WO2012066973A1

WO2012066973A1 - Method for manufacturing flexible multi-layered circuit substrate

Info

Publication number: WO2012066973A1
Application number: PCT/JP2011/075669
Authority: WO
Inventors: 大助寺師; 佐藤　禎倫; 隆司松川
Original assignee: 株式会社フジクラ
Priority date: 2010-11-17
Filing date: 2011-11-08
Publication date: 2012-05-24
Also published as: JP2012109406A

Abstract

Provided is a method for manufacturing flexible multi-layered circuit substrates, which is capable of stably manufacturing flexible multi-layered circuit substrates. The method for manufacturing a flexible multi-layered circuit substrate (1) comprises: a preparation process (P1) for preparing, on base films (15, 25), first and second transfer circuit substrates (16, 26) having first and second circuit layers (10, 20) formed thereon, and an insulating film (30) having through holes (31a, 31b) formed therein; an affixing process (P2) for affixing the first and second transfer circuit substrates (16, 26) to both surfaces of the insulating film (30) so that the through holes (31a, 31b), first connection parts (11a, 11b), and second connection parts (21a, 21b) overlap; a peeling process (P3) for peeling the base films (15, 25) from the first and second circuit layers (10, 20); and a connection process (P4) for connecting, by welding, the first and second circuit layers (10, 20) on both surfaces of the insulating film (30) at the through holes (31a, 31b).

Description

Method for manufacturing flexible multilayer circuit board

The present invention relates to a method for manufacturing a flexible multilayer circuit board, and more particularly to a method for manufacturing a flexible multilayer circuit board that can stably produce a flexible multilayer circuit board.

In a small electronic device represented by a mobile phone or PDA (Personal Digital Assistant), a flexible multilayer circuit board in which a plurality of flexible circuit boards each having a circuit layer formed on a flexible base film is used is used. There is.

The following Patent Document 1 describes a method for manufacturing such a flexible multilayer circuit board. In this flexible multilayer circuit board manufacturing method, a circuit layer made of copper foil or the like is formed on a flexible base film to obtain a flexible circuit board. Then, in the part of the part where the circuit layer is formed in each flexible circuit board, leaving only the circuit layer and peeling the base film, the both sides of the circuit layer are exposed in the part where the base film is peeled off. And make it a bridge without support. Then, the flexible circuit boards are laminated and bonded so that the bridge portions of the circuit layer overlap each other. Thereafter, the circuit layers of the flexible circuit boards are connected to each other by welding at the portion where the circuit layers of the flexible circuit boards are bridged, and the circuit layers formed on the flexible circuit boards are electrically connected to each other.

JP 2003-204160 A

In the method for manufacturing a flexible multilayer circuit board described in Patent Document 1, the strength of the periphery of each flexible circuit board where the base film is peeled is weakened, so this part is more easily deformed than the other parts. Then, when each of the flexible circuit boards is overlapped to form a multilayer, stress may be applied to the flexible circuit board. In this case, the periphery of the flexible circuit board from which the base film is peeled is deformed to form a bridge-like shape. There is a possibility that the circuit layer is disconnected. For this reason, the manufacturing method which can manufacture a flexible multilayer circuit board stably is calculated | required.

Therefore, an object of the present invention is to provide a method for manufacturing a flexible multilayer circuit board that can stably manufacture the flexible multilayer circuit board.

The method for producing a flexible multilayer circuit board of the present invention comprises a pair of transfer circuit boards in which a circuit layer is formed on a flexible base film, and a preparation step of preparing an insulating film in which through holes are formed. The transfer circuit board has the surface on which the circuit layer is formed facing toward the insulating film, and the transfer hole is placed on both sides of the insulating film so that the through holes and a part of the circuit layer overlap each other. Bonding step of bonding the circuit board for use, a peeling step of peeling the base film of each of the circuit boards for transfer bonded to the insulating film from the circuit layer, and both surfaces of the insulating film in the through hole A connection step of connecting the circuit layers together by welding.

