TW202247714A - Flexible printed circuit board, manufacturing method therefor and electronic devices capable of transmitting both analog signals and digital signals - Google Patents

Abstract

The present invention provides a flexible printed circuit board capable of transmitting both analog signals and digital signals, and capable of being easily built into the case of electronic devices such as smart phones in a bent state, a manufacturing method therefor, and electronic devices. The flexible circuit board of the embodiment has a signal line area, a connector area, a bending area, one or more analog signal lines, one or more digital signal lines and ground layers. The one or more analog signal lines are arranged along the signal line area formed in such a way as to extend in the long side direction, which is to transmit analog signals. The one or more digital signal lines are formed in a manner to extend along the long side direction of the signal line area, which is to transmit digital signals. The ground layers are formed in such a way that the analog signal line is covered by an insulating layer. The bending area connects the signal line area and the connector area, and compared with the signal line area, at least either the number of wiring layers or the number of insulating layers is smaller than that in the signal line area.

Description

Flexible circuit board, manufacturing method thereof, and electronic device

The invention relates to a flexible circuit board, its manufacturing method and electronic equipment.

In recent years, due to the popularity of the fifth-generation mobile communication system (5G), the number of antenna connection cables in electronic devices such as smartphones has increased. In addition, the miniaturization of casings such as smartphones is also advancing. Therefore, a flexible circuit board in which antenna connection cables are further densely wired is required.

In the 5G system, the radio waves of the SUB6 frequency band and the millimeter wave band are used, and the radio waves of the current fourth-generation mobile communication system (4G) are also used. Therefore, in the 5G system, the number of antenna connection cables increases. Conventionally, a coaxial cable for transmitting an analog signal and a cable for transmitting a digital signal are built into the housing as separate cables. However, in the 5G system, as the number of antenna connection cables increases, it is required to combine these two types of cables into a multilayer flexible circuit board.

In addition, Japanese Patent Publication No. 5204871 and Japanese Patent Laid-Open Publication No. 2004-311927 describe general multilayer flexible circuit boards.

As mentioned above, with the popularization of 5G systems, the number of antennas in electronic devices such as smartphones has increased. In the 5G system, in addition to cables for transmitting analog signals such as wireless signals, cables for transmitting digital signals received by digital terminals such as USB, and cables for transmitting power for power supply are also required. These cables are arranged across the upper surface of the battery. On the other hand, coils for wireless power feeding and the like are also increasingly being arranged on the upper surface of batteries. Therefore, the cables arranged on the upper surface of the battery are required to save space. In addition, a method of arranging the cable other than the upper surface of the battery is also required, for example, arranging the cable on the side surface of a case of a smartphone or the like.

The present invention is based on the above-mentioned technical understanding. One of the objects of the present invention is to provide a device that can transmit both analog and digital signals and can be easily built into the case of an electronic device such as a smart phone in a bent state. A flexible circuit board, its manufacturing method, and electronic equipment incorporating the flexible circuit board.

The flexible circuit board of the first aspect of the present invention has a signal line area, a connector area, a bending area, one or more analog signal lines, one or more digital signal lines, and a ground layer, and the one or more analog signal lines The one or more digital signal lines are formed to extend along the long side direction of the signal line area and transmit digital signals , the ground layer is formed by covering the analog signal line with an insulating layer, the bending area connects the signal line area and the connector area, compared with the signal line area, the number of wiring layers and At least one of the number of insulating layers is smaller.

In addition, in the flexible printed circuit board, at least one of the number of wiring layers and the number of insulating layers in the connector region is smaller than that in the signal line region.

The flexible circuit board of the second aspect of the present invention has a signal line area, a connector area, a bending area, one or more analog signal lines, one or more digital signal lines, and a ground layer, and the one or more analog signal lines The one or more digital signal lines are formed to extend along the long side direction of the signal line area and transmit digital signals , the ground layer is formed by covering the analog signal line with an insulating layer, the bent area connects the signal line area and the connector area, and there is no wiring layer inside the bent area and insulation space.

In addition, in the flexible circuit board, there are cutouts on one or both sides of the space in the thickness direction of the flexible circuit board, and the direction of the cutout is the same as the length of the signal line region. The direction of the component of the width direction perpendicular to the side direction.

In addition, in the flexible printed circuit, when the flexible printed circuit is viewed from above, the space is formed in a meander shape (meander shape) or on both sides in the thickness direction of the flexible printed circuit. Crack shape.

In addition, in the flexible circuit board, an interlayer connection channel connected to the analog signal line or the digital signal line is provided in the connector area.

In addition, in the flexible circuit board, the interlayer connection channel has: a plated through hole, connected to the analog signal line or the digital signal line; and a filled via (filled via), through the conductive layer and the Plated through hole connections.

In addition, in the flexible circuit board, a connector component is installed in the connector area, and the connector component is electrically connected to the analog signal line and the digital signal line through the interlayer connection channel.

The electronic device of the present invention includes: a housing; the flexible circuit board configured in the housing; a first module configured in the housing; a second module configured in the housing; and a battery, It is disposed between the first module and the second module in the housing.

In addition, in the electronic device, the flexible printed circuit board is disposed so as to pass between the side surface of the case and the battery.

In addition, in the electronic device, the flexible circuit board is disposed so as to pass between the back or front of the case and the battery.

The method for manufacturing a flexible circuit board according to the first aspect of the present invention includes the step of: preparing a first single-sided metal foil-clad laminate, the first single-sided metal foil-clad laminate having: a first insulating base material having a second a main surface, and a second main surface on the opposite side to the first main surface; a first metal foil, disposed on the first main surface of the first insulating substrate; and a first protective film layer, through The first adhesive layer is disposed on the second main surface of the first insulating substrate; the first metal foil is patterned to form a first conductive pattern; a first bottomed hole is formed, and the first A bottomed hole passes through the first protective film layer, the first adhesive layer, and the first insulating substrate and reaches the first metal foil; filling the first bottomed hole with a first conductive paste ; Peel off the first protective film layer to obtain a first wiring substrate; prepare a first double-sided metal foil-clad laminate, the first double-sided metal foil laminate has: a second insulating substrate with a third a main surface, and a fourth main surface opposite to the third main surface; a second metal foil disposed on the third main surface of the second insulating substrate; and a third metal foil disposed on the the fourth main surface of the second insulating substrate; pattern the second metal foil to form a second conductive pattern; form a second bottomed hole, and the second bottomed hole passes through the second Insulating the base material and reaching the second metal foil; depositing the first metal plating layer on the side wall and the bottom surface of the second bottomed hole; patterning the third metal foil to form a third conductive pattern; A second adhesive layer is formed on the third metal foil by means of the third conductive pattern of the third metal foil and the first metal plating layer deposited on the second bottomed hole; forming a first covering material layer on the second adhesive layer; forming a third adhesive layer having a first opening on the first covering material layer; A second protective film layer is formed on the third adhesive layer by means of an opening; a third bottomed hole is formed, and the third bottomed hole passes through the second protective film layer and the third adhesive layer , the first covering material layer and the second adhesive layer and reaching the third metal foil; filling the third bottomed hole with a second conductive paste; peeling off the second protective film layer to obtain second wiring base material; preparing a second double-sided metal foil-clad laminate having: a third insulating base material having a fifth principal surface; The sixth main surface on the opposite side; the fourth metal foil is provided on the fifth main surface of the third insulating base material; and the fifth metal foil is provided on the sixth main surface of the third insulating base material. The main surface; patterning the fourth metal foil to form a fourth conductive pattern; patterning the fifth metal foil to form a fifth conductive pattern; forming a fourth bottomed hole, and the fourth bottomed hole The hole penetrates the third insulating substrate and reaches the fifth metal foil; the second metal plating layer is deposited on the side wall and the bottom surface of the fourth bottomed hole; The first through hole of the five metal foils is obtained to obtain the third wiring substrate; so that all The first wiring base material is laminated on the second wiring base material in such a manner that the first conductive paste is in contact with the second conductive pattern, so that the second conductive paste is in contact with the third conductive pattern. The third wiring base material is laminated on the second wiring base material in a pattern contact manner.

The method for manufacturing a flexible circuit board according to the second aspect of the present invention includes the step of: preparing a first single-sided metal foil-clad laminate, the first single-sided metal foil-clad laminate having: a first insulating base material having a first a main surface, and a second main surface on the opposite side to the first main surface; a first metal foil, disposed on the first main surface of the first insulating substrate; and a first protective film layer, through The first adhesive layer is disposed on the second main surface of the first insulating substrate; the first metal foil is patterned to form a first conductive pattern; a first bottomed hole is formed, and the first A bottomed hole passes through the first protective film layer, the first adhesive layer, and the first insulating substrate and reaches the first metal foil; filling the first bottomed hole with a first conductive paste ; Peel off the first protective film layer to obtain a first wiring substrate; prepare a first double-sided metal foil-clad laminate, the first double-sided metal foil laminate has: a second insulating substrate with a third a main surface, and a fourth main surface opposite to the third main surface; a second metal foil disposed on the third main surface of the second insulating substrate; and a third metal foil disposed on the the fourth main surface of the second insulating substrate; pattern the second metal foil to form a second conductive pattern; form a second bottomed hole, and the second bottomed hole passes through the second Insulating the base material and reaching the second metal foil; depositing the first metal plating layer on the side wall and the bottom surface of the second bottomed hole; patterning the third metal foil to form a third conductive pattern; A second adhesive layer is formed on the third metal foil by means of the third conductive pattern of the third metal foil and the first metal plating layer deposited on the second bottomed hole; forming a first covering material layer on the second adhesive layer; forming a third adhesive layer having a first opening on the first covering material layer; A second protective film layer is formed on the third adhesive layer by means of an opening; a third bottomed hole is formed, and the third bottomed hole passes through the second protective film layer and the third adhesive layer , the first covering material layer and the second adhesive layer and reaching the third metal foil; filling the third bottomed hole with a second conductive paste; peeling off the second protective film layer to obtain second wiring base material; preparing a second double-sided metal foil-clad laminate having: a third insulating base material having a fifth principal surface; The sixth main surface on the opposite side; the fourth metal foil is provided on the fifth main surface of the third insulating base material; and the fifth metal foil is provided on the sixth main surface of the third insulating base material. The main surface; patterning the fourth metal foil to form a fourth conductive pattern; patterning the fifth metal foil to form a fifth conductive pattern; forming a fourth bottomed hole, and the fourth bottomed hole The hole penetrates the third insulating base material and reaches the fifth metal foil; the second metal plating layer is deposited on the side wall and the bottom surface of the fourth bottomed hole; to bury the third part of the fourth metal foil conductive pattern and the second metal plating layer deposited on the fourth bottomed hole Forming a fourth adhesive layer on the fourth metal foil; forming a second covering material layer on the fourth adhesive layer; forming a third protective film layer on the second covering material layer; A fourth protective film layer is formed on the third protective film layer; a fifth bottomed hole is formed, and the fifth bottomed hole passes through the fourth protective film layer, the third protective film layer, and the first Two covering material layers and the third adhesive layer reach the fourth metal foil; fill the fifth bottomed hole with a third conductive paste; peel off the third protective film layer and the fourth protective film layer film layer to obtain a third wiring substrate; the first wiring substrate is laminated on the second wiring substrate in such a manner that the first conductive paste is in contact with the second conductive pattern, so that The third wiring base material is laminated on the second wiring base material in such a manner that the second conductive paste is in contact with the third conductive paste.

