JP2003243824A - Flexible substrate for forming wiring, flexible wiring board, and method of manufacturing flexible wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make variation hardly occur in the thickness of wiring that is reduced in thickness to about 8-18 μm so as to obtain a finer pitch at the time of manufacturing a flexible wiring board having a double-sided wiring structure. <P>SOLUTION: A flexible substrate for forming wiring is prepared by respectively laminating copper foil 31 and 32 having thicknesses of about 1-5 μm, releasable layers 32 and 35, and carrier copper foil 33 and 36 having thicknesses of about 18-50 μm upon both surfaces of a film substrate 21. Then the carrier copper foil 33 is removed together with the releasable layer 32 and upper and lower continuity holes are respectively formed through the copper foil 31 and film substrate 21 with a laser beam. After the through holes are formed, the carrier copper foil 36 is removed together with the releasable layer 35 and plated layers for forming wiring are formed on the upper surface of the copper foil 31 and the lower surface of the copper foil 34 including the insides of the continuity holes. Finally, wiring is respectively formed on both surfaces of the film substrate 21 by patterning the copper foil 31 and 34 and plated layers for forming wiring. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring-forming flexible substrate, a flexible wiring substrate, and a method for manufacturing the flexible wiring substrate.

[0002]

2. Description of the Related Art Some flexible wiring boards have a double-sided wiring structure and are incorporated in electronic equipment such as mobile phones and personal computers. However, recently, with the miniaturization and high performance of such electronic devices, there is a demand for a fine pitch flexible wiring board having a double-sided wiring structure.

In order to meet this demand, the wiring thickness of the flexible wiring board is made relatively thin, for example, about 8 to 18 μm. That is, although the wiring formed by wet etching has a substantially trapezoidal cross-sectional shape, if the wiring has a relatively thin thickness of about 8 to 18 μm, even if a fine pitch is achieved, short-circuiting may occur between adjacent wirings. Can be prevented.

FIG. 19 is a partial sectional view of an example of such a conventional flexible wiring board. This flexible wiring board includes a film substrate 1 made of polyimide or the like. The upper surface side wiring 2 is provided on the upper surface of the film substrate 1, and the lower surface side wiring 3 is provided on the lower surface. The two wirings 2 and 3 are electrically connected to each other through a vertical conduction portion 5 provided in a vertical conical hole 4 for vertical conduction provided at a predetermined position of the film substrate 1. In this case, for convenience of illustration, the side surfaces of the wirings 2 and 3 are vertical, but in reality, since they are formed by wet etching as described later, the cross-sectional shapes of the wirings 2 and 3 are the same as those of the film substrate 1. It becomes a substantially trapezoidal shape in which the length of the side is larger than the length of the opposite side.

The upper wiring 2 is formed on the film substrate 1
It comprises a first copper layer 2a provided on top and a second copper layer 2b provided on this first copper layer 2a, and a protective plating layer 6 is provided on the surface thereof. The lower surface side wiring 3 is composed of a copper layer provided under the film substrate 1 so as to cover the vertical conduction hole 4, and a protective plating layer 7 is provided on the surface thereof.

The vertical conducting portion 5 extends from the second copper layer 2b of the upper surface side wiring 2, and is placed in the vertical conducting hole 4 in the lower surface side wiring 3.
It consists of a copper layer that is connected to the
A protective plating layer 8 extending from the protective plating layer 6 that covers the surface of the upper surface side wiring 2 is provided.

Here, an example of a partial thickness of the flexible wiring board will be described. The thickness of the film substrate 1 is about 25 to 75 μm. The thickness of the first copper layer 2a of the upper surface side wiring 2 is about 1 to 5 μm, and the total thickness of the first and second copper layers 2a and 2b is about 8 to 18 μm. The thickness of the lower surface side wiring 3 is about 8 to 18 μm.

Next, an example of a method of manufacturing this flexible wiring board will be described. First, as shown in FIG. 20, as a wiring forming flexible substrate, an upper surface side wiring forming layer 11 and a lower surface side wiring forming layer 12 made of copper foil are laminated on the upper surface and the lower surface of a film substrate 1 made of polyimide or the like. Prepare the prepared items. in this case,
The thickness of the film substrate 1 is about 25 to 75 μm. The thickness of both wiring forming layers 11 and 12 is about 8 to 18 μm.

Next, as shown in FIG. 21, the upper surface side wiring forming layer 11 is half-etched to a thickness of 1-5.
Set to about μm. This is so that the holes can be formed in the upper surface side wiring forming layer 11 when the holes for vertical conduction are formed in the film substrate 1 in the next step. Although it is conceivable to set the thickness of the upper surface side wiring forming layer 11 to about 1 to 5 μm from the beginning, such an extremely thin copper foil cannot be manufactured by the current copper foil manufacturing technology.

Next, as shown in FIG. 22, by irradiating a laser such as a UV laser or a CO 2 laser from the upper surface side, a hole 13 is opened at a predetermined position of the upper surface side wiring forming layer 11, and this hole 13 is formed. The upper and lower conduction holes 4 having a truncated conical shape are formed in the film substrate 1 below. Next, desmear processing is performed.

By the way, since the thickness of the upper surface side wiring forming layer 11 is extremely thin, about 1 to 5 μm, the holes 13 are formed in the upper surface side wiring forming layer 11 by the thermal energy of the laser, but the lower surface side wiring is formed. Since the thickness of the formation layer 12 is relatively large, about 8 to 18 μm, no holes are formed in the lower surface side wiring formation layer 12 due to its own heat dissipation effect. Therefore, in this state, the lower side of the vertical conduction hole 4 is covered with the lower surface side wiring forming layer 12.

Next, as shown in FIG. 23, a protective layer 14 made of a dry film is formed on the lower surface of the lower surface side wiring forming layer 12.
Are stacked. The role of the protective layer 14 will be described later. Next, by performing electroless plating of copper, the upper surface side wiring forming plating layer 15 is formed on the upper surface of the upper surface side wiring forming layer 11 including the inside of the vertical conduction hole 4.

In this case, the total thickness of the upper surface side wiring forming layer 11 and the upper surface side wiring forming plating layer 15 is substantially the same as the thickness of the original upper surface side wiring forming layer 11 before half-etching. It should be about 18 μm. In addition, the plating layer is not formed on the lower surface of the lower surface side wiring forming layer 12 due to the presence of the protective layer 14. Then, after this, the protective layer 14 is peeled off.

