JPH05243703A - Flexible board - Google Patents

Abstract

PURPOSE:To provide a flexible board which can fixedly be soldered to another board with a simple construction and work. CONSTITUTION:A flexible board 10 having a predetermined circuit pattern 11 formed thereon and soldered onto a circuit pattern 21 of another board 20, with the end portion thereof being folded back to upwardly expose the circuit pattern 11. Of a folding portion 12 where the folding-back occurs, the side containing no circuit pattern is used as a bonding surface, and the folding portion 12 is caused to extend beyond at least the portion that overlaps the folding portion 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible substrate used for internal wiring of various electronic devices, and more particularly to a technique for soldering the flexible substrate to another substrate.

[0002]

2. Description of the Related Art Conventionally, a flexible substrate, which is a flexible substrate, has been widely used for internal wiring in various electronic devices, particularly small electronic devices. By using this flexible substrate, it is possible to arrange a circuit board corresponding to the shape of the electronic device, effectively utilize the inside of the device, and contribute to downsizing of the device.

By the way, when connecting a circuit pattern formed on a flexible substrate to a circuit pattern on another rigid substrate, it is general to connect by soldering. A configuration in the case where conventional circuit boards are soldered together will be described with reference to FIGS. 5 and 6. For example, an end of a circuit pattern formed on one surface (back surface) of the strip-shaped flexible board 1 by a printing process or the like. When soldering the portion 1a to a circuit pattern on another board, first, the surface of the end 1a of the flexible board 1 having the circuit pattern 2 to be soldered on the back surface (the surface on which the circuit pattern is not formed) Then, the adhesive paper 3 is attached. The adhesive paper 4 is also attached to the back surface at a position slightly apart from the end 1a. The adhesive papers 3 and 4 are papers (or resin films) coated with adhesives or pressure-sensitive adhesives on both sides, and release papers are usually attached to the surfaces in an unused state.

Then, as shown by the arrow a in FIG. 5, the end portion 1a of the flexible substrate 1 to which the adhesive paper 3 is attached is folded back, and the surfaces are adhered by the adhesive paper 3 as shown in FIG. By doing so, the circuit pattern 2 on the rear surface of the folded back portion of the flexible substrate 1 is exposed to the upper side.

Then, as shown in FIG. 7, the circuit pattern 2 on the back surface thus folded back is exposed to the upper side, and the circuit pattern formed on the surface of the hard substrate 5 made of epoxy resin or the like. The circuit pattern 2 is brought into contact with a predetermined portion 6 a of the circuit 6. At this time, the flexible substrate 1 is temporarily fixed to the hard substrate 5 by the adhesive paper 4 attached to the back surface of the flexible substrate 1. In this state, solder 7 is poured between the circuit pattern 2 on the flexible substrate 1 side and the predetermined portion 6a of the circuit pattern 6 on the hard substrate 5 side to electrically connect the patterns,
Ensures secure fixation between boards.

As described above, the flexible substrate 1 is temporarily fixed to the hard substrate 5 by using the adhesive paper 4, and then soldering is performed, so that workability at the time of soldering is improved.

[0007]

However, if the two adhesive papers 3 and 4 are stuck on both sides of the flexible substrate 1 for soldering in this way, the sticking work and the like will be troublesome. There is an inconvenience that the amount of adhesive paper used increases and the manufacturing cost rises. In particular, as the sticking work with adhesive paper, it is necessary to peel off the release paper stuck to the surface, and if the number of adhesive paper is large, the work to peel off the peeling paper is also required, which is very troublesome. .. In addition, between the circuit pattern 2 of the flexible substrate 1 and the circuit pattern 6 of the hard substrate 5 to be soldered,
Since the adhesive paper 4 intervenes, the circuit patterns may not come into contact with each other merely by placing the flexible substrate 1 on the hard substrate 5, and the soldering state may become unstable.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a flexible board which can be reliably soldered to another board with a simple structure and work.

[0009]

According to the present invention, for example, as shown in FIG. 1, a predetermined circuit pattern 11 is formed, and the circuit pattern 11 is exposed to the upper side by folding back the end portion so that another substrate 20 can be formed. In the flexible substrate 10 to be soldered on the circuit pattern 21 of FIG. 3, the surface of the folded-back portion 12 on which the folding-back is performed does not have the circuit pattern is used as an adhesive surface, and the folded-back portion 12 protrudes at least from a portion overlapping the folded-back portion 12. It was done like this.

Further, for example, as shown in FIG. 4, in this case, the adhesive surface of the folded-back portion 12 is only the portion protruding when folded back.

[0011]

According to the present invention, by simply providing an adhesive surface on only one side of the flexible substrate, the folded portion is adhered and temporarily fixed to another substrate, and soldering using the flexible substrate can be performed at one location. It is possible only with the adhesive surface.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a state where the flexible substrate of this example is soldered to a hard substrate, and FIGS. 2 and 3 show the state of the flexible substrate side. First, referring to FIGS. 2 and 3, the configuration on the flexible substrate side will be described. In the figure, reference numeral 10 indicates a flexible substrate, and the flexible substrate 10 has a circuit pattern 1 formed on its back surface by printing or the like.
1 is formed. The width W2 of the end portion is made wider than the width W1 of the other portion, and this wide end portion is used as the folded portion 12. Then, the adhesive paper 13 having a width substantially the same as the width W2 is attached to the surface of the folded portion 12. And FIG.
As shown in FIG. 1, the folded-back portion 12 to which the adhesive paper 13 is attached is folded back so that the surfaces thereof are overlapped,
This folded state is maintained by the adhesive force of 3.