In addition, in the manufacturing method of the flexible circuit board, the second conductive pattern includes analog signal lines.

In addition, in the manufacturing method of the flexible circuit board, the fifth conductive pattern includes a digital signal line.

The flexible circuit board of the present invention can transmit both analog signals and digital signals at high speed and with low loss, and can be easily built into the case of electronic equipment in a bent state.

Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same reference numerals are assigned to components having equivalent functions. The drawings are schematic diagrams, and the relationship between the thickness and the planar size (aspect ratio), the ratio of the thickness of each layer, and the like do not necessarily match the actual ones.

<Overall structure of the flexible printed circuit 100>

First, an overall structure of a flexible printed circuit 100 according to the embodiment will be described with reference to FIG. 1 . FIG. 1 shows a top view of a flexible circuit board 100 . The flexible circuit board 100 is provided with a connector area 110 , a signal line area 120 and a bending area 130 . The flexible circuit board 100 is electrically connected to the first module 200 (refer to FIG. 13A ) and the second module 300 (refer to FIG. 13A ). The first module 200 has a wireless communication antenna for receiving analog signals and a digital terminal for receiving digital signals. , the second module 300 performs signal processing on the analog signal and the digital signal.

The connector area 110 is disposed at both ends of the signal line area 120 . One connector area 110 is connected to an antenna module for transmitting and receiving analog signals such as wireless signals, and the other connector area 110 is connected to a signal processing module equipped with a signal processing chip. The signal line area 120 is formed to extend along its long side, and includes analog signal lines and digital signal lines. The analog signal line transmits analog signals such as wireless signals, and the digital signal line transmits digital signals.

In addition, the antenna module can also have digital terminals for receiving digital signals. In the flexible circuit board 100 of the first embodiment, the first module 200 is an antenna module, and the second module 300 is a signal processing module. The flexible circuit board 100 is electrically connected to the first module 200 and the second module 300 . Specifically, one connector area 110 is electrically connected to the first module 200 , and the other connector area 110 is electrically connected to the second module 300 . Moreover, the analog signal lines and the digital signal lines included in the signal line area 120 are electrically connected to the connector area 110 on one side and the other side. In other words, the first module 200 and the second module 300 are electrically connected through the connector area 110 and the signal line area 120 of the flexible circuit board 100 .

Next, the bending region 130 will be described with reference to FIG. 2 . FIG. 2 is an enlarged plan view of area A in FIG. 1 , showing an enlarged view of one end of the flexible circuit board 100 . The bending area 130 connects the connector area 110 and the signal line area 120 . Even in the bending area 130, analog signal lines and digital signal lines are included. Details will be described later, but the bending region 130 has a reduced-layer structure in which the number of wiring layers and/or the number of insulating layers is smaller than that of the signal line region 120 . Alternatively, the bent region 130 has a hollow structure in which neither a wiring layer nor an insulating layer is provided inside the bent region 130 .

(first embodiment)

<Structure of flexible wiring board 100>

Next, the cross-sectional structure of the flexible printed circuit 100 according to the first embodiment will be described with reference to FIG. 3 . Fig. 3 is a schematic sectional view taken along line B-B of Fig. 2 . In FIG. 3 , the left side of the figure shows an area corresponding to the connector area 110 , and the right side of the figure shows an area corresponding to the signal line area 120 . Moreover, the bending area 130 is located between the connector area 110 and the signal line area 120 . The curved region 130 has a layer-reduced structure. That is, the bending region 130 of the flexible printed circuit 100 of the first embodiment has a reduced-layer structure in which the number of wiring layers and/or the number of insulating layers is smaller than that of the connector region 110 and the signal line region 120 .

In more detail, the bending area 130 has three wiring layers, and the signal line area 120 has five wiring layers. Specifically, the bending area 130 has conductive patterns (wirings 12b, 22i, and 23b) as wiring layers, and the signal line area 120 has conductive patterns (wirings 12b, 22i, 23b, 32b, and 33i) as wiring layers. Therefore, the bending region 130 has a reduced-layer structure in which the number of wiring layers is two less than that of the signal line region 120 . Likewise, the bending area 130 has two insulating layers, and the signal line area 120 has three insulating layers. Specifically, the bending region 130 has a first insulating layer (insulating substrate 11 and adhesive layer 13), a second insulating layer (insulating substrate 21) and a third insulating layer (adhesive layer 24 and covering material layer 71). . On the other hand, the signal line region 120 has a first insulating layer (insulating substrate 11 and adhesive layer 13), a second insulating layer (insulating substrate 21), a third insulating layer (adhesive layer 24 and covering material layer 71). ) and the fourth insulating layer (insulating substrate 31 ). Therefore, the bending region 130 has a reduced-layer structure with one less insulating layer than the signal line region 120 .

As described above, the bending region 130 has a reduced-layer structure with fewer wiring layers and insulating layers than the signal line region 120 . Therefore, compared with the signal line region 120, the bending region 130 can relax stress during bending. Therefore, when the flexible wiring board 100 is built into the case of an electronic device such as a smartphone, it becomes easy to build the flexible wiring board 100 in a bent state (hereinafter sometimes referred to as bent built-in). Specifically, when the flexible printed circuit 100 is built into the case in a bent state, the flexible printed circuit 100 is bent at the bending region 130 and built into the case. At this time, the bending region 130 relatively relaxes the stress, so it can be bent relatively easily. Accordingly, it is possible to easily perform bending and fitting of the flexible wiring board 100 into the case.

In addition, in the flexible printed circuit 100, the analog signal line is arranged on the wiring 22i, and the digital signal line is arranged on the wiring 33i. In this way, both the analog signal line and the digital signal line are built in the flexible printed circuit 100 . Thus, by using the flexible printed circuit 100 , both the analog signal line and the digital signal line can be arranged, thereby achieving space saving in the casing of the electronic device.

In addition, the flexible printed circuit 100 has a ground layer formed so as to cover the analog signal lines through an insulating layer. Specifically, the ground layers 12 b and 23 b (the wirings 12 b and 23 b ) cover the wiring 22 i of the analog signal line through an insulating layer. As shown in FIG. 3 , the first insulating layer (adhesive layer 13 and insulating base material 11 ) is laminated on the wiring 22 i , and the ground layer 12 b (wiring 12 b ) is formed on the first insulating layer. Similarly, the second insulating layer (insulating base material 21 ) is stacked under the wiring 22 i , and the ground layer 23 b (wiring 23 b ) is stacked under the second insulating layer. In this way, the flexible wiring board 100 has the ground layers 12 b and 23 b formed so as to cover the analog signal lines (wiring 22 i ) through the first insulating layer and the second insulating layer, respectively. That is, the flexible circuit board 100 has a three-layer stripline structure.

In the connector region 110 of the flexible circuit board 100 , an interlayer connection channel electrically connected to an analog signal line or a digital signal line is provided. The interlayer connection channels are disposed in the holes H1 - H4 of the connector area 110 shown in FIG. 3 , and are electrically connected to the analog signal lines or the digital signal lines. For example, the interlayer connection channel provided in the hole H2 is electrically connected to the analog signal line (wiring 22i). In addition, the interlayer connection path provided in the hole H4 is electrically connected to the digital signal line (wiring 33i).

In addition, the interlayer connection channels of the connector region 110 may be formed of plated through holes. In detail, the first metal plating layer 61 is deposited on the hole H2, and the second metal plating layer 62 is deposited on the hole H4, respectively forming plated through holes. In this way, the interlayer connection channel of the connector region 110 has a plated through hole (hole H2 or hole H4 ) connected to an analog signal line (wiring 22 i ) or a digital signal line (wiring 33 i ).

In addition, the interlayer connection channels in the connector region 110 may also be formed by filled vias. More specifically, the conductive paste is filled into the hole H1 to form a filled via hole. Also, the filled via formed in the hole H1 is connected to the wiring 22i. Similarly, the conductive paste is also filled into the hole H3 to form a filled via hole. Also, a filled via formed in the hole H3 is connected to the land 32a. Landing 32a is connected to the plated-through hole of hole H4. The interlayer connection channel of the connector area 110 has a plated through hole and a filled via connected to the plated through hole through the conductive layer (landing 22 a or 32 a ). In addition, a connector component (not shown) electrically connected to the analog signal line and the digital signal line through the above-mentioned interlayer connection channel may also be installed in the connector region 110 .

The schematic configuration of the flexible wiring board 100 according to the first embodiment has been described above. According to the first embodiment, the bending region 130 of the flexible circuit board 100 has a reduced-layer structure in which the number of wiring layers and the number of insulating substrates are smaller than those of the signal line region 120 . Therefore, the stress when bending the bending region 130 can be relaxed. Therefore, flexible wiring board 100 can be easily bent and built into the casing of an electronic device such as a smartphone.

In addition, both analog signal lines and digital signal lines are accommodated in the flexible printed circuit 100 . This eliminates the need to separately arrange cables for analog signal lines and cables for digital signal lines in the casing of the electronic device. Therefore, space saving in housings of electronic devices such as smartphones can be realized.

In addition, compared with the signal line region 120 , the bending region 130 can reduce the number of wiring layers and the number of insulating layers, so it can reduce the materials of the wiring layer and the insulating substrate required for manufacturing the flexible circuit board 100 , thereby reducing the manufacturing cost.

<Manufacturing method of flexible wiring board 100>

Next, a method of manufacturing the flexible wiring board 100 according to the first embodiment will be described with reference to the process sectional views of FIGS. 4 to 6 .