Next, as shown in FIG. 24, the upper surface side resist pattern 16 made of a dry film is formed at a predetermined position on the upper surface of the upper surface side wiring forming plating layer 15 and the lower surface side wiring forming layer 12 is formed. A lower surface side resist pattern 17 also made of a dry film is formed at a predetermined position on the lower surface. In this state, the upper surface side resist pattern 16 covers the surface side of the upper surface side wiring forming plating layer 15 formed in the vertical conduction hole 4.

Next, as shown in FIG. 25, the upper surface side resist pattern 16 is used as a mask to wet-etch the upper surface side wire forming plating layer 15 and the upper surface side wire forming layer 11 to form a layer below the upper surface side resist pattern 16. The upper surface side wiring 2 including the first and second copper layers 2a and 2b is formed, and the vertical conduction portion 5 is formed in the vertical conduction hole 4. Also,
When the lower surface side wiring forming layer 12 is wet-etched using the lower surface side resist pattern 17 as a mask, the lower surface side wiring 3 is formed on the lower surface side resist pattern 17. In this case, the thickness of both wirings 2 and 3 is relatively thin, about 8 to 18 μm.

Next, both resist patterns 16 and 17 are peeled off. Next, as shown in FIG. 19, protective plating layers 6, 7, and 8 made of tin, silver, gold, or the like are formed on the surfaces of the wirings 2 and 3 and the upper and lower conducting portions 5 by electroless plating. Thus, the flexible wiring board shown in FIG. 19 is obtained.

[0017]

However, in the above-mentioned conventional method for manufacturing a flexible wiring board, the first copper layer 2a of the upper surface side wiring 2 is for forming the upper surface side wiring formed of a copper foil having a thickness of about 8 to 18 μm. Although the layer 11 is formed by half-etching, it is difficult to control the thickness by half-etching. Therefore, the thickness of the upper surface side wiring 2 is likely to vary. Since the formed upper surface side wiring 2 has a substantially trapezoidal cross-sectional shape, there is a problem that a short circuit may occur between the upper surface side wirings 2 adjacent to each other when a fine pitch is achieved. Therefore, it is an object of the present invention to provide a structure and a method capable of preventing variations in wiring thickness from occurring.

[0018]

