JP2013030548A - Flexible printed wiring board and manufacturing method of the same - Google Patents

Abstract

The present invention provides a flexible printed wiring board capable of suppressing the occurrence of delamination of each wiring board by greatly improving the moisture absorption reflow resistance, and a manufacturing method thereof.
Two or more wiring boards having an insulating layer, a conductive circuit formed on one surface of the insulating layer, and an interlayer conductive portion electrically connected to the conductive circuit and penetrating the insulating layer are stacked. In the flexible printed wiring board 1, the plurality of wiring boards include a first outer layer wiring board 10 (specific wiring board) provided with a barrier layer 15 having a moisture-proof function.

Description

  The present invention relates to a flexible printed wiring board and a method for manufacturing the same.

As electronic devices become lighter, thinner and smaller, semiconductor chips and components are miniaturized, and terminals have a narrower pitch, higher density and higher multilayer wiring are being studied in multilayer printed wiring boards (see, for example, Patent Document 1). ).
Rigid printed wiring boards and flexible printed wiring boards are well known as multilayer printed wiring boards. In particular, in recent years, flexible printed wiring boards have been increasingly adopted to reduce the weight and thickness of electric and electronic devices.

  The multilayer flexible printed wiring board is formed by laminating a plurality of wiring boards each having an insulating layer made of a resin material such as polyimide and a conductive circuit formed on the main surface of the insulating layer.

  By the way, although the insulating layer of a flexible printed wiring board is generally comprised with resin, such as a polyimide, a polyimide tends to absorb a water | moisture content. Therefore, for example, at a high temperature such as a reflow process, moisture absorbed in the insulating layer is vaporized and expanded in the insulating layer, which may cause expansion of the insulating layer and delamination of each wiring board. .

  In order to solve such problems, in recent years, a method of forming a multilayer flexible printed wiring board by fixing and laminating a wiring board with a main surface of a conductor layer roughened with an adhesive or the like has been proposed. According to this method, the adhesion area of each layer interface is increased by roughening the main surface of the conductor layer, so that the adhesion of each layer can be improved and the occurrence of delamination of each wiring board can be suppressed. That is, good moisture absorption reflow resistance can be secured.

  However, in the above method, there is a limit to improving the adhesion of each layer by roughening the main surface of the conductor layer. Moreover, the water absorption of the insulating layer which is the cause of the fall of moisture absorption reflow tolerance cannot be solved. Accordingly, when a material having a higher water absorption rate is used for the insulating layer, delamination may occur.

JP-A-6-268345

  Then, this invention makes it a subject to provide the flexible printed wiring board which can suppress generation | occurrence | production of the delamination of each wiring board, and its manufacturing method by aiming at the drastic improvement of moisture absorption reflow tolerance.

  The flexible printed wiring board according to claim 1 of the present invention includes an insulating layer, a conductive circuit formed on at least one surface of the insulating layer, and electrically connected to the conductive circuit and passing through the insulating layer. A flexible printed wiring board in which two or more wiring boards having an interlayer conductive portion are stacked, and a specific wiring board of the wiring boards includes a barrier layer having a moisture-proof function. Yes.

  The flexible printed wiring board according to claim 2 of the present invention is characterized in that, in claim 1, the barrier layer is formed on the one or other surface of the insulating layer.

  A flexible printed wiring board according to a third aspect of the present invention is the flexible printed wiring board according to the first aspect, wherein the barrier layer is formed on the one and other surfaces of the insulating layer.

  A flexible printed wiring board according to a fourth aspect of the present invention is characterized in that, in any one of the first to third aspects, the specific wiring board is arranged in an outermost layer.

  The flexible printed wiring board according to claim 5 of the present invention is the flexible printed wiring board according to any one of claims 1 to 4, wherein the barrier layer is made of metal oxide, polyethylene, fluororesin, polyparaxylene, polyester, polyvinylidene chloride. It is characterized by comprising polyacrylonitrile or a material containing these.