As shown in (1) of FIG. 4 , first, a single-sided metal foil-clad laminate 10 is prepared. The single-sided metal foil-clad laminate 10 has an insulating substrate 11, a metal foil 12 disposed on the upper surface of the insulating substrate 11, and a metal foil disposed on the lower surface of the insulating substrate 11 through an adhesive layer (micro-adhesive layer) 13. Protective film layer 14. The metal foil 12 is formed on the insulating base material 11 through a seed layer (not shown) formed on the main surface of the insulating base material 11 . In addition to liquid crystal polymer (LCP), the insulating substrate 11 may also be, for example, polyimide (PI), modified polyimide (MPI), polyethylene naphthalate (PEN), polyethylene Ether ether ketone (PEEK), fluororesin (PFA, PTEE, etc.) and the like are not particularly limited.

The thickness of the insulating base material 11 is, for example, 100 μm. Metal foil 12 is, for example, silver or aluminum other than copper. The thickness of the metal foil 12 is, for example, 12 μm. The protective film layer 14 is disposed on the lower surface of the insulating substrate 11 through the adhesive layer 13 . The protective film layer 14 is, for example, an insulating film such as PET (polyethylene terephthalate). The thickness of the protective film layer 14 is, for example, 10 μm. The adhesive layer 13 has a thickness of, for example, 10 μm.

Next, as shown in (2) of FIG. 4 , the metal foil 12 of the single-sided metal foil-clad laminate 10 is patterned by a known lithography method to form a first conductive pattern. The first conductive pattern includes a land 12a and a wiring 12b. The diameter of the land 12a is, for example, φ350 μm. Wiring 12 b functions as a ground layer in flexible wiring board 100 .

Next, as shown in (2) of FIG. 4 , the protective film layer 14 , the adhesive layer 13 and the insulating base material 11 are removed by irradiating laser light to the protective film layer 14 to form a bottomed substrate with the landing portion 12 a exposed on the bottom surface. Hole H1. The diameter of the hole H1 is, for example, φ150 to 200 μm. More specifically, an infrared laser that is a carbon dioxide laser is used to irradiate a predetermined position of the protective film layer 14 with laser pulses to perforate. The beam diameter of the infrared laser was set to 150 μm, which is the same as the diameter of the hole H1. In addition, the pulse width of the infrared laser was set to 10 microseconds, and the energy per pulse of the infrared laser was set to 5 mJ.

The protective film layer 14 is irradiated with the infrared laser set as described above, for example, five times to obtain the hole H1. In addition, as described above, the beam diameter of the infrared laser is substantially the same as the diameter of the hole H1. In other words, it is only necessary to adjust the beam diameter of the infrared laser so as to match the diameter of the hole H1. Therefore, it is suitable that the beam diameter of the infrared laser can be easily adjusted in the formation of the hole H1. In addition, in forming the hole H1, a UV-YAG laser or the like may be used, and it is not limited to an infrared laser.

After the hole H1 is pierced by an infrared laser, desmearing treatment is performed. In the desmear process, the resin residue (residual film) at the boundary between the insulating base material 11 and the land 12 a and the backside treatment film (Ni or Cr, etc.) of the land 12 a are removed.

Next, as shown in (3) of FIG. 4 , the inside of the hole H1 is filled with the conductive paste 51 by a printing method such as screen printing. The conductive paste 51 is obtained by dispersing metal particles in a resin binder which is a paste-like thermosetting resin.

Next, as shown in (4) of FIG. 4 , the protective film layer 14 is peeled off from the adhesive layer 13 . Thereby, a part of the conductive paste 51 filled in the hole H1 protrudes, and the protrusion part 51a is formed. In addition, the height of the protruding portion 51 a is about the same as the thickness of the protective film layer 14 .

Through the above steps, the wiring base material 101 (first wiring base material) is obtained.

Next, as shown in (1) of FIG. 5A , a double-sided metal foil-clad laminate 20 is prepared. This double-sided metal foil-clad laminate 20 has an insulating base material 21 , a metal foil 22 provided on the upper surface of the insulating base material 21 , and a metal foil 23 provided on the lower surface of the insulating base material 21 . In addition to liquid crystal polymer (LCP), the insulating substrate 21 may also be, for example, polyimide (PI), modified polyimide (MPI), polyethylene naphthalate (PEN), polyethylene Ether ether ketone (PEEK), fluororesin (PFA, PTEE, etc.) and the like are not particularly limited.

The thickness of the insulating base material 21 is, for example, 100 μm. Metal foil 22 and metal foil 23 are, for example, silver or aluminum other than copper. The thicknesses of the metal foil 22 and the metal foil 23 are each 12 μm, for example. The metal foil 22 is formed on the insulating base material 21 through a seed layer (not shown) formed on the upper surface of the insulating base material 21 . Likewise, the metal foil 23 is formed under the insulating base material 21 through a seed layer (not shown) formed on the lower surface of the insulating base material 21 .

Next, as shown in (2) of FIG. 5A , the metal foil 22 of the double-sided metal foil-clad laminate 20 is patterned by a known lithography method to form a second conductive pattern. The second conductive pattern includes a land 22a and a wire 22i. The diameter of the land 22a is, for example, φ350 μm. Wiring 22 i functions as an analog signal line in flexible printed circuit 100 . That is, the second conductive pattern includes analog signal lines.

Next, as shown in (3) of FIG. 5A , the metal foil 23 of the double-sided metal foil-clad laminate 20 is patterned by a known lithography method to form a third conductive pattern. The third conductive pattern includes a land 23a and a wire 23b. The diameter of the land 23 a is, for example, φ350 μm. Wiring 23 b functions as a ground layer in flexible wiring board 100 .

Next, as shown in (4) of FIG. 5A , the insulating base material 21 is removed by irradiating the landing portion 23 a with a laser as a conformal mask, and a bottomed hole exposing the landing portion 22 a is formed on the bottom surface. H2. The diameter of the hole H2 is, for example, φ150 to 200 μm. Hereinafter, the formation of the hole H2 is the same as the formation of the hole H1. That is, using an infrared laser that is a carbon dioxide laser, a laser pulse is irradiated to a predetermined position of the landing portion 23a to pass through the hole H2. The beam diameter of the infrared laser was set to 150 μm, which is the same as the diameter of the hole H2. In addition, the pulse width of the infrared laser was set to 10 microseconds, and the energy per pulse of the infrared laser was set to 5 mJ.

For example, the infrared laser set as described above is irradiated five times to obtain the hole H2. In addition, in forming the hole H2, a UV-YAG laser or the like may be used, and it is not limited to an infrared laser.

After the hole H2 is pierced by an infrared laser, desmearing treatment is performed. In the desmear process, resin residue (residual film) at the boundary between the insulating base material 21 and the land 23 a is removed. In addition, in the desmear process, the back surface treatment film (Ni or Cr, etc.) of the land 23 a and the land 22 a is removed.

Next, as shown in ( 5 ) of FIG. 5A , the first metal plating layer 61 is deposited on the sidewall and bottom surface of the hole H2 . The first metal plating layer 61 is, for example, a copper plating layer. In addition, the first metal plating layer 61 may be deposited by partial plating or full plate plating. The plating thickness of the first metal plating layer 61 is, for example, 16 μm.

Next, as shown in (1) of FIG. 5B , the adhesive layer 24 is formed to bury the third conductive pattern (landing 23 a and wiring 23 b ) and the first metal plating layer 61 deposited in the hole H2 . The adhesive layer 24 is, for example, a micro-adhesive layer with a thickness of 10 μm. Next, as shown in ( 2 ) of FIG. 5B , the covering material layer 71 is formed on the adhesive layer 24 . The cover material layer 71 is, for example, an insulating resin film. As the insulating resin film, for example, liquid crystal polymer (LCP) or polyimide is used. The thickness of the covering material layer 71 is, for example, 12 μm.

Next, as shown in (3) of FIG. 5B , the adhesive layer 25 having the opening A1 is formed on the cover material layer 71 . The adhesive layer 25 is, for example, a micro-adhesive layer with a thickness of 10 μm. Next, as shown in (4) of FIG. 5B , the protective film layer 26 is formed on the adhesive layer 25 so as to fill the opening A1 of the adhesive layer 25 . The protective film layer 26 is, for example, a PET film with a thickness of 20 μm and microadhesive. The dimensions of the opening A1 are, for example, 30 mm in the longitudinal direction and 2 mm in the lateral direction.

Next, as shown in (1) of FIG. 5C , the protective film layer 26 , the adhesive layer 25 , the covering material layer 71 and the adhesive layer 24 are removed by irradiating laser light on the protective film layer 26 , and the landing is exposed on the bottom surface. Bottomed hole H3 at 23a. The diameter of the hole H3 is, for example, φ150 to 200 μm. Hereinafter, the formation of the hole H3 is the same as the formation of the hole H1. That is, a predetermined position of the protective film layer 26 is irradiated with a laser pulse using an infrared laser that is a carbon dioxide laser to perforate. The beam diameter of the infrared laser was set to 150 μm which is the same as the diameter of the hole H3. In addition, the pulse width of the infrared laser was set to 10 microseconds, and the energy per pulse of the infrared laser was set to 5 mJ.

Next, as shown in (2) of FIG. 5C , the inside of the hole H3 is filled with the conductive paste 52 by a printing method such as screen printing. The conductive paste 52 is obtained by dispersing metal particles in a resin binder which is a paste-like thermosetting resin.

Next, as shown in (3) of FIG. 5C , the protective film layer 26 is peeled off from the adhesive layer 25 and the cover material layer 71 . Thereby, a part of the conductive paste 52 filled in the hole H3 protrudes, and the protrusion part 52a is formed. In addition, the height of the protruding portion 52 a is about the same as the thickness of the protective film layer 26 formed on the adhesive layer 25 .

Through the above steps, the wiring base material 102 (second wiring base material) is obtained.

Next, as shown in (1) of FIG. 6 , a double-sided metal foil-clad laminate 30 is prepared. This double-sided metal foil-clad laminate 30 has an insulating base material 31 , a metal foil 32 provided on the upper surface of the insulating base material 31 , and a metal foil 33 provided on the lower surface of the insulating base material 31 . In addition to liquid crystal polymer (LCP), the insulating substrate 31 may also be, for example, polyimide (PI), modified polyimide (MPI), polyethylene naphthalate (PEN), polyethylene Ether ether ketone (PEEK), fluororesin (PFA, PTEE, etc.) and the like are not particularly limited.