According to a first aspect of the present invention, there is provided a wiring-forming flexible substrate in which a wiring-forming layer, a release layer and a carrier layer are laminated on one surface of a film substrate. Flexible substrate for wiring formation. According to a second aspect of the invention, there is provided a wiring-forming flexible substrate according to the first aspect, wherein the wiring-forming layer and the carrier layer are made of copper foil. A flexible substrate for wiring formation according to the invention of claim 3 is characterized in that, in the invention of claim 1, the wiring formation layer is made of copper foil, and the carrier layer is made of a resin film. Is.
A flexible substrate for wiring formation according to a fourth aspect of the present invention is the flexible substrate according to the second or third aspect, wherein the thickness of the wiring formation layer is less than 8 μm. According to a fifth aspect of the present invention, in the wiring formation flexible substrate in the first aspect, the other wiring formation layer, the other release layer, and the other carrier layer are provided on the other surface of the film substrate. It is characterized by being laminated. According to a sixth aspect of the present invention, there is provided a wiring forming flexible substrate in the fifth aspect, wherein the both wiring forming layers and the two carrier layers are made of copper foil. According to a seventh aspect of the present invention, there is provided a wiring forming flexible substrate according to the fifth aspect, wherein the both wiring forming layers and the other carrier layer are made of copper foil. The layer is characterized by comprising a resin film. The flexible substrate for wiring formation according to the invention of claim 8 is characterized in that, in the invention of claim 6 or 7, the thickness of both of the wiring formation layers is about 1 to 5 μm. is there. The flexible substrate for wiring formation according to the invention described in claim 9 is the flexible substrate according to claim 6 or 7.
In the invention described in (3), the thickness of the wiring forming layer on the one surface side is about 1 to 5 μm, and the thickness of the other wiring forming layer is about 8 to 18 μm. Is. The wiring forming flexible substrate according to the invention of claim 10, wherein one wiring forming layer is laminated on one surface of the film substrate, and the other wiring forming layer and a peeling layer are formed on the other surface of the film substrate. And a carrier layer is laminated. According to an eleventh aspect of the invention, there is provided a wiring-forming flexible substrate according to the tenth aspect of the invention, wherein the both wiring-forming layers and the carrier layer are made of copper foil.
According to a twelfth aspect of the present invention, in the wiring formation flexible substrate according to the eleventh aspect of the present invention, the one wiring formation layer has a thickness of about 8 to 18 μm, and the other wiring formation layer. Is about 1 to 5 μm in thickness. According to a thirteenth aspect of the present invention, in the wiring formation flexible substrate according to the eleventh aspect, the thickness of the both wiring formation layers is 8 to 18 μm.
It is characterized by being a degree. According to a fourteenth aspect of the present invention, there is provided a wiring-forming flexible substrate in which one surface of the film substrate is provided with a wiring made of copper foil having a thickness of less than 8 μm. A flexible wiring board according to the invention of claim 15 comprises a film substrate having holes for vertical conduction, a first wiring layer made of a metal foil provided on one surface of the film substrate, and a metal plating layer. One wiring having a two-layer structure including a second wiring layer, and a first wiring layer and a metal plating layer made of a metal foil provided on the other surface of the film substrate so as to cover the vertical conduction hole. The other wiring of the two-layer structure consisting of the second wiring layer and the second wiring layer of the one wiring, and the second wiring of the other wiring is extended in the vertical conduction hole of the film substrate. It is characterized in that it is provided with an up-and-down conduction part composed of a metal plating layer provided so as to be connected to one wiring layer. A flexible wiring board according to a sixteenth aspect of the present invention is the flexible wiring board according to the fifteenth aspect of the present invention, wherein the thickness of the both wirings is about 8 to 18 μm. The flexible wiring board according to the invention of claim 17 is the same as the invention of claim 16,
The thickness of both the first wiring layers is about 1 to 5 μm. The flexible wiring board according to the invention of claim 18 comprises a film substrate having vertical conduction holes, a first wiring layer made of a metal foil provided on one surface of the film substrate, and a metal plating layer. One wiring having a two-layer structure including a second wiring layer, the other wiring made of a metal foil provided on the other surface of the film substrate so as to cover the vertical conduction hole, and the one wiring And a vertical conduction part formed of a metal plating layer extending from the second wiring layer and provided in the vertical conduction hole of the film substrate and connected to the other wiring. Is. A flexible wiring board according to a nineteenth aspect of the present invention is the flexible wiring board according to the eighteenth aspect, wherein the thickness of the both wirings is about 8 to 18 μm. The flexible wiring board according to the invention of claim 20 is the same as the invention of claim 19,
The thickness of the first wiring layer is about 1 to 5 μm. The method for producing a flexible wiring board according to the invention of claim 21, wherein the carrier layer is a flexible wiring forming board in which a wiring forming layer, a release layer and a carrier layer are laminated on one surface of a film substrate. Is peeled off together with the peeling layer, and the wiring forming layer is patterned to form a wiring. According to a twenty-second aspect of the invention, there is provided a method of manufacturing a flexible wiring board according to the twenty-first aspect, wherein the wiring forming layer and the carrier layer are made of copper foil. The method for manufacturing a flexible wiring board according to the invention of claim 23 is characterized in that, in the invention of claim 21, the wiring forming layer is made of copper foil, and the carrier layer is made of a resin film. It is a thing. The method of manufacturing a flexible wiring board according to the invention of claim 24 is characterized in that, in the invention of claim 22 or 23, the thickness of the wiring forming layer is about 1 to 5 μm. is there. The method for manufacturing a flexible wiring board according to the invention of claim 25, wherein one wiring forming layer, one peeling layer and one carrier layer are laminated on one surface of the film substrate,
Of the wiring forming flexible substrate in which the other wiring forming layer, the other peeling layer and the other carrier layer are laminated on the other surface of the film substrate, the one carrier layer is peeled together with the one peeling layer. The vertical wiring holes are formed in the one wiring forming layer and the film substrate. A method of manufacturing a flexible wiring board according to the invention of claim 26 is the method of claim 25.
In the invention according to claim 1, after forming the vertical conduction hole, the other carrier layer is peeled off together with the other peeling layer, and the vertical conduction is performed on the surface of the one wiring forming layer including the inside of the vertical conduction hole. Forming one wiring forming plating layer including a portion, and forming the other wiring forming plating layer on the surface of the other wiring forming layer, the both wiring forming layer and the both wiring forming plating The layer is patterned to form a wiring having a two-layer structure on both surfaces of the film substrate. The method for manufacturing a flexible wiring board according to the invention of claim 27,
In the invention described in, the other carrier layer is peeled off together with the other peeling layer after forming the vertical conduction hole, and a plating layer is formed on the surface of the one wiring forming layer including the inside of the vertical conduction hole. Forming one wiring layer including a vertical conducting portion, and forming another wiring layer made of a plating layer on the surface of the other wiring forming layer, and forming both wiring layers under the both wiring layers. It is characterized in that a wiring layer composed of layers is formed to form a wiring having a two-layer structure on both surfaces of the film substrate. The method for manufacturing a flexible wiring board according to the invention described in claim 28 is the invention according to claim 25, wherein the one wiring forming layer includes the inside of the vertical conduction hole after forming the vertical conduction hole. Forming one wiring formation plating layer including a vertical conduction portion on the surface of, and forming a plating layer on the surface of the other carrier layer, the other carrier layer and the plating layer formed on the surface On the one surface and the other surface of the film substrate by patterning the one wiring forming layer, the one wiring forming plating layer, and the other wiring forming layer together with the other peeling layer. 2 each
It is characterized in that a wiring having a layer structure and a wiring having a one-layer structure are formed. A method for manufacturing a flexible wiring board according to a twenty-ninth aspect of the present invention is the method according to any one of the twenty-sixth to twenty-eighth aspects, wherein the both wiring forming layers and the both carrier layers are made of copper foil. The plated layer is composed of a copper plated layer. A method for manufacturing a flexible wiring board according to the invention of claim 30 is the invention according to any one of claims 26 to 28, wherein the both wiring forming layers and the other carrier layer are made of copper foil, One of the carrier layers is made of a resin film. A method for manufacturing a flexible wiring board according to the invention of claim 31,
The invention according to claim 29 or 30 is characterized in that the thickness of the both wirings is about 8 to 18 μm. A method of manufacturing a flexible wiring board according to a thirty-second aspect of the present invention is characterized in that, in the thirty-first aspect of the present invention, the one wiring forming layer has a thickness of about 1 to 5 μm. is there. The method for manufacturing a flexible wiring board according to the invention of claim 33, wherein one wiring forming layer made of a copper foil having a thickness of about 8 to 18 μm is laminated on one surface of the film substrate, Of the wiring forming flexible substrate in which the other wiring forming layer made of a copper foil, a release layer and a carrier layer made of a copper foil are laminated on the surface of the one side, the one wiring forming layer is half-etched to obtain the thickness thereof. The thickness is set to about 1 to 5 μm, and a hole for vertical conduction is formed in the half-etched one wiring forming layer and the film substrate. A method of manufacturing a flexible wiring board according to a thirty-fourth aspect of the invention is the method of the thirty-third aspect of the invention, in which the carrier layer is peeled off together with the peeling layer after the vertical conduction hole is formed. On the surface of the one wiring forming layer including the inside of the hole, to form one wiring forming plating layer including a vertical conduction portion made of a copper plating layer,
And, the other wiring forming plating layer formed of a copper plating layer is formed on the surface of the other wiring forming layer, and the both wiring forming layers and the both wiring forming plating layers are patterned to form the film substrate. It is characterized in that a wiring having a two-layer structure is formed on each of both surfaces. A method of manufacturing a flexible wiring board according to the invention of claim 35,
34. The invention according to claim 33, wherein after forming the hole for vertical conduction, the carrier layer is peeled off together with the peeling layer, and a copper plating layer is formed on the surface of the one wiring forming layer including the inside of the hole for vertical conduction. Forming one wiring layer including a vertical conductive portion, and forming the other wiring layer made of a copper plating layer on the surface of the other wiring forming layer, and forming the both wiring layers under the both wiring layers. It is characterized in that a wiring layer composed of a working layer is formed to form a wiring having a two-layer structure on both surfaces of the film substrate. The method for manufacturing a flexible wiring board according to a thirty-sixth aspect of the present invention is the method for manufacturing a flexible wiring board according to the thirty-third aspect, wherein the one wiring forming layer includes the inside of the vertical conduction hole after forming the vertical conduction hole. To form one wiring forming plating layer including a vertical conduction portion consisting of a copper plating layer on the surface of, and forming a copper plating layer on the surface of the other carrier layer, on the other carrier layer and its surface The formed copper plating layer is peeled off together with the peeling layer, and the one wiring forming layer, the one wiring forming plating layer, and the other wiring forming layer are patterned to form one surface of the film substrate. And a wiring having a two-layer structure and a wiring having a one-layer structure are formed on the other surfaces, respectively. A method of manufacturing a flexible wiring board according to a thirty-seventh aspect of the present invention is characterized in that, in the invention according to any one of the thirty-fourth to thirty-sixth aspects, the thickness of the both wirings is about 8 to 18 μm. Is. According to a thirty-eighth aspect of the present invention, the method of manufacturing a flexible wiring board according to the thirty-seventh aspect is characterized in that the other wiring forming layer has a thickness of about 1 to 5 μm. is there. The method for manufacturing a flexible wiring board according to a thirty-ninth aspect of the invention is the method according to the twenty-fifth or thirty-third aspect, in which the one wiring formation layer and the vertical conduction hole in the film substrate are formed by laser It is characterized in that it is performed by irradiation of. According to the present invention, as the flexible substrate for wiring formation, a film substrate on which a wiring formation layer, a peeling layer and a carrier layer are laminated is used, and when the carrier layer is peeled together with the peeling layer, it does not depend on half etching. So, only the wiring formation layer remains on the film substrate,
Therefore, it is possible to prevent variations in the thickness of the remaining wiring forming layer, and thus to prevent variations in the thickness of the wiring.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a sectional view of a main part of a flexible wiring board according to a first embodiment of the present invention. This flexible wiring board includes a film substrate 21 made of polyimide or the like. The upper surface wiring 22 is provided on the upper surface of the film substrate 21, and the lower surface wiring 23 is provided on the lower surface. The two wirings 22 and 23 are electrically connected to each other via a vertical conduction portion 25 provided in a truncated conical hole 24 for vertical conduction provided at a predetermined position of the film substrate 21. Also in this case, for convenience of illustration, the side surfaces of the wirings 22 and 23 are vertical, but in reality, since they are formed by wet etching as described later, the cross-sectional shapes of the wirings 22 and 23 are substantially trapezoidal. (The same applies to the following similar drawings.)

