JPH07283579A - Shielded type flexible wiring board - Google Patents

Abstract

PURPOSE:To obtain a shielded type flexible wiring board being excellent in flexibility and properties of preventing a crosstalk and electromagnetic noise radiation. CONSTITUTION:A first insulative film 1 and a second insulative film 7 are provided oppositely with an adhesive layer 4 interlaid and a plurality of conductor circuits 3 are formed at prescribed intervals from each other on the first insulative film 1 surface side. Besides, a metal thin film layer 6 is formed on the second insulative film 7 surface side facing the film surface of the first insulative film 1, and a grounding conductor circuit 31 being an arbitrary circuit part out of the conductor circuits 3 in a plurality is connected electrically with the metal thin film layer 6 by conductive paste 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield type flexible wiring board suitable for transmitting high frequency signals and digital signals.

[0002]

2. Description of the Related Art Conventionally, flexible printed wiring boards have been widely used for connecting printed circuit boards on which electronic components are mounted. In such a flexible printed wiring board, since the conductor lines provided are generally formed in parallel, electromagnetic field coupling between the conductor lines is strong, crosstalk occurs, and an electronic device easily malfunctions. In addition, there is a problem that a harmonic component generated from a digital signal flowing through the conductor line is radiated as electromagnetic noise, which causes other electronic devices to malfunction. In order to solve such a problem, for example, a shield metal layer such as a metal foil or a conductive paste is adhered to the conductor line formation surface via an insulating layer such as a plastic film or an adhesive layer, and the shield metal is formed. It has been proposed to reduce the electromagnetic field coupling between the conductor lines and prevent the emission of electromagnetic noise by electrically connecting the layers and the conductor lines.

[0003]

In the flexible printed circuit board constructed according to the above-mentioned proposal, since the metal foil having substantially the same thickness as the conductor line is used as the shield metal layer, the flexible printed circuit board has the greatest feature. The problem arises that some flexibility is reduced. Further, when the conductive paste is used, in order to obtain the same conductivity as that of the metal foil, there is a problem that the thickness becomes large and the flexibility also deteriorates. Further, in order to prevent an electrical short circuit accident due to the shield metal layer coming into contact with other electronic components in the electronic device, it is necessary to provide an insulating layer on the outside of the flexible printed wiring board, which increases the number of manufacturing steps, and The presence of the insulating layer causes a problem that the flexibility is further reduced.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a shield type flexible wiring board which is excellent in flexibility and crosstalk and prevention of electromagnetic noise emission.

[0005]

In order to achieve the above-mentioned object, the shield type flexible wiring board of the present invention has a first structure.
The insulating film and the second insulating film are opposed to each other via an adhesive layer, and a plurality of circuit portions are formed on the surface of the first insulating film at a predetermined interval from each other. A metal thin film layer is formed on the side of the second insulating film surface facing the film surface of the first insulating film, and any circuit portion of the plurality of circuit portions is electrically connected to the metal thin film layer. Is connected to.

[0006]

That is, in the shielded flexible wiring board of the present invention, the metal thin film layer provided on the second insulating film surface is one of the plurality of circuit portions provided on the first insulating film surface side. It is electrically connected to any circuit part. Therefore, the metal thin film layer and an arbitrary circuit portion have the same potential, electromagnetic field coupling between a plurality of circuits can be reduced, crosstalk can be prevented, and the characteristic impedance of the metal thin film layer and the adhesive layer are significantly different. Therefore, it is possible to prevent the emission of electromagnetic noise. In addition, since the crosstalk and the electromagnetic noise emission are prevented by electrically coupling the metal thin film layer and an arbitrary circuit portion, the flexibility, which is the greatest feature of the flexible wiring board, is not impaired. Furthermore, when the end of the metal thin film layer is positioned so as not to protrude from the end of the insulating film, the metal thin film layer is not exposed on the surface or the end face portion of the flexible wiring board, and other electronic devices in the electronic device are not exposed. Insulation from parts is maintained. Further, by forming a second metal thin film layer on the surface of the first insulating film and electrically connecting the arbitrary circuit part and the second metal thin film layer, more excellent crosstalk is generated. The prevention and the prevention of electromagnetic noise emission are realized.

Next, the present invention will be described in detail based on embodiments.