According to such a method for manufacturing a flexible multilayer circuit board, the base film is peeled off after the respective transfer circuit boards are bonded to both sides of the insulating film, so when the transfer circuit board is bonded to the insulating film, Even when stress is applied to the circuit board for transfer, the base film can suppress deformation of the insulating film in the vicinity of the through hole, and the circuit layer can be prevented from being disconnected by deformation of the insulating film. And after disconnection is prevented in this way and laminated | stacked, a base film is peeled and each circuit layer is electrically connected by welding the exposed circuit layers. Thus, the flexible multilayer circuit board can be stably manufactured.

Moreover, it is preferable to further include a protection step of providing an insulating protection layer so as to cover at least a part of at least one of the circuit layers after the connection step in the method for manufacturing a flexible multilayer substrate.

By providing such a protective layer, it is possible to prevent the circuit layer from touching other members and being damaged or short-circuiting.

In the method for manufacturing a flexible multilayer substrate, at least a part of the circuit layer may be an antenna.

As described above, according to the present invention, a method for manufacturing a flexible multilayer circuit board capable of stably manufacturing a flexible multilayer circuit board is provided.

1 is a plan view showing a flexible multilayer circuit board according to an embodiment of the present invention. It is sectional drawing in the II-II line of FIG. It is a flowchart which shows the manufacturing method of the flexible multilayer circuit board of FIG. It is a figure which shows the mode after a preparatory process. It is a figure which shows the mode after a bonding process. It is a figure which shows the mode after a peeling process. It is a figure which shows the mode of a connection process.

Hereinafter, preferred embodiments of a method for producing a flexible multilayer substrate according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a plan view showing a flexible multilayer circuit board according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line II-II in FIG.

As shown in FIG. 1, the flexible multilayer circuit board 1 of the present embodiment includes an insulating film 30, a first circuit layer 10 provided on one surface of the insulating film 30, and the other surface of the insulating film 30. And the second circuit layer 20 provided in the main structure.

The insulating film 30 is made of an insulating resin having flexibility. As shown in FIGS. 1 and 2, the insulating film 30 is formed with a pair of circular through

holes

31 a and 31 b. The material of the insulating film 30 is not particularly limited, and examples thereof include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), and the like.

The first circuit layer 10 includes an antenna 13 and a pair of

first connection portions

11 a and 11 b connected to both ends of the antenna 13. The pair of

first connection portions

11a and 11b are circular with a diameter larger than that of the through

holes

31a and 31b, and the pair of penetrations formed in the insulating film 30 when the flexible multilayer circuit board 1 is viewed in plan view. It is formed so as to cover the

holes

31a and 31b. The antenna 13 has a thin conductor formed in a line shape having a substantially rectangular loop shape, and the first connection portion 11a is connected to the outer peripheral end of the antenna 13 so that the antenna A first connection portion 11b is connected to an end portion on the inner peripheral side of 13.

The material of the antenna 13 is not particularly limited as long as it is a conductive material, and examples thereof include metals such as copper (Cu), nickel (Ni), and aluminum (Al). Moreover, the material of the

1st connection parts

11a and 11b consists of a conductive material which can be welded, and the metal similar to the antenna 13 is mentioned as such a material. The antenna 13 and the first connecting

portions

11a and 11b may be made of the same material, or may be made of different materials.

The second circuit layer 20 includes a pair of

circuit layers

20a and 20b. The pair of

circuit layers

20a and 20b are connected to the

lines

23a and 23b and one end of each of the

lines

23a and 23b.

Second connection portions

21a and 21b, and

terminals

22a and 22b connected to the other ends of the

respective lines

23a and 23b. Each of the

second connection portions

21a and 21b has substantially the same size and the same shape as the

first connection portions

11a and 11b, and when the flexible multilayer circuit board 1 is viewed in plan as shown in FIG. Each of the first circuit layers 10 is provided at a position overlapping the

first connection portions

11a and 11b. However, in each figure, the size of the

second connection portions

21a and 21b is written slightly larger than that of the

first connection portions

11a and 11b for easy understanding. The

terminals

22a and 22b are provided outside the outer periphery of the antenna 13, and have substantially the same size and the same shape as the

second connection portions

21a and 21b. The pair of

lines

23a and 23b are linearly formed from the

second connection portions

21a and 21b to the

terminals

22a and 22b, respectively.