  The method for manufacturing a flexible printed wiring board according to claim 6 of the present invention includes an insulating layer, a conductive circuit formed on at least one surface of the insulating layer, and the insulating circuit electrically connected to the conductive circuit. A method for manufacturing a flexible printed wiring board in which two or more wiring boards having an interlayer conductive portion penetrating a layer are stacked, and a barrier layer having a moisture-proof function with respect to a specific wiring board among the wiring boards It includes the process of forming.

  The method for producing a flexible printed wiring board according to claim 7 of the present invention is the method according to claim 6, wherein, in the step, metal oxide, polyethylene, fluororesin, polyparaxylene, polyester, polyvinylidene chloride, polyacrylonitrile, or these The barrier layer is formed of a material containing.

  According to the present invention, the specific wiring board includes the barrier layer having a moisture-proof function, so that water absorption of the insulating layer can be suppressed and the amount of moisture contained in the insulating layer can be reduced. Thereby, even if the water | moisture content contained in the insulating layer vaporizes under high temperature, rapid expansion of a volume can be suppressed. Therefore, the occurrence of delamination of each wiring board can be suppressed by greatly improving the moisture absorption reflow resistance.

It is side surface sectional drawing of a flexible printed wiring board. It is explanatory drawing of the manufacturing process of an inner-layer wiring board, Fig.2 (a) is explanatory drawing before conductive circuit formation, FIG.2 (b) is explanatory drawing after conductive circuit formation. It is explanatory drawing of the formation process of a conductive circuit among the manufacturing processes of a 1st outer layer wiring board. It is explanatory drawing of the formation process of a barrier layer among the manufacturing processes of a 1st outer layer wiring board. It is explanatory drawing of the formation process of a contact bonding layer, and the arrangement | positioning process of a film material among the manufacturing processes of a 1st outer layer wiring board. It is explanatory drawing of the formation process of an interlayer conduction | electrical_connection part among the manufacturing processes of a 1st outer layer wiring board. It is explanatory drawing of a lamination process. It is explanatory drawing of the flexible printed wiring board of the 1st modification of embodiment. It is explanatory drawing of the flexible printed wiring board of the 2nd modification of embodiment.

(Flexible printed wiring board)
Below, the flexible printed wiring board of this embodiment is demonstrated, referring drawings.
FIG. 1 is a side sectional view of the flexible printed wiring board 1 of the present embodiment. The drawings are schematic, and the thicknesses and ratios of the layers are different from actual ones.
As shown in FIG. 1, the flexible printed wiring board 1 of this embodiment is formed by laminating a plurality of wiring boards (three in this embodiment). Specifically, the flexible printed wiring board 1 includes an inner layer wiring board 30 having conductive circuits 31 and 32 on both sides, a first outer layer wiring board 10 disposed on one side of the inner layer wiring board 30 (upper side in FIG. 1), A second outer layer wiring board 20 disposed on the other side (lower side in FIG. 1) of the inner layer wiring board 30 is laminated and formed.

The inner wiring board 30 includes an insulating layer 30a formed of an insulating resin such as polyimide having flexibility. Further, a conductive circuit 31 is formed on one (upper side in FIG. 1) surface 30b of the insulating layer 30a, and a conductive circuit 32 is formed on the other (lower side in FIG. 1) surface 30c. ing. The conductive circuits 31 and 32 are both made of a highly conductive metal such as copper.
In the insulating layer 30a, an interlayer conductive portion 34 that penetrates the insulating layer 30a in the thickness direction is formed. The interlayer conductive portion 34 is formed by plating a metal such as copper on the inner peripheral surface of the via hole 33 formed in the insulating layer 30a. By the interlayer conductive portion 34, the conductive circuit 31 on one surface 30b of the inner wiring board 30 and the conductive circuit 32 on the other surface 30c are electrically connected.

The first outer wiring board 10 disposed on one side of the inner wiring board 30 includes an insulating layer 10a. The insulating layer 10a is formed to a thickness of about 12 to 50 μm by an insulating resin such as flexible polyimide.
A conductive circuit 11 is formed of a metal such as copper on one surface 10b (upper side in FIG. 1) of the insulating layer 10a.
The insulating layer 10a has an interlayer conductive portion 14 that penetrates the insulating layer 10a in the thickness direction. The interlayer conductive portion 14 is formed by filling the via hole 13 formed in the insulating layer 10a with a conductive paste made of a material used for solder, for example. The conductive layer 11 on the one surface 10 b of the first outer layer wiring substrate 10 and the conductive circuit 31 on the one surface 30 b of the inner layer wiring substrate 30 are electrically connected by the interlayer conductive portion 14.

The first outer layer wiring board 10 includes a barrier layer 15 on the other surface 10c of the insulating layer 10a. The barrier layer 15 is formed so as to cover the entire other surface 10c of the insulating layer 10a.
The barrier layer 15 is formed, for example, by depositing a metal that easily oxidizes, such as aluminum, with a thickness of about several hundred to 1 μm. The material for forming the barrier layer 15 is not limited to aluminum. For example, other metals that are easily oxidized, polyethylene, fluororesin, polyparaxylene, polyester, polyvinylidene chloride, polyacrylonitrile, or a transparent material containing these metals. Any material with low wettability may be used.

Since the basic configuration of the second outer layer wiring board 20 disposed on the other side of the inner layer wiring board 30 is the same as that of the first outer layer wiring board 10, a detailed description thereof will be omitted.
In the insulating layer 20a, an interlayer conductive portion 24 penetrating in the thickness direction of the insulating layer 20a is formed. The conductive circuit 21 on one surface 20 b of the second outer layer wiring substrate 20 and the conductive circuit 32 on the other surface 30 c of the inner layer wiring substrate 30 are electrically connected by the interlayer conductive portion 24.
The second outer layer wiring board 20 includes a barrier layer 25 on the other surface 20c of the insulating layer 20a. The barrier layer 25 is formed so as to cover the entire surface of the other surface 20c of the insulating layer 20a.

  The flexible printed wiring board 1 is formed by placing the first outer layer wiring board 10 on one side of the inner layer wiring board 30 and laminating the second outer layer wiring board 20 on the other side. The inner layer wiring board 30 and the first outer layer wiring board 10 are bonded together by an adhesive layer 41a, and the inner layer wiring board 30 and the second outer layer wiring board 20 are bonded together by an adhesive layer 41b. The adhesive layers 41a and 41b are formed by solidifying the adhesive applied between the wiring boards.

  By the way, since polyimide, which is a material of the insulating layers 10a, 20a, and 30a, generally has a high water absorption rate, moisture is absorbed into the insulating layers 10a, 20a, and 30a. For this reason, for example, at a high temperature such as a reflow process, moisture absorbed in the insulating layers 10a, 20a, and 30a is vaporized and expanded in the insulating layers 10a, 20a, and 30a. The insulating layers 10a, 20a, and 30a may also expand due to vaporization and expansion of moisture in the insulating layers 10a, 20a, and 30a, which may cause delamination that causes the adhesive layers 41a and 41b and each wiring board to peel off. It has been known.

However, the first outer layer wiring board 10 and the second outer layer wiring board 20 of the present embodiment include the barrier layer 15 and the barrier layer 25, respectively, as described above. The barrier layer 15 and the barrier layer 25 are formed of a material having low moisture permeability and have a moisture-proof function.
The barrier layer 15 having a moisture-proof function covers the entire surface of the other surface 10 c of the insulating layer 10 a of the first outer layer wiring substrate 10, and the barrier layer 25 is formed on the other surface 20 c of the insulating layer 20 a of the second outer layer wiring substrate 20. Covers the entire surface. Thereby, the water absorption of the insulating layers 10a and 20a is suppressed, and the amount of water contained in the insulating layers 10a and 20a is reduced.

  The first outer layer wiring board 10 provided with the barrier layer 15 and the second outer layer wiring board 20 provided with the barrier layer 25 are respectively disposed in the outermost layers. Thereby, the barrier layer 15 is disposed on one side (the upper side in FIG. 1) of the insulating layer 30a of the inner layer wiring board 30, and the barrier layer 25 is disposed on the other side (the lower side in FIG. 1) of the insulating layer 30a of the inner layer wiring board 30. Is placed. Therefore, the barrier layer 15 and the barrier layer 25 suppress water absorption from one side and the other side of the insulating layer 30a of the inner layer wiring board 30 and reduce the amount of moisture contained in the insulating layer 30a.

(Method for manufacturing flexible printed wiring board)
Then, the manufacturing method of the flexible printed wiring board 1 is demonstrated, referring drawings.
In addition, although the manufacturing method of the flexible printed wiring board 1 is not specifically limited, As an example, it manufactures through each process shown below.
In the following, the barrier layer 15 is disposed on one side (upper side in FIG. 1) of the insulating layer 30a of the inner layer wiring board 30, and the barrier is disposed on the other side (lower side in FIG. 1) of the insulating layer 30a of the inner layer wiring board 30. A method for manufacturing the flexible printed wiring board 1 (see FIG. 1) on which the layer 25 is disposed will be described.

(Inner layer wiring board manufacturing process)
Below, the manufacturing process of the inner-layer wiring board 30 is demonstrated.
2A and 2B are explanatory diagrams of the manufacturing process of the inner layer wiring board 30, FIG. 2A is an explanatory diagram before the formation of the conductive circuit, and FIG. 2B is an explanatory diagram after the formation of the conductive circuit.
In the manufacturing process of the inner wiring board 30, first, as shown in FIG. 2A, a double-sided copper-clad laminate 39 in which copper foils 31a and 32a are laminated on both sides of an insulating layer 30a made of polyimide or the like is a starting material. And Then, as shown in FIG. 2B, via holes 33 are formed in the thickness direction of the double-sided copper-clad laminate 39 using a laser or the like at predetermined positions of the double-sided copper-clad laminate 39. Here, the double-sided copper-clad laminate 39 may be obtained by directly laminating the insulating layer 30a and the copper foils 31a and 32a, and the insulating layer 30a and the copper foil 31a, 32a may be bonded.

Next, the inner peripheral surface of the via hole 33 is plated to form an interlayer conductive portion 34. The interlayer conductive portion 34 electrically connects the copper foil 31a on one side of the double-sided copper-clad laminate 39 and the copper foil 32a on the other side.
Subsequently, the copper foil 31a and the copper foil 32a are patterned to form the conductive circuit 31 on one surface 30b of the inner wiring board 30 and the conductive circuit 32 on the other surface 30c. The patterning of the copper foil 31a and the copper foil 32a is performed by, for example, forming a mask pattern on the surfaces of the copper foil 31a and the copper foil 32a by a photolithography technique and then etching the copper foil 31a and the copper foil 32a.
The manufacturing process of the inner layer wiring board 30 is thus completed.

(Outer layer wiring board formation process)
Below, the manufacturing process of the 1st outer-layer wiring board 10 is demonstrated. The manufacturing process of the first outer layer wiring board 10 and the manufacturing process of the second outer layer wiring board 20 are the same. Therefore, hereinafter, the manufacturing process of the first outer layer wiring board 10 will be described, and the description of the manufacturing process of the second outer layer wiring board 20 will be omitted.

FIG. 3 is an explanatory diagram of a process of forming the conductive circuit 11 in the manufacturing process of the first outer layer wiring board 10.
In the manufacturing process of the first outer layer wiring substrate 10, first, as shown in FIG. 3, a single-sided copper-clad laminate 19 in which a copper foil 11a is laminated on one surface 10b of an insulating layer 10a made of polyimide or the like is prepared. Subsequently, similarly to the manufacturing process of the inner layer wiring substrate 30, the copper foil 11 a is patterned to form the conductive circuit 11 on the one surface 10 b of the first outer layer wiring substrate 10.

(Barrier layer formation process)
FIG. 4 is an explanatory diagram of the formation process of the barrier layer 15 in the manufacturing process of the first outer layer wiring board 10.
Next, as shown in FIG. 4, the barrier layer 15 is formed on the other surface 10c of the insulating layer 10a.
In the step of forming the barrier layer 15, for example, aluminum oxide (alumina) may be directly formed by a vacuum deposition method, but aluminum is formed on the other surface 10 c of the insulating layer 10 a by a thickness of about several hundreds of millimeters by a deposition method or the like. After the film formation, the aluminum formed by UV ozone method or the like is irradiated with ultraviolet rays, so that the formed aluminum is completely oxidized and the non-conductive alumina (barrier) layer 15 is formed. In addition, since the surface roughness of the barrier layer 15 formed in this manner is increased in surface roughness due to oxidation, the adhesion between the barrier layer 15 and the adhesive layer 41a formed in the next step can be improved by the anchor effect. I can expect.

  The barrier layer 15 may be formed of an insulator such as polyethylene, fluororesin, polyparaxylene, polyester, polyvinylidene chloride, polyacrylonitrile, or the like. In this case, the barrier layer 15 can be formed by, for example, a screen printing method, a laminating method, a CVD method, or the like.

FIG. 5 is an explanatory diagram of the formation process of the adhesive layer 41 a and the arrangement process of the film material 45 in the manufacturing process of the first outer layer wiring board 10.
Next, as shown in FIG. 5, an adhesive layer 41 a is formed over the barrier layer 15, and a film material 45 is further disposed.
The adhesive layer 41a is formed by applying and solidifying a fluid adhesive made of, for example, an epoxy resin.
The film material 45 is disposed so as to cover the adhesive layer 41a. The film material 45 serves as a mask when the conductive paste is applied in the next step, and is formed by, for example, heat laminating a polyester film having a thickness of about 25 μm at 100 ° C. for 30 seconds.

FIG. 6 is an explanatory diagram of a process of forming the interlayer conductive portion 14 in the manufacturing process of the first outer layer wiring board 10.
Next, as shown in FIG. 6, an interlayer conductive portion 14 that penetrates one surface 10 b and the other surface 10 c of the insulating layer 10 a is formed.
In the step of forming the interlayer conductive portion 14, first, the laser beam is irradiated from the other side (the lower side in FIG. 6) of the film material 45 to form the via hole 13 penetrating the film material 45, the adhesive layer 41 a and the insulating layer 10 a. .
Subsequently, using the film material 45 as a mask, the via hole 13 is filled with a conductive paste 14a such as a silver paste by screen printing, for example.
Finally, the film material 45 is peeled from the adhesive layer 41a. As a result, the interlayer conductive portion 14 that is electrically connected to the conductive circuit 11 and protrudes from the other side (lower side in FIG. 6) of the adhesive layer 41a is formed.
Thus, the manufacturing process of the first outer layer wiring board 10 is completed.

(Lamination process)
FIG. 7 is an explanatory diagram of the stacking process.
In the stacking step, the inner layer wiring board 30, the first outer layer wiring board 10 and the second outer layer wiring board 20 formed as described above are stacked in the thickness direction and stacked.
Specifically, with the adhesive layer 41a of the first outer layer wiring board 10 and the conductive circuit 31 of the inner layer wiring board 30 facing each other, the first outer layer is placed on one side (upper side in FIG. 7) of the inner layer wiring board 30. The wiring board 10 is disposed. Further, the second outer layer wiring board is disposed on the other side (lower side in FIG. 7) of the inner layer wiring board 30 with the adhesive layer 41b of the second outer layer wiring board 20 and the conductive circuit 32 of the inner layer wiring board 30 facing each other. 20 is arranged. Then, the first outer layer wiring substrate 10, the inner layer wiring substrate 30, and the second outer layer wiring substrate 20 are heated and pressed while being aligned with each other.

By the laminating step, the adhesive layer 41a of the first outer layer wiring substrate 10 and the adhesive layer 41b of the second outer layer wiring substrate 20 are stacked in close contact with the inner layer wiring substrate 30. Further, the interlayer conductive portion 14 of the first outer layer wiring substrate 10 is electrically connected to the conductive circuit 31 of the inner layer wiring substrate 30, and the interlayer conductive portion 24 of the second outer layer wiring substrate 20 is connected to the conductive circuit 32 of the inner layer wiring substrate 30. Electrically connected. That is, the conductive circuits 11 of the first outer layer wiring board 10, the conductive circuit 31 of the inner layer wiring board 30, the conductive circuit 32 of the inner layer wiring board 30, and the conductive circuits 21 of the second outer layer wiring board 20 are electrically connected. Connected.
When the wiring boards are laminated by the laminating process and the flexible printed wiring board 1 shown in FIG. 1 is formed, all the manufacturing processes of the flexible printed wiring board 1 are completed.

(First modification of embodiment)
FIG. 8 is an explanatory diagram of the flexible printed wiring board 1 according to the first modification of the embodiment.
In the above-described embodiment, the barrier layer 15 is disposed on one side (the upper side in FIG. 1) of the insulating layer 30a of the inner layer wiring board 30, and the barrier layer is disposed on the other side (the lower side in FIG. 1) of the insulating layer 30a. The flexible printed wiring board 1 (see FIG. 1) on which 25 is disposed and the manufacturing method thereof have been described.
On the other hand, the flexible printed wiring board 1 of the first modified example of the embodiment has a barrier on one surface 10b (upper side in FIG. 8) of the insulating layer 10a in the first outer layer wiring board 10, as shown in FIG. This is different from the embodiment in that the layer 15 is formed and the barrier layer 25 is formed on one surface 20b (the lower side in FIG. 8) of the insulating layer 20a in the second outer layer wiring substrate 20.

  When the barrier layers 15 and 25 are formed on the flexible printed wiring board 1 of the first modified example, first, aluminum is applied to one surface 10b or 20b of the insulating layers 10a and 20a by a vacuum deposition method as in the embodiment. After film formation, non-conductive barrier layers 15 and 25 made of alumina or the like are formed by a UV ozone method or the like. Thereafter, a copper seed layer is formed on the barrier layers 15 and 25 by sputtering or the like, and plating is performed on the seed layer to form conductive circuits 11 and 21.

(Second modification of the embodiment)
FIG. 9 is an explanatory diagram of the flexible printed wiring board 1 according to a second modification of the embodiment.
As shown in FIG. 9, the flexible printed wiring board 1 according to the second modification of the embodiment includes a barrier layer 15 formed on both surfaces 10 b and 10 c of the insulating layer 10 a in the first outer layer wiring board 10, and the second outer layer wiring board. 20 differs from the embodiment and the first modification in that barrier layers 25 are formed on both surfaces 20b and 20c of the insulating layer 20a.

  In the case of the flexible printed wiring board 1 of the second modified example, the barrier layers 15 and 25 and the conductive circuits 11 and 21 are formed on the one surfaces 10b and 20b of the insulating layers 10a and 20b in the same manner as the first modified example. After that, barrier layers 15 and 25 are formed on the other surfaces 10c and 20c of the insulating layers 10a and 20a. In addition, since the formation method of the barrier layers 15 and 25 in the other surfaces 10c and 20c of the insulating layers 10a and 20a is the same as that of the embodiment and the modification, detailed description is omitted.

(effect)
According to the present embodiment, the first outer layer wiring board 10 and the second outer layer wiring board 20 are provided with the barrier layers 15 and 25 having a moisture-proof function, respectively, so that water absorption of the insulating layers 10a, 20a, and 30a is suppressed. The amount of moisture contained in the insulating layers 10a, 20a, and 30a can be reduced. Thereby, even if the moisture contained in the insulating layers 10a, 20a, and 30a is vaporized at a high temperature during reflow, rapid expansion of the volume can be suppressed. Therefore, the occurrence of delamination of each wiring board can be suppressed by significantly improving the moisture absorption reflow resistance of the flexible printed wiring board 1.

  Moreover, according to this embodiment, the water absorption of the insulating layers 10a, 20a, and 30a can be suppressed by forming the barrier layers 15 and 25 with existing materials such as aluminum. Thus, since the barrier layers 15 and 25 are provided without selecting a special material, the flexible printed wiring board 1 with high reliability and low cost can be provided.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  Although the four-layer flexible printed wiring board 1 has been described in this embodiment, the number of layers of the flexible printed wiring board 1 is not limited to four.

  In the present embodiment, the barrier layers 15 and 25 are formed of aluminum. However, the barrier layers 15 and 25 may be formed of an easily oxidizable metal other than aluminum, such as iron or silver. Further, the barrier layers 15 and 25 may be other than metal, and may be a resin material having low moisture permeability such as polyethylene, fluororesin, polyparaxylene, polyester, polyvinylidene chloride, polyacrylonitrile and the like.

  In this embodiment, the barrier layers 15 and 25 are formed by the vapor deposition method. However, the film formation method of the barrier layers 15 and 25 is not limited to the vapor deposition method, and for example, a film formation method such as a sputtering method or a CVD method is adopted. May be.

  In the present embodiment, the barrier layers 15 and 25 are formed so as to cover the surfaces 10c and 20c on the other side opposite to the surfaces 10b and 20b on the one side where the conductive circuits 11 and 21 are formed. Barrier layers 15 and 25 may be formed on the one side surfaces 10b and 20b on which the circuits 11 and 21 are formed. Moreover, you may form the barrier layers 15 and 25 on both surfaces of the one side surfaces 10b and 20b and the other side surfaces 10c and 20c of the insulating layers 10a and 10b.

  DESCRIPTION OF SYMBOLS 1 Flexible printed wiring board, 10 1st outer layer wiring board (specific wiring board), 10a Insulating layer, 10b One side, 10c The other side, 11 Conductive circuit, 14 Interlayer conduction | electrical_connection part, 15 Barrier layer, 20 2nd outer layer Wiring board (specific wiring board), 20a insulating layer, 20b one side, 20c the other side, 21 conductive circuit, 24 interlayer conduction part, 25 barrier layer, 30 inner layer wiring board (wiring board).

Claims (7)

Two or more wiring boards having an insulating layer, a conductive circuit formed on at least one surface of the insulating layer, and an interlayer conductive portion that is electrically connected to the conductive circuit and penetrates the insulating layer are stacked. A flexible printed wiring board,
A specific printed circuit board among the printed circuit boards includes a barrier layer having a moisture-proof function.   The flexible printed wiring board according to claim 1, wherein the barrier layer is formed on the one or other surface of the insulating layer.   The flexible printed wiring board according to claim 1, wherein the barrier layer is formed on the one and other surfaces of the insulating layer.   4. The flexible printed wiring board according to claim 1, wherein the specific wiring board is disposed in an outermost layer. 5.   5. The barrier layer according to claim 1, wherein the barrier layer is made of a metal oxide, polyethylene, fluororesin, polyparaxylene, polyester, polyvinylidene chloride, polyacrylonitrile, or a material containing them. Flexible printed wiring board. Two or more wiring boards having an insulating layer, a conductive circuit formed on at least one surface of the insulating layer, and an interlayer conductive portion that is electrically connected to the conductive circuit and penetrates the insulating layer are stacked. A method for producing a flexible printed wiring board comprising:
The manufacturing method of the flexible printed wiring board characterized by including the process of forming the barrier layer which has a moisture-proof function with respect to a specific wiring board among the said wiring boards.   The flexible layer according to claim 6, wherein in the step, the barrier layer is formed of a metal oxide, polyethylene, fluororesin, polyparaxylene, polyester, polyvinylidene chloride, polyacrylonitrile, or a material containing them. Manufacturing method of printed wiring board.

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