JP2011146427A - Flexible printed wiring board, method of manufacturing flexible printed wiring board, and electronic equipment with flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible printed wiring board that can have necessary wiring circuits sufficiently structured on top and reverse surfaces of a substrate at a both-surface wiring portion, have electric connections sufficiently made between the wiring circuits formed on the top and reverse surfaces of the board, and can be improved more in bendability at a bent portion and also improved in durability against repetitive bending, and to provide a method of manufacturing the flexible printed wiring board, and electronic equipment with the flexible printed wiring board. <P>SOLUTION: The flexible printed wiring board 200 has: a region of the both-surface wiring portion 210 having the wiring circuits formed on the top and reverse surfaces of the substrate 20; and a region of the bent portion 220 which is repeatedly bent. Here, a land through hole 21 is formed in the both-surface wiring portion 210 to electrically connect the wiring circuits on the top and reverse surfaces of the substrate at the both-surface wiring portion 210, and the bent portion 220 has the wiring circuit formed only on one of the top and reverse surfaces of the substrate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a flexible printed wiring board, a method for manufacturing the flexible printed wiring board, and an electronic device including the flexible printed wiring board.

Flexible printed wiring boards used in electronic devices such as cellular phones are arranged in a narrowed space, so that improvement in wiring density, improvement in flexibility and flexibility, durability against repeated bending, etc. are required. .
Conventionally, as a flexible printed wiring board used for an electronic device such as a cellular phone, a flexible printed wiring having a through-hole plating in which a through hole is formed on a substrate and an electrolytic copper plating layer is formed on both surfaces of the substrate. There was a board.
In such a flexible printed wiring board subjected to through-hole plating, the copper foil that becomes a wiring circuit becomes thick, and thus durability against repeated bending is low.
In order to compensate for these disadvantages, flexible printed wiring boards with land through-holes that are masked or shielded so that the through-hole plating is not applied to the bent portions and plating is applied only to areas with through holes (so-called button plating). Are used in electronic devices such as mobile phones.
As such a thing, there exists the following patent document 1, for example.
In the following Patent Document 1, a conventional technique related to a flexible printed wiring board provided with land through holes is disclosed.

JP-A-11-195849

In recent years, the space allowed for a flexible printed wiring board has become narrower as electronic devices equipped with a flexible printed wiring board have become smaller and more multifunctional.
In particular, in a so-called slide type mobile phone, the gap between the upper housing and the lower housing is remarkably narrowed due to slimming of the mobile phone.
A flexible printed wiring board used for such a sliding mobile phone has a bent portion of the flexible printed wiring board arranged in a U-shape in a gap between the upper casing and the lower casing. Due to the narrowing of the gap with the lower housing, the radius of curvature at which the flexible printed wiring board is bent in a U-shape has become smaller, and the bending conditions have become more severe.
The flexible printed wiring board disclosed in Patent Document 1 has a configuration in which wiring circuits are formed on both sides of a substrate. When such a flexible printed wiring board is used in a slide-type mobile phone, there has been a problem that it does not satisfy the bending conditions in recent years, particularly the durability against repeated bending. Therefore, in the flexible printed wiring board, technical development relating to improvement of durability against repeated bending particularly in a bent portion has been an issue.

  Therefore, the present invention solves the above-described conventional problems, and in the double-sided wiring section, it is possible to sufficiently construct the wiring circuit necessary for the front and back of the board and to electrically connect the wiring circuits formed on the front and back of the board. A flexible printed wiring board which can be sufficiently performed and can further improve bendability at a bent portion, and can improve durability against repeated bending, a method for producing the flexible printed wiring board, and the flexible print An object is to provide an electronic device including a wiring board.

  The flexible printed wiring board of the present invention is a flexible printed wiring board having a double-sided wiring portion area in which wiring circuits are formed on the front and back sides of the substrate, and a bent portion area where bending is repeatedly performed. In the wiring portion, the entire surface of the inner hole of the through hole penetrating the substrate is plated, and a land through hole is formed by plating only the peripheral area of the front and back opening portions of the through hole as a land. The first feature is that the wiring circuits on the front and back sides of the wiring portion are electrically connected, and the wiring circuit is formed only on one surface of the front and back sides of the substrate in the bent portion.