The thickness of the insulating base material 31 is, for example, 50 μm. Metal foil 32 and metal foil 33 are, for example, silver or aluminum other than copper. The thicknesses of the metal foil 32 and the metal foil 33 are, for example, 12 μm, respectively. The metal foil 32 is formed on the insulating base material 31 through a seed layer (not shown) formed on the upper surface of the insulating base material 31 . Likewise, the metal foil 33 is formed under the insulating base material 31 through a seed layer (not shown) formed on the lower surface of the insulating base material 31 .

By making the thickness of the insulating base material 31 as thin as 50 μm, the line width of the signal line can be reduced. More specifically, the line width of the signal line (wiring 33 i ) matching the characteristic impedance represented by Z0=√(L/C) can be reduced. where L is the inductance per unit length and C is the capacitance between lines. In this way, by making the thickness of the insulating base material 31 thinner, the line width of the signal line can be reduced, so the width of the flexible circuit board 100 can be reduced. Therefore, when the flexible printed circuit 100 is built into the case of electronic equipment such as a smartphone, space can be saved.

Next, as shown in (2) of FIG. 6 , the metal foil 32 is patterned to form a fourth conductive pattern including a land 32 a as a conformal mask. Thereafter, as shown in (3) of FIG. 6 , the insulating base material 31 is removed by irradiating the land 32 a as a conformal mask with laser to form a bottomed hole H4 exposing the land 33 a on the bottom surface. The diameter of the hole H4 is, for example, φ150 to 200 μm. The hole H4 is formed similarly to the hole H1. That is, using an infrared laser that is a carbon dioxide laser, laser pulses are irradiated to the openings of the conformal mask to penetrate the holes H4. The beam diameter of the infrared laser was set to 150 μm which is the same as the diameter of the hole H4. In addition, as shown in (2) of FIG. 6 , the metal foil 33 is patterned to form a fifth conductive pattern (landing 33 a and wiring 33 i ). The diameter of the land 33a is, for example, φ350 μm. In addition, wiring 33 i functions as a digital signal line in flexible wiring board 100 . That is, the fifth conductive pattern includes digital signal lines.

After the hole H4 is pierced by an infrared laser, desmearing treatment is performed. In the desmearing process, resin residue (residual film) at the boundary between the land 33 a and the insulating base material 31 is removed. In addition, in the desmear process, the back surface treatment film (Ni or Cr, etc.) of the land 33 a is removed.

Next, as shown in ( 4 ) of FIG. 6 , the second metal plating layer 62 is deposited on the sidewall and bottom surface of the hole H4 . The second metal plating layer 62 is, for example, a copper plating layer. In addition, the second metal plating layer 62 is deposited by partial plating or full plate plating. The plating thickness of the second metal plating layer 62 is, for example, 16 μm.

Next, as shown in (5) of FIG. 6 , the metal foil 32 , the insulating base material 31 , and a part of the land 33 a are removed by a die cutter or the like to form the window W. The size of the window W is, for example, about the same as the size of the opening A1 of the adhesive layer 25 shown in (3) of FIG. 5B , for example, 30 mm in the long direction and 2 mm in the short direction.

Through the above steps, the wiring base material 103 (third wiring base material) is obtained.

In addition, in the above-mentioned steps, the metal foils of the respective wiring base materials 101 , 102 , and 103 may be roughened. Through the roughening treatment, the bonding strength between the metal foil and the insulating substrate can be improved.

Hereinafter, the process of laminating the wiring base material 101 , the wiring base material 102 , and the wiring base material 103 obtained in the above steps will be described with reference to FIG. 7 .

First, the wiring base material 101 is laminated on the wiring base material 102 . Specifically, the stacking is performed so that the protrusions 51 a of the conductive paste 51 of the wiring base 101 come into contact with the lands 22 a of the wiring base 102 .

Next, the laminate composed of wiring base material 101 and wiring base material 102 obtained in the above steps is laminated on wiring base material 103 . Specifically, the stacking is performed so that the protrusions 52 a of the conductive paste 52 of the wiring base 102 come into contact with the lands 32 a of the wiring base 103 . By doing so, the wiring base material 101, the wiring base material 102, and the wiring base material 103 are electrically connected between layers. In addition, the order of laminating wiring base materials 101 , 102 , and 103 is not limited to the order described above.

In the above lamination step of forming the laminated body composed of the wiring base material 101, the wiring base material 102, and the wiring base material 103, a vacuum pressing device or a vacuum laminator is used. The laminated body is heated and pressurized by the vacuum pressing device or the vacuum lamination device. For example, the laminate is heated at about 200° C., and the laminate is pressurized with a pressure of several MPa (for example, 2.0 MPa). The temperature at which the flexible wiring board 100 is heated is, for example, about 50° C. or more lower than the temperature at which the liquid crystal polymer (LCP) constituting the insulating base materials 11 , 21 , and 31 softens.

In the case of using a vacuum pressing device in the lamination step, the laminate is heated and pressurized under the above-mentioned conditions for about 30 to 60 minutes. Thermal curing of the adhesive layers 13 , 24 , and 25 and thermal curing of the conductive pastes 51 and 52 are also completed by heating and pressurizing the laminate with the vacuum pressurization device.

On the other hand, when a vacuum laminator is used in the lamination process, the laminate is heated and pressurized for about several minutes under the above-mentioned conditions. Therefore, after the laminated body is heated and pressurized by a vacuum laminator, the laminated body is moved to an oven apparatus to perform post-curing treatment. In the post-curing treatment, for example, the laminate is heated at about 200° C. for about 60 minutes. Through the post-curing treatment, the thermal curing of the adhesive layers 13 , 24 and 25 and the thermal curing of the conductive pastes 51 and 52 are also completed.

Next, if necessary, surface treatment, solder resist, and contour processing of the first conductive pattern and the fifth conductive pattern exposed to the outside may be performed.

Through the above steps, the flexible circuit board 100 having the cross-sectional structure shown in FIG. 3 is obtained.

As described above, according to the method for manufacturing a flexible printed circuit according to the first embodiment, it is possible to obtain a flexible circuit having a reduced-layer structure in which the number of wiring layers and/or the number of insulating layers in the bending region 130 is smaller than that of the signal line region 120 Plate 100. Therefore, compared with the signal line region 120 , the bending region 130 can relax the stress during bending, so that the flexible circuit board 100 can be easily built into the case of an electronic device such as a smartphone by bending.

In addition, in the flexible printed circuit 100, the analog signal line is formed as the wiring 22i, and the digital signal line is formed as the wiring 33i. As shown in FIG. 3 , analog signal lines and digital signal lines are embedded in the flexible circuit board 100 . Therefore, by embedding the flexible circuit board 100 in the case of electronic devices such as smartphones, it is possible to centrally configure the analog signal line for transmitting the analog signal received by the wireless communication antenna and the line for transmitting the digital signal received by the digital terminal such as USB. Digital signal line. As a result, space saving in housings of electronic devices such as smartphones can be achieved.

In addition, the bending region 130 of the flexible circuit board 100 reduces the number of wiring layers and the number of insulating layers compared with the signal line region 120, so it is possible to reduce the wiring layer and insulating substrate materials required by the flexible circuit board 100, thereby enabling Reduce manufacturing costs.

In addition, the flexible circuit board 100 is manufactured by laminating the wiring base material 101 , the wiring base material 102 , and the wiring base material 103 . That is, since the flexible printed circuit 100 is manufactured by laminating three wiring base materials, positional displacement between the wiring base materials can be relatively suppressed. Therefore, the yield of the manufacturing process of the flexible wiring board 100 can be improved. Furthermore, the above-mentioned margin of positional deviation can be made small, and the wiring structure of the wiring layer of the flexible printed circuit 100 can be densified.

(Second Embodiment)

<Structure of flexible printed circuit board 100A>

Next, the configuration of a flexible wiring board 100A according to the second embodiment will be described with reference to FIG. 8 . Compared with the flexible circuit board 100 of the first embodiment having a reduced layer structure in the bending region 130 , the flexible circuit board 100A of the second embodiment has a hollow structure in the bending region 130 . Hereinafter, description will be made centering on parts different from the first embodiment.

Fig. 8 is a schematic cross-sectional view taken along line B-B in Fig. 2 . In FIG. 8 , the left side of the figure shows an area corresponding to the connector area 110 , and the right side of the figure shows an area corresponding to the signal line area 120 . The bending area 130 is located between the connector area 110 and the signal line area 120 . The curved region 130 has a hollow structure. That is, as shown in FIG. 7 , the flexible wiring board 100A of the second embodiment has a space (hollow region) HS in which neither a wiring layer nor an insulating layer is provided in a bending region 130 .

Specifically, in the bending region 130 , a space HS is provided between the covering material layer 71 and the covering material layer 72 . Therefore, compared with the signal line region 120, the bending region 130 can relax stress during bending. Therefore, when the flexible wiring board 100A is built into a case of an electronic device such as a smartphone, the flexible wiring board 100A can be easily built in a bent state. Specifically, when the flexible wiring board 100A is built into the case in a bent state, the flexible wiring board 100A is bent in the bending region 130 and built into the case. At this time, the bending region 130 can relatively relax the stress, and thus can be bent relatively easily. Thereby, flexible wiring board 100A can be easily built into the case by bending.

As in the case of the first embodiment, in the flexible printed circuit 100A, the analog signal line is composed of the wiring 22i, and the digital signal line is composed of the wiring 33i. That is, the analog signal line and the digital signal line can be built in the flexible printed circuit 100A, thereby achieving space saving in the casing.

In addition, the flexible wiring board 100A has a ground layer formed so as to cover the analog signal lines through an insulating layer. Specifically, as in the first embodiment, in the flexible printed circuit 100A, there is an analog signal covered by the first insulating layer (adhesive layer 13 and insulating base material 11 ) and the second insulating layer (insulating base material 21 ). The ground layers 12 b and 23 b (wiring 12 b and 23 b ) are formed as lines (wiring 22 i ). That is, the flexible printed circuit 100A has a three-layer stripline structure.

In the connector area 110 of the flexible circuit board 100A, interlayer connection channels connected with analog signal lines or digital signal lines are provided. Similar to the first embodiment, interlayer connection channels are provided in the holes H1 to H4 of the connector region 110 shown in FIG. 8 . Furthermore, the interlayer connection path provided in the hole H2 is connected to the analog signal line (wiring 22i). In addition, the interlayer connection path provided in the hole H4 is connected to the digital signal line (wiring 33i).

