JP2001313448A - Both-side flexible wiring board, ic card, and manufacturing method of the both-side flexible wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a both-side flexible wiring board at a low cost using a small number of simple steps, an IC card with the both side flexible wiring board, and a manufacturing method for the both side flexible wiring board. SOLUTION: A first conductive layer 13, made of a metal foil as a prescribed wiring pattern, is formed on one face of an insulating layer 12. After a through- hole 15 is formed at a given position of the insulating layer 12, the other face of the insulating layer 12 is coated with a conductive paste to form a second conductive layer 14. At the same time, the through-hole 15 is filled with conductive paste, so that a conductive path 16 for connecting the first conductive layer 13 and the second conductive layer 14 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a double-sided flexible wiring board, and an IC using the double-sided flexible wiring board.
The present invention relates to a card and a method for manufacturing a double-sided flexible wiring board.

[0002]

2. Description of the Related Art A double-sided flexible wiring board is, for example, as shown in FIG.
The first conductor layer 2 is formed with a predetermined circuit pattern, and the second conductor layer 3 is formed on the other surface of the insulating layer 1 with a predetermined circuit pattern. A circuit board in which the second conductor layer 3 is electrically connected to the second conductor layer 3 by a conductive path 4 formed in a through hole 5 penetrating the insulating layer 1 and is widely used in the field of electronic devices and the like. .

[0003] Such a double-sided flexible wiring board has conventionally been manufactured, for example, as follows. That is, first, the first conductor layer 2 and the second conductor layer 3 are formed on both surfaces of the insulating layer 1 as a predetermined circuit pattern by, for example, a subtractive method, an additive method, a semi-additive method, or the like. Next, a through hole 5 is formed at a predetermined position of the first conductor layer 2 and the insulating layer 1 so that the second conductor layer 2 is exposed, and a conduction path 4 is formed in the through hole 5 by plating.

[0004]

However, the above-described method involves many manufacturing steps. In particular, the formation of the conductive path 4 and the second insulating layer 3 involves complicated processes such as plating, formation of a resist, and etching. Since a process is required, it takes time and effort to manufacture a double-sided flexible wiring board, resulting in an increase in cost.

In recent years, a flexible wiring board has been used for an IC card which is being used instead of a magnetic card. The IC card has a much larger storage capacity than the magnetic card, but has a problem that it is expensive to manufacture and expensive. Therefore, there is a strong demand for a double-sided flexible wiring board used for such an IC card to be efficiently manufactured and supplied at low cost.

The present invention has been made in view of such circumstances, and has as its object to reduce the number of manufacturing steps.
Another object of the present invention is to provide a double-sided flexible wiring board manufactured by a simple process and supplied at low cost, an IC card using the double-sided flexible wiring board, and a method of manufacturing the double-sided flexible wiring board.

[0007]

To achieve the above object, a double-sided flexible wiring board according to the present invention has a first conductor layer formed on one surface of an insulating layer and a second conductor layer formed on the other side of the insulating layer. A second conductive layer is formed on the surface of the double-sided flexible wiring board, wherein the first conductive layer and the second conductive layer are electrically connected by a conductive path penetrating the insulating layer. The first conductor layer is made of a metal foil, and the second conductor layer and the conduction path are formed by applying a conductive paste.

In this double-sided flexible wiring board, the first conductor layer is preferably made of a copper foil or an aluminum foil, and the conductive paste is preferably a silver paste, a copper paste or an aluminum paste. .

The present invention also includes an IC card using the above-mentioned double-sided flexible wiring board of the present invention.

Further, the present invention provides a method for forming a first conductor layer on one surface of an insulating layer, a process for forming a through hole at a predetermined position on the insulating layer, and a method for forming a through hole on the other surface of the insulating layer. Forming a second conductive layer by applying a conductive paste, filling the through-hole with the conductive paste at the same time as electrically connecting the first conductive layer and the second conductive layer to each other. The method also includes a method for manufacturing a double-sided flexible wiring board, which includes a step of forming a conduction path connected to the flexible wiring board.