According to the first aspect of the present invention, there is provided a flexible printed wiring board having a double-sided wiring portion area in which wiring circuits are formed on the front and back sides of the substrate, and a bent portion area where bending is repeatedly performed. The double-sided wiring portion is formed with land through holes formed by plating the entire surface of the inner hole of the through hole penetrating the substrate and plating only the peripheral area of the front and back opening portions of the through hole as lands. The wiring circuit on both sides of the double-sided wiring part is configured to be electrically connected, and the bent part has a wiring circuit formed only on one side of the board front and back. Wiring circuits required on the front and back sides of the substrate can be sufficiently constructed, and the wiring circuits formed on the front and back sides of the substrate can be sufficiently electrically connected.
In addition, by forming a wiring circuit only on one surface of the front and back of the substrate at the bent portion, the thickness of the bent portion can be reduced. Therefore, the flexibility of the bent portion can be further improved, and the durability against repeated bending can be improved.

  In addition to the first feature of the present invention, the flexible printed wiring board of the present invention has a second feature that the wiring circuit layer of the bent portion is covered with an electromagnetic wave shielding layer.

  According to the second feature of the present invention, in addition to the function and effect of the first feature of the present invention, the flexible printed wiring board has the wiring circuit layer of the bent portion covered with an electromagnetic wave shielding layer. Therefore, it is possible to prevent the wiring circuit formed in the bent portion from being adversely affected by error motion or the like due to electromagnetic wave noise.

  The method for producing a flexible printed wiring board according to the present invention also includes a flexible printed wiring comprising a double-sided wiring part region in which a wiring circuit is formed on the conductive layers on the front and back sides of the substrate, and a bent part region where bending is repeatedly performed. A through hole forming step for forming a through hole penetrating the substrate in the double-sided wiring portion, and a resist pattern forming for forming a resist pattern on both sides of the substrate leaving only a peripheral region of the opening of the through hole Forming a wiring circuit on the conductive layers on the front and back of the substrate in the step, a land through hole plating step of plating and covering the entire surface of the inner hole of the through hole and the peripheral area of the opening as a land, In the bent portion, the conductive layer on one side of the front and back sides of the substrate is removed and a wiring circuit is formed only on the remaining side. Further comprising a road-forming step is the third feature.

  According to the third aspect of the present invention, a flexible printed wiring board comprising a double-sided wiring part region in which wiring circuits are formed on the conductive layers on the front and back sides of the substrate, and a bent part region where bending is repeatedly performed. A through hole forming step of forming a through hole penetrating the substrate in the double-sided wiring portion, and a resist pattern forming step of forming a resist pattern on both sides of the substrate leaving only the peripheral region of the opening of the through hole. And a land through hole plating step of plating and covering the entire surface of the inner hole of the through hole and the peripheral area of the opening as a land, and forming a wiring circuit on the conductive layers on the front and back of the substrate in the double-sided wiring part, and The bent portion includes a wiring circuit forming step of removing a conductive layer on one surface of the substrate front and back and forming a wiring circuit only on the remaining surface. Since, by the through-hole forming step, it can be in the double-sided wiring portion, forming a through hole penetrating the substrate. Further, the resist pattern can be formed on both sides of the substrate, leaving only the peripheral region of the through hole opening by the resist pattern forming step. Further, the land through hole plating step can form a land through hole that covers and coats the entire surface of the inner hole of the through hole and the peripheral area of the opening as a land. In addition, the wiring circuit forming process allows the wiring circuit to be formed on the conductive layers on the front and back sides of the substrate in the double-sided wiring portion, while removing the conductive layer on one side of the front and back sides of the substrate and removing the conductive layer on the other side in the bent portion. Only a wiring circuit can be formed.

  According to a fourth aspect of the present invention, there is provided an electronic apparatus comprising the flexible printed wiring board according to the first or second aspect.