[0008]

1 is a sectional view showing an embodiment of a shield type flexible wiring board of the present invention. Reference numeral 1 is a first insulating film, and a conductor circuit 3 having a predetermined pattern is formed on the first insulating film via an adhesive layer 2. Any conductor circuit of the conductor circuits 3 is set to the ground conductor circuit 31. A metal thin film layer 6 is formed on the surface of the second insulating film 7 facing the first insulating film 1. The metal thin film layer 6 is formed from the end portion of the second insulating film 7 so that a short circuit or the like does not occur due to contact with another wiring board or the like.
Are positioned so that the ends of the do not protrude. The metal thin film layer 6 is connected to the ground conductor circuit 31 by the conductive paste 5. In the figure, 4 is an adhesive layer that fills the space between the conductor circuit 3 and the metal thin film layer 6.

In the wiring board having the above structure, the metal thin film layer 6 formed on the surface of the second insulating film 7 and the ground conductor circuit 31 are connected by the conductive paste 5. For this reason,
The metal thin film layer 6 and the ground conductor circuit 31 have the same potential,
Electromagnetic field coupling between a plurality of circuits is reduced and crosstalk is prevented. Further, since the end portion of the metal thin film layer 6 is positioned so as not to protrude from the end portion of the second insulating film 7, it does not come into contact with another wiring board or the like to cause a short circuit or the like.

The first insulating film 1 and the second insulating film 7 are not particularly limited as long as they are electrically insulating. For example, a conventionally known flexible film such as a polyimide resin film, a polyester resin film, or a fluororesin film can be used. The materials of the first insulating film 1 and the second insulating film 7 may be the same as or different from each other. Of these, a polyimide resin film or a polyester resin film is preferably used from the viewpoint of mechanical properties. further,
The thickness of each of the insulating films 1 and 7 is 12.5 to
The thickness is preferably set in the range of 125 μm, and particularly preferably 25 to 100 μm.

The conductor circuit 3 (including the ground conductor circuit 31)
The metal material for forming is not particularly limited, and may be a conventionally known metal such as copper, aluminum, nickel, iron, gold, or a composite system of these metals. Among them, copper and aluminum are preferably used from the viewpoint of conductivity. Furthermore, the thickness of the conductor circuit 3 is 1 to 75.
The thickness is preferably set in the range of μm, particularly preferably 12 to 35 μm.

The metal material for forming the metal thin film layer 6 is not particularly limited, and copper, aluminum,
Examples include conventionally known metals such as nickel, iron and gold, or composites of these metals and metal oxides. Among them, copper and aluminum are preferably used from the viewpoint of conductivity. In addition, when it is necessary to check the internal conductor circuit 3, tin-doped indium oxide (ITO) is used.
Is preferably used. Furthermore, the thickness of the metal thin film layer 6 is preferably set within the range of 0.1 to 10 μm, and particularly preferably 0.5 to 3 μm.

The adhesive material for forming the adhesive layers 2 and 4 may be any material having high adhesiveness to the insulating films 1 and 7, the conductor circuit 3 and the metal thin film layer 6, For example, polyimide resin type, epoxy resin type,
Conventionally known adhesives containing a polyester resin type, an acrylic resin type, a fluororesin type or the like as a main component can be used. Similarly to the above, each of the adhesive layers 2 and 4 may be formed of the same adhesive or different adhesives. The thickness of the adhesive layer 2 is 5 to 5
The thickness is preferably set in the range of 0 μm, particularly preferably 10 to 30 μm. The thickness of the adhesive layer 4 is preferably set within the range of 5 to 100 μm, particularly preferably 15 to 50 μm.

As a conductive material for forming the conductive paste 5 for electrically connecting the metal thin film layer 6 and the ground conductor circuit 31, a polyimide resin type, an epoxy resin type, an acrylic resin type, a polyester resin type or the like is used. As a binder
It is preferable to use a material in which copper, silver, carbon, etc. are dispersed. In particular, from the viewpoint of conductivity and heat resistance, it is preferable to use an epoxy resin binder in which silver is dispersed.