Further, according to the present invention, on the first insulating layer,
Forming a first conductive layer, forming a second insulating layer having a through hole at a predetermined position on the first conductive layer, forming a conductive layer on the second insulating layer; At the same time as forming the second conductor layer by applying the paste,
Filling the through-hole with the conductive paste, the first
And a method of manufacturing a double-sided flexible wiring board, which comprises a step of forming a conductive path for electrically connecting the conductive layer and the second conductive layer.

In the method for manufacturing a double-sided flexible wiring board, when the second conductive layer is formed by applying the conductive paste, the second conductive layer is simultaneously formed into a predetermined circuit pattern. Preferably, it is formed. Further, it is preferable that the first conductor layer is made of a copper foil or an aluminum foil, and that the conductive paste is a silver paste, a copper paste or an aluminum paste.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing a main part of an embodiment of a double-sided flexible wiring board according to the present invention. In FIG. 1, this double-sided flexible wiring board 11 has an insulating layer 1
A first conductor layer 13 is formed on a first surface 12a of the insulating layer 12 in a predetermined circuit pattern, and a second conductor layer 14 is formed on the other surface 12b of the insulating layer 12 in a predetermined circuit pattern. ing. The first conductor layer 13 and the second conductor layer 14 form a through hole 15 penetrating the insulating layer 12.
Are electrically connected by a conductive path 16 formed at the bottom.

In order to manufacture such a double-sided flexible wiring board 11, for example, a method as shown in FIG. 2 is used. That is, first, as shown in FIG. 2A, the first conductor layer 13 is formed on one surface 12a of the insulating layer 12 as a predetermined circuit pattern.

The insulating layer 12 is not particularly limited as long as it can be used as an insulating layer of a flexible wiring board. For example, polyimide resin, acrylic resin, polyether nitrile resin, polyether sulfone resin And synthetic resin films such as polyethylene terephthalate resin, polyethylene naphthalate resin and polyvinyl chloride resin. Of these synthetic resins, considering heat resistance and dimensional stability, etc., preferably, a polyimide resin, considering cost reduction,
Preferably, a polyethylene terephthalate resin is used. The thickness of the insulating layer 12 is usually 5 to 100.
μm, preferably 5 to 50 μm.

The first conductor layer 13 formed as a predetermined circuit pattern is a metal foil that can be used as a conductor layer of a flexible wiring board, such as a copper foil, an aluminum foil, a nickel foil, and a gold foil. Is mentioned. In consideration of cost reduction, preferably, copper foil and aluminum foil are used. The thickness of the first conductor layer 13 is usually 1
５０50 μm, and preferably 2 to 35 μm.

Then, on one surface 12a of the insulating layer 12,
In order to form the first conductor layer 13, for example, the insulating layer 12 is attached to the first conductor layer 13, and a resin solution for forming the insulating layer 12 is applied to the first conductor layer 13 and dried. Or a method of providing the first conductor layer 13 on the insulating layer 12 by plating.

When the insulating layer 12 is bonded to the first conductor layer 13, for example, the first conductor layer 13 made of a metal foil is used.
Then, the insulating layer 12 formed in a film shape may be attached as it is by heat fusion or the like, or may be attached via an adhesive or an adhesive. As the pressure-sensitive adhesive or adhesive, for example, epoxy-nitrile butyl rubber-based resin, epoxy-acrylic rubber-based resin, acrylic resin,
A known adhesive or adhesive such as a butyral resin or a urethane resin is used. And these insulating layers 12
After the first conductor layer 13 is bonded to the first conductor layer 13, for example, the first conductor layer 13 may be formed as a predetermined circuit pattern by a known patterning method such as a subtractive method. In the subtractive method, the first conductor layer 1
An etching resist is formed on the surface of the substrate 3 so as to correspond to a predetermined circuit pattern, the first conductive layer 13 is etched using the etching resist as a resist, and then the etching resist is removed.

When a resin solution for forming the insulating layer 12 is applied to the first conductor layer 13 and dried,
For example, a resin solution of a monomer such as a polyamic acid solution,
The insulating layer 12 may be formed by forming a film on the surface of the first conductor layer 13 made of a metal foil and drying and curing the film. After the insulating layer 12 is formed on the surface of the first conductor layer 13, the first conductor layer 13 may be formed as a predetermined circuit pattern by a known patterning method such as a subtractive method.

