Flexible circuit board and method of manufacturing the same

Abstract

This invention provides a flexible circuit board and its manufacturing method. The flexible circuit board includes an insulating substrate, and each of the two opposite end faces of the insulating substrate has a groove. A signal line is disposed in the insulating substrate, and the insulating substrate surrounds the signal line. Two flexible circuit boards are respectively located on opposite surfaces of the insulating substrate, and each flexible circuit board includes a conductive layer and a power layer. The conductive layer extends from one surface of the insulating substrate toward the end face and extends along the end face into the groove. The power layer is located between the conductive layer and the insulating substrate and is electrically connected to the conductive layer. One conductive layer connects to the other conductive layer within the groove, and the two conductive layers are electrically connected to each other. In this way, the electromagnetic shielding effect of the flexible circuit board can be improved.

Description

Technical Field

[0001] This invention relates to a flexible circuit board, and more particularly to a flexible circuit board for high-frequency signal transmission and a method for manufacturing the same. Background Technology

[0002] With the rapid development of wireless communication, the requirements for signal transmission speed and terminal network density are gradually increasing, leading to the development of Multiple-Input Multiple-Output (MIMO) wireless communication antenna technology. Although existing electromagnetic shielding technology can meet the transmission signal requirements within a specific frequency range, with the increasing demand for high-frequency transmission, for example, when the signal frequency exceeds 50GHz, the interference of external signals on communication antennas and transmission lines will become more severe.

[0003] On the other hand, the main method for achieving electromagnetic shielding of transmission lines or antennas is to set conductive vias between the various circuit layers of the transmission line and use these vias to block signals. However, this method of setting conductive vias has limited electromagnetic shielding effect on high-frequency signals and also restricts the layout of circuit layers inside the transmission line. Summary of the Invention

[0004] Therefore, the present invention provides a flexible circuit board and a method for manufacturing the same, thereby improving the electromagnetic shielding effect of the flexible circuit board on high-frequency signals.

[0005] An embodiment of the present invention provides a flexible circuit board comprising an insulating substrate, wherein each of the two opposite end faces of the insulating substrate has a groove. A signal line is disposed in the insulating substrate, and the insulating substrate surrounds the signal line. Two flexible circuit boards are respectively located on opposite surfaces of the insulating substrate, wherein each of the flexible circuit boards comprises a conductive layer and a power layer. The conductive layer extends from one surface of the insulating substrate toward the end face and extends along the end face into the groove. The power layer is located between the conductive layer and the insulating substrate and is electrically connected to the conductive layer. One of the conductive layers is connected to the other conductive layer within the groove, and the conductive layers are electrically connected to each other.

[0006] In at least one embodiment of the present invention, the flexible circuit board further includes two conductive structures located in the groove, and one conductive layer is connected to the other conductive layer through the conductive structure.

[0007] In at least one embodiment of the present invention, each conductive structure includes a ground terminal and two welding materials. The welding materials are respectively located on opposite sides of the ground terminal. The conductive layers are electrically connected to the ground terminal through the welding materials, and the power layers are electrically connected to the ground terminal through the welding materials.

[0008] In at least one embodiment of the invention, each conductive structure further comprises two metallic materials located on opposite sides of the grounding terminal and on the bottom surface of the groove. The conductive layer is electrically connected to the grounding terminal via a welding material and the metallic materials.

[0009] In at least one embodiment of the invention, the power layer includes two ground wires and a power supply wire. A portion of each ground wire is located within a recess and connected to a conductive structure. The power supply wire is located between the two ground wires and is electrically connected to the ground wires.

[0010] In at least one embodiment of the present invention, each flexible circuit board further includes an insulating layer, wherein a conductive layer and a power layer are located on opposite sides of the insulating layer, and the thickness of the power layer is greater than the thickness of the conductive layer.

[0011] In at least one embodiment of the present invention, the insulating substrate comprises a liquid crystal polymer material.