The materials of the

terminals

22a and 22b and the

lines

23a and 23b are not particularly limited as long as they are conductive materials. For example, the same material as the material of the antenna 13 can be used. . The material of the

second connection portions

21a and 21b is made of a conductive material that can be welded. Examples of such a material include the same materials as those of the

first connection portions

11a and 11b. In addition, each

terminal

22a, 22b, each

line

23a, 23b, and each

2nd connection part

21a, 21b may be comprised from the same material, and each may be comprised from another material. good.

And as shown in FIG. 2, the 1st connection part 11a and the 2nd connection part 21a are connected by welding in the through-hole 31a, and the 1st connection part 11b and the 2nd connection part 21b pass through. The holes 31b are connected by the same method.

In addition, as shown in FIG. 2, the first circuit layer 10 is covered with a protective layer 41 on the surface opposite to the insulating film 30 side, and the second circuit layer 20 is opposite to the insulating film 30 side. This surface is covered with a protective layer 42 except for the

terminals

22a and 22b. Such a material of the

protective layers

41 and 42 is not particularly limited as long as it is an insulating material, and examples thereof include resins such as polyimide. In FIG. 1, the

protective layers

41 and 42 are not shown.

In addition, a plurality of through holes 39 used in the manufacturing process of the flexible multilayer circuit board 1 are formed in the insulating film 30.

Thus, the flexible multilayer circuit board 1 is an antenna

device having terminals

22a and 22b as external terminals.

Next, a method for manufacturing the flexible multilayer circuit board 1 will be described.

FIG. 3 is a flowchart showing a method for manufacturing the flexible multilayer circuit board of FIG.

As shown in FIG. 3, the manufacturing method of the flexible multilayer circuit board 1 of this embodiment includes a preparation process P1, a bonding process P2, a peeling process P3, a connection process P4, and a protection process P5.

(Preparation process P1)
First, as shown in FIG. 4, a first transfer circuit board 16 having a first circuit layer 10 formed on one surface of a flexible base film 15, and a flexible base film 25. A second transfer circuit board 16 having the second circuit layer 20 formed on one surface thereof and an insulating film 30 having through

holes

31a and 31b are prepared. In addition, although it does not specifically limit as a material of this base film, PI and PET are mentioned.

The first transfer circuit board 16 is prepared as follows. First, the base film 15 is prepared, and a metal layer to be the first circuit layer 10 is formed on the entire one surface of the base film 15. Formation of a metal layer is performed by sticking a metal layer on a base film using an adhesive. Next, a pinnacle cutter having the same shape as that of the first circuit layer 10 is prepared, and only the metal layer is cut into the same shape as the first circuit layer 10 with this pinnacle cutter. Then, the first transfer circuit board 16 shown in FIG. 4 may be obtained by peeling off and removing the unnecessary metal layer. The thickness of the metal layer is not particularly limited, but is preferably 6 μm to 18 μm from the viewpoint of obtaining a predetermined strength. Alternatively, after forming a metal layer on one whole surface of the base film 15 in the same manner as described above, a mask is formed with a resist or the like on the portion of the metal layer that becomes the first circuit layer 10, and unnecessary metal is etched. The first transfer circuit board 16 shown in FIG. 4 is obtained by removing the layer and then removing the resist. Further, as shown in FIG. 4, a plurality of through holes 19 are formed in the base film 15 at the same positions as the plurality of through holes 39 formed in the insulating film 30 shown in FIG. 1. The through hole 19 may be formed by punching or the like.

Further, the second transfer circuit board 26 is prepared on the second surface of the base film 25 by the same method as that for preparing the base film 25 and forming the first circuit layer 10 on the base film 15. A circuit layer 20 is formed. Also in the second transfer circuit board 26, the base film 25 has a plurality of through holes 29 at the same position as the plurality of through holes 39 formed in the insulating film 30 shown in FIG. Form. In forming the second circuit layer 20, the second circuit layer 20 is formed on the base film 15 of the second transfer circuit board 26 and the positions of the plurality of through holes 19 formed in the base film 15 of the first transfer circuit board 16. When the first transfer circuit board 16 and the second transfer circuit board 26 are overlapped with the positions of the plurality of through holes 29, the

second connection portions

21 a and 21 b are respectively connected to the first circuit layer 10. The

terminals

22 a and 22 b are provided outside the outer periphery of the antenna 13 so as to overlap the

first connection portions

11 a and 11 b. In this way, the second transfer circuit board 26 shown in FIG. 4 is obtained.

The insulating film 30 prepares a flexible insulating film constituting the insulating film 30, and forms the through

holes

31 a and 31 b and the plurality of through holes 39. The plurality of through holes 39 are formed at the same positions as the plurality of through holes 19 formed in the base film 15 of the first transfer circuit board 16. And when the through-

holes

31a and 31b match | combine the several through-hole 39 with the several through-hole 19 of the circuit board 16 for 1st transfer, the insulating film and the circuit board 16 for 1st transfer were piled up, In the position which overlaps with the

1st connection parts

11a and 11b, it forms in the circle | round | yen smaller than the

1st connection parts

11a and 11b. The formation of the through

holes

31a and 31b and the plurality of through holes 39 is not particularly limited, but may be formed by punching, for example. Although not shown, a thermoplastic resin as an adhesive is applied to both surfaces of the insulating film 30. The adhesive strength of the thermoplastic resin is that the adhesive that bonds the base film 15 of the first transfer circuit board 16 and the first circuit layer 10 and the base film 25 of the second transfer circuit board 26 and the first film It has stronger adhesive force than the adhesive that bonds the two circuit layers 20 together. In this way, the insulating film 30 shown in FIG. 4 is obtained.

(Lamination process P2)
In the bonding step P2, first, the insulating film 30 and the first transfer circuit board 16 are overlapped so that the first circuit layer 10 of the first transfer circuit board 16 faces the insulating film 30 side. At this time, the plurality of through holes 19 of the first transfer circuit board 16 and the plurality of through holes 39 of the insulating film 39 are passed through the plurality of pins of a jig (not shown), thereby the first transfer with the insulating film 30. The position with the circuit board 16 is adjusted. Next, the insulating film 30 and the second transfer circuit board 26 are overlaid. At this time, the positions of the insulating film 30 and the second transfer circuit board 26 are aligned by using the plurality of through holes 29 of the second transfer circuit board 26 as pins of the jig described above. Thus, the first transfer circuit board 16, the insulating film 30, and the second transfer circuit board 26 are aligned and overlapped with each other, and the through

holes

31 a and 31 b of the insulating film 30 and the first transfer circuit board 16 are overlapped. The

first connection portions

11a and 11b and the

second connection portions

21a and 21b of the second transfer circuit board 26 are overlapped with each other. At this time, the first transfer circuit board 16, the insulating film 30, and the second transfer circuit board 26 are preferably temporarily fixed with an adhesive (not shown) from the viewpoint of preventing positional deviation.

Next, the laminate in which the first transfer circuit board 16, the insulating film 30, and the second transfer circuit board 26 are overlapped is roll-pressed at a high temperature. The temperature of the roll press is a temperature at which the thermoplastic resin as the adhesive applied to the insulating film 30 is melted and the first transfer circuit board 16, the insulating film 30, and the second transfer circuit board 26 are not damaged. Although not particularly limited, for example, the temperature is set to 150 ° C.

Thus, as shown in FIG. 5, the

first transfer portion

11a, 11b and the

second connection portion

21a, 21b face each other through the through

holes

31a, 31b, and the first transfer is performed on one surface of the insulating film 30. The circuit board 16 for application is bonded, and the second transfer circuit board 26 is bonded to the other surface of the insulating film 30. As shown in FIG. 5, at least the insulating film 30 may be bonded to the first circuit layer 10 and the second circuit layer 20, and the base film 15 and the base film 25 are bonded to the insulating film 30. It is not necessary.

(Peeling process P3)
Next, the base film 15 is peeled from the first transfer circuit board 16. That is, the base film 15 is peeled from the first circuit layer 10. The base film 15 may be peeled by peeling the base film 15 from the insulating film 30. At this time, as described above, the first transfer is performed using the adhesive having stronger adhesive force than the adhesive that bonds the base film 15 and the first circuit layer 10 in the first transfer circuit board 16. Since the circuit board 16 and the insulating film 30 are bonded together, the first circuit layer 10 remains on one surface of the insulating film 30 by peeling off the base film 15. Next, the base film 25 is peeled from the second transfer circuit board 26 in the same manner as the base film 15 is peeled off. That is, the base film 25 is peeled from the second circuit layer 20. At this time, as described above, the second transfer is performed using the adhesive having stronger adhesive force than the adhesive that bonds the base film 25 and the second circuit layer 20 in the second transfer circuit board 26. Since the circuit board 26 and the insulating film 30 are bonded together, the second circuit layer 20 remains on the other surface of the insulating film 30 by peeling off the base film 25. Thus, as shown in FIG. 6, the first circuit layer 10 is formed on one surface of the insulating film 30, and the second circuit layer 20 is formed on the other surface of the insulating film 30.

(Connection process P4)
Next, in each of the through

holes

31a and 31b, the

first connection portions

11a and 11b of the first circuit layer 10 formed on one surface of the insulating film 30 and the other surface of the insulating film 30 are formed. The

second connection portions

21a and 21b of the second circuit layer 20 are connected. As shown in FIG. 7, this connection is performed by sandwiching the first connection portion 11a and the second connection portion 21a between the

electrodes

51a and 52a. Examples of this welding include resistance welding, ultrasonic welding, and laser welding. Moreover, the 1st connection part 11b and the 2nd connection part 21b are inserted | pinched with the

electrodes

51b and 52b by the same method, and welding is performed.

(Protection process P5)
Next, the entire one surface of the insulating film 30 on which the first circuit layer 10 is formed is covered with a protective layer 41. The protective layer 41 can be provided, for example, by applying an uncured ultraviolet curable resin and then curing the ultraviolet curable resin, or by attaching an insulating film. Next, a portion other than the

terminals

22 a and 22 b on the other surface of the insulating film 30 on which the second circuit layer 20 is formed is covered with the protective layer 42. The protective layer 42 may be provided by the same method as the protective layer 41, for example. In this way, the flexible multilayer circuit board 1 shown in FIGS. 1 and 2 is obtained.

According to the method for manufacturing the flexible multilayer circuit board 1 of the present embodiment, after the first transfer circuit board 16 and the second transfer circuit board 26 are bonded to the respective surfaces of the insulating film 30, the respective base films 15. , 25 are peeled off, and stress is applied to the first transfer circuit board 16 and the second transfer circuit board 26 when the first transfer circuit board 16 and the second transfer circuit board 26 are bonded to the insulating film 30. Even in such a case, since the insulating films near the through

holes

31a and 31b can be suppressed by the

base films

15 and 25, the first circuit layer 10 or the second circuit layer 20 is disconnected due to the deformation of the insulating film. Can be prevented. Then, after the first circuit layer 10 or the second circuit layer 20 is prevented from being disconnected in this way and the first transfer circuit board 16 and the second transfer circuit board 26 are laminated, the

respective base films

15 and 25 are attached. By peeling and welding the exposed first circuit layer 10 and second circuit layer 20, the first circuit layer 10 and the second circuit layer 20 are electrically connected to each other. Thus, the flexible multilayer circuit board 1 can be manufactured stably.

Furthermore, according to the method for manufacturing the flexible multilayer circuit board 1 of the present embodiment, the first transfer circuit board 16 and the second transfer circuit board 26 are bonded to the respective surfaces of the insulating film 30, and then the respective bases. Since the

films

15 and 25 are peeled off and then connected by welding, the time during which the connecting portions of the first and second circuit layers 10 and 20 remain unsupported on the through

holes

31a and 31b is shortened. Can do.

Moreover, in the manufacturing method of the flexible multilayer circuit board 1 of this embodiment, by providing the

protective layers

41 and 42, the first circuit layer 10 and the second circuit layer 20 may be damaged by touching other members or short-circuited. Can be prevented.

As mentioned above, although this invention was demonstrated to the example for embodiment, this invention is not limited to these.

For example, in the above embodiment, only the first circuit layer 10 has the antenna 13, but an antenna may also be formed in the second circuit layer 20. In this case, the antennas can be connected to form an antenna with higher radiation intensity or an antenna with a smaller area.

In the above embodiment, the antenna device is described as an example of the flexible multilayer circuit board 1, but the present invention is not limited to this and can be applied to other circuits.

Moreover, in the said embodiment, stronger adhesion than the adhesive which adhere | attaches the

base films

15 and 25 and the 1st, 2nd circuit layers 10 and 20 in the

circuit boards

16 and 26 for 1st, 2nd transfer. The first and second

transfer circuit boards

16 and 26 and the insulating film 30 are bonded to each other by using a strong adhesive, but the first and second circuit layers 10 and 20 are insulated in the peeling process. For example, an adhesive that bonds the

base films

15 and 25 and the first and second circuit layers 10 and 20 in the first and second

transfer circuit boards

16 and 26 to the first and second circuit layers 10 and 20; The adhesive strength of the adhesive that bonds the first and second

transfer circuit boards

16 and 26 and the insulating film 30 may have the same strength. Alternatively, the first and second circuit layers 10 and 20 may be provided on the

base films

15 and 25 by a method other than using an adhesive, and the

base films

15 and 25 on the first and second

transfer circuit boards

16 and 26 may be provided. 25 and the first and second circuit layers 10 and 20 may be bonded with an adhesive having a low strength.

Moreover, in the said embodiment, although the

protective layers

41 and 42 are provided and the 1st circuit layer 10 and the 2nd circuit layer 20 are protected, the

protective layers

41 and 42 are not essential, the protective layer 41, Only one of 42 may be provided.

As described above, according to the present invention, a method for manufacturing a flexible multilayer circuit board capable of stably manufacturing the flexible multilayer circuit board 1 is provided.

DESCRIPTION OF SYMBOLS 1 ... Flexible multilayer circuit board 10 ...

1st circuit layer

11a, 11b ... 1st connection part 13 ... Antenna 15 ... Base film 16 ... Circuit board for 1st transfer 19 ... -Through-hole 20 ...

2nd circuit layer

21a, 21b ...

2nd connection part

22a, 22b ... Terminal 23a, 23b ... Line 25 ... Base film 26 ... 2nd transfer circuit Substrate 29 ... Through hole 30 ... Insulating

film

31a, 31b, 39 ... Through

hole

41, 42 ... Protective layer P1 ... Preparation process P2 ... Lamination process P3 ... Peeling process P4 ... connection process P5 ...

protection process

51a, 51b, 52a, 52b ... electrode

Claims

Preparing a pair of circuit boards for transfer in which a circuit layer is formed on a base film having flexibility, and an insulating film in which through holes are formed;
The surface on which the circuit layer is formed of each of the circuit boards for transfer is directed to the insulating film side so that the through hole and a part of the circuit layer overlap with each other, and the transfer film is formed on both surfaces of the insulating film. A laminating process for laminating circuit boards;
A peeling step of peeling the base film of each of the transfer circuit boards bonded to the insulating film from the circuit layer;
A connecting step of connecting the circuit layers on both sides of the insulating film by welding in the through hole;
The manufacturing method of the flexible multilayer substrate characterized by the above-mentioned.
The method for manufacturing a flexible multilayer substrate according to claim 1, further comprising a protective step of providing an insulating protective layer so as to cover at least a part of at least one of the circuit layers after the connecting step.
3. The method for manufacturing a flexible multilayer substrate according to claim 1, wherein at least a part of the circuit layer is an antenna.