In the case where the first conductor layer 13 is provided on the insulating layer 12 by plating, the first conductor layer 13 is directly formed on the insulating layer 12 formed into a film by a known patterning method such as an additive method or a semi-additive method. The first conductor layer 13 made of a metal foil may be formed as a predetermined circuit pattern. That is, in the additive method, first,
A plating resist is formed on the surface of the insulating layer 12 in a pattern opposite to the predetermined circuit pattern, and then the first conductor as a predetermined circuit pattern is formed on the surface of the insulating layer 12 where the plating resist is not formed by plating. The layer 13 is formed, and thereafter, the plating resist is removed. In the semi-additive method, first, the insulating layer 12
A thin film of a conductor serving as a base is formed on the surface of the base by a vacuum deposition method or the like, and then, on the base, a plating resist is formed in a pattern opposite to a predetermined circuit pattern, and then a plating resist on the base is formed. The first conductor layer 1 is formed as a predetermined circuit pattern on the uncoated surface by plating.
Then, the plating resist and the base on which the plating resist is laminated are removed.

The patterning of the first conductive layer 13 by the above-described subtractive method, additive method, semi-additive method, etc.
At any time before and after the formation of.

After the first conductor layer 13 is formed as a predetermined circuit pattern on one surface 12a of the insulating layer 12 as described above, as shown in FIG.
A through hole 15 is formed at a predetermined position of the insulating layer 12. The through hole 15 can be formed by a known perforation method such as punching, drilling, laser ablation, chemical etching, and plasma etching. When the through hole 15 is formed only in the insulating layer 12 so as to expose the first conductor layer 13 on the bottom surface as shown in FIG. An etching method and a plasma etching method are used. The hole diameter of the through-hole 15 is usually 30 to 2000, preferably 100 to 1000 μ, and the shape may be any shape such as a round hole or a square hole.

Incidentally, such a through hole 15 is usually formed after the first conductor layer 13 is formed in the insulating layer 12. In some cases, the first conductor layer 13 is formed in the insulating layer 12. Before the formation, the insulating layer 12 previously formed into a film shape
May be formed in advance.

Next, as shown in FIG. 2C, a second conductor layer 14 is formed as a predetermined circuit pattern on the other surface 12b of the insulating layer 12, and a conduction path 16 is formed in the through hole 15. Form. In the present embodiment, the second conductor layer 14 and the conductive path 16 are formed by applying a conductive paste to the other surface 12 b of the insulating layer 12 to form the second conductor layer 14. At the same time, by filling the through holes 15 with a conductive paste,
6 is formed.

The conductive paste is a paste in which conductive fine particles such as copper, silver, and aluminum are dispersed in a viscous binder. Examples of the binder include an epoxy resin, a phenol resin, and a urethane. A thermosetting resin such as a resin or a thermoplastic resin such as a polyamide resin or a polyethylene resin is used. As the conductive paste, a copper paste in which fine copper particles are dispersed, a silver paste in which fine silver particles are dispersed, and an aluminum paste in which fine aluminum particles are dispersed are preferably used. By using such a conductive paste, cost can be reduced.

The conductive paste may be applied by, for example, screen printing or dispensing. That is, in screen printing, the other surface 12b of the insulating layer 12 is used.
A screen plate is placed on top of this, and the conductive paste is extruded from above with a squeegee or the like, so that the second
While a predetermined circuit pattern corresponding to the conductive layer 14 is formed, the conductive paste is filled into the through holes 15 at the same time. In the dispensing method, a conductive paste is discharged from the nozzle of the dispenser onto the other surface 12b of the insulating layer 12 to form a predetermined circuit pattern corresponding to the second conductive layer 14, and at the same time, The conductive paste is filled in the through holes 15. Then, the applied conductive paste is dried and cured at a temperature corresponding to the conductive paste, and the second conductive layer 1
4 is formed as a predetermined circuit pattern, and the conduction path 16 is formed. The other surface 12 of the insulating layer 12
b. The thickness of the conductive paste applied to b is 15 to 300 μm.
m, and the second after drying and curing.
The thickness of the conductor layer 14 is preferably 10 to 200 μm.