According to the fourth feature of the present invention, since the electronic device includes the flexible printed wiring board described in the first or second feature, the double-sided wiring portion has sufficient wiring circuits on both sides of the board. In addition to being able to construct, it is possible to sufficiently connect the wiring circuits formed on the front and back of the substrate, to further improve the bendability at the bent portion, and to withstand repeated bending. It can be set as an electronic device provided with the flexible printed wiring board which can be improved.
Moreover, it can be set as an electronic device provided with the flexible printed wiring board which can prevent that the wiring circuit formed in a bending part receives bad influences, such as an error motion, by electromagnetic noise.

  According to the flexible printed wiring board of the present invention, the method for manufacturing the flexible printed wiring board, and the electronic device provided with the flexible printed wiring board, it is possible to sufficiently construct the necessary wiring circuits on the front and back sides of the board in the double-sided wiring portion. At the same time, it is possible to sufficiently connect the wiring circuits formed on the front and back of the substrate, to further improve the flexibility at the bent portion, and to improve the durability against repeated bending. A flexible printed wiring board, a method for producing the flexible printed wiring board, and an electronic device including the flexible printed wiring board can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the mobile telephone which concerns on the 1st Embodiment of this invention, (a) is a whole perspective view, (b) is a right view which shows the principal part. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the flexible printed wiring board concerning the 1st Embodiment of this invention, (a) is a top view, (b) is sectional drawing of the principal part of the AA line direction in (a), (c) is It is an enlarged plan view of the principal part of the broken line part in (a). It is sectional drawing which shows the manufacturing method of the flexible printed wiring board which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the flexible printed wiring board which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the flexible printed wiring board which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the flexible printed wiring board which concerns on the 1st Embodiment of this invention. It is sectional drawing of the principal part which shows the flexible printed wiring board which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the principal part which shows the modification of the flexible printed wiring board which concerns on the 2nd Embodiment of this invention.

  With reference to the drawings, a flexible printed wiring board used in a so-called slide-type mobile phone will be described as an example of an electronic apparatus and a flexible printed wiring board according to the present invention to provide an understanding of the present invention. However, the following description does not limit the invention described in the claims of the present invention.

First, a first embodiment according to the present invention will be described with reference to FIGS.
As shown in FIG. 1, the mobile phone 1 is a so-called slide type mobile phone.
The cellular phone 1 is mainly composed of a housing 100 and a flexible printed wiring board 200.

The casing 100 forms a main body of the mobile phone 1 and is composed of a pair of casings including a first casing 110 and a second casing 120 as shown in FIG.
As shown in FIG. 1A, the first casing 110 includes a display unit 111 such as a liquid crystal screen, and the second casing 120 includes an operation unit 121 configured with operation buttons and the like.
The first housing 110 and the second housing 120 contain various components that are normally provided in a mobile phone, such as an LED (not shown).

As shown in FIG. 1B, the flexible printed wiring board 200 is a flexible printed wiring board that is interposed between a pair of housings and connects electrical circuits of both housings.
More specifically, the circuit board 112 provided in the first housing 110 as a pair of housings and the circuit board 122 provided in the second housing 120 are electrically connected. It is arranged between the first housing 110 and the second housing 120 in a bent state.
Although not shown in detail in FIG. 1B, the circuit board 112 and the connector part provided on the circuit board 122 are connected to the connector part provided on the flexible printed wiring board 200, so that the circuit board 112 is connected. And the circuit board 122 are electrically connected via the flexible printed wiring board 200.

  As shown in FIG. 2, the flexible printed wiring board 200 includes a double-sided wiring portion 210 region and a bent portion 220 region as regions.

The area of the double-sided wiring portion 210 is an area where the wiring circuit is formed on the front and back of the substrate in the flexible printed wiring board 200.
As shown in FIG. 2B, the double-sided wiring part 210 includes a substrate 20, a land through hole 21, and a cover lay 22.