In addition, the interlayer connection channels in the connector area 110 have plated through holes connected with analog signal lines or digital signal lines. Similar to the first embodiment, the interlayer connection channel of the connector region 110 has a plated through hole (hole H2 or hole H4 ) connected to an analog signal line (wiring 22 i ) or a digital signal line (wiring 33 i ).

In addition, the interlayer connection channels in the connector region 110 may also be formed by filled vias. More specifically, as in the first embodiment, the conductive paste is filled into the holes H1 , H3 , and H5 to form filled via holes. Therefore, as described above, the interlayer connection channel of the connector region 110 has a plated through hole and a filled via connected to the plated through hole through the conductive layer (landing 22 a or 32 a ). In addition, a connector component (not shown) electrically connected to the analog signal line and the digital signal line through the above-mentioned interlayer connection channel may also be installed in the connector area.

The configuration of the flexible wiring board 100A of the second embodiment has been described above. According to the second embodiment, the bending region 130 of the flexible printed circuit 100A has a hollow structure obtained by providing a space HS (hollow region) in which no wiring layer and insulating base material are provided inside the bending region 130 . Thereby, the stress when the bending region 130 is bent can be relaxed. Therefore, the flexible wiring board 100A can be easily bent and built into the housing of an electronic device such as a smartphone.

In addition, both analog signal lines and digital signal lines are accommodated in the flexible wiring board 100A. This eliminates the need to separately arrange cables for analog signal lines and cables for digital signal lines in the housing of the electronic device. Therefore, space saving in housings of electronic devices such as smartphones can be realized.

In addition, compared with the signal line region 120, the bending region 130 reduces the number of wiring layers and/or the number of insulating layers, so it is possible to reduce the wiring layers and insulating substrate materials required for the manufacture of the flexible circuit board 100A, thereby enabling Reduce manufacturing costs.

<Manufacturing method of flexible wiring board 100A>

Next, a method of manufacturing the flexible wiring board 100A according to the second embodiment will be described with reference to the process cross-sectional views of FIGS. 9A to 10 .

Even in the second embodiment, the flexible circuit is produced by laminating the wiring base material 101 (first wiring base material), wiring base material 102 (second wiring base material), and wiring base material 103A (third wiring base material) Plate 100A. In addition, the manufacturing method of the wiring base material 101 and the wiring base material 102 is the same as that of the first embodiment. That is, the manufacturing method of wiring base material 101 according to the second embodiment is shown in FIG. 4 , and the manufacturing method of wiring base material 102 is shown in FIGS. 5A to 5C , so descriptions thereof are omitted. Hereinafter, a method for manufacturing the wiring base material 103A will be described.

As shown in (1) of FIG. 9A , a double-sided metal foil-clad laminate 30 is prepared. The double-sided metal foil-clad laminate 30 has an insulating base material 31 , a metal foil 32 provided on the upper surface of the insulating base material 31 , and a metal foil 33 provided on the lower surface of the insulating base material 31 . In addition to liquid crystal polymer (LCP), the insulating substrate 31 may also be, for example, polyimide (PI), modified polyimide (MPI), polyethylene naphthalate (PEN), polyethylene Ether ether ketone (PEEK), fluororesin (PFA, PTEE, etc.) and the like are not particularly limited.

The thickness of the insulating base material 31 is, for example, 50 μm. Metal foil 32 and metal foil 33 are, for example, silver or aluminum other than copper. The thicknesses of the metal foil 32 and the metal foil 33 are, for example, 12 μm, respectively. The metal foil 32 is formed on the insulating base material 31 through a seed layer (not shown) formed on the upper surface of the insulating base material 31 . Likewise, the metal foil 3 is formed under the insulating base material 31 through a seed layer (not shown) formed on the lower surface of the insulating base material 31 .

By making the thickness of the insulating base material 31 as thin as 50 μm, the line width of the signal line can be reduced. More specifically, the line width of the signal line (wiring 33 i ) matching the characteristic impedance represented by Z0=√(L/C) can be reduced. where L is the inductance per unit length and C is the capacitance between lines. In this way, by making the thickness of the insulating base material 31 thinner, the line width of the signal line can be reduced, and thus the width of the flexible wiring board 100A can be reduced. Thereby, when the flexible wiring board 100A is incorporated in the casing of electronic equipment such as a smartphone, it is possible to save space.

Next, as shown in (2) of FIG. 9A , the metal foil 32 is patterned to form a fourth conductive pattern including the land 32 a functioning as a conformal mask. Then, as shown in (3) of FIG. 9A , the metal foil 33 is patterned to form a fifth conductive pattern including the land 33 a and the wiring 33 i. The diameter of the land 33a is, for example, φ350 μm. In addition, wiring 33 i functions as a digital signal line in flexible wiring board 100 . That is, the fifth conductive pattern includes digital signal lines.

Next, as shown in (4) of FIG. 9A , the insulating base material 31 is removed by irradiating the land 32 a as a conformal mask with laser, and the hole H4 exposing the land 33 a is formed on the bottom surface. The diameter of the hole H4 is, for example, φ150 to 200 μm. In addition, the formation of the hole H4 is the same as the formation of the hole H1 of the first embodiment.

After the insulating base material 31 is penetrated by an infrared laser, desmearing treatment is performed. In the desmear process, resin residue (residual film) at the boundary between the land 33 a and the insulating base material 31 is removed. In addition, in the desmear process, the back surface treatment film (Ni or Cr, etc.) of the land 33 a is removed.

Next, as shown in (5) of FIG. 9A , the second metal plating layer 62 is deposited on the side wall and bottom surface of the hole H4 . The second metal plating layer 62 is, for example, a copper plating layer. In addition, the second metal plating layer 62 is deposited by partial plating or full plate plating. The plating thickness of the second metal plating layer 62 is, for example, 16 μm.

Next, as shown in (1) of FIG. 9B , the fourth conductive pattern (landing 32 a , wiring 32 b ) formed by patterning the metal foil 32 and the second metal plating layer 62 deposited in the hole H4 are embedded in the hole H4 . An adhesive layer 34 is formed on the metal foil 32 . In addition, the thickness of the adhesive layer 34 is, for example, 10 μm. Next, as shown in ( 2 ) of FIG. 9B , the covering material layer 72 is formed on the adhesive layer 34 . In addition, the cover material layer 72 is, for example, an insulating resin film. As the insulating resin film, for example, liquid crystal polymer (LCP) or polyimide is used. The thickness of the covering material layer 72 is, for example, 12 μm. Next, as shown in ( 3 ) of FIG. 9B , the protective film layer 35 is formed on the cover material layer 72 . In addition, the thickness of the protective film layer 35 is, for example, 10 μm.

Next, as shown in (1) of FIG. 9C , the protective film layer 35 , the covering material layer 72 and the adhesive layer 34 are removed by irradiating laser light to the protective film layer 35 , and the bottomed layer 32 a is exposed on the bottom surface. hole H5. The diameter of the hole H5 is, for example, φ150 to 200 μm. Hereinafter, the formation of the hole H5 is the same as the formation of the hole H1 of the first embodiment. That is, by using an infrared laser that is a carbon dioxide laser, laser pulses are irradiated to a predetermined position of the protective film layer 35 to perforate. The beam diameter of the infrared laser was set to 150 μm which is the same as the diameter of the hole H5. In addition, the pulse width of the infrared laser was set to 10 microseconds, and the energy per pulse of the infrared laser was set to 5 mJ.

Next, as shown in (2) of FIG. 9C , the inside of the hole H5 is filled with the conductive paste 53 by a printing method such as screen printing. The conductive paste 53 is obtained by dispersing metal particles in a resin binder which is a paste-like thermosetting resin.

Next, as shown in (3) of FIG. 9C , the protective film layer 35 is peeled off from the cover material layer 72 . Thereby, a part of the conductive paste 53 filled in the hole H5 protrudes, and the protruding part 53a is formed. In addition, the height of the protruding portion 53 a is about the same as the thickness of the protective film layer 35 .

Through the above steps, the wiring substrate 103A is obtained.

In the above-mentioned steps, the metal foil of each wiring base material may be roughened. Through the roughening treatment, the bonding strength between the metal foil and the insulating substrate can be improved.

Hereinafter, a step of laminating wiring base material 101 , wiring base material 102 , and wiring base material 103A obtained in the above steps will be described with reference to FIG. 10 .

First, the wiring base material 102 is laminated on the wiring base material 101 . Specifically, the stacking is performed so that the protrusions 51 a of the conductive paste 51 of the wiring base 101 come into contact with the lands 22 a of the wiring base 102 .

Next, the laminate composed of wiring base material 101 and wiring base material 102 obtained in the above steps is laminated on wiring base material 103A. Specifically, it laminates so that the protrusion part 52a of the electroconductive paste 52 may contact the protrusion part 53a of the electroconductive paste 53. By doing so, the wiring base material 101, the wiring base material 102, and the wiring base material 103A are electrically connected between layers. In addition, the order in which wiring base materials 101, 102, and 103A are laminated is not limited to the order described above.

In the above lamination step of forming the laminated body composed of wiring base 101 , wiring base 102 , and wiring base 103A, a vacuum pressing device or a vacuum laminator is used as in the first embodiment. The laminated body is heated and pressurized by the vacuum pressing device or the vacuum lamination device. For example, the laminated body is heated at about 200° C., and the laminated body is pressed at a pressure of several MPa (for example, 2.0 MPa). The temperature for heating the laminate is, for example, about 50° C. or more lower than the temperature at which the liquid crystal polymer (LCP) of the insulating substrates 11 , 21 , and 31 soften.

In the lamination process of the laminated body, when using a vacuum pressing device, the laminated body is heated and pressurized under the above-mentioned conditions for about 30 to 60 minutes. The thermal curing of the adhesive layers 13 , 24 , 25 , and 34 and the thermal curing of the conductive pastes 51 and 52 are also completed by heating and pressurizing the laminate with the vacuum pressurization device.

On the other hand, in the lamination step, when a vacuum laminator is used, the laminate is heated and pressurized for about several minutes under the above-mentioned conditions. Therefore, after the flexible wiring board 100A is heated and pressurized by the vacuum laminator, the laminated body is moved to an oven device to perform post-curing treatment. In the post-curing treatment, for example, heating is performed at about 200° C. for about 60 minutes. Through the post-curing treatment, the thermal curing of the adhesive layers 13 , 24 , 25 and 34 and the thermal curing of the conductive pastes 51 and 52 are also completed.