If the second conductor layer 14 and the conduction path 16 are simultaneously formed in this manner, the second conductor layer 14 and the conduction path 16 can be formed in one step. As compared with the case where the second conductor layer 14 and the conduction path 16 are formed in separate steps,
The manufacturing process can be simplified. Moreover, since the second conductor layer 14 and the conductive path 16 can be formed only by applying the conductive paste, complicated processes such as plating, formation of a resist, and etching are not required as in the related art. And can be manufactured by a simple process. Therefore, according to this manufacturing method, a double-sided flexible wiring board can be supplied at low cost.

Further, as described above, if a conductive paste is applied by screen printing or dispensing, the second conductor layer 14 can be directly formed as a predetermined circuit pattern. The double-sided flexible wiring board can be supplied at lower cost.

In the manufacturing method shown in FIG.
As shown in FIG. 3B, a through hole 15 is formed at a predetermined position of the insulating layer 12 only in the insulating layer 12 so that the first conductor layer 13 is exposed on the bottom surface. As shown in FIG.
May be formed so as to penetrate the first conductor layer 13 together with the insulating layer 12.

That is, in the manufacturing method shown in FIG.
First, as shown in FIG. 3A, a first conductor layer 13 is formed as a predetermined circuit pattern on one surface 12a of the insulating layer 12 as shown in FIG.
As shown in (b), in the step of forming the through hole 15 at a predetermined position of the insulating layer 12, the first conductor layer 13 is penetrated together with the insulating layer 12 at a predetermined position of the insulating layer 12. A through hole 15 is formed. When the through holes 15 are formed in this manner, punching and drilling are preferably used. Then, similarly to the manufacturing method shown in FIG. 2, as shown in FIG.
The second conductive layer 14 is formed by applying a conductive paste to the other surface 12 b of the second conductive layer 2, and the conductive path 1 is formed by filling the through-hole 15 with the conductive paste.
6, the double-sided flexible wiring board 11 may be manufactured.

Note that, as shown in FIG.
5 is formed only in the insulating layer 12, as shown in FIG. 3B, the through hole 15 is formed in the first conductive layer 13 rather than in the insulating layer 12 and the first conductive layer 13. , The contact area of the conduction path 16 with the contact can be increased, and the connection reliability of the circuit can be improved.

As shown in FIG. 4, the double-sided flexible wiring board of the present invention
Is formed in a predetermined circuit pattern, a second insulating layer 24 as an insulating layer is formed on the first conductive layer 23, and a second insulating layer 24 is formed on the second insulating layer 24. 2 conductor layers 25 are formed, and the first conductor layer 23 and the second conductor layer 25 are formed in the through holes 2 penetrating the second insulating layer 24.
6 may be electrically connected to each other by the conductive path 27.

In order to manufacture such a double-sided flexible wiring board 21, for example, a method as shown in FIG. 5 is used. That is, first, as shown in FIG.
A first conductor layer 23 is formed as a predetermined circuit pattern on the insulating layer 22 of FIG.

First insulating layer 22 and first conductor layer 23
Can be the same as the insulating layer 12 and the first conductor layer 13 used in the manufacturing method shown in FIG.
The method for forming the first conductor layer 23 as a predetermined circuit pattern on the first insulating layer 22 can be the same as the method shown in FIG.

Next, as shown in FIG. 5B, a second insulating layer 24 having a through hole 26 at a predetermined position is formed on the first conductor layer 23. On the first conductor layer 23,
In order to form the second insulating layer 24, for example, a film-shaped second insulating layer 24 in which a through hole 26 is formed at a predetermined position in advance is bonded to the first conductor layer 23, or
A solder resist ink or a resin solution for forming the second insulating layer 24 is formed on the first conductor layer 23 through the through holes 26.
For example, is applied so that is formed.

When the film-shaped second insulating layer 24 in which the through-hole 26 is formed in a predetermined position in advance is bonded to the first conductor layer 23, first, the through-hole 2 is formed in a predetermined position in advance.
A film-shaped second insulating layer 24 on which 6 is formed is prepared. The second insulating layer 24 is similar to the first insulating layer 22 and may be formed in a film shape. In order to form the through-hole 26 at a predetermined position of the second insulating layer 24, as in the manufacturing method shown in FIG.
Known perforation methods such as punching, drilling, laser ablation, chemical etching, and plasma etching may be used.