The shield type flexible wiring board of the present invention is manufactured, for example, as follows. That is, first, an adhesive is applied to the surface of the first insulating film 1 to form the adhesive layer 2, and a metal layer is formed on the adhesive layer 2 using a metal material. Then, the metal layer is formed into a predetermined conductor circuit 3 (including the ground conductor circuit 31) by a conventionally known etching process, for example, an unnecessary part of the metal layer is etched using a cupric chloride or ferric chloride solution. Form. On the other hand, a metal thin film is formed on the surface of the second insulating film 7 using a conventionally known method, such as vacuum deposition, sputtering, and plating, and an unnecessary portion of the metal thin film (a peripheral edge of the metal thin film) is treated with hydrochloric acid solution or the like. The metal thin film layer 6 is formed by removing the metal thin film layer 6. Alternatively, after the unnecessary portion of the metal thin film is masked, the metal thin film layer 6 may be formed by using a conventionally known method such as vacuum deposition, sputtering, and plating.
Then, through holes are formed in the adhesive layer 4 formed into a sheet, and the conductive paste 5 is filled in the through holes by screen printing or the like. Then, the adhesive layer 4 filled with the conductive paste 5 is laminated on the conductor circuit 3 formed on the side of the first insulating film 1 side, and the conductor layer 3 is formed on the adhesive layer 4. The second insulating film 7 is laminated so that the circuit 3 and the metal thin film layer 6 face each other. Then, the ground conductor circuit 31 of the conductor circuit 3 and the metal thin film layer 6
Are electrically connected to each other, that is, they are connected to each other by the conductive paste 5, and are laminated by hot pressing or the like.

In addition to the method of electrically connecting the ground conductor circuit 31 and the metal thin film layer 6 by filling the conductive paste 5 in advance in the through holes of the adhesive layer 4 and adhering and laminating, The conductive paste 5 is applied to predetermined positions of the ground conductor circuit 31 or the metal thin film layer 6, and the adhesive layer 4 is applied at the time of stacking.
Alternatively, a method may be used in which the conductive paste 5 is filled in the through-holes, and as a result, the ground conductor circuit 31 and the metal thin film layer 6 are electrically connected. Further, the ground conductor circuit 31 and the metal thin film layer 6 may be electrically connected at a plurality of positions in the flexible wiring board, but a portion that does not require flexibility as a shield-type flexible wiring board (conductor circuit). Three
Among them, it is preferable to dispose it at the end portion).

Further, the conductor circuit 3 may be directly formed on the surface of the first insulating film 1 without vacuuming the adhesive layer 2 by vacuum deposition or plating.

FIG. 2 is a sectional view showing another embodiment of the shield type flexible wiring board of the present invention. That is, in this shield type flexible wiring board, the second metal thin film layer 8 is formed on a predetermined portion of one surface of the first insulating film 1 by a conventionally known method, such as vacuum deposition, sputtering, and plating. Next, a metal layer is formed via the adhesive layer 2, and the conductor circuit 3 is formed by, for example, processing the metal layer by a conventionally known etching method or the like.
A through hole is formed at a predetermined position in the adhesive layer 2, and a ground conductor circuit 31, which is an arbitrary circuit of the conductor circuit 3, and a second metal are formed in the through hole. A conductive paste 5 is filled to electrically connect to the thin film layer 8. The other parts of the configuration are similar to those of FIG. 1, and the same reference numerals are given to the same parts.

In the shield type flexible wiring board having the above structure, the second metal thin film layer 8 is formed on the surface of the first insulating film 1.
Is formed and is electrically connected to the ground conductor circuit 31, it is possible to reduce the downward electromagnetic field coupling between the conductor circuits 3 (shown by a broken line). As described above, the above-described structure further prevents the occurrence of crosstalk, and more effectively prevents the occurrence of malfunction of the electronic device.

Furthermore, the method of electrically connecting the two metal thin film layers 6 and 8 and the ground conductor circuit 31 is not limited to the filling of the conductive paste 5, but conventionally known through-hole plating or the like is used. It is also possible to use a method of electrically connecting the two. For example, the first with the conductor circuit 3 formed
Second insulating film 1 and second metal thin film layer 6 formed thereon
After the insulating film 7 is aligned with the adhesive layer 4 and laminated and adhered, through holes are formed in predetermined portions, and metal plating is applied to the through holes to form the metal thin film layers 6 and 8 and the ground conductor circuit. 31 can be electrically connected.