Next, if necessary, surface treatment of the first conductive pattern and the fifth conductive pattern exposed to the outside, solder resist, and contour processing are performed.

Through the above steps, the flexible circuit board 100A having the cross-sectional structure shown in FIG. 8 is obtained.

As described above, according to the method of manufacturing the flexible wiring board 100A according to the second embodiment, a flexible circuit having a hollow structure in which a space HS (hollow region) in which no wiring layer or insulating layer is provided is provided inside the bending region 130 can be obtained. Plate 100A. Therefore, compared with the signal line region 120 , the bending region 130 can relax the stress at the time of bending, so that the flexible printed circuit board 100A can be easily bent and built into the case of an electronic device such as a smartphone.

In addition, like the first embodiment, in the flexible wiring board 100A, the analog signal line is formed as the wiring 22i, and the digital signal line is formed as the wiring 33i. As shown in FIG. 8 , the analog signal lines and the digital signal lines are embedded in the flexible circuit board 100A. Therefore, by embedding the flexible printed circuit board 100A in the case of a smartphone or the like, it is possible to collectively arrange the analog signal line for transmitting the analog signal received by the wireless communication antenna and the digital signal for transmitting the digital signal received by the digital terminal such as USB at one time. Wire. As a result, space saving in housings of electronic devices such as smartphones can be achieved.

In addition, the bending region 130 of the flexible circuit board 100A reduces the number of wiring layers and the number of insulating layers compared with the signal line region 120, so it is possible to reduce the wiring layer and insulating substrate materials required by the flexible circuit board 100A, thereby enabling Reduce manufacturing costs.

In addition, the flexible circuit board 100A is manufactured by laminating the wiring base material 101, the wiring base material 102, and the wiring base material 103A. That is, since the flexible wiring board 100A is manufactured by laminating three wiring base materials, it is possible to relatively suppress occurrence of positional deviation between the wiring base materials. Therefore, the yield of the manufacturing process of 100 A of flexible wiring boards can be improved. Furthermore, the above-mentioned margin for positional deviation can be made small, and the wiring structure of the wiring layer of the flexible wiring board 100A can be densified.

(third embodiment)

Next, a flexible wiring board 100B according to a third embodiment will be described with reference to FIG. 11A . Like flexible wiring board 100A of the second embodiment, flexible wiring board 100B has a hollow structure in bending region 130 . Also, the flexible printed circuit 100B is provided with a cutout on one side of the bending region 130 (lower surface 130 b side in FIG. 11A ). Hereinafter, description will be made centering on parts different from the second embodiment.

FIG. 11A is a schematic perspective view showing the bending region 130 of the flexible printed circuit 100B. FIG. 11A is a schematic perspective view of area C of FIG. 2 , showing a portion of the connector area 110 , a portion of the signal line area 120 and the bending area 130 .

In more detail, the bending region 130 of the flexible circuit board 100B has a space HS where no wiring layer and insulating layer are provided. That is, the bending area 130 has a hollow structure. In other words, a space HS as a hollow area is provided between the upper surface 130a of the curved area 130 and the lower surface 130b of the curved area 130 .

As shown in FIG. 11A , slits ST1 and ST2 are provided as cutouts on the lower surface 130 b of the curved region 130 . Specifically, the slit ST1 and the slit ST2 are provided in an area on one side of the space HS in the thickness direction of the flexible printed circuit 100B. In addition, the slit ST1 and the slit ST2 may also be provided on both sides of the bending region 130 . That is, the slit ST1 and the slit ST2 may be provided on the upper surface 130 a and the lower surface 130 b which are both sides of the bending region 130 . In FIG. 11A , slits ST1 and ST2 are provided along the width direction perpendicular to the long side direction of the signal line region 120 . In addition, not limited thereto, the slits ST1 and ST2 may also be provided along a direction intersecting the width direction of the bending region 130 . The slit ST1 and the slit ST2 may also be provided to have components in the width direction perpendicular to the longitudinal direction of the signal line region 120 of the flexible printed circuit 100B.

The other configurations of the flexible wiring board 100B are the same as those of the flexible wiring board 100A of the second embodiment, and thus description thereof will be omitted. In addition, the manufacturing method of the flexible wiring board 100B is also the same as that of the flexible wiring board 100A of the second embodiment, and thus description thereof will be omitted. The wirings 22i and 33i are formed in a meandering manner avoiding the slits ST1 and ST2.

As mentioned above, the bending region 130 of the flexible circuit board 100B has the space HS where no wiring layer and insulating layer are provided, and the lower surface 130 b of the bending region 130 has the slits ST1 and ST2 . Therefore, the bending region 130 can further relax the stress at the time of bending than the signal line region 120 , so that the flexible printed circuit board 100B can be more easily bent and built into a case of a smartphone or the like.

In addition, analog signal lines and digital signal lines are incorporated in the flexible printed circuit 100B similarly to the second embodiment. Accordingly, by arranging the flexible printed circuit 100B in the case, the analog signal lines and the digital signal lines can be collectively arranged at one time, thereby saving space in the case of a smartphone or the like.

In addition, the bending region 130 of the flexible circuit board 100B reduces the number of wiring layers and the number of insulating layers compared with the signal line region 120, so it is possible to reduce the wiring layer and insulating substrate materials required by the flexible circuit board 100B, thereby enabling Reduce manufacturing costs.

In addition, the flexible circuit board 100B is manufactured by laminating the wiring base material 101 (first wiring base material), the wiring base material 102 (second wiring base material), and the wiring base material 103A (third wiring base material). That is, since the flexible wiring board 100B is manufactured by laminating three wiring base materials, it is possible to relatively suppress the positional displacement between the wiring base materials. Thereby, the yield of the manufacturing process of flexible wiring board 100B can be improved. Furthermore, the margin for the above-mentioned positional deviation can be made small, and the wiring structure of the wiring layer of the flexible wiring board 100B can be increased in density.

(Fourth embodiment)

Next, a flexible wiring board 100C according to a fourth embodiment will be described with reference to FIGS. 11B and 11C . Like flexible wiring board 100A of the second embodiment, flexible wiring board 100C has a hollow structure in bending region 130 . Also, one side of the bending region 130 of the flexible printed circuit 100C (the lower surface 130 b side in FIGS. 11B and 11C ) is provided in a meander shape or a crank shape. Hereinafter, description will be made centering on parts different from the second embodiment.

11B and 11C are schematic perspective views showing the bending region 130 of the flexible printed circuit 100C. 11B and 11C are schematic perspective views of the area C in FIG. 2 , showing a part of the connector area 110 , a part of the signal line area 120 and the bending area 130 .

In more detail, the bending region 130 of the flexible circuit board 100C has a space HS where no wiring layer and insulating layer are provided, that is, the bending region 130 has a hollow structure. In other words, there is a space HS between the upper surface 130 a of the curved region 130 and the lower surface 130 b of the curved region 130 .

First, as shown in FIG. 11B , the lower surface 130 b of the curved region 130 has a meandering shape. Specifically, when the flexible circuit board 100C is viewed from above, the lower surface 130b of the bending region 130 is arranged in a meandering shape. In other words, the meander-shaped lower surface 130b is provided in an area on one side of the space HS in the thickness direction of the flexible printed circuit 100C. In addition, the upper surface 130a and the lower surface 130b, which are both sides of the curved region 130, may also be provided in a meandering shape.

On the other hand, as shown in FIG. 11C , the lower surface 130b of the bending region 130 may also have a crank shape. Specifically, when the flexible printed circuit 100C is viewed from above, the lower surface 130b of the bending region 130 is provided in a crank shape. In other words, the crank-shaped lower surface 130b is provided in an area on one side of the space HS in the thickness direction of the flexible printed circuit 100C. In addition, the upper surface 130a and the lower surface 130b, which are both sides of the bending region 130, may be provided in a crank shape.

The other configurations of the flexible wiring board 100C are the same as those of the flexible wiring board 100A of the second embodiment, and thus description thereof will be omitted. In addition, since the manufacturing method of 100 C of flexible wiring boards is the same as 100 A of flexible wiring boards of 2nd Embodiment, description is abbreviate|omitted. The wires 22i and 33i are formed along a meander shape or a crank shape.

As mentioned above, the bending region 130 of the flexible circuit board 100C has a space HS where no wiring layer and insulating layer are provided, and the lower surface 130 b of the bending region 130 is provided in a meander shape or a crank shape. Therefore, the bending region 130 can further relax the stress at the time of bending than the signal line region 120 , so that the flexible printed circuit 100C can be more easily bent and incorporated into a case of a smartphone or the like.

In addition, analog signal lines and digital signal lines are incorporated in the flexible printed circuit 100C similarly to the second embodiment. Thus, by arranging the flexible printed circuit 100C in the case, the analog signal lines and the digital signal lines can be collectively arranged at one time, thereby saving space in the case of a smartphone or the like.

In addition, the bending region 130 of the flexible circuit board 100C reduces the number of wiring layers and the number of insulating layers compared with the signal line region 120, so it is possible to reduce the wiring layer and insulating substrate materials required by the flexible circuit board 100C, thereby enabling Reduce manufacturing costs.

In addition, the flexible circuit board 100C is manufactured by laminating the wiring base material 101 (first wiring base material), the wiring base material 102 (second wiring base material), and the wiring base material 103A (third wiring base material). That is, since the flexible wiring board 100C is manufactured by laminating three wiring base materials, it is possible to relatively suppress occurrence of positional deviation between the wiring base materials. Therefore, the yield of the flexible wiring board 100C manufacturing process can be improved. Furthermore, the above-mentioned margin for positional deviation can be made small, and the wiring structure of the wiring layer of the flexible wiring board 100C can be densified.

(modified example)

Next, the configuration of a flexible wiring board 100D according to a modified example will be described with reference to FIG. 12 . While flexible wiring board 100 of the first embodiment has a layer-reducing structure in bending region 130 , flexible wiring board 100D of a modified example also has a layer-reducing structure in connector region 110A. Hereinafter, description will be made centering on parts different from the first embodiment.

FIG. 12 is a schematic plan view of a flexible wiring board 100D according to a modified example. As shown in FIG. 12 , a flexible printed circuit 100D according to a modified example includes a connector region 110 and a connector region 110A, a signal line region 120 , and a bending region 130 . In addition, FIG. 12 shows a state where the connector component 111 is attached to the connector region 110A.