The substrate 20 forms a circuit portion of the flexible printed wiring board 200, and is formed by laminating conductive layers 20b on both surfaces of an insulating layer 20a as shown in FIG.
The insulating layer 20a may be any material as long as it is normally used as an insulating layer constituting a substrate of a flexible printed wiring board, such as polyimide.
The conductive layer 20b may be any material as long as it is normally used as a conductive layer constituting a substrate of a flexible printed wiring board, such as a copper foil.

The land through hole 21 is obtained by subjecting the through hole 21 a to so-called button plating, and is for electrically connecting a wiring circuit formed on the conductive layer 20 b on the front and back of the substrate 20.
As shown in FIG. 2B, the land through hole 21 is plated on the entire surface of the through hole 21a penetrating the substrate 20 and the inner hole P of the through hole 21a, and the front and back openings of the through hole 21a. Only the peripheral region of the portion Q is plated as the land R. The portion formed by this plating is used as the conductor 21b.
Here, “land” refers to a portion of the land through hole 21 that protrudes in a button shape on the surface of the substrate 20.
In this way, the double-sided wiring unit 210 is configured such that the wiring circuits formed on the conductive layers 20b on the front and back sides of the substrate 20 are electrically connected by the land through holes 21, so that the double-sided wiring unit 210 has one surface. Thus, it is possible to sufficiently construct the necessary wiring circuit on the other surface electrically connected through the land through hole 21 while ensuring sufficient electrical connection with the circuit board 112 and the circuit board 122.

The cover lay 22 is for protecting the wiring circuit formed on the conductive layer 20b, and is composed of a cover lay film 22a and a cover lay adhesive 22b as shown in FIG. 2 (b). .
The coverlay film 22a may be any film as long as it is an insulating film such as polyimide.
Further, the coverlay adhesive 22b may be any one as long as it is normally used for bonding the coverlay film 22a to the substrate 20 such as a thermosetting resin.

  2C, the through hole 21a has a diameter S of about 0.1 mm, the land R has a diameter T of about 0.3 mm, and is formed in the land R portion of the wiring circuit formed in the conductive layer 20b. The diameter U of the substantially circular wiring circuit is preferably about 0.5 mm.

As shown in FIG. 1B, the bent portion 220 is formed in a space generated between a pair of casings 100 including a first casing 110 and a second casing 120 in the flexible printed wiring board 200. It is an area that is arranged in an exposed state and is repeatedly bent.
As shown in FIG. 2B, the bent portion 220 includes a substrate 20 and a cover lay 22.
Note that the substrate 20 and the cover lay 22 are the same as the substrate 20 and the cover lay 22 constituting the double-sided wiring section 210 described above, and therefore the same numbers are given and the following description is omitted.

Further, in the present embodiment, as shown in FIG. 2B, the bent portion 220 is configured such that a wiring circuit is formed only on the front side surface of the substrate 20 and the conductive layer 20b on the remaining back side surface is removed. .
With such a configuration, the wiring circuit for electrically connecting the circuit board 112 and the circuit board 122 can be concentrated only on the front side surface of the board 20, and the thickness of the bent portion 220 is reduced. be able to. Therefore, the bendability of the bent portion 220 can be further improved.
Therefore, it is possible to cope with a decrease in the radius of curvature of the bent portion by narrowing the gap between the upper housing and the lower housing in the slide-type mobile phone, and to improve the durability against repeated bending. 220.
In the present embodiment, the wiring circuit is formed only on the front side surface of the substrate 20 in the bent portion 220. However, the configuration is not necessarily limited to such a configuration, and the wiring circuit is formed only on the back side surface. It is good.

Next, with reference to FIGS. 3-6, the manufacturing method of the flexible printed wiring board 200 which concerns on the 1st Embodiment of this invention is demonstrated.
The flexible printed wiring board 200 according to the embodiment of the present invention includes a through-hole forming step 300, a resist pattern forming step 400, a land through-hole plating step 500, a wiring circuit forming step 600, and a coverlay lamination step 700. It is manufactured after.