In the shielded flexible wiring board having the above-mentioned structure, the relation between the distance (A) between the conductor circuits 3 and the distance (B) between the conductor circuit 3 and both metal thin film layers 6 and 8 is A> It is preferable to set B. By setting in this way, the effect of preventing the occurrence of crosstalk is further improved. Further, in forming the plurality of conductor circuits 3, it is preferable that the conductor circuits 3 be formed so as to keep a distance of 30 μm to 2 mm from each other.

[0022]

As described above, in the shield type flexible wiring board of the present invention, a plurality of metal thin film layers provided on the second insulating film surface are provided on the first insulating film surface side. It is electrically connected to any circuit portion of the circuit portions. Therefore, the metal thin film layer and an arbitrary circuit portion have the same potential, electromagnetic field coupling between a plurality of circuits can be reduced, crosstalk can be prevented, and the characteristic impedance of the metal thin film layer and the adhesive layer are significantly different. Therefore, it is possible to prevent the emission of electromagnetic noise. In addition, since the crosstalk and the electromagnetic noise emission are prevented by electrically coupling the metal thin film layer and an arbitrary circuit portion, the flexibility, which is the greatest feature of the flexible wiring board, is not impaired. Furthermore, by positioning the end portion of the metal thin film layer so that it does not protrude from the end portion of the insulating film, the metal thin film layer is not exposed on the surface or the end face portion of the flexible wiring board, so that other Since the insulating property with respect to the electronic components and the like is maintained, it is possible to realize high frequency, high speed, digitalization, and downsizing of electronic devices. Further, by forming a second metal thin film layer on the surface of the first insulating film and electrically connecting the arbitrary circuit portion and the second metal thin film layer, further excellent prevention of crosstalk is prevented. And the prevention of electromagnetic noise emission is realized.

Next, specific examples will be described together with comparative examples.

[0024]

SPECIFIC EXAMPLE 1 A 15 μm thick adhesive layer made of an epoxy resin adhesive was formed on a 25 μm thick polyimide film surface, and a 18 μm thick copper foil was bonded and laminated on this adhesive layer. Then, the copper foil was etched at a width of 150 μm to a width of 3 by etching using a ferric chloride solution.
Four 00 μm conductor circuits are formed, and as shown in FIG.
A first polyimide film 1 in which four conductor circuits 3 were formed via an epoxy resin adhesive layer 2 was produced. Here, the two outer conductor circuits are used as the ground conductor circuit 31, and the two inner conductor circuits are used as the conductor circuit 3 through which a signal flows. on the other hand,
A metal thin film is formed on the surface of a polyimide film having a thickness of 25 μm by vacuum vapor deposition using aluminum so as to have a thickness of 1 μm, and the unnecessary portion of the metal thin film is removed with a hydrochloric acid solution. As shown in FIG. Second formed 6
The polyimide film 7 of was produced. Next, as shown in FIG. 5, the thickness of the epoxy resin adhesive is 20 μm.
A through hole 9 having a diameter of 200 μm was formed at a predetermined portion of the adhesive layer 4 and the conductive paste 5 containing silver powder and an epoxy resin adhesive as a main component was filled in the through hole 9 by screen printing. Then, the first polyimide film 1 on which the conductor circuit 3 is formed, the adhesive layer 4 in which the through holes 9 are filled with the conductive paste 5, and the second on which the metal thin film layer 6 is formed.
The polyimide film 7 of No. 1 was laminated and bonded so that the ground conductor circuit 31 and the metal thin film layer faced each other, and the shield type flexible wiring board shown in FIG. 1 was produced. The distance between the conductor circuit 3 and the metal thin film layer 6 is 15
was μm.

The crosstalk coefficient between the conductor circuits 3 which are the signal lines of the thus obtained shield-type flexible wiring board was measured using a pulse generator and a digital oscilloscope, and it was 0.006.