The upper wiring 22 is composed of a first copper layer 22a provided on the film substrate 21 and a second copper layer 22b provided on the first copper layer 22a. A protective plating layer 26 is provided on the. The lower surface side wiring 23 is composed of a first copper layer 23a provided under the film substrate 21 so as to cover the vertical conduction portion 25, and a second copper layer 23b provided under the first copper layer 23a. A protective plating layer 27 is provided on the surface thereof.

The vertical conducting portion 25 is connected to the second wiring of the upper surface side wiring 22.
From the copper layer 22b, and is provided in the vertical conduction hole 24 so as to be connected to the first copper layer 23a of the lower surface side wiring 23, and the surface thereof is the surface of the upper surface side wiring 22. Protective plating layer 28 extending from protective plating layer 26
Is provided.

Here, an example of a partial thickness of the flexible wiring board will be described. The film substrate 21 has a thickness of about 25 to 75 μm. First of the upper surface side wiring 22
The thickness of the copper layer 22a is about 1 to 5 μm, and the total thickness of the first and second copper layers 22a and 22b is about 8 to 18 μm. The thickness of the first copper layer 23a of the lower surface side wiring 23 is 1
About 5 μm, and the first and second copper layers 23a, 23b
Has a total thickness of about 8 to 18 μm.

Next, an example of a method of manufacturing this flexible wiring board will be described. First, as shown in FIG.
As a wiring-forming flexible substrate, an upper surface side wiring-forming layer 31 made of a copper foil, a release layer 32 made of an inorganic metal such as zinc, nickel, cobalt, or chromium and a copper foil are formed on the upper surface of a film substrate 21 made of polyimide or the like. And a lower surface side wiring layer 34 made of copper foil on the lower surface of the film substrate 21.
A release layer 35 made of an inorganic metal such as zinc, nickel, cobalt, and chromium and a lower surface side carrier layer 36 made of a copper foil are laminated in this order.

In this case, the film substrate 21 has a thickness of 25.
It is about 75 μm. The thickness of both wiring forming layers 31 and 34 is about 1 to 5 μm. The thickness of both carrier layers 33 and 36 is about 18 to 50 μm. By the way, thickness 1
Wiring forming layer 3 made of an extremely thin copper foil of about 5 μm
The 1, 34 simple substance cannot be manufactured by the current copper foil manufacturing technology.

However, one surface of the carrier layers 33 and 36 made of copper foil having a thickness of about 18 to 50 μm is made of an inorganic metal such as zinc, nickel, cobalt or chromium by electrolytic plating, electroless plating, sputtering or the like. Thin release layers 32 and 35 are formed, and one surface of the release layers 32 and 35 is electroplated or electroless plated to a thickness of 1 to 5 μm.
It is possible to form the wiring forming layers 31 and 34 made of copper foil of about m.

Then, such carrier layers 33, 36
By laminating the wiring forming layers 31 and 34 with the marks on the upper surface and the lower surface of the film substrate 21, the one shown in FIG. 2 is obtained. As a stacking method, for example, the lower surface side carrier layer 36
The film substrate 2 is provided on the upper surface of the wiring forming layer 34 on the lower surface side.
1. The polyimide varnish for forming 1 is applied, and the upper surface side carrier layer 3 is formed on the upper surface of the applied polyimide varnish.
The upper surface side wiring forming layer 31 with 3 is directly attached. Alternatively, the bonding may be performed using a polyimide adhesive.

Next, the peeling layer 32 and the upper surface side wiring forming layer 3 are formed.
Since the adhesive force between the upper surface side wiring layer 31 and the film substrate 21 is weaker than the adhesive force between the upper surface side wiring forming layer 31 and the film substrate 21, the upper surface side carrier layer 33 is peeled together with the peeling layer 32 as shown in FIG. . In this state, only the upper surface side wiring forming layer 31 is laminated on the upper surface of the film substrate 21, and the thickness thereof is 1
The thickness is about 5 μm, and unlike the conventional half etching, it is possible to prevent variations in the thickness thereof.

In addition, the thickness of 1 to 1 is formed on the upper surface of the film substrate 21.
The reason why only the upper surface side wiring forming layer 31 having an extremely thin thickness of about 5 μm is left is to make a hole in the upper surface side wiring forming layer 31 when the vertical conduction hole is formed in the film substrate 21 in the next step. This is so that it can be done.

Next, as shown in FIG. 4, a UV laser and C
By irradiating a laser such as an O 2 laser from the upper surface side, a hole 37 is opened at a predetermined position in the upper surface side wiring forming layer 31, and a vertical conduction hole 24 is formed in the film substrate 21 under the hole 37. In this case, since the film substrate 21 is isotropically evaporated and removed by the thermal energy of the laser, the vertical conduction hole 24 has a truncated conical shape. Next, desmear processing is performed.

By the way, since the thickness of the upper surface side wiring forming layer 31 is extremely thin, about 1 to 5 μm, holes 37 are formed in the upper surface side wiring forming layer 31 by the thermal energy of the laser, but the lower surface side wiring is formed. Since the total thickness of the forming layer 34 and the lower surface side carrier layer 36 is relatively thick, about 19 to 55 μm, the lower surface side wiring forming layer 3 is formed by its own heat dissipation action.
No holes are formed in 4. Therefore, in this state, the lower side of the vertical conduction hole 24 is covered with the lower surface side wiring forming layer 34.

