JPH0722223B2 - Flexible wiring board connection device and connection method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting device and a connecting method for a flexible wiring board, and more particularly to a wiring pattern formed on the flexible wiring board on another hard circuit board. The present invention relates to a device and method for connecting to a wiring pattern.

[Outline of Invention]

According to the present invention, an access hole for connection is formed in a flexible wiring board, and a connecting tongue connected to a wiring pattern is provided so as to face the access hole. The other hard circuit board is formed with through holes connected to the wiring pattern, and the two boards are formed so that the access holes of the flexible wiring board and the through holes of the circuit board are substantially aligned with each other. By overlapping and joining, the connecting tongue on the flexible wiring board side is bent and inserted into the through hole of another circuit board, and this connecting tongue is connected to the through hole by soldering. Therefore, it is intended to surely achieve the connection by eliminating the connection failure.

[Conventional technology]

By using the flexible wiring board and another circuit board in combination, for example, a hard board, the electronic device can be made smaller and lighter. When using a flexible wiring board and other circuit boards in combination,
It becomes necessary to electrically connect both wiring patterns to each other.

Therefore, for example, as shown in FIG. 16, an access hole is formed in the base 1 so as to expose the connection portion of the wiring pattern 3 formed so as to be sandwiched between the insulating base 1 of the flexible wiring board and the insulating sheet 2 for covering. 4 is formed, and a preliminary solder 5 is formed on the access hole 4.
Keep. Then, this flexible wiring board is bonded to the hard circuit board 7 via the adhesive layer 6. In this case, the adhesive layer 6 is not arranged on the preliminary solder 5. Then, the preliminary solder 5 is attached to the hard circuit board 7
The wiring pattern 8 on the flexible wiring board side is connected to the wiring pattern 8 on the hard board 7 by facing the wiring pattern 8 of FIG. ing.

Alternatively, as shown in FIG. 17, the access hole 4 for providing the preliminary solder 5 is formed so as to penetrate the wiring pattern 3 of the flexible wiring board, and the access hole 9 larger than the access hole 4 is covered. The insulating sheet 2 is also formed, and a larger amount of the preliminary solder 5 is provided. Also in this case, after the flexible wiring board is joined to the hard board 7, the preliminary solder 5 is melted by the heat applied from the outside to join the wiring pattern 3 and the wiring pattern 8 on the board 7. .

[Problems to be solved by the invention]

According to the conventional method shown in FIG. 16, the wiring pattern 3 on the flexible wiring substrate side and the wiring pattern 8 on the hard substrate 7 side
Between the insulating base 1 and the adhesive layer 6 (about 45μ), the gap (about 70μm).
μ) occurs, and there is a gap too large to be connected by solder. Ie generally 50
If there is a gap of μ or more, the solder fillet cannot be formed well. This gap becomes larger due to the deterioration of the adhesive layer 6. Further, since the preliminary solder 5 is melted in the closed space, there is no escape area for gas associated with the solder connection, which increases the rate of connection failure. Further, according to this method, there is a problem that it is difficult to visually determine the quality of the connection portion from the outside, and it is difficult to correct the defective connection portion.

According to another conventional method shown in FIG. 17, since the space in which the preliminary solder 5 is melted is opened to the outside, the gas can be easily diffused when the solder is melted. Wiring pattern 8 on pattern 3 and hard substrate 7 side
The distance between and is the same as in the connection device described above, and there is a distance equal to the sum of the thickness of the insulating base 1 and the thickness of the adhesive layer 6. And, there is a drawback that this distance becomes large due to deterioration of the adhesive layer 6. Therefore, it is not possible to solve the connection failure due to such a large distance, and the ratio of connection failure is still high. Also in this method, the quality of the connected portion cannot be visually judged from the outside, and it is difficult to correct the defective portion.

The present invention has been made in view of such problems, and more reliably connects a wiring pattern on a flexible wiring board to a wiring pattern on another circuit board, and reduces the rate of connection failure. It is an object of the present invention to provide a connecting device and a connecting method as described above.

[Means for solving problems]

According to the present invention, an access hole is formed at a connection position of a flexible wiring board, a connection tongue is formed so as to be connected to a wiring pattern and face the access hole, and the connection tongue is provided at a connection position corresponding to the access hole. The flexible wiring board is provided with access holes and through holes to another rigid circuit board in which conductors on the inner peripheral surface of the through hole connect wiring patterns on both surfaces of this circuit board. Are overlapped with each other at least at the connecting position so that the connecting tongue provided so as to face the access hole is bent and inserted into the through hole, and in this state, the connecting tongue and the through hole are The present invention relates to a connecting device and a connecting method for a flexible wiring board, which are connected to a conductor on an inner peripheral surface by soldering.