Then, to bond the second insulating layer 24 to the first conductor layer 23, as in the manufacturing method shown in FIG.
For example, the second insulating layer 24 may be stuck to the second conductor layer 23 by heat fusion or the like, or may be stuck via an adhesive or an adhesive.

The first conductor layer 23 and the second insulating layer 2
4 is bonded via an adhesive or an adhesive, the second insulating layer 24 previously formed in a film shape is used.
, An adhesive or an adhesive is laminated on the second insulating layer 24.
To form a composite with the pressure-sensitive adhesive layer or adhesive layer,
After forming the through-hole 26 in this composite, the first conductor layer 2
It is preferable to stick to No. 3. Thus, the through hole 26
Is adhered to the first conductor layer 23,
Work can be simplified. In this case, if a composite including the second insulating layer 24 and the adhesive layer is formed using an adhesive, cost can be reduced.

When a solder resist ink or a resin solution for forming the second insulating layer 24 is applied to the first conductor layer 23 so that the through holes 26 are formed, for example, an epoxy resin is used. The through-hole 26 on the first conductor layer 23 is formed by using the above-described screen printing or dispensing method using a thermosetting type solder resist ink such as a resin or a resin solution of a monomer such as a polyamic acid solution. The second insulating layer 24 having the through-hole 26 at a predetermined position may be formed on the first conductor layer 23 by applying the material except for the portion to be formed and drying and curing the applied material.

Further, for example, a thermosetting solder resist ink such as a photosensitive epoxy resin or a resin solution of a monomer such as a photosensitive polyamic acid solution is used to form the first conductive layer 23. And apply photoresist on top
The second insulating layer 24 having the through hole 26 at a predetermined position is formed on the first conductor layer 23 by exposing and developing the second insulating layer 24 at a predetermined position for forming the through hole 26.
May be formed.

Next, as shown in FIG. 5C, a second conductor layer 25 is formed as a predetermined circuit pattern on the second insulating layer 24, and the conductive path 2 is formed in the through hole 26.
7 is formed. The second conductor layer 25 and the conductive path 27
The second conductive layer 25 is formed by applying a conductive paste on the second insulating layer 24 in the same manner as in the manufacturing method shown in FIG. The conductive path 27 may be formed by filling the conductive paste into the conductive paste.

If the second conductor layer 25 and the conductive path 27 are formed at the same time in this manner, the manufacturing process can be simplified as in the manufacturing method shown in FIG. It can be manufactured by a process, and a double-sided flexible wiring board can be supplied at low cost.

The double-sided flexible wiring board 21 shown in FIG. 4 has one more insulating layer than the double-sided flexible wiring board 11 shown in FIG. 1 and accordingly requires more constituent materials and steps. Depending on the use, the first insulating layer 22 can be used as it is as a protective layer or as a bonding layer for bonding to another material.

In the double-sided flexible wiring board 21 shown in FIG. 4, since the through-hole 26 is formed only in the second insulating layer 24, as shown in FIG.
5 can be made larger in the contact area of the conduction path 27 with the first conductor layer 23 than in the case where 5 is formed on the insulating layer 12 and the first conductor layer 13, and the connection reliability of the circuit can be improved. .

The double-sided flexible wiring board of the present invention thus manufactured is manufactured by a simple process and supplied at a low cost, so that it can be effectively used in various fields. In particular, the double-sided flexible wiring board of the present invention can be suitably used for manufacturing an IC card which has recently been used in place of a magnetic card.

That is, in the present invention, the IC card has a built-in antenna coil and IC chip in the card, receives a magnetic field generated when the coil on the transceiver side is energized, induces electric power, and communicates by inducing electric power. Contact type IC card,
Also, the present invention includes any contact type IC card having an external terminal built in instead of the antenna coil, but the double-sided flexible wiring board of the present invention is preferably used for a non-contact type IC card.