[0026]

Specific Example 2 A metal thin film layer was formed on a polyimide film surface having a thickness of 25 μm by a vacuum deposition method using aluminum so as to have a thickness of 1 μm by masking so that a metal thin film layer was not formed in an unnecessary portion. Then, an adhesive layer having a thickness of 15 μm and made of an epoxy resin adhesive in which one through hole having a diameter of 200 μm was formed in a predetermined portion was aligned and laminated on the metal thin film layer. Next, a conductive paste containing silver powder and an epoxy resin adhesive as a main component was filled in the through hole portion by screen printing. Then, a copper foil having a thickness of 18 μm is adhered and laminated on the adhesive layer, and four conductor circuits having a width of 300 μm are formed at intervals of 150 μm by an etching processing method using a ferric chloride solution. As shown in FIG. 6, the second metal thin film layer 8 is formed, and four conductor circuits 3 are formed on the second metal thin film layer 8 with the epoxy resin adhesive layer 2 interposed therebetween. The polyimide film 1 of No. 1 was produced. Here, the two outer conductor circuits are used as the ground conductor circuit 31, and the two inner conductor circuits are used as the conductor circuit 3 through which a signal flows. On the other hand, a metal thin film was formed on the surface of a polyimide film having a thickness of 25 μm using aluminum so as to have a thickness of 1 μm by a vacuum deposition method, and an unnecessary portion of the metal thin film was removed with a hydrochloric acid solution. A second polyimide film 7 having the thin film layer 6 formed was produced. Next, as shown in FIG. 5, one through-hole 9 having a diameter of 200 μm is formed at a predetermined portion of the adhesive layer 4 made of an epoxy resin adhesive and having a thickness of 20 μm, and silver powder is bonded to the epoxy resin adhesive by screen printing. The through hole 9 was filled with the conductive paste 5 containing the agent as a main component. Then, the first polyimide film 1 on which the conductor circuit 3 is formed, the adhesive layer 4 in which the through holes 9 are filled with the conductive paste 5, and the second polyimide film 7 on which the metal thin film layer 6 is formed, The ground type conductor circuit 31 and the metal thin film layer were overlapped with each other so as to face each other and bonded to each other to fabricate the shield type flexible wiring board shown in FIG. The distance between the conductor circuit 3 and the metal thin film layer 6 was 15 μm, and the distance between the conductor circuit 3 and the second metal thin film layer 8 was 15 μm.

The crosstalk coefficient between the conductor circuits 3 which are the signal lines of the thus obtained shield type flexible wiring board was measured using a pulse generator and a digital oscilloscope and was found to be 0.003.

[0028]

SPECIFIC EXAMPLE 3 A metal thin film layer was formed on a polyimide film surface having a thickness of 25 μm by a vacuum vapor deposition method using copper so as to have a thickness of 1 μm by masking so that a metal thin film layer was not generated in an unnecessary portion. Then, a copper foil having a thickness of 18 μm was bonded and laminated on the metal thin film layer via an adhesive layer having a thickness of 15 μm made of an epoxy resin adhesive. This copper foil is etched by a ferric chloride solution by an etching method to obtain 15
Four conductor circuits having a width of 300 μm were laminated at intervals of 0 μm.
Here, the two outer conductor circuits are used as ground conductor circuits, and the two inner conductor circuits are used as conductor circuits in which signals flow. On the other hand, a metal thin film is formed on the surface of a polyimide film having a thickness of 25 μm by a vacuum deposition method using copper so as to have a thickness of 1 μm, and an unnecessary portion of the metal thin film is removed with a ferric chloride solution to form a metal thin film layer. The second polyimide film thus prepared was produced. Next, a first polyimide film having a conductor circuit formed thereon, an adhesive layer having a thickness of 20 μm made of an epoxy resin adhesive, and a second polyimide film having a metal thin film layer formed on the ground conductor circuit and the metal. After overlaying and adhering the thin film layers so that they face each other, a plating resist is formed on both polyimide films 1 and 7, and one through hole 9a having a diameter of 300 μm is formed in a predetermined portion as shown in FIG. Then, a shield type flexible wiring board was produced by forming a copper foil 10 having a thickness of 5 μm on the inner peripheral wall surface of the through hole 9a by electroless plating. The distance between the conductor circuit 3 and the metal thin film layer 6 was 15 μm.

The crosstalk coefficient between the conductor circuits 3 which are the signal lines of the thus obtained shield type flexible wiring board was measured by using a pulse generator and a digital oscilloscope and was found to be 0.003.

[0030]

Comparative Example 1 The metal thin film layer 6 was not formed. Further, the through holes of the adhesive layer 4 were not formed and the conductive paste was not filled. A flexible wiring board was produced in the same manner as in Example 1 except for the above.

The crosstalk coefficient between the conductor circuits which are the signal lines of the thus obtained shield type flexible wiring board was measured by using a pulse generator and a digital oscilloscope, and it was 0.113.