Next, the lower surface side carrier layer 36 is separated from the release layer 35.
Peel with. Next, as shown in FIG. 5, electroless plating of copper or electroless plating and electrolytic plating is performed to form the upper surface side wiring forming layer 31 including the inside of the vertical conduction hole 24.
The upper surface side wiring forming plating layer 38 is formed on the upper surface of the above, and the lower surface side wiring forming plating layer 39 is formed on the lower surface of the lower surface side wiring forming layer 34.

The one shown in FIG. 4 is immersed in a carbon solution or a palladium solution to form a carbon layer or a palladium layer on both surfaces thereof, and both surfaces thereof are light-etched with a copper etching solution to be formed on the surface together with copper. It is also possible to remove the formed carbon layer and the palladium layer, leave the carbon layer and the palladium layer only on the inner surfaces of the vertical conduction holes 24 of the film substrate 21, and then perform electrolytic plating.

In any case, the upper surface side wiring forming layer 31 is formed.
And the total thickness of the upper surface side wiring forming plating layer 38 is 8 to 1
It should be about 8 μm. Further, the total thickness of the lower surface side wiring forming layer 34 and the lower surface side wiring forming plating layer 39 is set to about 8 to 18 μm.

Next, as shown in FIG. 6, an upper surface side resist pattern 40 made of a dry film is formed at a predetermined position on the upper surface of the upper surface side wiring forming plating layer 38, and
A lower surface side resist pattern 41 also made of a dry film is formed at a predetermined position on the lower surface of the lower surface side wiring forming plating layer 39.
To form. In this state, the surface of the wiring forming plating layer 38 formed in the vertical conduction hole 24 is covered with the upper surface side resist pattern 40.

Next, as shown in FIG. 7, the upper surface side resist pattern 40 is used as a mask to form the upper surface side wiring forming plating layer 3.
8 and the upper surface side wiring forming layer 31 are wet-etched to form the upper surface side wiring 22 including the first and second copper layers 22a and 22b under the upper surface side resist pattern 40,
Further, a vertical conduction portion 25 is formed in the vertical conduction hole 24.

Further, when the lower surface side wiring forming plating layer 39 and the lower surface side wiring forming layer 34 are wet-etched using the lower surface side resist pattern 41 as a mask, the first and second copper layers 23a are formed on the lower surface side resist pattern 41. , 23b are formed on the lower surface side wiring 23.

In this case, the thickness of both wirings 22 and 23 is 8 to.
It is relatively thin, about 18 μm, but the first of both wirings 22 and 23
Since the copper layers 22a and 23a are made of a copper foil having a thickness of about 1 to 5 μm, it is possible to prevent variations in the thickness of the wirings 22 and 23 as compared with the case of forming by conventional half etching. it can.

Next, both resist patterns 40 and 41 are peeled off. Next, as shown in FIG. 1, tin is formed by electroless plating on each surface of the wirings 22, 23 and the upper and lower conducting portions 25.
The protective plating layers 26, 27, 28 made of silver, gold or the like are formed. Thus, the flexible wiring board shown in FIG. 1 is obtained.

(Second Embodiment) Next, as a second embodiment of the present invention, another example of the method for manufacturing the flexible wiring board shown in FIG. 1 will be described. In this case, the steps up to the step shown in FIG. 4 are the same as those in the first embodiment. That is, by irradiating a laser such as a UV laser or a CO 2 laser, a hole 37 is opened at a predetermined position of the upper surface side wiring forming layer 31, and the film substrate 21 under the hole 37.
A vertical conduction hole 24 is formed in the upper surface and then desmear processing is performed. Next, the lower surface side carrier layer 36 is peeled off together with the peeling layer 35.

Next, as shown in FIG. 8, an upper surface side resist pattern 51 made of a dry film is formed at a predetermined position on the upper surface of the upper surface side wiring forming layer 31, and a lower surface of the lower surface side wiring forming layer 32 is formed. A lower surface side resist pattern 52 which is also made of a dry film is formed at a predetermined position.

Next, electroless plating of copper or electroless plating and electrolytic plating is performed to cover the upper surface side wiring forming layer 31 including the upper and lower conduction holes 24 with the upper surface side resist pattern 51. The second copper layer 22b and the vertical conducting portion 25 are formed in the non-existing region,
The second copper layer 2 is formed on the lower surface of the lower surface side wiring forming layer 34 in a region not covered by the upper surface side resist pattern 51.
3b is formed. In this case, both second copper layers 22b, 23
The thickness of b is set to about 8 to 18 μm or slightly thicker than that.

Next, when the two resist patterns 51 and 52 are peeled off, it becomes as shown in FIG. Next, when light etching is performed to pattern both wiring forming layers 31 and 34, a first copper layer 22b is formed under the second copper layer 22a, as shown in FIG. The first copper layer 23b is formed on the second copper layer 23a. in this case,
The surfaces of the second copper layers 22a and 23a are the same as the first copper layer 22.
Etching is performed by an amount corresponding to the thickness of b and 23b.
The total thickness of the first copper layers 22b and 23b and the second copper layers 22a and 23a in this state is 8 to 18 μm.
It will be about m.

Next, as shown in FIG.
3 and the respective surfaces of the upper and lower conducting portions 25 by electroless plating, the protective plating layers 26, 27, 28 made of tin, silver, gold or the like.
To form. Thus, the flexible wiring board shown in FIG. 1 is obtained.

By the way, also in this case, both wirings 22 and 23 are
Is relatively thin, about 8-18 μm, but both wirings 2
The first and second copper layers 22a and 23a of 2 and 23 have a thickness of 1 to 5 μm.
Since the copper foil is formed to a certain extent, it is possible to make the thicknesses of the wirings 22 and 23 less likely to vary as compared with the case of forming by conventional half etching.

(Third Embodiment) FIG. 11 shows a third embodiment of the present invention.
1 is a cross-sectional view of a main part of a flexible wiring board as an embodiment. In this figure, the same reference numerals are given to the same names as those in FIG. 1, and the description thereof will be omitted as appropriate.
This flexible wiring board is different from the case shown in FIG. 1 in that the lower surface side wiring 23 is made of a copper layer having a thickness of about 8 to 18 μm.

Next, an example of a method of manufacturing this flexible wiring board will be described. First, as shown in FIG. 12, an upper surface side wiring forming layer 31 made of a copper foil, a release layer 32 made of an inorganic metal and an upper surface side carrier layer 3 made of a copper foil are formed on an upper surface of a film substrate 21 made of polyimide or the like.
3 is laminated in this order, and a lower surface side wiring forming layer 34 made of a copper foil, a release layer 35 made of an inorganic metal, and a lower surface side carrier layer 36 made of a copper foil are laminated in this order on the lower surface of the film substrate 21. Prepare the items.

In this case, the film substrate 21 has a thickness of 25.
It is about 75 μm. The thickness of the upper surface side wiring forming layer 31 is about 1 to 5 μm. The thickness of the upper surface side carrier layer 33 is about 18 to 50 μm. Lower surface side wiring forming layer 34
Has a thickness of about 8 to 18 μm. Lower carrier layer 3
The thickness of 6 is about 12 to 50 μm.

Next, the carrier layer 33 on the upper surface side is separated from the release layer 32.
When it is peeled off together, it becomes as shown in FIG. In this state, only the upper surface side wiring forming layer 31 having an extremely thin thickness of about 1 to 5 μm is laminated on the upper surface of the film substrate 21. Next, as shown in FIG. 14, UV laser and CO2
By irradiating a laser such as a laser, a hole 37 is opened at a predetermined position of the upper surface side wiring forming layer 31, and the hole 37 is formed.
A vertical conduction hole 24 is formed in the lower film substrate 21. Next, desmear processing is performed.

Next, as shown in FIG. 15, electroless plating of copper or electroless plating and electroless plating are performed to form an upper surface side wiring forming layer 31 including the inside of the vertical conduction hole 24.
The upper surface side wiring forming plating layer 38 is formed on the upper surface of the above, and the plating layer 61 is formed on the lower surface of the lower surface side carrier layer 36. Next, the lower surface side carrier layer 36 and the plating layer 6
1 is peeled off together with the peeling layer 35. In this state, only the lower surface side wiring forming layer 34 having a thickness of about 8 to 18 μm remains on the lower surface of the film substrate 21.

Thereafter, the flexible wiring board shown in FIG. 11 is obtained by sequentially performing the steps shown in FIGS. 6, 7, and 1 in the case of the first embodiment. In the flexible wiring board thus obtained, since the lower surface side wiring 23 formed on the lower surface of the film substrate 21 is formed by patterning a copper foil having a thickness of about 8 to 18 μm, variations in the thickness are caused. Can be extremely small.

Other Embodiments In each of the above embodiments, the case where the copper foil is used as the upper surface side carrier layer 33 has been described, but the present invention is not limited to this, and a resin film or the like may be used. That is, the lower surface side carrier layer 36 needs to radiate the heat energy of the laser by itself, but the upper surface side carrier layer 33 has only to function as a carrier layer, and therefore, there is no problem even if it is formed of a resin film or the like. Absent.

In each of the above embodiments, the upper surface side wiring 2
The case where the second first copper layer 22a is formed by the upper surface side wiring forming layer 31 made of a copper foil having a thickness of about 1 to 5 μm has been described, but the present invention is not limited to this, and similar to the conventional case,
The upper surface side wiring forming layer made of a copper foil having a thickness of about 8 to 18 μm may be half-etched to form the upper surface side wiring forming layer made of a copper foil having a thickness of about 1 to 5 μm.

That is, in the case of manufacturing the flexible wiring board corresponding to FIG. 1, first, as shown in FIG.
8 to 18 μm thick on the upper surface of the film substrate 21 of about 5 μm
Only the upper surface side wiring forming layer 31 made of a copper foil having a thickness of about m is laminated, and the lower surface side wiring forming layer 34 made of a copper foil having a thickness of about 1 to 5 μm, the peeling layer 35 and the thickness are formed on the lower surface of the film substrate 21. Prepared is one in which a lower surface side carrier layer 36 made of a copper foil having a thickness of about 18 to 50 μm is laminated.

In the case of manufacturing a flexible wiring board corresponding to FIG. 11, first, as shown in FIG. 17, as a wiring forming flexible board, a thickness of 8 to 8 is formed on the upper surface of a film substrate 21 having a thickness of about 25 to 75 μm. Only the upper surface side wiring forming layer 31 made of a copper foil having a thickness of about 18 μm is laminated, and the lower surface side wiring forming layer 34 made of a copper foil having a thickness of about 8 to 18 μm, the peeling layer 35 and the thickness are formed on the lower surface of the film substrate 21. Bottom side carrier layer 3 made of copper foil having a thickness of about 12 to 50 μm
Prepare a stack of 6.

In any case, the thickness is 8-18 μm.
The upper surface side wiring forming layer 31 made of a copper foil having a thickness of about m is half-etched to form an upper surface side wiring forming layer made of a copper foil having a thickness of about 1 to 5 μm. The flexible wiring board corresponding to FIG. 1 or FIG. 11 can be obtained through the same steps as those in the above embodiments.

However, in any case, the thickness is 8 to 18 μm.
Since the upper surface side wiring forming layer 31 made of copper foil of about m is half-etched, it cannot be denied that there is a problem similar to the conventional one. However, the thickness after half etching is 1 to 5 μm.
After forming holes and holes for vertical conduction in the upper surface side wiring forming layer and the film substrate made of copper foil and performing desmear treatment, immediately without performing the conventional protective layer laminating step, the plating step Can be moved to.

That is, the dry film for the protective layer is
Usually, it is commercially available as a three-layer structure in which a carrier film and a protective film are laminated on both sides thereof. Then, usually, the dry film is thermocompression-bonded to the surface of the substrate together with the protective film while the carrier film is being peeled off by the thermocompression-bonding roller of the laminator, and then the protective film is peeled off. The process of sticking the film having the three-layer structure to the film substrate 21 is very difficult, resulting in poor productivity and poor yield.

On the other hand, as shown in FIGS. 16 and 17, the lower surface side wiring forming layer 3 is formed on the lower surface of the film substrate 21.
4. The operation of attaching the laminated layer of the peeling layer 35 and the lower surface side carrier layer 36 is simple and has high productivity. Also,
The step of peeling the peeling layer 35 together with the lower surface side carrier layer 36 from the film substrate 21 is not difficult at all, and is more efficient than the conventional method as a whole. Therefore, it is possible to omit such a protective layer laminating step.
The method shown in 1) has the effect of achieving higher production efficiency than in the past. Omission of this protective layer lamination step is
The same applies to the above embodiments.

