, the adhesive layer can increase the fixing strength of the conductive portion.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part according to an embodiment of the present invention.

FIG. 2 is a perspective view of a flexible connecting member.

FIG. 3 is an explanatory diagram of a manufacturing method.

FIG. 4 is a cross-sectional view of a main part according to another embodiment.

FIG. 5 is a perspective view according to a conventional example.

FIG. 6 is a cross-sectional view of a main part according to a conventional example.

FIG. 7 is a cross-sectional view of a main part according to another conventional example.

[Explanation of symbols]

 17 flexible circuit board 17a end part 19 flexible circuit board 19a end part 20 flexible base 21 copper thin part (thin part) 22 flexible base 23 copper thin part (thin part) 29 flexible connecting material 31 conductive hot melt (conductive part) 33 Flexible film 35 Insulating hot melt (adhesive layer)

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 19, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

The structure before the flexible connecting member 29 is connected is as shown in FIG. That is, a heat resistant flexible film 33 is used as a base, and an adhesive layer, for example, an insulating hot melt 35 is provided on the surface thereof. The insulating hot melt 35 is set to 50 μm or less,
In this embodiment, it is, for example, 10 μm. Further, a conductive hot melt 31 is provided on the surface of the insulating hot melt 35 as the heat melting conductive portion 3 that melts at a lower temperature than the flexible film. A plurality of conductive hot melts 31 are provided on the surface of the insulating hot melt 35 at predetermined intervals. Hot melt 35,31
Various types such as EVA type, acrylic type, polyester type, and epoxy type can be selected, and can be appropriately selected depending on the conditions such as heat resistance and adhesive strength. It is also possible to use a hot melt of the hardened type with the addition of cross-linking agent. Further, the hot melt 31 is formed on the flexible film 33 by printing or an appropriate method. If the thickness is thin, the conductivity will be poor, and if it is thick, it will spread to the left and right when melted and crushed, making it impossible to handle high pitches. Therefore 10μ
m to 50 μm is desirable. In this example, 2
It is 0 μm. The resistivity of the hot melt 37 is preferably 10 ^-1 Ω · cm or less.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

First, as shown in FIG. 3A, the end portions 17a and 19a of the flexible circuit boards 17 and 19 are aligned side by side so that the thin copper portions 21 and 23 are on the same side. Then, as shown in FIG. 3B, the ends 17a and 19a are overlapped. The cross section in the superposed state is as shown in FIG. Next, as shown in FIG. 3C, the flexible connecting member 29 is superposed on the end portions 17a and 19a. At this time, the conductive portions 31 are overlapped so as to contact the thin copper portions 21 and 23 and bridge the thin copper portions 21 and 23. Next, using hot press, insulating hot melt 3
5. Hold at a temperature not lower than the melting point of the conductive hot melt 31 for 10 seconds or more with an appropriate pressure to bond the conductive hot melt 31. For example, the temperature by hot pressing is kept at about 150 ° C. which is the heat resistant temperature of the flexible circuit boards 17 and 19, and for example, 1M for 10 seconds.
It is pressed at Pa. Incidentally, of the type with the addition of cross-linking agents are those pressed with a force of 20 seconds 1MPa at 0.99 ° C.. As a result, the insulating hot melt 35 is melted, and the thin copper parts 21 and 23 are electrically connected. The insulating hot melt 35 is adhered to the end portions 17a and 19a of the flexible circuit boards 17 and 19 while insulating to maintain the connection strength.

Claims (3)

[Claims] 1. A substrate connecting method for electrically connecting flexible circuit boards, each having a thin portion for conduction provided on a flexible base, wherein the end portions of the flexible circuit board are formed on the same side as the thin portion. Arranged or superposed so that a flexible connecting material having a heat-melting conductive portion on the surface is laminated on the thin portion between the end portions so that the conductive portion is in contact with both thin portions. A method of connecting substrates, characterized in that the thin portions are electrically connected to each other at the conducting portions by heating the thin portions at a temperature equal to or higher than the melting point for a certain period of time. 2. A board connection structure for electrically connecting flexible circuit boards, each having a thin portion for conduction provided on a flexible base, wherein end portions of the flexible circuit board are connected to each other on a surface on the same side as the thin portion. To be aligned side by side or to be overlapped with each other, a flexible connecting member having a heat-melting conductive portion on the surface is provided to each of the end portions, and the thin portions are electrically connected to each other by the conductive portion. Board connection structure. 3. A heat-resistant flexible film, an adhesive layer provided on the surface of the flexible film, and a heat-melting conductive portion provided on the surface of the adhesive layer and melting at a lower temperature than the flexible film. A flexible connecting material characterized by comprising: