JPH09148732A - Method of connection between flexible printed boards - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of connection between boards by which the productivity and reliability are improved. SOLUTION: A flexible printed board 1 is placed. Solder 21 is supplied to one side of the board 1 and 8 conductor connecting parts 5a are exposed correspondingly to the soldered parts 21 on the other side of the board 1. Another flexible printed board 2 is overlaid on the flexible printed board 1 in place. Through holes 17 for soldering are formed in a conductor 6 correspondingly to the soldered parts 21 on the side of the board 1 to which solder 21 is supplied. Conductor connecting parts 6a are exposed around the through holes 17. The conductors 5 and 6 of the flexible printed boards 1 and 2 are connected with each other by soldering the conductor connecting parts 5a and 6a to each other with the solder 21 through the through holes 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting flexible printed boards (FPCs) in which a plurality of flexible printed boards (FPCs) are superposed on each other in a multi-layered manner to connect conductors of the flexible printed boards to each other.

[0002]

2. Description of the Related Art Conventionally, as a method of stacking a plurality of flexible printed boards on each other in a multi-layered manner and connecting conductors of the flexible printed boards to each other, through holes are formed in the flexible printed boards to be connected to each other. A so-called solder leveler is used for solder coating on the through holes. After that, in a state where each through hole is aligned, the solder coated solder is so-called air reflow, or by applying an infrared ray, a high temperature iron, etc. There was a method of connecting the conductors of.

For example, it is as disclosed in JP-A-6-132666.

[0004]

However, according to the above-described conventional method for connecting flexible printed circuit boards,
In advance, a conductor such as a copper foil of a flexible printed circuit board needs a solder plating process using a solder leveler or the like, which increases the number of flexible printed circuit board manufacturing processes, which is not suitable for productivity and has a drawback of increasing production cost. .

Further, the flexible printed circuit board is damaged by heating during the solder leveling, and there is a problem in reliability.

[0006] Therefore, an object of the present invention is to provide a method for connecting flexible printed circuit boards, which improves productivity and reliability.

[0007]

A technical means for solving the above-mentioned problems is to provide a method of connecting flexible printed boards by superposing a plurality of flexible printed boards on each other and connecting conductors of the flexible printed boards to each other. , On the side opposite to the side to which the solder is supplied, the flexible printed circuit board having the exposed conductor connection portion corresponding to the soldering position is arranged, and on the side to which the solder of the flexible printed circuit board is supplied, to the soldering position. A flexible printed circuit board having a through hole portion for soldering formed in a corresponding conductor portion and a conductor connecting portion exposed at the peripheral portion of the through hole portion for soldering is polymerized in a positioning manner, and in that state, the through hole for soldering is formed. By soldering the conductor connecting parts of each flexible printed circuit board through the holes, Shi certain conductor Bull PCB to a point to be connected to each other.

Further, the conductor connecting portion of the flexible printed circuit board on the side to which the solder is supplied is exposed to be larger in diameter than the conductor connecting portion of the flexible printed circuit board arranged on the side opposite to the side to which the solder is supplied. The structure may be

Further, a structure may be adopted in which a flux gas vent hole is formed at a conductor connecting portion position of the flexible printed circuit board arranged on the side opposite to the side to which the solder is supplied.

Further, the structure may be such that the soldering is performed by jet soldering.

Further, a flexible printed circuit board having a conductor connection portion corresponding to a soldering position exposed is arranged on the side opposite to the side to which the solder is supplied, and the flexible printed circuit board is provided on the side to which the solder is supplied. Each flexible printed circuit board in which a through hole portion for soldering is formed in the conductor portion corresponding to the soldering position and the conductor connecting portion is exposed at the peripheral portion of the through hole portion for soldering is sequentially superposed in a positioning manner, and In this state, the conductors of the flexible printed boards may be connected to each other by soldering the conductor connecting portions of the flexible printed boards to each other through the soldering through holes.

Further, the through holes for soldering of the flexible printed circuit boards sequentially arranged on the side to which the solder is supplied are formed to have a gradually increasing diameter, and the conductor connecting portions are exposed to have a gradually increasing diameter. It may be a structure.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to the drawings.
Reference numerals 1 and 2 denote flexible printed circuit boards which are connected to each other, respectively, and include base films 3 and 4, and conductors 5 made of copper foil formed on the base films 3 and 4, respectively.
6 and cover lays 7, 8 covering the conductors 5, 6 and covering the base films 3, 4.

Numeral 10 is an FPC carrier for carrying the flexible printed circuit boards 1 and 2 and has an opening 10a at the center.
The FPC is mainly composed of a rectangular frame body having
Positioning pins 12 of appropriate lengths are provided at the corners of the FPC mounting surface 11 on the upper surface of the carrier 10 so as to project upward.

Pin insertion holes 14 are formed at one end of the upper flexible printed circuit board 1, that is, at positions corresponding to the positioning pins 12 of the FPC carrier 10. In addition, each pin insertion hole 1
4 are formed on the flexible printed circuit board 1 at positions avoiding the conductors 5, respectively.

Also, the cover lays 7 at the portions corresponding to the soldering positions of the conductors 5 are removed in a circular shape, and the conductor connecting portions 5 as the soldering portions of the conductors 5 are removed.
a is exposed downward.

Similarly, the other end, that is, the other end of the lower flexible printed board 2 is also formed with pin insertion holes 16 corresponding to the positions of the positioning pins 12 of the FPC carrier 10. . Each pin insertion hole 16 is also formed at a position avoiding each conductor 6 of the flexible printed circuit board 2 as in the above.

Further, the positions where the conductors 6 are soldered,
That is, through-holes 17 for soldering having the same diameter as the removed cover lay 7 are formed at the portions of the flexible printed circuit board 1 corresponding to the conductor connection portions 5a.

Further, the cover lay 8 corresponding to the peripheral portion of each soldering through-hole 17 is removed into a circular shape having a larger diameter, and the conductor connecting portion 6a as the soldering portion of each conductor 6 is directed downward. Exposed in a ring shape.

To connect the conductors 5 and 6 of the flexible printed boards 1 and 2 to each other, the FPC of the FPC carrier 10 is connected as shown in FIGS.
On the mounting surface 11, the flexible printed boards 1 and 2 are mounted in a superposed manner with the soldering surface side facing down.

At this time, the lower flexible printed circuit board 2 is mounted on the FPC mounting surface 11 with the respective positioning pins 12 inserted into the pin insertion holes 16 of the lower flexible printed circuit board 2, and the upper flexible printed circuit board 1 is supported by the respective pins. Each of the positioning pins 12 is inserted into the insertion hole 14 to form a flexible printed circuit board 2.
Place on top.

Here, both flexible printed circuit boards 1,
As shown in FIG. 4, the conductors 2 are overlapped in a positioning manner, and the conductor connecting portions 5a of the upper flexible printed board 1 and the soldering through-holes 17 of the lower flexible printed board 2 are positioned, that is, The conductor connecting portion 6a is matched.

In the superposed state of the flexible printed boards 1 and 2, as shown in FIGS. 2 and 4, the FPC carrier 10 is transferred in the direction of arrow P above the jet type soldering device 19.

When the flexible printed boards 1 and 2 in the superposed state are transferred, as shown in FIG. 4, the molten solder 21 ejected upward by the jet soldering device 19 is opened in the FPC carrier 10. It is supplied to the flexible printed circuit boards 1 and 2 through 10a.

Then, as shown in FIG. 5, the solder 21 supplied to the position of the cover lay 8 falls back into the jet type soldering device 19 without adhering, and the conductor connecting portion 5
The solder 21 supplied to the portions a and 6a, that is, the positions of the soldering through holes 17, adheres and solidifies. here,
The conductor connecting portions 5a and 6a of the flexible printed boards 1 and 2 are soldered 21 to each other through the soldering through holes 17, and the conductors 5 and 6 of the flexible printed boards 1 and 2 are connected to each other.