Even in the flexible printed circuit 100D of the modified example, the bending region 130 has a reduced layer structure. That is, the bending region 130 of the flexible circuit board 100D has a reduced-layer structure in which the number of wiring layers and/or the number of insulating layers is smaller than that of the signal line region 120 .

Also, in a modified example, in addition to the bending region 130, the connector region 110A also has a layer-reduced structure. That is, the connector region 110A has a reduced-layer structure in which the number of wiring layers and/or the number of insulating layers is smaller than that of the signal line region 120 . In addition, the cross-sectional structure of the connector region 110A may be the same as that of the bending region 130 . That is, the cross-sectional structure of the connector region 110A may be the same as the cross-sectional structure of the bending region 130 shown in FIG. 3 . In addition, in the flexible wiring board 100D shown in FIG. 12 , a connector region 110A which is one connector region has a layer-reduced structure. In the flexible printed circuit 100D of the modified example, both connector regions (the connector region 110 and the connector region 110A) may have a layer-reduced structure.

The other structures of the flexible wiring board 100D are the same as those of the flexible wiring board 100 of the first embodiment. In addition, the manufacturing method of the flexible wiring board 100D is also the same as that of the flexible wiring board 100 of the first embodiment. That is, in the method of manufacturing the flexible printed circuit 100D, it is only necessary to apply the step of forming the layer-reduced structure of the bending region 130 to the step of forming the layer-reduced structure of the connector region 110A.

As described above, according to the flexible printed circuit 100D of the modified example, the connector region 110A has a reduced-layer structure in which the number of wiring layers and/or the number of insulating layers is smaller than that of the signal line region 120 in addition to the bending region 130 . Therefore, it is possible to further reduce the wiring layer and the material of the insulating base material required for the flexible wiring board 100D, thereby further reducing the manufacturing cost.

In addition, the connector region 110A and the bending region 130 can relax the stress at the time of bending compared with the signal line region 120 . Therefore, similarly to the flexible wiring board 100 of the first embodiment, the flexible wiring board 100D can be easily bent and incorporated into a case of a smartphone or the like.

In addition, analog signal lines and digital signal lines are built in the flexible printed circuit 100D. Thus, by arranging the flexible printed circuit 100D inside the case, the analog signal lines and the digital signal lines can be collectively arranged at one time, thereby saving space in the case of a smartphone or the like.

In addition, the flexible circuit board 100D is manufactured by laminating the wiring base material 101 (first wiring base material), the wiring base material 102 (second wiring base material), and the wiring base material 103 (third wiring base material). That is, since the flexible wiring board 100D is manufactured by laminating three wiring base materials, it is possible to relatively suppress occurrence of positional deviation between the wiring base materials. Thereby, the yield rate of the manufacturing process of flexible wiring board 100D can be improved. Furthermore, the margin for the above-mentioned positional deviation can be made small, and the wiring structure of the wiring layer of the flexible wiring board 100D can be densified.

＜Electronic equipment with built-in flexible circuit board＞

(fifth embodiment)

Next, an embodiment of an electronic device incorporating the flexible wiring board 100 according to the first to fourth embodiments or modifications described above will be described with reference to FIG. 13A . In the electronic device of this embodiment, the flexible printed circuit 100 is bent and built into the side surface of the housing of the electronic device.

The figure on the right side of FIG. 13A is a perspective view schematically showing a state before flexible wiring board 100 is bent. The figure in the center of FIG. 13A is a perspective view schematically showing a state in which flexible wiring board 100 is bent. As shown in the right and center diagrams of FIG. 13A , when the flexible printed circuit 100 is built into the case of an electronic device, the bending region 130 of the flexible printed circuit 100 is bent into a desired shape and built in. In FIG. 13A , the flexible circuit board 100 is built into the side of the casing of the electronic device. In the diagram on the right side of FIG. 13A , the connector region 110 a and the bending region 130 stand upright on the signal line region 120 . From this state, as shown in the central figure of FIG. 13A , the bending region 130 is bent forward (in the direction of the built-in flexible wiring board 100 ), and the connector region 110b is in a state of falling forward.

The diagram on the left side of FIG. 13A schematically shows an electronic device UE incorporating a flexible printed circuit 100 . In the electronic equipment UE, the flexible circuit board 100 and other electronic components are built in the casing 500 . Specifically, the electronic equipment UE has a housing 500 , and the flexible circuit board 100 of the above-mentioned embodiment or modification is built in the housing 500 . In addition, the first module 200 and the second module 300 are arranged inside the casing 500 , and the battery 400 is arranged between the first module 200 and the second module 300 .

In the electronic equipment UE in this embodiment, the first module 200 has a wireless communication antenna for receiving analog signals, and a digital terminal for receiving digital signals. The second module 300 performs signal processing on the analog signal and the digital signal received by the first module 200 . In addition, as shown in FIG. 13A , the processor 210 for overall control of the electronic equipment UE may also be configured on the first module 200 .

A connector part 220 is provided on the first module 200 . The first module 200 is electrically connected to the connector area 110 a through the connector part 220 . On the other hand, the second module 300 is also provided with a connector part 310 . The second module 300 is electrically connected to the connector area 110 b through the connector part 310 . Thus, the first module 200 is electrically connected to the second module 300 through the flexible circuit board 100 . In other words, the flexible circuit board 100 is electrically connected to the first module 200 and the second module 300 .

As described above, in the present embodiment, the flexible printed circuit 100 is built along the side surface of the casing 500 of the electronic device UE. That is, the bending region 130 is bent so that the connector part 220 and the connector part 310 are respectively fitted with the first module 200 and the second module 300, and the signal line region 120 is along the side surface of the housing 500, so that the flexible The circuit board 100 is built in the housing 500 .

As described above, according to this embodiment, the first module 200 and the second module 300 can be electrically connected by the flexible printed circuit 100 . Therefore, it is possible to save space in the casing of the electronic device UE, so that the size of the battery 400 can be increased. In addition, since the flexible printed circuit 100 can be arranged without straddling the battery 400, coils for wireless power feeding and the like can be arranged on the upper surface of the battery.

(sixth embodiment)

Next, another embodiment of an electronic device incorporating the flexible wiring board 100 according to the above-mentioned first to fourth embodiments or modified examples will be described with reference to FIG. 13B . In the present embodiment, the flexible printed circuit 100 is built into the bottom surface of the housing of the electronic device in a state where the bending region 130 is bent. Hereinafter, description will be made centering on parts different from the fifth embodiment.

FIG. 13B is a diagram showing electronic equipment UE incorporating flexible wiring board 100 . (1) of FIG. 13B is a schematic top view of the electronic device UE, and (2) of FIG. 13B is a schematic cross-sectional view of the electronic device UE. As shown in (1) of FIG. 13B and (2) of FIG. 13B , in the electronic device UE, the flexible circuit board 100 and other electronic components are built in the casing 500 . Specifically, the electronic equipment UE has a housing 500 , and the flexible circuit board 100 of the above-mentioned embodiment or modification is built in the housing 500 . In addition, the first module 200 and the second module 300 are arranged inside the casing 500 , and the battery 400 is arranged between the first module 200 and the second module 300 .

( 3 ) of FIG. 13B shows a perspective view of flexible printed circuit 100 in a state built in case 500 (states shown in ( 1 ) and ( 2 ) of FIG. 13B ). As shown in (3) of FIG. 13B , flexible wiring board 100 is bent at P1 and P2 at bending region 130B, and at P3 and P4 at bending region 130A. In other words, the curved region 130A and the curved region 130B are curved at two places, respectively. That is, in the flexible printed circuit 100 according to the first to fourth embodiments or modified examples, since the stress when bending the bending region 130 can be reduced, it is possible to bend both sides of the bending region 130 as shown in this embodiment. A part is bent.

In addition, like the fifth embodiment, the first module 200 and the second module 300 can be electrically connected by the flexible printed circuit 100 . Therefore, it is possible to save space in the casing of the electronic device UE, so that the size of the battery 400 can be increased. In addition, since the flexible printed circuit 100 can be arranged without straddling the upper surface of the battery 400 , coils for wireless power feeding and the like can be arranged on the upper surface of the battery.

Based on the above description, those skilled in the art may conceive additional effects and various modifications of the present invention, but the aspects of the present invention are not limited to the respective embodiments described above. Constituent elements across different embodiments may be combined appropriately. Various additions, modifications, and partial deletions can be made without departing from the concept and gist of the present invention derived from the contents specified in claims and equivalents thereof.

10: Single-sided metal foil laminated board 20, 30: double-sided metal foil laminated board 11, 21, 31: insulating substrate 12, 22, 23, 32, 33: metal foil 13, 24, 25, 34: Adhesive layer 14, 26, 35: protective film layer 12a, 22a, 23a, 32a, 33a: Landings 12b, 23b: Ground plane (wiring) 22i: wiring (analog signal line) 32b: Wiring 33i: wiring (digital signal line) 51, 52, 53: Conductive paste 61, 62: metal plating 71, 72: Layers of covering material 100:Flexible circuit board 101, 102, 103: wiring substrate 110, 110a: Connector area 120: Signal line area 130, 130A, 130B: bending area 200: The first module 300: Second module 400: battery 500: shell A1: Opening H1, H2, H3, H4, H5: holes HS: space ST1, ST2: Slits W: window opening UE: electronic equipment

FIG. 1 is a plan view of a flexible wiring board according to an embodiment. FIG. 2 is an enlarged plan view of area A of FIG. 1 . Fig. 3 is a schematic sectional view taken along line B-B of Fig. 2 . Fig. 4 is a cross-sectional view illustrating the steps of the method of manufacturing the flexible wiring board according to the first embodiment. 5A is a cross-sectional view illustrating the process of the method for manufacturing the flexible printed circuit according to the first embodiment following FIG. 4 . FIG. 5B is a diagram illustrating the method of manufacturing the flexible printed circuit board according to the first embodiment following FIG. 5A 5C is a cross-sectional view for explaining the method of manufacturing the flexible wiring board according to the first embodiment following FIG. 5B . 6 is a cross-sectional view for explaining the method of manufacturing the flexible printed circuit according to the first embodiment following FIG. 5C . FIG. 7 is a cross-sectional view for explaining the method of manufacturing the flexible wiring board according to the first embodiment following FIG. 6 . Fig. 8 is a schematic cross-sectional view taken along line B-B in Fig. 2 of the second embodiment. 9A is a cross-sectional view for explaining the process of the method of manufacturing the flexible wiring board according to the second embodiment. 9B is a cross-sectional view for explaining the method of manufacturing the flexible wiring board according to the second embodiment following FIG. 9A . 9C is a cross-sectional view for explaining the method of manufacturing the flexible wiring board according to the second embodiment following FIG. 9B . FIG. 10 is a cross-sectional view for explaining the method of manufacturing the flexible wiring board according to the second embodiment following FIG. 9C . FIG. 11A is a schematic perspective view of a region C in FIG. 2 of the third embodiment. FIG. 11B is a schematic perspective view of a region C of FIG. 2 of the fourth embodiment (serpentine shape). 11C is a schematic perspective view of the region C of FIG. 2 of the fourth embodiment (crank shape). Fig. 12 is a plan view of a flexible wiring board according to a modified example. 13A is a schematic perspective view of an electronic device of a fifth embodiment. 13B is a schematic plan view and a schematic cross-sectional view of an electronic device according to a sixth embodiment.