Further, in the above description, the case where the present invention is applied to the flexible wiring board having the double-sided wiring structure has been described, but the present invention is not limited to this and can be applied to the flexible wiring board having the single-sided wiring structure. For example, referring to FIG. 2, first, as a wiring forming flexible substrate, a wiring forming layer 31 made of a copper foil having a thickness of about 1 to 5 μm only on the upper surface of a film substrate 21 having a thickness of about 25 to 75 μm. A laminate is prepared in which the release layer 32 and the carrier layer 33 made of a copper foil having a thickness of about 18 to 50 μm are laminated.

Then, the carrier layer 33 is peeled off together with the peeling layer 32, and the wiring forming layer 31 is patterned to form wirings 22A made of only copper foil having a thickness of about 1 to 5 μm, as shown in FIG. Next, the protective plating layer 26 is formed on the surface. In this case, the thickness of the wiring 22A is 1
The thickness can be made extremely thin to about 5 μm, and since half etching is not used, it is possible to prevent variations in the thickness of the wiring 22A. Wiring 2
The thickness of 2A may be 1 μm or more and less than 8 μm.

[0061]

As described above, according to the present invention, as the flexible substrate for wiring formation, the one in which the wiring formation layer, the peeling layer and the carrier layer are laminated on the film substrate is used. When peeled together, only the wiring forming layer is left on the film substrate without using half-etching. Therefore, it is possible to prevent variations in the thickness of the remaining wiring forming layer from occurring, and by extension It is possible to prevent variations in thickness from occurring.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a flexible wiring board as a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of an item initially prepared when manufacturing the flexible wiring board shown in FIG.

FIG. 3 is a sectional view of a step following FIG. 2;

FIG. 4 is a sectional view of a step following FIG. 3;

5 is a sectional view of a step following FIG. 4; FIG.

FIG. 6 is a sectional view of a step following FIG. 5;

FIG. 7 is a sectional view of a step following FIG. 6;

FIG. 8 is a sectional view of a predetermined process in manufacturing the flexible wiring board according to the second embodiment of the present invention.

9 is a sectional view of a step following FIG. 8;

FIG. 10 is a sectional view of a step following FIG. 9;

FIG. 11 is a sectional view of an essential part of a flexible wiring board according to a third embodiment of the present invention.

FIG. 12 is a cross-sectional view of an initially prepared item in manufacturing the flexible wiring board shown in FIG.

FIG. 13 is a sectional view of a step following FIG. 12;

FIG. 14 is a sectional view of a step following FIG. 13;

FIG. 15 is a sectional view of a step following FIG. 14;

16 is a cross-sectional view of an initially prepared item in another production of the flexible wiring board shown in FIG.

FIG. 17 is a cross-sectional view of an initially prepared item in another production of the flexible wiring board shown in FIG.

FIG. 18 is a cross-sectional view showing an example of the case where the present invention is applied to a flexible wiring board having a single-sided wiring structure.

FIG. 19 is a partial cross-sectional view of an example of a conventional flexible wiring board.

FIG. 20 is a cross-sectional view of an initially prepared item in manufacturing the flexible wiring board shown in FIG.

21 is a sectional view of a step following FIG. 20. FIG.

22 is a sectional view of a step following FIG. 21. FIG.

23 is a sectional view of a step following FIG. 22. FIG.

24 is a sectional view of a step following FIG. 23.

25 is a sectional view of a step following FIG. 24. FIG.

[Explanation of symbols]

21 film substrate 22 Top side wiring 22a First copper layer 22b Second copper layer 23 Bottom surface wiring 23a First copper layer 23b Second copper layer 24 Vertical conduction hole 25 Vertical conduction part 26, 27, 28 Protective plating layer

Claims (39)

[Claims] 1. A wiring forming layer on one surface of a film substrate,
A flexible substrate for forming a wiring, wherein a peeling layer and a carrier layer are laminated. 2. The wiring formation flexible substrate according to claim 1, wherein the wiring formation layer and the carrier layer are made of copper foil. 3. The wiring forming flexible substrate according to claim 1, wherein the wiring forming layer is made of copper foil, and the carrier layer is made of a resin film. 4. The wiring formation flexible substrate according to claim 2 or 3, wherein the wiring formation layer has a thickness of less than 8 μm. 5. The wiring formation according to claim 1, wherein the other wiring forming layer, the other peeling layer, and the other carrier layer are laminated on the other surface of the film substrate. Flexible substrate. 6. The wiring-forming flexible substrate according to claim 5, wherein the both wiring-forming layers and the both carrier layers are made of copper foil. 7. The invention according to claim 5, wherein the both wiring forming layers and the other carrier layer are made of copper foil, and the one surface side carrier layer is made of a resin film. Flexible substrate for wiring formation. 8. The flexible substrate for wiring formation according to claim 6 or 7, wherein the thickness of the both wiring formation layers is about 1 to 5 μm. 9. The invention according to claim 6 or 7, wherein the wiring forming layer on the one surface side has a thickness of about 1 to 5 μm, and the other wiring forming layer has a thickness of 8 to 5 μm. 18μ
A flexible substrate for wiring formation, which is about m. 10. One of the wiring forming layers is laminated on one surface of the film substrate, and the other wiring forming layer, a release layer and a carrier layer are laminated on the other surface of the film substrate. Flexible substrate for wiring formation. 11. The flexible board for wiring formation according to claim 10, wherein the both wiring formation layers and the carrier layer are made of copper foil. 12. The invention according to claim 11, wherein the one wiring forming layer has a thickness of about 8 to 18 μm, and the other wiring forming layer has a thickness of about 1 to 5 μm. A flexible substrate for wiring formation, characterized by: 13. The flexible board for wiring formation according to claim 11, wherein the both wiring formation layers have a thickness of about 8 to 18 μm. 14. A wiring-forming flexible substrate, wherein a wiring made of a copper foil having a thickness of less than 8 μm is provided on one surface of the film substrate. 15. One of a film substrate having a hole for vertical conduction, a first wiring layer made of a metal foil and a second wiring layer made of a metal plating layer provided on one surface of the film substrate. And the other wiring comprising the first wiring layer made of a metal foil and the second wiring layer made of a metal plating layer provided on the other surface of the film substrate so as to cover the vertical conduction hole. And a metal plating layer extending from the second wiring layer of the one wiring and connected to the first wiring layer of the other wiring in the vertical conduction hole of the film substrate. A flexible wiring board comprising a conductive portion. 16. The flexible wiring board according to claim 15, wherein the thickness of the both wirings is about 8 to 18 μm. 17. The flexible wiring board according to claim 16, wherein the first wiring layers have a thickness of about 1 to 5 μm. 18. One of a film substrate having vertical conduction holes, a first wiring layer made of a metal foil and a second wiring layer made of a metal plating layer, which are provided on one surface of the film substrate. Wiring, the other wiring made of a metal foil provided on the other surface of the film substrate so as to cover the vertical conduction hole, and the second wiring layer of the one wiring, the film extending from the second wiring layer. A flexible wiring board, comprising: a vertical conduction part formed of a metal plating layer provided in the vertical conduction hole of the substrate so as to be connected to the other wiring. 19. The flexible wiring board according to claim 18, wherein the thickness of the both wirings is about 8 to 18 μm. 20. The flexible wiring board according to claim 19, wherein the first wiring layer has a thickness of about 1 to 5 μm. 21. A wiring forming flexible substrate comprising a wiring forming layer, a peeling layer and a carrier layer laminated on one surface of a film substrate, wherein the carrier layer is peeled together with the peeling layer to form the wiring. A method for manufacturing a flexible wiring board, which comprises patterning layers to form wiring. 22. The method of manufacturing a flexible wiring board according to claim 21, wherein the wiring forming layer and the carrier layer are made of copper foil. 23. The method of manufacturing a flexible wiring board according to claim 21, wherein the wiring forming layer is made of copper foil, and the carrier layer is made of a resin film. 24. The method of manufacturing a flexible wiring board according to claim 22 or 23, wherein the wiring forming layer has a thickness of about 1 to 5 μm. 25. One wiring forming layer, one peeling layer and one carrier layer are laminated on one surface of the film substrate, and the other wiring forming layer is formed on the other surface of the film substrate.
Of the wiring-forming flexible substrate in which the other peeling layer and the other carrier layer are laminated, the one carrier layer is peeled off together with the one peeling layer, and the one wiring forming layer and the film substrate are vertically stacked. A method for manufacturing a flexible wiring board, comprising forming a hole for conduction. 26. The invention according to claim 25, wherein after forming the hole for vertical conduction, the other carrier layer is peeled together with the other peeling layer, and the one wiring including the inside of the hole for vertical conduction. One wiring forming plating layer including a vertical conduction portion is formed on the surface of the forming layer, and the other wiring forming plating layer is formed on the surface of the other wiring forming layer. A method for manufacturing a flexible wiring board, characterized in that a layer and a wiring layer for forming both wirings are patterned to form wirings having a two-layer structure on both surfaces of the film substrate. 27. The wiring according to claim 25, wherein the other carrier layer is peeled together with the other peeling layer after the vertical conduction hole is formed, and the one wiring includes the inside of the vertical conduction hole. One wiring layer including a vertical conduction portion formed of a plating layer is formed on the surface of the formation layer, and the other wiring layer formed of the plating layer is formed on the surface of the other wiring formation layer, and both wirings are formed. A method of manufacturing a flexible wiring board, characterized in that a wiring layer composed of the both wiring forming layers is formed under the layer, and wiring having a two-layer structure is formed on both surfaces of the film substrate. 28. The invention according to claim 25, wherein after forming the vertical conduction hole, one wiring formation including a vertical conduction portion is formed on the surface of the one wiring formation layer including the inside of the vertical conduction hole. Forming a plating layer for, and forming a plating layer on the surface of the other carrier layer, peeling the plating layer formed on the other carrier layer and the surface together with the other peeling layer, the one Wiring forming layer, the one wiring forming plating layer, and the other wiring forming layer are patterned to form a two-layer structure wiring and a one-layer structure wiring on one surface and the other surface of the film substrate, respectively. A method for manufacturing a flexible wiring board, comprising: 29. The invention according to any one of claims 26 to 28, wherein the wiring forming layers and the carrier layers are made of copper foil, and the plating layers are made of copper. Flexible wiring board manufacturing method. 30. The invention according to any one of claims 26 to 28, wherein the both wiring forming layers and the other carrier layer are made of copper foil, and the one carrier layer is made of a resin film. Flexible wiring board manufacturing method. 31. The method for manufacturing a flexible wiring board according to claim 29 or 30, wherein the thickness of the both wirings is about 8 to 18 μm. 32. The method of manufacturing a flexible wiring board according to claim 31, wherein the one wiring forming layer has a thickness of about 1 to 5 μm. 33. A thickness of 8 to 18 on one surface of a film substrate.
One wiring forming layer made of copper foil of about μm is laminated, and the other wiring forming layer made of copper foil, a release layer and a carrier layer made of copper foil are laminated on the other surface of the film substrate. Of the wiring forming flexible substrate, the one wiring forming layer is half-etched to a thickness of about 1 to 5 μm, and the half-etched one wiring forming layer and the film substrate are provided with holes for vertical conduction. A method for manufacturing a flexible wiring board, comprising: 34. The invention according to claim 33, wherein the carrier layer is peeled off together with the release layer after the vertical conduction hole is formed, and the one wiring formation layer including the inside of the vertical conduction hole is formed. Forming one wiring forming plating layer including a vertical conduction part made of a copper plating layer on the surface, and forming the other wiring forming plating layer made of a copper plating layer on the surface of the other wiring forming layer. A method for manufacturing a flexible wiring board, wherein the both wiring forming layers and the both wiring forming plating layers are patterned to form wirings having a two-layer structure on both surfaces of the film substrate. 35. The invention according to claim 33, wherein the carrier layer is peeled off together with the peeling layer after the vertical conduction hole is formed, and the one wiring formation layer including the inside of the vertical conduction hole is formed. One wiring layer including a vertical conduction part made of a copper plating layer is formed on the surface, and the other wiring layer made of a copper plating layer is formed on the surface of the other wiring forming layer. A method of manufacturing a flexible wiring board, characterized in that a wiring layer composed of the both wiring forming layers is formed on the both sides, and wiring having a two-layer structure is formed on both surfaces of the film substrate. 36. In the invention according to claim 33, after forming the vertical conduction hole, a vertical conduction portion made of a copper plating layer is formed on the surface of the one wiring formation layer including the inside of the vertical conduction hole. Forming one wiring formation plating layer including
And, forming a copper plating layer on the surface of the other carrier layer, peeling the other carrier layer and the copper plating layer formed on the surface together with the peeling layer, the one wiring forming layer and the One wiring forming plating layer and the other wiring forming layer are patterned to form a two-layer structure wiring and a one-layer structure wiring on one surface and the other surface of the film substrate, respectively. Flexible wiring board manufacturing method. 37. The method of manufacturing a flexible wiring board according to any one of claims 34 to 36, wherein the thickness of both of the wirings is about 8 to 18 μm. 38. The method of manufacturing a flexible wiring board according to claim 37, wherein the other wiring forming layer has a thickness of about 1 to 5 μm. 39. The flexible wiring board according to claim 25 or 33, wherein the formation of the vertical conduction hole in the one wiring formation layer and the film substrate is performed by laser irradiation. Manufacturing method.