As described above, according to the method of this embodiment,
By positioning the flexible printed boards 1 and 2 on the FPC carrier 10 in a positioning manner and soldering 21 with the jet soldering device 19, the conductors 5 and 6 of the flexible printed boards 1 and 2 are mutually bonded at once. Connection is possible, and there is no need to apply a solder coat such as a solder leveler as in the conventional example, the number of manufacturing steps can be reduced, and productivity can be improved. In addition, there is no fear of damage due to heating during solder leveling, and product reliability can be improved.

Further, since the conductor connecting portion 6a of the lower flexible printed circuit board 2 is exposed to the conductor connecting portion 5a of the upper flexible printed circuit board 1 in the shape of a ring having a larger diameter, soldering accuracy of the solder 21 is increased. Can be improved.

FIG. 6 shows a second embodiment, which has a structure in which a flux gas vent hole 23 having a small diameter is formed in a portion of the upper flexible printed circuit board 1 corresponding to the position where the solder 21 is attached.

In this case, when the solder 21 is soldered by the same method as in the first embodiment, the flux gas is easily released through the flux gas vent hole 23, and the solder 21 soldering accuracy is further improved.

FIG. 7 shows a third embodiment, which has a structure in which a lead insertion hole 25 having a small diameter is formed in a portion of the upper flexible printed circuit board 1 corresponding to a position where the solder 21 is attached.

In this case, the lead 26 of the mounted component and the conductors 5 and 6 of the flexible printed boards 1 and 2 can be soldered 21 at the same time.

FIG. 8 shows a fourth embodiment, in which a positioning pin 29 of an appropriate length is provided so as to project upward at each corner position on the upper surface of the positioning base 28 having a rectangular plate shape.

Further, each flexible printed circuit board 1, 2
In the same manner as in the first embodiment, pin insertion holes 30 and 31 are formed corresponding to the positions of the positioning pins 29, respectively. Other than that, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

Then, on the positioning table 28, by using each positioning pin 29, each flexible printed circuit board 1,
The two are superposed in a positioning manner, and in this state, the soldering iron 33 and the solder with solder 34 are used for soldering 35.

The same effect as that of the first embodiment can be obtained by the above method.

In each of the above embodiments, the method of connecting the conductors 5 and 6 between the two flexible printed boards 1 and 2 is shown, but three or more flexible printed boards are superposed in the same manner. A method of connecting may be used. In this case, the through holes for soldering of the flexible printed circuit boards, which are sequentially positioned and overlapped, are gradually increased in diameter on the solder supplied side of the flexible printed circuit board arranged on the side opposite to the solder supplied side. If the structure is formed so that the conductor connection portion is gradually exposed to the larger diameter, the soldering accuracy can be improved as described above.

The number of wirings of the conductors 5 and 6 of the flexible printed boards 1 and 2 connected to each other is not limited to two.

[0038]

As described above, according to the method of connecting flexible printed circuit boards of the present invention, the flexible printed board in which the conductor connecting portion corresponding to the soldering position is exposed on the side opposite to the side to which the solder is supplied. A board is arranged, a soldering through hole is formed in a conductor portion corresponding to a soldering position on the side of the flexible printed circuit board to which solder is supplied, and a conductor is provided in a peripheral portion of the soldering through hole. Connect the conductors of each flexible printed circuit board to each other by stacking the exposed flexible printed circuit board in a positioning pattern and then soldering the conductor connection parts of each flexible printed circuit board to each other through the soldering through holes. It is possible to connect each conductor of each flexible printed circuit board at once by soldering. , Hakare a reduction in number of manufacturing steps, the thus improving productivity, without fear of thermal damage, such as during solder leveler, there is an advantage that improvement of reliability can be achieved.

Further, the conductor connection portion of the flexible printed circuit board on the side to which the solder is supplied is exposed in a larger diameter than the conductor connection portion of the flexible printed circuit board arranged on the side opposite to the side to which the solder is supplied. Then, there is an advantage that the soldering accuracy can be improved.