[Action]

Therefore, the wiring pattern formed on the flexible wiring board and the wiring pattern provided on the hard circuit board are connected to each other by soldering and connecting tongue pieces and conductors on the inner peripheral surface of the through hole. And the flexible board and the other rigid circuit board are electrically connected to each other.

〔Example〕

The present invention will be described below with reference to the illustrated embodiments. First, the first embodiment will be described with reference to FIGS. A sheet of polyimide or the like that constitutes the insulating base 11 of the flexible wiring board is prepared as shown in FIG. 2, and the access hole 12 is formed in this sheet by a method such as punching. Then, a copper foil 13 is bonded onto the base 11 through an adhesive means (not shown) as shown in FIG. On the exposed surface of this copper foil 13, after printing a circuit pattern, by removing unnecessary portions by an etching method,
A wiring pattern 14 is formed as shown in FIG. Next, as shown in FIG. 5, an access hole is previously placed at a predetermined position.
Wiring pattern with insulating sheet 16 for coating on which 15 is formed
It is made to join so as to cover 14 through an adhesive means (not shown). At this time, the access hole 15 of the insulating cover sheet 16 is made to coincide with the access hole 12 of the base 11.

In this way, the flexible wiring board 17 as shown in FIGS. 5 and 6 is obtained. This flexible wiring board 17 is provided with access holes 12 and 15 at a portion connected to another circuit board, and
A wiring pattern 14 that crosses 12 and 15 is provided. The wiring pattern 14 exposed by the access holes 12 and 15 can be subjected to electric solder plating if necessary. Further, as shown in FIG. 6, a ring-shaped pattern 18 is formed along the edges of the access holes 12 and 15, and a protrusion-shaped pattern 19 corresponding to the tip of the wiring pattern 14 is formed into a ring-shaped pattern 18. Are formed continuously. The ring-shaped pattern 18 is provided for taking measures when the cutting margin becomes short and the circuit cannot be connected when the connecting tongue is formed in the cutting step of the wiring pattern 14 described later. is there. The protruding pattern 19 is formed in order to favorably etch the wiring pattern 14.

Further, in this embodiment, the inner diameters of the access holes 12 and 15 are 2 mm, and the width of the wiring pattern 14 that crosses the access holes 12 and 15 is 0.65 mm. The outer shape of the ring-shaped pattern 18 has a diameter of 2.5 mm. In particular, the inner diameter of the ring-shaped pattern 18 and the inner diameter of the access holes 12 and 15 are 2 mm, which is a value for preventing clogging of the solder when connecting with solder and facilitating gas emission. However, if the size of this portion is reduced, the defective rate of connection tends to increase.

Such a flexible wiring board 17 is bonded to a hard board 21 via an adhesive layer 20, as shown in FIG. The adhesive layer 20 is formed by bonding an adhesive having a release paper to the surface of the flexible wiring board 17 and removing the release paper afterwards to form the flexible wiring board 17.
It is designed to be formed on the surface of the base 11. It should be noted that the release paper is preliminarily formed with openings corresponding to the access holes 12 and 15 so that the adhesive 20 is not attached to the exposed wiring pattern 14. Further, the flexible wiring board 17 and the hard board 21 are joined by heating to 60 to 80 ° C. and holding for 5 to 10 seconds while applying a pressure of 7 kg / cm ² through the adhesive layer 20. They are joined together by the hot pressing method.

Through holes 22 are formed in advance at predetermined positions in the hard substrate 21 to which the flexible wiring substrate 17 is joined in this manner before being joined. Access holes 12 and 15
If the diameter is 2 mm, the diameter of the through hole 22 may have a value of 1.3 mm. The inner surface of the through hole 22 is plated 23 to form a conductive layer. Furthermore, in this hard substrate 21,
A wiring pattern 24 is formed on at least one surface so as to be connected to the plating 23, and a resist layer (not shown) is further formed.

In this way, the flexible wiring board 17 is formed on the hard board 21.
After joining, the wiring pattern 14 extending across the access holes 12 and 15 of the flexible wiring board 17 is cut by the cutting tool 25 shown in FIG. The cutting force at this time may be a value of approximately 300 to 500 g. Further, by inserting the tool 25 into the through hole 22, the connecting tongue piece 27 formed by cutting the wiring pattern 14 is bent so as to be inserted into the through hole 22. The cutting of the wiring pattern 14 with the tool 25 can be performed in the same process as the hot pressing with the adhesive 20. The cutting tool 25 used here has an angle of 30 degrees at the edge 26 at the tip thereof. By setting such an angle,
The edge 26 of the tool 25 makes it possible to easily cut the exposed wiring pattern 14 in the access holes 12 and 15, and the connecting tongue piece 27 formed by cutting after that.
Can be easily pushed into the through hole 22. Furthermore, when the tool 25 is pulled out, the tongue piece 27 is prevented from coming off together. The cutting of the connecting tongue piece 27 and the pushing into the through hole 22 may be performed in separate steps.