[0012] In at least one embodiment of the present invention, a cover layer is further included, disposed on the conductive layer of the flexible circuit board and surrounding the insulating substrate and the flexible circuit board.

[0013] The present invention also provides a method for manufacturing a flexible circuit board, comprising providing a substrate including signal lines and two ground terminals, with the signal lines located between the ground terminals; removing a portion of the substrate to form grooves on two opposite end faces of the substrate, exposing a portion of the ground terminals, wherein one of the grooves has two first boundaries with respect to one of the end faces; providing two flexible circuit boards, each of the flexible circuit boards including a conductive layer and a power layer, wherein the conductive layer is electrically connected to the power layer; after removing a portion of the substrate, disposing the flexible circuit boards on opposite surfaces of the substrate, with the power layer located between the conductive layer and the substrate, wherein the surface of the substrate has two second boundaries with respect to one of the end faces; and after disposing the flexible circuit boards on the substrate, bending one of the flexible circuit boards at opposite ends along the second boundaries and along the first boundaries, such that one conductive layer connects to the other conductive layer within a groove, and the conductive layers are electrically connected to each other.

[0014] In at least one embodiment of the present invention, providing a substrate includes providing an initial substrate comprising an insulating layer and a metal layer respectively located on opposite sides of the initial substrate; forming two metal materials on each opposite side of the initial substrate; patterning the metal layers to form signal lines and ground terminals spaced apart from each other, wherein the metal materials are respectively located on the ground terminals and electrically connected to the ground terminals; and after forming the ground terminals and signal lines, disposing insulating materials on the insulating layer and the signal lines respectively to form a substrate, wherein the insulating layer, the ground terminals and the signal lines are located between two insulating materials, and the insulating materials cover the signal lines and the ground terminals.

[0015] In at least one embodiment of the present invention, providing a flexible circuit board includes providing an initial flexible circuit board comprising a conductive layer and a metal layer, wherein the thickness of the conductive layer is less than the thickness of the metal layer; forming a metal block on the metal layer; and patterning the metal layer to form a flexible circuit board including a power layer. The power layer includes a power supply line and two ground lines, with the power supply line located between the two ground lines, and the metal block located on the power supply line.

[0016] In at least one embodiment of the present invention, the method further includes removing another portion of the substrate to form recessed regions on the surface of the substrate; and aligning a metal block of the flexible circuit board with the recessed regions and disposing it on the substrate.

[0017] In at least one embodiment of the invention, one of the flexible circuit boards further includes, after a patterned metal layer, a cover layer attached to a conductive layer, wherein the cover layer covers a power supply line and a portion of each ground line.

[0018] Based on the above, the flexible circuit board extends along the surface and end face of the insulating substrate, and extends into a groove on the end face of the insulating substrate, so that the conductive layers of the flexible circuit board are interconnected in the groove. In this way, the conductive layers surround the outside of the insulating substrate, thereby forming a fully shielded electromagnetic shielding layer, which helps to improve the electromagnetic shielding effect of the flexible circuit board. Attached Figure Description

[0019] The nature of the invention can be understood from the following detailed description and accompanying drawings. It should be noted that many features are not drawn to industry-standard scale. In fact, for clarity of discussion, the dimensions of various features may be arbitrarily increased or decreased.

[0020] Figure 1 A cross-sectional view of a flexible circuit board according to an embodiment of the present invention is shown.

[0021] Figures 2A to 2E A cross-sectional view illustrating a method for manufacturing a flexible circuit board according to an embodiment of the present invention is shown.

[0022] Figures 3A to 3C A cross-sectional view illustrating a method for manufacturing a flexible circuit board according to an embodiment of the present invention is shown.

[0023] Figure 4 A cross-sectional view illustrating a method for manufacturing a flexible circuit board according to an embodiment of the present invention is shown.