Further, if the structure is such that the flux gas vent holes are formed at the conductor connecting portions of the flexible printed circuit board arranged on the side opposite to the side where the solder is supplied, the flux gas will not escape during soldering. There is an advantage that it becomes easier and the soldering accuracy is further improved.

On the side opposite to the side where the solder is supplied,
A flexible printed circuit board having a conductor connection portion corresponding to the soldering position exposed is arranged, and a soldering through-hole portion is provided in the conductor portion corresponding to the soldering position on the side of the flexible printed circuit board to which solder is supplied. The flexible printed circuit boards which are formed and have the conductor connecting portions exposed at the peripheral edge of the soldering through holes are sequentially superposed in a positioning manner, and in that state, the conductors of the flexible printed circuit boards are passed through the respective soldering through holes. The method of connecting the conductors of each flexible printed circuit board to each other by soldering the connecting portions to each other also has the advantage of improving productivity and reliability.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an assembly in a first embodiment of the present invention.

FIG. 2 is a plan view of the same assembled state.

FIG. 3 is a sectional view showing the assembly.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2;

FIG. 5 is a sectional view of a soldered state.

FIG. 6 is a cross-sectional view of an essential part showing a second embodiment.

FIG. 7 is a main-portion cross-sectional view showing a third embodiment.

FIG. 8 is a sectional explanatory view showing a fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible printed circuit board 2 Flexible printed circuit board 5 Conductor 5a Conductor connecting part 6 Conductor 6a Conductor connecting part 10 FPC carrier 12 Positioning pin 14 Pin insertion hole 16 Pin insertion hole 17 Through hole part for soldering 19 Jet soldering device 21 Solder 23 Flux gas vent

Claims (6)

[Claims] 1. A method of connecting flexible printed boards, wherein a plurality of flexible printed boards are polymerized with each other and conductors of the respective flexible printed boards are connected to each other, the soldering position corresponding to a side opposite to a side to which solder is supplied. A flexible printed circuit board having an exposed conductor connection portion is arranged, and a soldering through-hole portion is formed in a conductor portion corresponding to a soldering position on the side of the flexible printed circuit board to which solder is supplied, and Positioning the flexible printed circuit board where the conductor connection part is exposed at the periphery of the through hole for soldering in a positioning manner, and then soldering the conductor connection parts of each flexible printed circuit board to each other through the through hole for soldering. Characterized in that the conductors of each flexible printed circuit board are connected to each other. A method of connecting a flexible printed circuit board that. 2. The conductor connecting portion of the flexible printed circuit board on the side to which the solder is supplied is exposed to be larger than the conductor connecting portion of the flexible printed circuit board arranged on the side opposite to the side to which the solder is supplied. The method for connecting between flexible printed circuit boards according to claim 1, wherein 3. A flexible printed circuit board according to claim 2, wherein a flux gas vent hole is formed at a conductor connecting portion position of the flexible printed circuit board arranged on the side opposite to the side to which the solder is supplied. How to connect between. 4. The method for connecting flexible printed circuit boards according to claim 1, wherein the soldering is performed by jet soldering. 5. A method for connecting flexible printed boards, wherein a plurality of flexible printed boards are polymerized with each other and conductors of the respective flexible printed boards are connected to each other, the soldering position corresponding to a side opposite to a side to which solder is supplied. A flexible printed circuit board having an exposed conductor connection portion is arranged, and a soldering through-hole portion is formed in a conductor portion corresponding to a soldering position on the side of the flexible printed circuit board to which solder is supplied, and The flexible printed boards with conductor connection portions exposed at the periphery of the through holes for soldering are sequentially stacked in a positioning manner, and in that state, the conductor connection portions of the flexible printed boards are soldered to each other through the through holes for soldering. By connecting the conductors of each flexible printed circuit board to each other A method of connecting a flexible printed circuit board, characterized. 6. The through holes for soldering of each flexible printed circuit board, which are sequentially arranged on the side to which the solder is supplied, are formed to have a gradually increasing diameter, and the conductor connecting portions are exposed to have a gradually increasing diameter. The method for connecting between flexible printed circuit boards according to claim 5, wherein: