TW201913236A - Flexible circuit board and manufacturing method thereof - Google Patents

Abstract

A flexible circuit board includes a flexible base roll and a patterned circuit layer. The flexible base roll is formed by a flexible base rolling up and a length of the flexible base is substantially greater than 500 mm. The patterned circuit layer includes a plurality of first circuit portions, a plurality of second circuit portions and a plurality of pad portions respectively connected between the first circuit portions and the second circuit portions, wherein each of the first circuit portions is substantially collinear with the corresponding second circuit portion and connected thereto via the corresponding pad portion.

Description

Flexible circuit board and manufacturing method thereof

The invention relates to a circuit board and a manufacturing method thereof, and in particular to a flexible circuit board and a manufacturing method thereof.

Tape and Reel Chip Carrier Package (TCP), Flip-Chip Flexible Board (COF), and Flexible Printed Circuit Board (FPC) are driver integrated circuits for flat display devices such as liquid crystal displays (LCD) and organic light-emitting displays (OLED). IC) is the most commonly used flexible circuit board. When these flexible circuit boards are used to join the display panel and the printed circuit board (PCB), thermal compression is usually used. Therefore, the reaction temperature needs to be increased to facilitate the electrical pins of the packaging film board and the electrical pins on the display panel. , Or the electrical pins on the printed circuit board can be smoothly joined.

However, as the display continues to trend toward large size, the size of flexible circuit boards has also increased. However, the exposure machine used to make circuits on flexible circuit boards has its size limitations, so that flexible circuits The size of the board has its process limits. Therefore, it is conventional to form a large-sized flexible circuit board by using a connector to join a plurality of flexible circuit boards to each other. However, using a connector to connect multiple lines on a flexible circuit board will affect the transmission speed of the line and cause signal loss.

The invention provides a flexible circuit board and a manufacturing method thereof, which can use a multi-stage patterning process to form a plurality of segments connected to each other on a large-sized flexible circuit board.

A method for manufacturing a flexible circuit board of the present invention includes the following steps. Provide a flexible substrate roll, which is formed by winding a flexible substrate; setting a photoresist layer on the flexible substrate; performing a first exposure process on a first section of the first photoresist layer, A first exposure region is formed on the first segment; a second exposure process is performed on a second segment of the photoresist layer to form a second exposure region on the second segment, wherein the first exposure The area is partially overlapped with the second exposure area; a developing process is performed on the photoresist layer to remove the first exposure area and the second exposure area to form a patterned photoresist layer; a pattern process is performed using the patterned photoresist layer To form a patterned circuit layer, wherein the patterned circuit layer includes a plurality of first circuit portions, a plurality of second circuit portions, and a plurality of pad portions connected between the first circuit portion and the second circuit portion, respectively; and In addition to the patterned photoresist layer.

In an embodiment of the invention, a length of the flexible substrate is substantially greater than 500 millimeters (mm).

In an embodiment of the present invention, the first exposure area includes a plurality of first line exposure patterns corresponding to the first line portion and a plurality of pad exposure patterns corresponding to the pad portion, which are respectively connected to the first line exposure pattern. The second patterned photoresist layer includes a plurality of second circuit exposure patterns corresponding to the second circuit portion.

In an embodiment of the present invention, each of the second line exposure patterns and the pad exposure patterns partially overlap.

In one embodiment of the present invention, the pad portions are arranged alternately with each other along a length direction of the flexible base material.

In an embodiment of the present invention, each of the pad portions described above is offset by a distance from one side of the soft substrate compared to the arrangement when the first line portions are linear, and each of the first line portions and each second line The part is bent and extended to the side to connect each pad part.

In an embodiment of the present invention, a width of each of the pad portions is substantially between a line width of each second circuit portion plus 10 micrometers (μm) to 1000 micrometers (μm).

In an embodiment of the present invention, the method for manufacturing a flexible circuit board further includes: forming a first cover film on the flexible substrate; and forming a second cover film on the flexible substrate, wherein the second cover film The first cover film is connected to each other, and a joint surface between the second cover film and the first cover film is located on the pad portion.

A flexible circuit board of the present invention includes a flexible substrate roll, a first patterned circuit layer and a second patterned circuit layer. The flexible substrate roll is a flexible substrate wound and a length of the flexible substrate is substantially greater than 500 mm. The patterned circuit layer includes a plurality of first circuit portions, a plurality of second circuit portions, and a plurality of pad portions connected between the first circuit portion and the second circuit portion, respectively. The two circuit portions are substantially collinear and connected to each other via corresponding pad portions. .

Based on the above, the embodiments of the present invention can perform multiple patterning processes in sections on a long flexible substrate to form multiple exposure patterns that are connected to each other and form a patterned circuit layer accordingly. In the case of a connector, a longer length flexible circuit board is manufactured by overcoming process limitations. Therefore, without using a connector, the linear circuit board and the manufacturing method thereof according to the embodiments of the present invention can effectively improve the transmission speed of the circuit, and the signal loss can be reduced accordingly.

In order to make the above features and advantages of the present invention more comprehensible, embodiments are hereinafter described in detail with reference to the accompanying drawings.

The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of each embodiment with reference to the drawings. The directional terms mentioned in the following embodiments, such as: "up", "down", "front", "rear", "left", "right", etc., are only directions referring to the attached drawings. Therefore, the directional terms used are used for illustration, but not for limiting the present invention. And, in the following embodiments, the same or similar elements will be given the same or similar reference numerals.

FIG. 1 to FIG. 4 are schematic top views of processes of a method for manufacturing a flexible circuit board according to an embodiment of the present invention. The method for manufacturing a flexible circuit board in this embodiment may include the following steps. First, a flexible substrate roll 110 is provided. The flexible substrate roll 110 is formed by winding a flexible substrate 110 integrally formed. It should be noted that FIG. 1 to FIG. 3 of the present embodiment show only a top view of a partial section after the flexible substrate roll 110 is unfolded. In this embodiment, the length of the flexible substrate 110 is greater than 500 millimeters (mm), and this length refers to the total unfolded length of the flexible substrate 110. As such, in this embodiment, the long flexible substrate roll 110 can be applied to a roll-to-roll process to facilitate mass production, and can be applied to large-sized electronic devices, such as large-sized display devices. Of course, The embodiments of the present invention are not limited thereto.

Next, a photoresist layer 140 a as shown in FIG. 1 is disposed on the flexible substrate 110. Next, a first exposure process is performed on a first segment R1 of the photoresist layer 140a to form a first exposure region 142 on the first segment R1. The first exposure area 142 may include a plurality of first line exposure patterns 142a and a plurality of pad exposure patterns 142b, as shown in FIG. 1, which are respectively connected to the first line exposure patterns 142a.

In this embodiment, the photoresist layer 140a may be a positive photoresist, that is, a portion of the photoresist layer 140a irradiated with ultraviolet light may cause a chemical reaction to loosen chemical bonds and be easily dissolved by a developing solution in a subsequent development process. In other words, the exposed portion of the photoresist layer 140a (for example, the first exposure region 142) can be dissolved and removed by the developing solution. Of course, in other embodiments, the photoresist layer 140a may also be a negative photoresist, and a portion of the photoresist layer 140a irradiated with ultraviolet light may cause a chemical reaction to make the chemical bond strong and not easily be used by the developing solution in the subsequent development process. Dissolving, in other words, the portion of the photoresist layer 140a that is not exposed can be dissolved and removed by the developer. In the embodiment in which the photoresist layer 140a is a negative photoresist, ultraviolet light may be irradiated to an area other than the area surrounded by the first exposure area 142 in FIG. 1, so that the area surrounded by the first exposure area 142 It can then be dissolved and removed by the developer.

Next, referring to FIG. 2, a second exposure process is performed on a second segment R2 of the photoresist layer 140 a to form a second exposure region 144 on the second segment R2. The first exposure region 142 and The second exposure area 144 partially overlaps. In this embodiment, the second exposure area 144 may include a plurality of second line exposure patterns 144a. In this embodiment, the second line exposure pattern 144a in the second exposure region 144 may partially overlap the corresponding pad exposure pattern 142b in the first exposure region 142. In other embodiments, the second exposure region 144 may further include a pad exposure pattern (similar to the pad exposure pattern 142 b) for later forming a pad portion 128 as shown in FIG. 4A accordingly. In this embodiment, the first exposure areas 142 and the second exposure areas 144 on the photoresist layer 140 a may be alternately arranged with each other, and the adjacent first exposure areas 142 and the second exposure areas 144 partially overlap each other. In this way, a good connection can be formed between the first exposure area 142 and the second exposure area 144 formed by different exposure processes, and the connection failure will not occur due to tolerances, and the patterns formed accordingly can be avoided. A gap may be generated in the circuit layer 120 to cause disconnection.

Next, referring to FIG. 3, a developing process is performed on the photoresist layer 140 a to remove the first exposure region 142 and the second exposure region 144 to form a patterned photoresist layer 141 as shown in FIG. 3. In this embodiment, the developing process may include dissolving the first exposure region 142 and the second exposure region 144 formed in the foregoing exposure process by using a developing solution. In this embodiment, the patterned photoresist layer 141 may include a plurality of openings 146.

Next, referring to FIG. 3 and FIG. 4 at the same time, a pattern process is performed by using the patterned photoresist layer 141 to form a patterned circuit layer 120 as shown in FIG. 4, which includes a plurality of first circuit portions 122 and a plurality of connection portions. The pad portion 124 and the plurality of second circuit portions 126 are connected to the first circuit portion 122 and the second circuit portion 126, respectively. The first circuit portion 122 corresponds to the first line exposure pattern 142a, and the pad The portion 124 corresponds to the pad exposure pattern 142b, and the second line portion 126 corresponds to the second line exposure pattern 144a. In this embodiment, each of the first circuit portions 122 and the corresponding second circuit portion 126 are substantially collinear and are connected to each other via the corresponding pad portion 124. In this embodiment, therefore, the first circuit portion 122, the pad portion 124, and the second circuit portion 126 are integrally formed. In this embodiment, the patterned circuit layer 120 is integrally extended to the edge of the flexible substrate 110.

For example, in this embodiment, the patterned circuit layer 120 may be formed by a semi-additive method, that is, the above-mentioned circuit process may include a semi-additive method. In detail, the patterned photoresist layer 141 may include a plurality of openings 146. The patterned photoresist layer 141 is used as a mask to perform electroplating to form a patterned circuit layer 120 as shown in FIG. 4. Therefore, the shape of the opening 146 of the patterned photoresist layer 141 may correspond to (match) the shape of the patterned circuit layer 120 to be formed.

Further more. In this embodiment, before the photoresist layer 140a is disposed on the flexible substrate 110, a sublayer may be formed on the upper surface of the flexible substrate 110 by, for example, a sputtering process, and then a first photoresist layer 140a is disposed. The opening 146 of the patterned photoresist layer 141 is formed on the flexible substrate 110 by using the first exposure process, the second exposure process, and the development process to expose the seed layer below, and then, the exposure by the opening 146 can be utilized. Part of the seed layer is plated as a conductive path to form a patterned circuit layer 120 in the opening 146. Of course, this embodiment is only for illustration. In other embodiments, the patterned circuit layer 120 may also be formed by an addition method or a subtraction method, that is, the above-mentioned circuit process may further include an addition method or a subtraction method. Cheng Fa. It should be noted that if the patterned circuit layer 120 is formed by a subtractive method, the patterned photoresist layer 141 is used to cover a region where the patterned circuit layer 120 is to be formed, that is, the patterned photoresist layer The shape of 141 corresponds to the shape of the patterned circuit layer 120. The embodiment of the present invention does not limit the manufacturing method of the patterned circuit layer 120, as long as the patterned circuit layer 120 is formed by using the patterned photoresist layer 141 to perform a circuit process.

FIG. 4A is a schematic partial top view of a flexible circuit board according to another embodiment of the present invention. It must be noted here that the flexible circuit board 100 of this embodiment is similar to the flexible circuit board of FIG. 4. Therefore, in this embodiment, the component numbers and parts of the foregoing embodiments are used, and the same reference numerals are used to indicate the same or similar And the description of the same technical content is omitted. For the description of the omitted parts, reference may be made to the foregoing embodiment, which is not repeatedly described in this embodiment. The differences between the flexible circuit board 100 of this embodiment and the flexible circuit board of FIG. 4 will be described below.

Referring to FIG. 4A, in this embodiment, the patterned circuit layer 120 located in the second section R2 may further include a plurality of pad portions 128, so as to facilitate communication with the next section (for example, the third section R3). The line section 129 is connected. The wiring section 129 of the third section R3 may be formed in a similar manner to the manufacturing process of the wiring section 122 of the first section R1 to be connected to the pad section 128 of the second section R2. That is, in this embodiment, a three-stage exposure process can be performed on the photoresist layer 140a on the first section R1, the second section R2, and the third section R3, so as to form three sections of exposure areas partially overlapping each other. Thereafter, a development process and a circuit process are performed to form a patterned circuit layer 120 in which the three-segment circuit portions 122, 126, and 129 are connected to each other as shown in FIG. 4A. Of course, the exposure pattern of the exposure area of the third section R3 may be different from the first exposure area 142 of the first section R1. That is to say, in the embodiment shown in FIG. 4, the patterned circuit layer 120 may be composed of a circuit portion and a pad portion of a first section R1 and a second section R2 connected to each other. However, in this embodiment, The example does not limit the number of exposure areas and the number of exposure processes. Therefore, the embodiment of the present invention can be divided into sections (for example, the first section R1, the second section R2, the third section R3, etc.) on the flexible substrate 110 having a long length (at least about 500 mm). ) Perform multiple exposure processes to form multiple exposure areas that are connected to each other and partially overlap each other. Therefore, the size limitation of the exposure machine can be overcome without using a connector to connect a plurality of flexible substrates, and a flexible circuit board 100 having a longer length (at least about 500 mm) can be manufactured. In an embodiment, the flexible circuit board 100 shown in FIG. 4 or FIG. 4A manufactured by the above process can be regarded as a panel, and a plurality of panels can be connected to each other (for example, they can be connected to each other through a connector). Connection) to form longer flexible circuit boards. It should be noted that the pad portions 124 and 128 in this embodiment are dummy pads used to connect the first circuit portion 122, the second circuit portion 126, and the third circuit portion 129, and are not used for components. For mounting, that is, the pad portions 124 and 128 are not connected to other electronic components, and are not connected to other through holes below.

FIG. 5 is a schematic partial top view of a flexible circuit board according to an embodiment of the present invention. Please refer to FIG. 5. In this embodiment, after forming the patterned circuit layer 120, a first coverlay 162 may be selectively formed on the flexible substrate 110, wherein the first coverlay 162 covers the first A circuit portion 122 and at least a portion of the pad portion 124. Next, a second cover film 164 may be formed on the flexible substrate 110, wherein the second cover film 164 covers the second circuit portion 126 and the pad portion 124 of another portion not covered by the first cover film 162. In this embodiment, the second cover film 164 and the first cover film 162 are connected to each other, and a joint surface 163 between the second cover film 164 and the first cover film 162 is located on the pad portion 124, that is, The first cover film 162 and the second cover film 164 are bonded to each other on the pad portion 124 and cover the pad portion 124 together. In this embodiment, the materials of the first cover film 162 and the second cover film 164 may include polyimide (PI).

Please refer to FIG. 4 and FIG. 5. In this embodiment, in terms of structure, the flexible circuit board 100 formed according to the above manufacturing method may include a flexible substrate roll 110 and a patterned circuit layer 120. The flexible substrate roll 110 is formed by winding a flexible substrate 110 integrally formed. The patterned circuit layer 120 includes a plurality of first circuit portions 122, a plurality of second circuit portions 126, and a plurality of pad portions 124 connected between the first circuit portion 122 and the second circuit portion 126, respectively. The circuit portions 122 are substantially co-linear with the corresponding second circuit portions 126 and connected to each other via the corresponding pad portions 124.

In this embodiment, the arrangement of the second exposure area 144 and the first exposure area 142 slightly overlapping with each other can effectively prevent the second circuit portion 126 and the pad portion formed according to the tolerance deviation in the length direction D1. 124. A gap is generated in the length direction D1, and a disconnection is caused. In addition, the width of the pad exposure pattern is designed to be greater than the width of each of the second line exposure patterns 144a, so it is possible to effectively prevent the second line formed therefrom due to a tolerance deviation in the width direction (perpendicular to the length direction D1). The portion 126 and the pad portion 124 may have a gap in the width direction and may be disconnected. Therefore, the width W1 of each of the pad portions 124 formed in this way is larger than the line width W2 of each of the second circuit portions 126. For example, a width W1 of each pad portion 124 is approximately between a line width W2 of each second circuit portion 126 plus 10 μm to 1000 μm. That is, the width W1 of each pad portion 124 is approximately one line width W2 of each second circuit portion 126 plus 10 μm to 1000 μm. Therefore, the configuration of this embodiment can further improve the tolerance when the first exposure area 142 and the second exposure area 144 are connected to each other, and can further improve the yield of the flexible circuit board 100 in this embodiment.

In addition, the flexible circuit board 100 of this embodiment may further include a first cover film 162 and a second cover film 164 as shown in FIG. 5. The first cover film 162 is disposed on the flexible substrate 110 and covers the first circuit portion 122 and at least a portion of the pad portion 124. The second cover film 164 is disposed on the flexible substrate 110 and covers the second circuit portion 126 and the pad portion 124 of another portion that is not covered by the first cover film 162. In this embodiment, the positions of the second cover film 164 and the first cover film 162 on the flexible substrate 110 may be the same or different from each other in the first section R1 and the second section R2.

FIG. 6 is a schematic partial top view of a flexible circuit board according to an embodiment of the present invention. FIG. 7 is a schematic partial top view of a flexible circuit board according to an embodiment of the present invention. It must be noted here that the flexible circuit board 100 of the embodiments of FIGS. 6 and 7 is similar to the flexible circuit board 100 of FIG. 4. Therefore, the component numbers and parts of the foregoing embodiments are used in this embodiment, and the same components are used. Numbers are used to indicate the same or similar elements, and descriptions of the same technical content are omitted. For the description of the omitted parts, reference may be made to the foregoing embodiment, which is not repeatedly described in this embodiment. Please refer to FIG. 1 and FIG. 3. Differences between the flexible circuit board 100 of FIGS. 6 and 7 and the flexible circuit board 100 of FIG. 4 will be described below.

As mentioned above, in order to ensure that the first exposure area 142 and the second exposure area 144 formed in two successive sections are not disconnected due to tolerances, the width of the pad portion 124 is not caused due to tolerances. It is usually larger than the line width. In this configuration, when the required fine pitch is small, the pad portions 124 can be staggered with each other along the length direction D1 of the flexible substrate 110 to further reduce the distance between the circuit portions 122 and 126. . Referring to FIG. 7, in other embodiments, each pad portion 124 may be offset by a distance T1 from one side (for example, the upper side) of the flexible substrate 110 compared to the configuration when the first circuit portions 122 are linear. Each first circuit portion 122 and each second circuit portion 126 are bent and extended toward the side to connect each pad portion 124. Of course, the embodiments of the present invention are only used for illustration, and the present invention does not limit the layout and configuration of the first circuit portion 122, the pad portion 124, and the second circuit portion 126.

In summary, the embodiments of the present invention can perform multiple exposure processes in sections on a long flexible substrate to form multiple exposure areas that are spaced from each other and connected to each other, so they can be connected without using a connector. In the case of a multi-stage flexible substrate, the size limitation of the exposure machine can be overcome, and a flexible circuit board with a long length and integrated molding can be manufactured. In addition, the linear circuit board and the manufacturing method thereof according to the embodiments of the present invention can effectively improve the transmission speed of a circuit without reducing the loss of a signal without using a connector to connect multiple sections of flexible substrates.

In addition, the multi-segment exposure process can be partially overlapped. Therefore, the multiple exposure areas formed in sections can be partially overlapped with each other, thereby avoiding the occurrence of disconnection between the multiple-segment exposure areas due to process tolerances. Therefore, the linear circuit board and the manufacturing method thereof according to the embodiments of the present invention can effectively improve the process yield.

Although the present invention has been disclosed as above with the examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field can make some modifications and retouching without departing from the spirit and scope of the present invention. The protection scope of the present invention shall be determined by the scope of the attached patent application.

100‧‧‧ flexible circuit board

110‧‧‧Flexible substrate roll, flexible substrate

120‧‧‧ patterned circuit layer

122‧‧‧First Line Department

124‧‧‧ pad department

126‧‧‧Second Line Department

128‧‧‧ pad department

129‧‧‧Third Line Department

140a‧‧‧Photoresistive layer

141‧‧‧patterned photoresist layer

142‧‧‧First exposure area

142a‧‧‧First line exposure pattern

142b‧‧‧ Pad exposure pattern

144‧‧‧Second exposure area

144a‧‧‧Second line exposure pattern

146‧‧‧ opening

162‧‧‧The first cover film

164‧‧‧Second cover film

163‧‧‧Joint surface

D1‧‧‧length direction

R1‧‧‧Section 1

R2‧‧‧Second Section

R3‧‧‧ third section

T1‧‧‧distance

W1‧‧‧Width

W2‧‧‧line width

FIG. 1 to FIG. 4 are schematic top views of processes of a method for manufacturing a flexible circuit board according to an embodiment of the present invention. FIG. 4A is a schematic partial top view of a flexible circuit board according to another embodiment of the present invention. FIG. 5 is a schematic partial top view of a flexible circuit board according to an embodiment of the present invention. FIG. 6 is a schematic partial top view of a flexible circuit board according to an embodiment of the present invention. FIG. 7 is a schematic partial top view of a flexible circuit board according to an embodiment of the present invention.