[0032]

Comparative Example 2 A 15 μm-thick adhesive layer made of an epoxy resin adhesive was formed on a 25 μm-thick polyimide film surface, and a 18 μm-thick copper foil was adhered and laminated on this adhesive layer. Then, the copper foil was removed from the peripheral portion of the polyimide film by an etching method using a ferric chloride solution. Then, a 20 μm thick adhesive layer made of an epoxy resin adhesive is formed on the copper foil, and a 18 μm thick copper foil is bonded onto the adhesive layer.
Laminated. Then, this copper foil was etched at a width of 300 μm at 150 μm intervals by an etching method using a ferric chloride solution.
Four conductor circuits of m were formed. Here, the two outer conductor circuits are used as ground conductor circuits, and the two inner conductor circuits are used as conductor circuits in which signals flow. On the other hand, a copper foil having a thickness of 18 μm was formed on the surface of a polyimide film having a thickness of 25 μm by the same method as described above, and unnecessary portions of the copper foil were removed by an etching method. Next, a polyimide film on which a conductor circuit is formed, an adhesive layer having a thickness of 20 μm made of an epoxy resin adhesive, and a polyimide film on which a copper foil is formed,
After overlaying and adhering the ground conductor circuit and the copper foil so that they face each other, a plating resist is formed on the polyimide film surface, and one through hole with a diameter of 300 μm is drilled at a predetermined part and the thickness is obtained by electroless plating. A shield type flexible wiring board was produced by forming a copper foil of 5 μm on the inner wall surface of the through hole. The distance between the conductor circuit and the copper foil was 15 μm.

The crosstalk coefficient between the conductor circuits 3 which are the signal lines of the thus obtained shield type flexible wiring board was measured using a pulse generator and a digital oscilloscope, and it was 0.003.

In each of the shield-type flexible wiring boards obtained in this way, the concrete example 1, the concrete example 2, the concrete example 3 and the comparative example 1 showed similar flexibility, but the comparative example 2
Had significantly reduced flexibility. In addition, from the measurement results of the crosstalk coefficient, low values were obtained in Example 1, Example 2, Example 3 and Comparative Example 2. from these things,
It can be seen that the specific examples 1, the specific examples 2 and the specific examples 3 are excellent in the crosstalk preventing effect without impairing the flexibility.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a shield type flexible wiring board of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the shield type flexible wiring board of the present invention.

FIG. 3 is a cross-sectional view showing a first polyimide film on which a conductor circuit is formed via an adhesive layer.

FIG. 4 is a cross-sectional view showing a second polyimide film having a metal thin film layer formed thereon.

FIG. 5 is a cross-sectional view showing an adhesive layer in which a conductive paste is filled in the through holes.

FIG. 6 is a cross-sectional view showing a second metal thin film layer and a first polyimide film on which a conductor circuit is formed via an adhesive layer.

FIG. 7 is a sectional view showing still another example of the shield-type flexible wiring board of the present invention.

[Explanation of symbols]

 1 First Insulating Film 2,4 Adhesive Layer 3 Conductor Circuit 5 Conductive Paste 6 Metal Thin Film Layer 7 Second Insulating Film 31 Ground Conductor Circuit

Claims (4)

[Claims] 1. A first insulating film and a second insulating film are opposed to each other with an adhesive layer interposed therebetween, and a plurality of circuit portions are arranged at predetermined intervals on the surface of the first insulating film. While being kept, a metal thin film layer is formed on the second insulating film surface side facing the film surface of the first insulating film, and an arbitrary circuit portion of the plurality of circuit portions is formed. A shield type flexible wiring board, which is electrically connected to the metal thin film layer. 2. The shield type flexible wiring board according to claim 1, wherein the end portion of the metal thin film layer is positioned so as not to protrude from the end portion of the second insulating film. 3. A second metal thin film layer is formed on a surface of the first insulating film facing the second insulating film, and a plurality of second metal thin film layers are formed on the second metal thin film layer with an adhesive layer interposed therebetween. 3. The shielded flexible wiring board according to claim 1, wherein a circuit portion is formed, and any circuit portion of the plurality of circuit portions and the second metal thin film layer are electrically connected. 4. The shield type flexible wiring board according to claim 3, wherein the second metal thin film layer is positioned so as not to protrude from an end portion of the first insulating film.