First, the through hole forming step 300 is a step of forming a through hole in the substrate 20.
Specifically, as shown in the upper part of FIG. 3, through holes 21a are formed in the substrate 20 in which the conductive layers 20b are laminated on both surfaces of the insulating layer 20a by using drill holes or the like.
The diameter of the through hole 21a is preferably about 0.1 mm.

Next, the resist pattern forming step 400 is a step for coating the substrate 20 with a resist pattern so that the plating solution contacts only the portion where the land through hole 21 is to be formed.
Specifically, as shown in the middle of FIG. 3, a resist film 410 is laminated on both surfaces of the substrate 20 on which the through holes 21a are formed. Thereafter, as indicated by black arrows in the lower part of FIG. 3, the front side surface and the back side surface of the substrate 20 are exposed to ultraviolet rays through the pattern mask 420 and developed to remove unnecessary portions of the resist film 410. As a result, as shown in the uppermost part of FIG. 4, the front and back surfaces of the substrate 20 are covered with the resist pattern 430 while leaving only the portions where the land through holes 21 are to be formed.

Next, the land through hole plating step 500 is a step of plating and coating only the entire surface of the inner hole P of the through hole 21a and the peripheral region of the front and back opening Q as the land R.
Specifically, although not shown in detail in the middle of FIG. 4, electroless plating as the first plating process is performed using only the entire surface of the inner hole P of the through hole 21 a and the peripheral region of the front and back opening Q as the land R. Do. By this step, a conductive film (not shown) is formed only on the entire surface of the inner hole P of the through hole 21a and the peripheral area of the front and back opening Q.
Further, electrolytic copper plating as the second plating step is performed using only the entire surface of the inner hole P of the through hole 21a and the peripheral region of the front and back opening Q as the land R.

  In the present embodiment, the first plating step is configured to use electroless plating, but is not necessarily limited to such a configuration. For example, a configuration using carbon conductive treatment can be employed.

Thereafter, as shown in the middle of FIG. 4, the resist pattern 430 is peeled off. As a result, the entire surface of the inner hole P of the through hole 21a is plated, and the land through hole 21 configured to plate only the peripheral region of the front and back opening Q of the through hole 21a as the land R is formed. .
In the land R, the length V of the portion protruding from the surface of the substrate 20 is preferably 5 μm to 20 μm.

Next, in the wiring circuit forming step 600, the wiring circuit is formed on the conductive layer 20b on the front and back sides of the substrate in the double-sided wiring portion 210, and at the same time, the conductive layer 20b on the back side surface of the substrate 20 is removed at the bent portion 220. This is a step of forming a wiring circuit.
Specifically, as shown in the lowermost part of FIG. 4, a resist film 610 is laminated on both surfaces of the substrate 20 with the land through holes 21 formed.

Thereafter, as shown by the black arrows in the upper and middle stages of FIG. 5, the front and back sides of the substrate 20 are exposed to ultraviolet rays through the pattern mask 620 and developed, and as shown in the middle stage of FIG. Only the resist film 610 laminated on the back side surface at 220 is removed. Thereby, the front and back of the substrate 20 are covered with the resist pattern 630.
Thereafter, as shown in the lowermost part of FIG. 5, a wiring circuit is formed on the conductive layer 20 b on the front and back sides of the substrate in the double-sided wiring portion 210 by etching, and the conductive layer 20 b on the back side surface of the substrate 20 is removed at the bent portion 220. A wiring circuit is formed only on the remaining front side.
In the present embodiment, the wiring circuit is formed only on the front side surface of the substrate 20 in the bent portion 220. However, the configuration is not necessarily limited to such a configuration, and the wiring circuit is formed only on the back side surface. It is good.

  Thereafter, as shown in the upper part of FIG. 6, the resist pattern 630 is peeled off.

Next, the cover lay stacking process 700 is a process for covering the cover lay 22 on the front and back of the substrate 20 in order to insulate and protect the wiring circuit formed in the conductive layer 20b.
Specifically, as shown in the lower part of FIG. 6, the coverlay film 22a is bonded to the front and back of the substrate 20 via the coverlay adhesive 22b.
The flexible printed wiring board 200 is manufactured through the above steps.