[0024] Figure 5 A cross-sectional view illustrating a method for manufacturing a flexible circuit board according to an embodiment of the present invention is shown. Detailed Implementation

[0025] The present invention will be described in detail with reference to the following embodiments. It should be noted that the following description of the embodiments of the present invention is for illustrative purposes only and is not intended to disclose all embodiments exhaustively or to limit the specific embodiments of the invention. For example, the phrase "a first feature is formed on a second feature" in the description includes various implementations, covering both situations where the first and second features are in direct contact, and situations where an additional feature is formed between the first and second features so that they are not in direct contact. Furthermore, the same element symbols used in the drawings and specification will, as far as possible, represent the same or similar elements.

[0026] Spatially relative terms, such as "lower," "below," "below," "above," and "above," are used here to simply describe the relationship between an element or feature as shown in the figure and another element or feature. These spatially relative terms cover not only the orientation depicted in the figure but also different orientations when using or operating the device. Furthermore, when the element is rotatable (rotating 90 degrees or other angles), the spatially relative descriptive terms used here can also be interpreted accordingly.

[0027] In the following text, to clearly present the technical features of this application, the dimensions (e.g., length, width, thickness, and depth) of the elements (e.g., layers, films, substrates, and regions) in the accompanying drawings will be enlarged proportionally. Therefore, the description and explanation of the embodiments below are not limited to the dimensions and shapes presented by the elements in the drawings, but should cover dimensions, shapes, and deviations from both due to actual manufacturing processes and / or tolerances. For example, a flat surface shown in the drawings may have rough and / or non-linear characteristics, and an acute angle shown in the drawings may be replaced by an obtuse angle. Therefore, the elements presented in the accompanying drawings are primarily illustrative and not intended to precisely depict the actual shape of the elements, nor are they intended to limit the claims of this application.

[0028] Furthermore, the terms "approximately," "approximately," or "substantially" used in this case not only encompass explicitly stated numerical values ​​and ranges, but also the permissible deviation range understandable to someone skilled in the art, where such deviation range can be determined by errors arising during measurement, such as those caused by limitations of the measurement system or process conditions. Additionally, "approximately" can indicate a deviation within one or more standard deviations of the aforementioned numerical values, such as ±30%, ±20%, ±10%, or ±5%. The terms "approximately," "approximately," or "substantially" used in this case can be chosen based on optical, etching, mechanical, or other properties to select an acceptable deviation range or standard deviation, and do not apply a single standard deviation to all optical, etching, mechanical, and other properties.

[0029] This invention discloses a flexible circuit board; please refer to [reference needed]. Figure 1 The flexible circuit board 10 includes an insulating substrate 100, signal lines 102, and two flexible circuit boards 120. The signal lines 102 are disposed within the insulating substrate 100, and the insulating substrate 100 surrounds the signal lines 102. The flexible circuit boards 120 are located on opposite surfaces of the insulating substrate 100. Specifically, one flexible circuit board 120 is located on surface 100f of the insulating substrate 100, while the other flexible circuit board 120 is located on surface 100s of the insulating substrate 100. In this embodiment, the material of the insulating substrate 100 may include materials with good thermoplasticity, such as liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE), or polyetheretherketone (PEEK). Furthermore, since these materials have low dielectric constants and loss coefficients, they facilitate the transmission of high-frequency signals in the flexible circuit board 10.

[0030] It is worth mentioning that, since the insulating substrate 100 completely covers the signal line 102, the signal line 102 is separated by two flexible circuit boards 120. Figure 1 As shown, each of the two opposing end faces 100a and 100b of the insulating substrate 100 has a groove 104. In addition, each flexible circuit board 120 includes a conductive layer 122. The conductive layer 122 of the flexible circuit board 120 located on surface 100f extends from surface 100f of the insulating substrate 100 toward end faces 100a and 100b, and extends along end faces 100a and 100b into the two grooves 104. The conductive layer 122 of the flexible circuit board 120 located on surface 100s extends from surface 100s of the insulating substrate 100 toward end faces 100a and 100b, and extends along end faces 100a and 100b into the two grooves 104.

[0031] In detail, each conductive layer 122 extends from one of the surfaces of the insulating substrate 100 (e.g., surface 100f or surface 100s) toward end face 100a and end face 100b respectively, and extends along end face 100a and end face 100b to the sidewall 104w of the groove 104 respectively.