The main part of the non-contact type IC card is shown in FIG.
As shown in FIG. 3, an antenna coil 32 formed in a coil shape and an IC chip 33 are built in a card 31, and both ends 32a and 32b of the antenna coil 32 are
It is configured to be connected to the IC chip 33 via the connection wires 34a and 34b. In order to connect the inner end 32b of the antenna coil 32 to the IC chip 33, the connection wiring 34b needs to cross the antenna coil 32. Therefore, as shown in FIG. 7, in the double-sided flexible wiring board of the present invention, on one surface of the insulating layer 35, the antenna coil 32 and the outer end 32a of the antenna coil 32 A wiring 34a for connecting to the chip 33 is formed, and the antenna coil 32 is formed on the other surface of the insulating layer 35.
By forming a connection wiring 34b for connecting the inner end 32b of the IC chip 33 and the IC chip 33, and using the double-sided flexible wiring board as the card antenna board 36 of the IC card, the antenna coil 32 and the IC chip 33 are connected. Can be connected well.

The IC card shown in FIG. 7 is formed by laminating decorative boards 38 on which characters and figures are designed on both sides of a card antenna board 36 via an adhesive sheet 37. I have.

[0049] Further, the IC card has a much larger storage capacity than the magnetic card and is rapidly spreading, but has a problem that the manufacturing cost is high and the cost is high. Therefore, if the double-sided flexible wiring board of the present invention is used, a large number of IC cards can be supplied at low cost.

Further, for example, if both the first conductor layer and the second conductor layer are formed of a conductive paste,
Although the cost can be further reduced, in such a case, the electrical resistance increases and the signal characteristics and connection reliability decrease, so that good performance cannot be maintained. Therefore, if the first conductor layer is formed of a metal foil and the second conductor layer is formed of a conductive paste as in the present invention, good performance can be maintained while reducing costs. Can be. In particular,
As described above, as the first conductor layer made of metal foil,
By using the antenna coil 32 and the connection wiring 34a as a second conductor layer made of a conductive paste, the connection wiring 34
By forming each of b, while the antenna coil 32 can be accurately and reliably formed as a predetermined pattern by the metal foil, the connection wiring 34b can be formed by the inexpensive conductive paste. The IC card can be manufactured and supplied at low cost while maintaining good performance.

In FIG. 7, the IC chip 33
Are arranged on the opposite side to the antenna coil 32 as the first conductor layer and the connection wiring 34a and the insulating layer 35. For example, as shown in FIG.
May be arranged on the same side with respect to the antenna coil 32 as the first conductor layer, the connection wiring 34a, and the insulating layer 35. If the IC chip 33 is arranged on the same side, the IC chip 33 is
a, 34b, an IC chip connection terminal (not shown) for connecting to the antenna coil 32 and the connection wiring 3
4a and the first conductor layer can be simultaneously formed with high precision, whereby an IC card can be manufactured and supplied at lower cost while maintaining better performance.

[0052]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which by no means limit the present invention.

Example 1 First, an aluminum foil having a thickness of 15 μm was adhered as a first conductor layer to one surface of a polyethylene terephthalate film having a thickness of 25 μm as an insulating layer via a urethane-based adhesive. A predetermined circuit pattern was formed on the first conductor layer by a subtractive method.
After that, through-holes penetrating the insulating layer and the first conductor layer are formed at predetermined positions by punching with a mold.
It was formed with a square hole of 0 mm square.

Next, on the other surface of the first insulating layer, a silver paste using a thermoplastic resin as a binder (Electro, manufactured by Nippon Acheson Co., Ltd., by screen printing using a # 300 mesh screen plate).
dag6036SS) was applied. At the time of application, the silver paste flowed on the wall surface of the through hole by its own weight, and reached the first conductor layer. Then at 80 ° C. for 30 minutes, and
By drying and curing at 120 ° C. for 15 minutes, the second conductor layer and the conductive path were simultaneously formed. Note that the thickness of the second conductor layer after drying and curing was about 10 μm.

The thus obtained double-sided flexible wiring board has a configuration corresponding to FIG. 3 (c), can be manufactured by a simple method, and can be supplied at low cost. Was.

Example 2 First, a 15 μm-thick aluminum foil was adhered as a first conductor layer to one surface of a 25 μm-thick polyethylene terephthalate film as an insulating layer via a urethane-based adhesive. A predetermined circuit pattern was formed on the first conductor layer by a subtractive method.
Thereafter, a through hole penetrating only the insulating layer was formed by a laser ablation method at a predetermined position with a 0.1 mmφ round hole without penetrating the first conductor layer.

Next, a copper paste (DD paste NF2000EX, manufactured by Tatsuta Electric Wire Co., Ltd.) using a phenol resin as a binder was applied to the other surface of the first insulating layer by screen printing. At the time of application, the copper paste flowed on the wall surface of the through hole by its own weight, and accumulated on the surface of the first conductor layer. Thereafter, by drying and curing at 160 ° C. for 30 minutes, the second conductor layer and the conductive path were simultaneously formed.

The thus obtained double-sided flexible wiring board has a configuration corresponding to that of FIG. 1, can be manufactured by a simple method, and can be supplied at low cost.

Example 3 First, a 12 μm-thick aluminum foil was adhered as a first conductor layer on a 25 μm-thick polyethylene terephthalate film as an insulating layer via a urethane-based adhesive. Then, a predetermined circuit pattern was formed on the first conductor layer by a subtractive method. Thereafter, an epoxy solder resist ink (Shikoku Chemical Industry Co., Ltd.) was formed on the first conductive layer by screen printing using a mesh screen plate of # 200 size.
Co., Ltd., FC Hard CF-30G), and then apply
By drying at 0 ° C. for 30 minutes, a second insulating layer was formed. In this screen printing, the second
A through hole made of a 2.0 mmφ round hole was formed at a predetermined position in the insulating layer.

Then, a silver paste using a thermoplastic resin as a binder (Electrodag 603, manufactured by Nippon Acheson Co., Ltd.) was formed on the second insulating layer by screen printing using a # 300 mesh screen plate.
6SS) was applied. At the time of application, the silver paste flowed on the wall surface of the through-hole by its own weight and accumulated on the surface of the first conductor layer. Thereafter, at 80 ° C. for 30 minutes, and at 120 ° C.
For 15 minutes, thereby simultaneously forming the second conductor layer and the conductive path. Note that the thickness of the second conductor layer after drying and curing was about 10 μm.

It was found that the double-sided flexible wiring board thus obtained has a configuration corresponding to FIG. 4, can be manufactured by a simple method, and can be supplied at low cost.

[0062]

As described above, according to the method for manufacturing a double-sided flexible wiring board of the present invention, the second conductor layer and the conductive path can be formed simultaneously in one step. As described above, the second conductive layer and the conductive path
The manufacturing process can be simplified as compared with the case where the components are formed in separate processes. Moreover, since the second conductive layer and the conductive path can be formed only by applying the conductive paste, complicated processes such as plating, formation of a resist, and etching are not required as in the related art. It can be manufactured at low cost by a simple process.

Therefore, the double-sided flexible wiring board of the present invention can be supplied at a low cost, and the first conductor layer formed on one surface of the insulating layer is formed of metal foil. A second layer formed on the other surface of the insulating layer.
Since the conductive layer and the conductive path are formed of a conductive paste, the flexibility is better than that of a conventional double-sided flexible wiring board.

Since the IC card of the present invention uses such a double-sided flexible wiring board of the present invention, it can be supplied in large quantities at low cost. Further, in the IC card using the double-sided flexible wiring board of the present invention, the first conductor layer is formed of a metal foil and the second conductor layer is formed of a conductive paste. Good performance can be exhibited while reducing the amount.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing one embodiment of a double-sided flexible wiring board of the present invention.

2A and 2B are process diagrams showing a method for manufacturing the double-sided flexible wiring board shown in FIG. 1, wherein FIG. 2A shows a process of forming a first conductor layer as a predetermined circuit pattern on one surface of an insulating layer; (B) is a cross-sectional view showing a step of forming a through hole at a predetermined position of the insulating layer, and (c) is a step of applying a conductive paste to the other surface of the insulating layer. It is sectional drawing which shows the process of forming a 2nd conductor layer and forming a conduction path by filling a through-hole with a conductive paste.

3A and 3B are process diagrams showing a method for manufacturing a double-sided flexible wiring board according to an embodiment different from the double-sided flexible wiring board shown in FIG. 1, wherein FIG. 3A shows a first conductor on one surface of an insulating layer; FIG. 4B is a cross-sectional view illustrating a step of forming a layer as a predetermined circuit pattern, FIG. 4B is a cross-sectional view illustrating a step of forming a through hole at a predetermined position in the insulating layer, and FIG. FIG. 9 is a cross-sectional view showing a step of forming a conductive path by applying a conductive paste to form a second conductor layer and filling a through-hole with the conductive paste.

FIG. 4 is a sectional view of a main part showing a double-sided flexible wiring board of an embodiment different from the double-sided flexible wiring board shown in FIG. 1;

5A and 5B are process diagrams showing a method for manufacturing the double-sided flexible wiring board shown in FIG. 4, in which FIG. 5A shows the formation of a first conductor layer as a predetermined circuit pattern on a first insulating layer. FIG. 4B is a cross-sectional view illustrating a step, FIG. 4B is a cross-sectional view illustrating a step of forming a second insulating layer having a through hole at a predetermined position on the first conductive layer, and FIG. It is sectional drawing which shows the process of forming a 2nd conductor layer by apply | coating a conductive paste on an insulating layer, and filling a through-hole with a conductive paste, and forming a conduction path.

FIG. 6 is a main part plan view showing an embodiment of the IC card of the present invention.

FIG. 7 is a sectional view of a main part of the IC card shown in FIG. 6;

8 is a sectional view of a main part of an embodiment different from the IC card shown in FIG. 7;

FIG. 9 is a sectional view of a main part showing a conventional double-sided flexible wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Double-sided flexible wiring board 12 Insulating layer 13 1st conductor layer 14 2nd conductor layer 15 Through-hole 16 Conductive path 21 Double-sided flexible wiring board 22 1st insulation layer 23 1st conductor layer 24 2nd insulation layer 25 Second conductor layer 26 Through hole 27 Conducting path

Claims (9)

[Claims] 1. A first conductor layer is formed on one surface of an insulating layer, and a second conductor layer is formed on the other surface of the insulating layer. In a double-sided flexible wiring board in which a second conductor layer and the second conductor layer are electrically connected by a conduction path penetrating the insulating layer, the first conductor layer is made of metal foil, and the second conductor layer and the second conductor layer A double-sided flexible wiring board, wherein the conductive path is formed by applying a conductive paste. 2. The double-sided flexible wiring board according to claim 1, wherein the first conductor layer is made of a copper foil or an aluminum foil. 3. The double-sided flexible wiring board according to claim 1, wherein the conductive paste is a silver paste, a copper paste, or an aluminum paste. 4. The double-sided flexible wiring board according to claim 1 is used.
IC card. 5. A step of forming a first conductor layer on one surface of the insulating layer, a step of forming a through hole at a predetermined position of the insulating layer, and a step of forming a conductive paste on the other surface of the insulating layer. Is applied, the second conductive layer is formed, and at the same time, the conductive paste is filled in the through-holes to form a conductive layer for electrically connecting the first conductive layer and the second conductive layer. A method for manufacturing a double-sided flexible wiring board, comprising a step of forming a passage. 6. A step of forming a first conductor layer on the first insulation layer, and forming a second insulation layer having a through hole at a predetermined position on the first conductor layer. Forming a second conductive layer by applying a conductive paste on the second insulating layer, and simultaneously filling the through-hole with the conductive paste to form the first conductive layer; Forming a conductive path for electrically connecting the second conductive layer to the second conductive layer. 7. The method according to claim 1, wherein the second conductive layer is formed as a predetermined circuit pattern when the second conductive layer is formed by applying the conductive paste. 7. The method for producing a double-sided flexible wiring board according to 5 or 6. 8. The method for manufacturing a double-sided flexible wiring board according to claim 5, wherein the first conductor layer is made of a copper foil or an aluminum foil. 9. The method according to claim 5, wherein the conductive paste is a silver paste, a copper paste or an aluminum paste.