Next, a flexible printed wiring board 200 according to a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment of the present invention, the wiring circuit layer of the bent portion 220 is covered with an electromagnetic wave shielding layer. Other configurations are the same as those of the first embodiment of the present invention described above. The same member and the same function are given the same number, and the following description is omitted.

  As shown in FIG. 7, the electromagnetic wave shielding layer 800 covers the layer in which the wiring circuit is formed in the bent portion 220, and includes an adhesive layer 810, a shielding layer 820, and an insulating layer 830.

The adhesive layer 810 is a layer for bonding the electromagnetic wave shielding layer 800 to the coverlay 22.
The adhesive layer 810 is formed of a conductive adhesive, and a part of the adhesive layer 810 is formed on the conductive layer 20b via a circuit connection hole 22c formed in the cover lay 22 as shown in FIG. Not connected to the ground circuit.
The thickness of the adhesive layer 810 is desirably about 5 μm to 25 μm.
As the conductive adhesive, any epoxy resin can be used as long as it is usually used as a conductive adhesive.

The shield layer 820 is a layer made of a conductive material.
In this embodiment, silver is used as the conductive material, and the shield layer 820 is formed by physical vapor deposition.
The thickness of the shield layer 820 is preferably about 0.1 μm.
The conductive material is not limited to silver, but may be configured to use other conductive metals such as gold, copper, aluminum, nickel, conductive particles, conductive fibers, conductive resins, It is desirable to use silver.
The conductive physical vapor deposition method may be any method as long as it is normally used as a physical vapor deposition method, such as sputtering or ion beam vapor deposition.

The insulating layer 830 is an insulating layer of the electromagnetic wave shielding layer 800 and is formed of an insulating film.
The insulating film may be any film as long as it is normally used as an insulating film, such as polyimide.
Note that the thickness of the insulating layer 830 is preferably about 3 μm to 10 μm.

The electromagnetic wave shielding layer 800 is formed by integrating the adhesive layer 810, the shielding layer 820, and the insulating layer 830 described above, and bonding them to the coverlay 22 on the front side surface where the wiring circuit is formed at the bent portion 220. .
Thus, by covering the wiring circuit layer of the bent portion 220 with the electromagnetic wave shielding layer 800, it is possible to prevent the wiring circuit formed in the bent portion 220 from being adversely affected by electromagnetic wave noise such as error motion.
Further, in the bent portion 220, a wiring circuit is formed only on the front side surface, and the thickness of the electromagnetic wave shielding layer 800 that covers the wiring circuit layer is set to about 8 μm to 35 μm, so that the thickness of the bent portion 220 is reduced. can do. Therefore, it is possible to cope with a decrease in the radius of curvature of the bent portion by narrowing the gap between the upper housing and the lower housing in the slide type mobile phone, and the bent portion can improve durability against repeated bending. 220.

Next, a modification of the flexible printed wiring board 200 according to the second embodiment of the present invention will be described with reference to FIG.
In this modification, the configuration of the electromagnetic wave shielding layer is changed. Other configurations are the same as those of the second embodiment of the present invention described above. The same member and the same function are given the same number, and the following description is omitted.

  As shown in FIG. 8, the electromagnetic wave shielding layer 800 covers the layer in which the wiring circuit is formed in the bent portion 220, and includes a shielding layer 820 and an insulating layer 830.

The shield layer 820 is a layer made of a conductive material.
In the present embodiment, a silver paste is used as the conductive material, and the shield layer 820 is formed on the cover lay 22 by screen printing.
Further, as shown in FIG. 8, a part thereof is connected to a ground circuit (not shown) formed in the conductive layer 20 b through a circuit connection hole 22 c formed in the cover lay 22.
The thickness of the shield layer 820 is preferably about 15 μm to 20 μm.

  Note that the conductive material is not limited to the silver paste, and other conductive metal pastes such as gold, copper, aluminum, and nickel may be used, but it is desirable to use the silver paste.

The insulating layer 830 becomes an insulating layer of the electromagnetic wave shielding layer 800, and is formed on the shielding layer 820 by screen printing using an insulating coating agent.
The insulating coating agent may be any material as long as it is usually used as an insulating coating agent, such as silicon-based or ceramic-based.
The thickness of the insulating layer 830 is preferably about 15 μm to 20 μm.

The electromagnetic wave shielding layer 800 is formed by forming the insulating layer 830 on the shield layer 820 after forming the shield layer 820 described above on the cover lay 22.
Thus, by covering the wiring circuit layer of the bent portion 220 with the electromagnetic wave shielding layer 800, it is possible to prevent the wiring circuit formed in the bent portion 220 from being adversely affected by electromagnetic wave noise such as error motion.
Furthermore, in the bent portion 220, a wiring circuit is formed only on the front side surface, and the thickness of the electromagnetic wave shielding layer 800 covering the wiring circuit layer is set to about 30 μm to 40 μm, so that the thickness of the bent portion 220 is reduced. can do. Therefore, it is possible to cope with a decrease in the radius of curvature of the bent portion by narrowing the gap between the upper housing and the lower housing in the slide type mobile phone, and the bent portion can improve durability against repeated bending. 220.

  INDUSTRIAL APPLICABILITY The present invention can be used as a flexible printed wiring board used for electronic devices such as a mobile phone and a hard disk device and a method for manufacturing the flexible printed wiring board.

DESCRIPTION OF SYMBOLS 1 Cellular phone 20 Board | substrate 20a Insulating layer 20b Conductive layer 21 Land through hole 21a Through hole 21b Conductor 22 Coverlay 22a Coverlay film 22b Coverlay adhesive 22c Circuit connection hole 100 Housing 110 First housing 111 Display section 112 Circuit board 120 Second housing 121 Operation part 122 Circuit board 200 Flexible printed wiring board 210 Double-sided wiring part 220 Bending part 300 Through hole forming process 400 Resist pattern forming process 410 Resist film 420 Pattern mask 430 Resist pattern 500 Land through hole plating process 600 Wiring circuit formation process 610 Resist film 620 Pattern mask 630 Resist pattern 700 Coverlay lamination process 800 Electromagnetic wave shielding layer 810 Adhesive Layer 820 Shield layer 830 Insulating layer P Inner hole Q Opening R Land S Diameter T Diameter U Diameter V Length

Claims (4)

  A flexible printed wiring board having a double-sided wiring part region in which wiring circuits are formed on the front and back sides of the substrate and a bending part region where bending is repeatedly performed, and the double-sided wiring part penetrates the substrate In addition to plating the entire surface of the inner hole of the through hole, land through holes are formed by plating only the peripheral areas of the front and back opening portions of the through hole as lands, thereby electrically connecting the front and back wiring circuits of the double-sided wiring portion. A flexible printed wiring board configured to be connected, wherein a wiring circuit is formed only on one side of the front and back of the substrate at the bent portion.   2. The flexible printed wiring board according to claim 1, wherein the wiring circuit layer of the bent portion is covered with an electromagnetic wave shielding layer.   A flexible printed wiring board having a double-sided wiring part region in which a wiring circuit is formed on a conductive layer on both sides of the substrate and a bending part region where bending is repeatedly performed, wherein the substrate is mounted on the double-sided wiring part. A through hole forming step for forming a through hole penetrating; a resist pattern forming step for forming a resist pattern on both surfaces of the substrate leaving only the peripheral region of the opening of the through hole; and the entire surface of the inner hole of the through hole; A land through-hole plating process in which the peripheral edge region of the opening is plated and covered, a wiring circuit is formed on the conductive layer on the front and back sides of the substrate in the double-sided wiring portion, and one surface of the front and back sides of the substrate is formed in the bent portion. A flexible printed wiring board having a wiring circuit forming step of removing a conductive layer and forming a wiring circuit only on the other surface remaining Method.   An electronic apparatus comprising the flexible printed wiring board according to claim 1.

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