[0032] One conductive layer 122 connects to the other conductive layer 122 within the groove 104, and the two conductive layers 122 are electrically connected to each other. In other words, the connection between the two conductive layers 122 is located within the two grooves 104, and because the two conductive layers 122 are electrically connected to each other, an electromagnetic shielding layer is formed around the insulating substrate 100 (and around the signal line 102). It is worth mentioning that one conductive layer 122 does not necessarily directly contact the other conductive layer 122; one conductive layer 122 can also be connected (and electrically connected) to the other conductive layer 122 through other components.

[0033] Each flexible circuit board 120 includes a power layer 124 located between the conductive layer 122 and the insulating substrate 100, and electrically connected to the conductive layer 122. In this embodiment, each flexible circuit board 120 further includes an insulating layer 126, with the conductive layer 122 and the power layer 124 located on opposite sides of the insulating layer 126. The materials of the conductive layer 122 and the power layer 124 may include conductive materials such as copper, while the material of the insulating layer 126 may include organic resin materials such as modified polyimide (MPI) or fluorinated polyimide, or similar materials. Notably, in this embodiment, the thickness of the power layer 124 is greater than the thickness of the conductive layer 122. For example, the thickness of the power layer 124 may fall between 18 μm and 90 μm, while the thickness of the conductive layer 122 may fall between 0.2 μm and 12 μm.

[0034] In addition, the flexible circuit board 120 and the insulating substrate 100 include two bonding layers 110. The bonding layers 110 are located on the surfaces 100f and 100s of the insulating substrate 100, respectively, and cover the surface of the power layer 124. The material of the bonding layers 110 may include, for example, epoxy resin or other insulating adhesives with bonding properties.

[0035] In this embodiment, the flexible circuit board 10 may further include two conductive structures 140, each located within a recess 104 of the insulating substrate 100. One conductive layer 122 is connected to the other conductive layer 122 via a conductive structure 140, and the two conductive layers 122 are electrically connected to each other via the two conductive structures 140. For example, please refer to... Figure 1 The left end of the upper conductive layer 122 is connected to the left conductive structure 140, and the left end of the lower conductive layer 122 is also connected to this conductive structure 140. On the other hand, the right end of the upper conductive layer 122 is connected to the right conductive structure 140, and the right end of the lower conductive layer 122 is also connected to this conductive structure 140, thereby forming an electromagnetic shielding layer surrounding the insulating substrate 100 (and surrounding the signal line 102).

[0036] In this embodiment, each conductive structure 140 may further include a ground terminal 142 and two welding materials 144. The welding materials 144 are located on opposite sides of the ground terminal 142, and the two conductive layers 122 located on opposite sides of the conductive structure 140 are electrically connected to the ground terminal 142 through the welding materials 144. For example, please refer to... Figure 1 In the conductive structure 140 on the left, the upper welding material 144 is electrically connected to the upper conductive layer 122 and the ground terminal 142, while the lower welding material 144 is electrically connected to the lower conductive layer 122 and the ground terminal 142.

[0037] In addition, the two power layers 124 located on opposite sides of the conductive structure 140 are also electrically connected to the ground terminal 142 via solder material 144. For example, please refer to... Figure 1 In the conductive structure 140 on the left, the upper solder material 144 is electrically connected to the upper power layer 124 and the ground terminal 142, while the lower solder material 144 is electrically connected to the lower power layer 124 and the ground terminal 142. The ground terminal 142 may contain a conductive metal material such as copper, while the solder material 144 may contain, for example, solder paste, copper paste, or silver paste.

[0038] Notably, in this embodiment, each conductive structure 140 also includes two metal materials 146, located on opposite sides of the grounding terminal 142, wherein the metal materials 146 may include copper. Figure 1 As shown, metal material 146 is located on the bottom surface (not shown) of groove 104, and solder material 144 is located between metal material 146 and flexible circuit board 120. Furthermore, the conductive layer 122 of flexible circuit board 120 can be electrically connected to ground terminal 142 via solder material 144 and metal material 146, and the power layer 124 of flexible circuit board 120 can also be electrically connected to ground terminal 142 via solder material 144 and metal material 146.