Claims (13)

A method for manufacturing a flexible circuit board includes: providing a flexible substrate roll, which is formed by winding a flexible substrate integrally formed; setting a photoresist layer on the flexible substrate; and performing a first exposure process A first exposure region is formed on a first section of the photoresist layer; a second exposure process is performed on a second section of the photoresist layer, so that A second exposure area is formed on the second section, wherein the first exposure area and the second exposure area partially overlap; a developing process is performed on the photoresist layer to remove the first exposure area and the second exposure area. A patterned photoresist layer is formed by exposing the area; a circuit process is performed using the patterned photoresist layer to form a patterned circuit layer, wherein the patterned circuit layer includes a plurality of first circuit portions and a plurality of second circuit portions And a plurality of pad portions are respectively connected between the first circuit portions and the second circuit portions; and the patterned photoresist layer is removed. The method for manufacturing a flexible circuit board according to item 1 of the scope of patent application, wherein a length of the flexible substrate is substantially greater than 500 millimeters (mm). The method for manufacturing a flexible circuit board according to item 1 of the scope of patent application, wherein the first exposure area includes a plurality of first circuit exposure patterns corresponding to the first circuit portions and a plurality of connection portions corresponding to the pad portions. The pad exposure patterns are respectively connected to the first line exposure patterns, and the second exposure area includes a plurality of second line exposure patterns corresponding to the second line portions. The method for manufacturing a flexible circuit board according to item 3 of the scope of patent application, wherein each of the second circuit exposure patterns partially overlaps with each of the pad exposure patterns. The method for manufacturing a flexible circuit board according to item 1 of the scope of patent application, wherein the pad portions are arranged alternately with each other along a length direction of the flexible substrate. According to the method for manufacturing a flexible circuit board according to item 1 of the scope of patent application, wherein each of the pad portions is offset from the side of the flexible substrate by a distance compared to the configuration when the first circuit portions are linear, Each of the first circuit portions and each of the second circuit portions are bent and extended toward the side to connect each of the pad portions. The method for manufacturing a flexible circuit board according to item 1 of the scope of patent application, wherein a width of each of the pad portions is substantially between a line width of each of the second circuit portions plus 10 micrometers (μm) to 1000 micrometers (μm). )between. The method for manufacturing a flexible circuit board according to item 1 of the patent application scope further comprises: forming a first cover film on the flexible substrate; and forming a second cover film on the flexible substrate, wherein the first The two cover films and the first cover film are connected to each other, and a joint surface between the second cover film and the first cover film is located on the pad portions. A flexible circuit board includes: a flexible substrate roll, which is formed by winding a flexible substrate integrally formed and a length of the flexible substrate is substantially greater than 500 mm; a patterned circuit layer including a plurality of layers A first circuit portion, a plurality of second circuit portions, and a plurality of pad portions are respectively connected between the first circuit portions and the second line portions, and the pad portions are respectively connected to the first lines. And the second circuit portions, and each of the first circuit portions is substantially collinear with the corresponding second circuit portion and is connected to each other via a corresponding pad portion. The flexible circuit board according to item 9 of the scope of patent application, wherein the pad portions are staggered with each other along a length direction of the flexible substrate. The flexible circuit board according to item 9 of the scope of patent application, wherein each of the pad portions is offset by a distance from one side of the flexible substrate compared to the arrangement when the first circuit portions are linear. A circuit portion and each of the second circuit portions are bent and extended toward the side to connect each of the pad portions. The flexible circuit board according to item 9 of the scope of patent application, wherein a width of each of the pad portions is substantially between a line width of each of the second circuit portions plus 10 micrometers (μm) to 1000 micrometers (μm). . The flexible circuit board according to item 9 of the scope of patent application, further comprising: a first cover film provided on the flexible substrate; and a second cover film provided on the flexible substrate, wherein the second cover film The cover film and the first cover film are connected to each other, and a joint surface between the second cover film and the first cover film is located on the pad portions.