Then, as shown in FIG. 1, the end portion of the flexible substrate 10 folded back in this manner is replaced by the hard substrate 2
The circuit pattern 21 of 0 is placed on a predetermined portion 22. At this time, the flexible substrate 10 is temporarily fixed on the hard substrate 20 by the adhesive force of the adhesive paper 13 at the protruding portion of the folded-back portion 12 (the portion where the folded flexible substrates do not overlap each other). In this state, solder 23 is poured between the circuit pattern 11 on the flexible substrate 10 side and the predetermined portion 22 of the circuit pattern 21 on the hard substrate 20 side to electrically connect the patterns, and at the same time, between the substrates. Secure the fixation.

As described above, after the flexible substrate 10 is temporarily fixed on the hard substrate 20 by using the adhesive paper 13,
By performing soldering, workability at the time of soldering is improved as in the conventional example. In this example, the adhesive paper 1 is applied only to one side of the folded-back portion 12 on the flexible substrate 10 side.
Although only 3 is attached, the two folded portions, that is, the folded portion 12 and the hard substrate 20 are bonded. Therefore, unlike the conventional case, it is not necessary to attach two pieces of adhesive paper to the flexible substrate side, the structure for soldering is simple, and it is necessary for the operation of attaching the adhesive paper and the operation of peeling the release paper. Less effort. Further, since there is no adhesive paper on the back surface side of the flexible substrate 10 on which the circuit pattern 11 is formed, the circuit pattern 11 comes into direct contact with the circuit pattern 21 on the hard substrate 20, so that soldering is surely performed. Done.

In this example, the folded portion 12 of the flexible substrate 10 needs to be formed wider than in the conventional case. However, by forming such a shape when forming the flexible substrate, the manufacturing cost of the flexible substrate is reduced. It rarely rises.

Further, in the above embodiment, the adhesive paper 13 is adhered to almost the entire one surface of the folded-back portion 12, but as shown in FIG. 4, the folded-back portion 12 is folded back as the flexible substrate 10 '. In this case, the adhesive papers 13a and 13b may be adhered only to the protruding portions, and the adhesive paper may not be arranged at the portions where the folded back flexible substrates overlap. By doing so, the amount of adhesive paper used is reduced. In the case of the example of FIG. 4, the folded-back portion 12 cannot be maintained by simply folding back the folded-back portion 12, and therefore the folded-back state cannot be maintained. Thirteen
The folded-back portion 12 folded back by a and 13b is bonded to the surface of the hard substrate, and the folded state is maintained at the same time as the temporary fixing to the hard substrate, and the same soldering as in the example of FIG. 1 is performed.

In the above embodiment, the adhesive paper is attached to the flexible substrate to form the adhesive surface on the flexible substrate. However, an adhesive or the like is directly applied on the substrate to form the adhesive surface. It may be formed.

[0019]

According to the present invention, by simply providing an adhesive surface on only one side of a flexible substrate, the folded portion can be adhered and temporarily fixed to another substrate, and soldering using a flexible substrate can be reduced to one. This is possible only with the adhesive surface at one point (single side), which simplifies the structure of the flexible board at the soldering point and simplifies the work of forming the adhesive surface for soldering, improving workability during soldering. improves.
Further, since the circuit pattern on the flexible substrate side and the circuit pattern on the other substrate are soldered in a state of being in direct contact with each other, the soldering is surely performed and the reliability of the connection by the soldering is improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a soldering state according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a flexible substrate according to an embodiment.

FIG. 3 is a perspective view showing a flexible substrate after bending according to an embodiment.

FIG. 4 is a perspective view showing a flexible substrate according to another embodiment of the present invention.

FIG. 5 is a perspective view showing a conventional flexible substrate.

FIG. 6 is a perspective view showing a conventional flexible substrate after being bent.

FIG. 7 is a perspective view showing a soldered state of a conventional flexible substrate.

[Explanation of symbols]

 10, 10 'Flexible substrate 11 Circuit pattern 12 Folding part 13, 13a, 13b Adhesive paper 20 Hard substrate 21 Circuit pattern 23 Solder

Claims (2)

[Claims] 1. A predetermined circuit pattern is formed, and the end portion is folded back to expose the circuit pattern to the upper side,
In a flexible board that is soldered onto a circuit pattern of another board, a surface of the folded-back portion where the folding-back is performed does not have the circuit pattern as an adhesive surface, and the folded-back portion at least protrudes from a portion overlapping the folded-back portion. The flexible substrate characterized in that 2. The flexible substrate according to claim 1, wherein the adhesive surface of the folded-back portion is only a portion protruding when folded back.