[0039] Since the conductive layer 122 and the power layer 124 of the flexible circuit board 120 are respectively connected to the soldering material 144, in this embodiment, the power layer 124 is electrically connected to the conductive layer 122 through the soldering material 144. However, the present invention is not limited to this. For example, in other embodiments, conductive vias may be provided in the insulating layer 126, and the conductive layer 122 and the power layer 124 may be electrically connected through the conductive vias.

[0040] In this embodiment, the power layer 124 further includes two ground wires 124g and one power supply wire 124p. A portion of each ground wire 124g is located within a recess 104 and connected to the conductive structure 140. Specifically, the ground wire 124g located within the recess 104 is electrically connected to a ground terminal 142 via a soldering material 144. On the other hand, the power supply wire 124p is located between the two ground wires 124g and is electrically connected to the ground wires 124g. Notably, in some embodiments of the present invention, the thickness of a portion of the power supply wire 124p may be greater than the thickness of other portions (e.g., ...). Figure 1 (Central area of ​​power supply line 124p) to increase the current carrying capacity of power layer 124.

[0041] The flexible circuit board 10 may further include a cover layer 160, which is disposed on the conductive layer 122 of the flexible circuit substrate 120 and surrounds the insulating substrate 100 and the two flexible circuit substrates 120. In other words, the cover layer 160 covers the outer surfaces of the two flexible circuit substrates 120 and encapsulates the flexible circuit substrates 120 and the insulating substrate 100, thereby isolating the flexible circuit substrates 120 from the outside world. The material of the cover layer 160 may include insulating materials such as resin to protect the flexible circuit substrates 120 from external influences that may cause reactions such as oxidation.

[0042] This invention discloses a method for manufacturing a flexible circuit board. Taking the aforementioned flexible circuit board 10 as an example, this manufacturing method may include the following steps: Figures 2A to 2E , Figures 3A to 3C , Figure 4 and Figure 5 The steps are shown. In this embodiment, firstly, a substrate 200 (labeled as shown) is provided. Figure 2E For detailed steps on providing substrate 200, please refer to [link / reference needed]. Figures 2A to 2E .like Figure 2A As shown, an initial substrate 210 is first provided, which includes an insulating layer 212 and a metal layer 214. In various embodiments of the present invention, the initial substrate 210 may be a flexible copper foil substrate (FCCL) containing a liquid crystal polymer material, wherein the insulating layer 212 and the metal layer 214 are respectively located on opposite sides of the initial substrate 210.

[0043] Next, please refer to Figure 2BAt least two openings 212p can be formed on the insulating layer 212 by means such as ablation with a laser or a similar method. The metal layer 214 covers one side of the opening 212p, meaning that the opening 212p does not connect the opposite sides of the insulating layer 212. After forming the openings 212p, a photoresist layer (not shown) is respectively disposed on the insulating layer 212 and the metal layer 214, and the photoresist layer is patterned by a lithography process to form multiple openings (not shown) on the photoresist layer, which overlap with the openings 212p of the insulating layer 212.

[0044] Please refer to this as well. Figure 2A and Figure 2B After forming openings in the photoresist layer, two metal materials 146 can be formed on each of the opposite sides of the initial substrate 210 by means of, for example, electroplating. These metal materials 146 are formed in the openings of the photoresist layers on both sides, and the openings overlap with the openings 212p of the insulating layer 212. Therefore, two of the metal materials 146 will overlap at one of the openings 212p, while the other two metal materials 146 will overlap at the other opening 212p.