In this way, the flexible wiring board 17 is
It is joined with 21, passes through the appropriate mounting process, and is automatically soldered by a dip or flow soldering device. Then, as a result of this soldering process, as shown in FIG. 1, a plating tongue piece 27 having a tip end extending into the through hole 22 is formed on the peripheral surface of the through hole 22.
And will be connected by solder 28.

According to such a connection, the connection can be made without paying attention to the deterioration of the adhesive agent and the gap between the wiring patterns 14 and 24 of the solder connection portion. Further, the through hole 22 and the access holes 12 and 15 allow the gas to be diffused well, and a highly reliable connection can be obtained. When an experiment was conducted on the connection of this example, no defects were found at the connection of the 18049 holes.

Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, the insulating base 11 is first prepared. Here, the insulating base 11 is not provided with an access hole as shown in FIG. And this insulation base
As shown in FIG. 9, copper foil 13 is adhered to 11 and unnecessary portions are removed by etching to form a wiring pattern 14.
Are formed (see FIG. 10). Next, this wiring pattern 14
The insulating cover sheet 16 is bonded so as to cover the exposed surface of the. The access holes 15 are formed in the sheet 16 in advance.

The connection portion of the flexible wiring board 17 thus obtained is punched as shown in FIG. At this time, a punching tool 31 having a sectional shape as shown in FIG. 13 is used. This tool 31 has the same outer shape as the access hole 15 and is provided with a slit-shaped notch. Therefore, when the flexible wiring board 17 is punched out by this notch, the connecting portion is formed as shown in FIGS. 12 and 14. That is, by this punching, the wiring pattern 14 is projected so as to be exposed in the access holes 12 and 15, and the insulating base 11 is joined to the wiring pattern 14. Therefore, the strength is greater than that of the connecting tongue formed of only the wiring pattern 14. Further, in this embodiment, the tongue piece 27 formed by the wiring pattern extends from one place around the access holes 12 and 15.

The flexible wiring board 17 thus formed is
As shown in FIG. 15, through holes similar to those of the first embodiment
A hard substrate 21 provided with 22 is joined via an adhesive layer 20, and at the same time, a tongue piece 27 extended in the access holes 12 and 15 by a bending tool 32 is in the through hole 22. It will be bent so as to enter. Then, when soldering is performed by the dip or flow solder device after mounting the components, the tongue piece 27 is electrically connected to the plating 23 of the through hole 22 by the solder 28.

In this embodiment, the tongue for connecting the flexible wiring board 17 from the beginning so as to face the access holes 12 and 15.
Since 27 is formed, the wiring pattern 14 is not cut by the tool 32. Therefore, it is possible to bend the tongue piece 27 with a tool having a hemispherical tip as shown in FIG. Then, instead of such a tool 32, it is possible to use a lead of an electronic component and substitute the tool 32 with this lead. Further, in this embodiment, the upper surface of the tongue piece 27 is reinforced by the insulating base 11, but the opposite surface can be reinforced by the insulating sheet 16.

In general, the combination of the flexible wiring board 17 and the rigid board 21 is rapidly increasing in its applications as electronic devices are downsized. Then, as in this embodiment, by inserting the connecting tongue piece 27 forming a part of the wiring pattern 14 of the flexible wiring board 17 into the through hole 22 of the opposing hard board 21 and performing soldering, solder connection is performed. The gas generated at this time can be diffused, and the tongue piece 27 and the through hole 22 can be firmly soldered to each other by the solder 28. Further, the quality of the connection portion of the solder 28 can be easily judged visually from the outside. Further, according to this embodiment, since the soldering process can be performed by an automatic soldering device such as a flow or dip method without using manual soldering, there is an advantage that the productivity of the connection device can be increased and the cost can be reduced. It will be.

The present invention has been described above with reference to the two illustrated embodiments.
The present invention is not limited to the above two embodiments, and various modifications can be made based on the technical idea of the present invention. For example, a pair of connecting tongues each having one surface covered with an insulating base or a covering insulating sheet are provided so as to extend from two places around the access hole, and these tongues are soldered to another circuit. You may connect to the through hole of a board | substrate.

〔The invention's effect〕

According to the present invention as described above, the connecting tongue provided so as to face the access hole of the flexible wiring board is bent and inserted into the through hole of the other hard circuit board, and the connecting tongue is also provided. Is connected to the through hole with solder. Therefore, according to the present invention, it becomes possible to reliably connect the connecting tongue on the flexible wiring board side and the through hole on the hard circuit board side by the solder introduced into the through hole, and reduce the defective rate of connection. It is possible to significantly reduce it. This makes it possible to provide a highly reliable connection device and connection method for connecting the flexible wiring board and another circuit board.
Further, according to the present invention, the quality of the connecting portion can be directly visually judged from the outside by the access hole, and the defective portion can be easily corrected. Further, by performing the soldering by using the automatic soldering device, it is possible to improve the productivity and reduce the cost.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing a connection device according to a first embodiment of the present invention, FIG. 2 is a sectional view of an insulating base of a flexible wiring board, and FIG. 3 is a copper foil bonded to this insulating base. FIG. 4 is a sectional view of a state in which a copper foil is etched, FIG. 5 is a sectional view of a state in which a covering insulating sheet is further joined, and FIG. 6 is a connection portion of the obtained flexible wiring board. 7 is an enlarged plan view of FIG. 7, FIG. 7 is a vertical cross-sectional view showing a state in which a wiring pattern extending to an access hole is cut to form a connecting tongue piece, and FIG. 8 relates to a second embodiment of the present invention. Sectional view of an insulating base of a flexible wiring board used in a connection device, FIG. 9 is a sectional view of a state in which a copper foil is joined to this insulating base, FIG. 10 is a sectional view of a state in which a copper foil is etched, and FIG. Is a cross-sectional view of a state in which a covering insulating sheet is further joined. Fig. 13 is a sectional view showing a state in which an access hole is formed by punching, Fig. 13 is a sectional view showing a punching die for forming an access hole, and Fig. 14 is an enlarged plan view of an essential part showing a connecting portion of the obtained flexible wiring board. FIG. 15 is a cross-sectional view of such a flexible wiring board joined to a rigid substrate, FIG. 16 is a cross-sectional view showing a conventional flexible wiring board connecting device, and FIG. 17 is another conventional flexible wiring board. It is sectional drawing which shows the connection device of FIG. In the reference numerals used in the drawings, 12, 15 ... access holes 14, 24 ... wiring pattern 17 ... flexible wiring board 21 ... hard board 22 ... through hole 23 ... plating (conductive layer) 27 ... connection It is a tongue.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Zenzo Ito 9-15-22 Hongo-cho, Minokamo City, Gifu Prefecture Sony Minokamo Co., Ltd. Address Nippon Mektron Co., Ltd., Minami-Ibaraki Plant (56) References Actual Development Sho 55-22147 (JP, U) Japanese Patent Sho 48-8419 (JP, B2)

Claims (6)

[Claims] 1. An apparatus for connecting a wiring pattern formed on a flexible wiring board to a wiring pattern on another hard circuit board, comprising: an access hole formed at a connection position of the flexible board; A connecting tongue connected to the wiring pattern of the board and formed to face the access hole; and a through hole formed to correspond to the access hole at the connection position of the hard circuit board. ,
The flexible board and the rigid circuit board are respectively provided with through holes which connect the wiring patterns on both surfaces of the circuit board to each other by the conductors formed on the inner peripheral surface of the through hole. The access hole and the through hole are overlapped at least at the connecting position so that the connecting tongue piece is bent and inserted into the through hole, and is connected to the conductor on the inner peripheral surface of the through hole by soldering. A flexible wiring board connecting device characterized by being provided. 2. The flexible wiring board connection according to claim 1, wherein an insulating sheet covering the surface of the flexible wiring board is bonded to one surface of the connecting tongue piece. apparatus. 3. The connection tongue piece according to claim 1, wherein the connection tongue piece is provided so as to extend from two substantially symmetrical locations around the access hole of the flexible substrate. Flexible wiring board connection device. 4. The connection tongue piece is provided so as to extend from one location around the access hole of the flexible substrate.
A flexible wiring board connecting device according to item. 5. A method of connecting a wiring pattern formed on the flexible wiring board to a wiring pattern on another hard circuit board, wherein an access hole is formed at a connection position of the flexible wiring board, and the wiring pattern is formed. A connecting tongue is formed so as to face the access hole, and the conductor on the inner peripheral surface of the through hole provided at the connection position corresponding to the access hole has wiring patterns on both sides of the rotating substrate. A through hole connecting the flexible wiring board with respect to the other hard circuit board is formed in advance, at least at the bonding position so that the access hole and the through hole substantially coincide with each other, Inside the through hole by bending the connecting tongue provided so as to face the access hole. Insert, a method of connecting a flexible wiring board, characterized in that so as to connect the conductor of the inner peripheral surface of the through hole and the connecting tongue piece in this state by soldering. 6. A wiring pattern is formed so as to cross the access hole of the flexible wiring board, and the access hole of the flexible board and the through hole of the printed board are superposed so as to be substantially aligned with each other, and the cutting tool is cut. The connecting tongue piece is formed by inserting the connecting tongue piece into the access hole by cutting the wiring pattern, and the connecting tongue piece is bent and inserted into the through hole. The method for connecting a flexible substrate according to claim 5.