11,21,31: insulating substrate

13,24,25: Adhesive layer

12a, 22a, 23a, 32a, 33a: landing place

12b, 23b: Ground layer (wiring)

22i: wiring (analog signal line)

32b: Wiring

33i: wiring (digital signal line)

51,52: Conductive paste

61,62: metal plating

71: Covering material layer

100:Flexible circuit board

110: Connector area

120: Signal line area

130: Bending area

H1, H2, H3, H4: holes

Claims (15)

A flexible circuit board, wherein the flexible circuit board has a signal line area, a connector area, a bending area, one or more analog signal lines, one or more digital signal lines, and a ground layer, and the one or more The analog signal line is formed to extend along the long side direction of the signal line area to transmit an analog signal, and the one or more digital signal lines are formed to extend along the long side direction of the signal line area, The digital signal is transmitted, the ground layer is formed by covering the analog signal line through an insulating layer, the bending area connects the signal line area and the connector area, compared with the signal line area, the wiring layer At least one of the number of layers and the number of insulating layers is less. The flexible printed circuit board according to claim 1, wherein the connector region has at least one of the number of wiring layers and the number of insulating layers smaller than that of the signal line region. A flexible circuit board, wherein the flexible circuit board has a signal line area, a connector area, a bending area, one or more analog signal lines, one or more digital signal lines, and a ground layer, and the one or more The analog signal line is formed to extend along the long side direction of the signal line area to transmit an analog signal, and the one or more digital signal lines are formed to extend along the long side direction of the signal line area, The digital signal is transmitted, the ground layer is formed by covering the analog signal line through an insulating layer, the curved area connects the signal line area and the connector area, and there is no Wiring layer and insulating layer space. The flexible circuit board according to claim 3, wherein, there are cutouts on one or both sides of the space in the thickness direction of the flexible circuit board, and the direction of the cutouts is in line with the signal line The direction of the component in the width direction perpendicular to the longitudinal direction of the region. The flexible circuit board according to claim 3, wherein, when the flexible circuit board is viewed from above, the area on one side or both sides of the thickness direction of the flexible circuit board in the space is formed in a meander shape or a crank shape. The flexible circuit board according to any one of claims 1 to 5, wherein an interlayer connection channel is provided in the connector area, and the interlayer connection channel is connected to the analog signal line or the digital signal line. The flexible circuit board as described in claim 6, wherein the interlayer connection channel has: a plated through hole connected to the analog signal line or the digital signal line; and a filled via hole connected to the plated through a conductive layer through-hole connection. The flexible circuit board according to claim 6 or 7, wherein a connector part is installed in the connector area, and the connector part is connected to the analog signal line and the digital signal line through the interlayer connection channel electrical connection. An electronic device, comprising: a casing; the flexible circuit board according to any one of claims 1 to 8, configured in the casing; a first module, configured in the casing; a second module, disposed in the casing; and a battery disposed between the first module and the second module in the casing. The electronic device according to claim 9, wherein the flexible circuit board is configured to pass between the side of the housing and the battery. The electronic device according to claim 9, wherein the flexible circuit board is configured to pass between the back or front of the housing and the battery. A method for manufacturing a flexible circuit board, wherein the method for manufacturing the flexible circuit board includes the following steps: preparing a first single-sided metal foil-clad laminate, the first single-sided metal-clad laminate having: a first insulating base a material having a first main surface and a second main surface opposite to the first main surface; a first metal foil disposed on the first main surface of the first insulating base material; and a first protection A film layer is disposed on the second main surface of the first insulating substrate through a first adhesive layer; patterning the first metal foil to form a first conductive pattern; forming a first bottomed hole, The first bottomed hole passes through the first protective film layer, the first adhesive layer, and the first insulating substrate and reaches the first metal foil; the first bottomed hole is filled with a second A conductive paste; peeling off the first protective film layer to obtain a first wiring substrate; preparing a first double-sided metal foil-clad laminate, the first double-sided metal foil-clad laminate has: a second insulating substrate , having a third main surface and a fourth main surface opposite to the third main surface; a second metal foil disposed on the third main surface of the second insulating substrate; and a third metal foil , disposed on the fourth main surface of the second insulating substrate; patterning the second metal foil to form a second conductive pattern; forming a second bottomed hole, the second bottomed hole penetrates The second insulating substrate reaches the second metal foil; depositing the first metal plating layer on the side wall and bottom surface of the second bottomed hole; patterning the third metal foil to form a third conductive pattern; forming a second adhesive on the third metal foil by embedding the third conductive pattern of the third metal foil and the first metal plating layer deposited on the second bottomed hole layer; forming a first covering material layer on the second adhesive layer; forming a third adhesive layer having a first opening on the first covering material layer; filling the third adhesive layer A second protective film layer is formed on the third adhesive layer by means of the first opening; a third bottomed hole is formed, and the third bottomed hole passes through the second protective film layer, the first Three adhesive layers, the first cover material layer and the second adhesive layer reach the third metal foil; fill the third bottomed hole with a second conductive paste; peel off the second protection film layer to obtain a second wiring base material; prepare a second double-sided metal foil-clad laminate, the second double-sided metal foil-clad laminate has: a third insulating base material with a fifth main surface and the The sixth main surface on the opposite side of the fifth main surface; the fourth metal foil is provided on the fifth main surface of the third insulating base material; and the fifth metal foil is provided on the third insulating base material The sixth main surface; patterning the fourth metal foil to form a fourth conductive pattern; patterning the fifth metal foil to form a fifth conductive pattern; forming a fourth bottomed hole, the The fourth bottomed hole penetrates through the third insulating substrate and reaches the fifth metal foil; depositing the second metal plating layer on the side wall and bottom surface of the fourth bottomed hole; forming a hole through the third insulating substrate and the first through hole of the fifth metal foil, obtaining a third a wiring base material; and laminating the first wiring base material on the second wiring base material in such a manner that the first conductive paste is in contact with the second conductive pattern that the second conductive The third wiring base material is laminated on the second wiring base material in such a manner that the paste is in contact with the third conductive pattern. A method for manufacturing a flexible circuit board, wherein the method for manufacturing the flexible circuit board includes the following steps: preparing a first single-sided metal foil-clad laminate, the first single-sided metal-clad laminate having: a first insulating base a material having a first main surface and a second main surface opposite to the first main surface; a first metal foil disposed on the first main surface of the first insulating base material; and a first protection A film layer is disposed on the second main surface of the first insulating substrate through a first adhesive layer; patterning the first metal foil to form a first conductive pattern; forming a first bottomed hole, The first bottomed hole passes through the first protective film layer, the first adhesive layer, and the first insulating substrate and reaches the first metal foil; the first bottomed hole is filled with a second A conductive paste; peeling off the first protective film layer to obtain a first wiring substrate; preparing a first double-sided metal foil-clad laminate, the first double-sided metal foil-clad laminate has: a second insulating substrate , having a third main surface and a fourth main surface opposite to the third main surface; a second metal foil disposed on the third main surface of the second insulating substrate; and a third metal foil , disposed on the fourth main surface of the second insulating substrate; patterning the second metal foil to form a second conductive pattern; forming a second bottomed hole, the second bottomed hole penetrates The second insulating substrate reaches the second metal foil; depositing the first metal plating layer on the side wall and bottom surface of the second bottomed hole; patterning the third metal foil to form a third conductive pattern; forming a second adhesive on the third metal foil by embedding the third conductive pattern of the third metal foil and the first metal plating layer deposited on the second bottomed hole layer; forming a first covering material layer on the second adhesive layer; forming a third adhesive layer having a first opening on the first covering material layer; filling the third adhesive layer A second protective film layer is formed on the third adhesive layer by means of the first opening; a third bottomed hole is formed, and the third bottomed hole passes through the second protective film layer, the first Three adhesive layers, the first cover material layer and the second adhesive layer reach the third metal foil; fill the third bottomed hole with a second conductive paste; peel off the second protection film layer to obtain a second wiring base material; prepare a second double-sided metal foil-clad laminate, the second double-sided metal foil-clad laminate has: a third insulating base material with a fifth main surface and the The sixth main surface on the opposite side of the fifth main surface; the fourth metal foil is provided on the fifth main surface of the third insulating base material; and the fifth metal foil is provided on the third insulating base material The sixth main surface; patterning the fourth metal foil to form a fourth conductive pattern; patterning the fifth metal foil to form a fifth conductive pattern; forming a fourth bottomed hole, the The fourth bottomed hole passes through the third insulating substrate and reaches the fifth metal foil; depositing the second metal plating layer on the side wall and bottom surface of the fourth bottomed hole; to bury the fourth metal foil The third conductive pattern and deposited on the fourth bottomed hole In the manner of the second metal plating layer, a fourth adhesive layer is formed on the fourth metal foil; a second covering material layer is formed on the fourth adhesive layer; a second covering material layer is formed on the second covering material layer A third protective film layer; a fourth protective film layer is formed on the third protective film layer; a fifth bottomed hole is formed, and the fifth bottomed hole passes through the fourth protective film layer, the third protective film layer The film layer, the second cover material layer and the third adhesive layer reach the fourth metal foil; fill the fifth bottomed hole with a third conductive paste; peel off the third protective film layer and the fourth protective film layer to obtain a third wiring base; and laminating the first wiring base on the second On the wiring base material, the third wiring base material is laminated on the second wiring base material so that the second conductive paste is in contact with the third conductive paste. The method for manufacturing a flexible circuit board according to claim 12 or 13, wherein the second conductive pattern includes analog signal lines. The method for manufacturing a flexible circuit board according to any one of claims 12 to 14, wherein the fifth conductive pattern includes a digital signal line.

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