[0045] Please refer to Figure 2C After forming the metal material 146, a patterned metal layer 214 is formed to create signal lines 102 and two ground terminals 142 that are separated from each other. The signal lines 102 are located between the two ground terminals 142, while the metal materials 146 are located on the ground terminals 142 respectively and are electrically connected to the ground terminals 142. Specifically, two metal materials 146 are located on opposite sides of one of the ground terminals 142, and two other metal materials 146 are located on opposite sides of the other ground terminal 142.

[0046] After forming ground terminal 142 and signal line 102, please refer to Figure 2D Insulating material 222 is disposed on insulating layer 212 and signal line 102 respectively to form substrate 200 (marked on Figure 2E Specifically, an insulating material 222 is disposed on the surface 212s of the insulating layer 212, and another insulating material 222 is disposed on the surface 102s of the signal line 102, such that the insulating layer 212, the ground terminal 142, and the signal line 102 are located between the two insulating materials 222. The insulating material 222 covers the signal line 102 and the ground terminal 142. In addition, the insulating material 222 is also covered with a metallic material 146.

[0047] It is worth mentioning that, in this embodiment, the insulating material 222 may comprise materials with good thermoplasticity, such as liquid crystal polymers, polytetrafluoroethylene, or polyetheretherketone. The steps for respectively setting the insulating material 222 on the insulating layer 212 and the signal line 102 are detailed as follows: Two flexible copper foil substrates 220 containing the insulating material 222 are respectively disposed on the insulating layer 212 and the signal line 102 by hot pressing. Next, the copper foil 205 on the flexible copper foil substrates 220 is removed by etching.

[0048] Please refer to Figure 2E After insulating material 222 is applied to insulating layer 212 and signal line 102 respectively, a portion of substrate 200 is removed to form grooves 104 on two opposing end faces 200a and 200b of substrate 200, exposing a portion of each metal material 146 and a portion of ground terminal 142. One groove 104 has two first boundaries A1 between it and end face 200a, while the other groove 104 has two additional first boundaries B1 between it and end face 200b.

[0049] Next, two flexible circuit boards 120 are provided, each flexible circuit board 120 including a conductive layer 122 and a power layer 124, and the conductive layer 122 is electrically connected to the power layer 124. For detailed steps on providing one of the flexible circuit boards 120, please refer to [link to documentation]. Figures 3A to 3C First, as Figure 3A As shown, an initial flexible circuit board 120' is provided, which includes a conductive layer 122 and a metal layer 324, and the conductive layer 122 and the metal layer 324 are located on opposite sides of the insulating layer 126.

[0050] It is worth mentioning that this initial flexible circuit board 120' can be a flexible copper foil substrate containing liquid crystal polymer material, that is, the materials of the conductive layer 122 and the metal layer 324 can contain copper foil, and the material of the insulating layer 126 can contain liquid crystal polymer material. In addition, in this embodiment, the thickness of the conductive layer 122 is less than the thickness of the metal layer 324, but the present invention is not limited thereto.

[0051] Next, please refer to Figure 3B By means of, for example, electroplating, on metal layer 324 (indicated in Figure 3A A metal block 324b is formed on the metal layer 324. The material of this metal block 324b can be the same as the material of the metal layer 324 (in this embodiment, a metal material containing copper), in other words, the metal block 324b can be equivalent to a thickening layer of the metal layer 324. However, the invention is not limited to this, and in other embodiments, the metal block 324b may not be formed on the metal layer 324.

[0052] After forming the metal block 324b, the metal layer 324 can be patterned, for example, by chemical etching, to form a flexible circuit substrate 120 containing the power layer 124. Figure 3B As shown, the power layer 124 includes a power supply line 124p and two ground lines 124g, with the power supply line 124p located between the two ground lines 124g. Notably, a metal block 324b is located on the power supply line 124p. Although in this embodiment, the step of patterning the metal layer 324 is performed after the metal block 324b is formed, the invention is not limited thereto. In other embodiments, the metal layer 324 may be patterned before the metal block 324b is formed.

[0053] Thus, a flexible circuit board 120 is formed, and the manufacturing steps of both flexible circuit boards 120 in this invention can be described as above. Next, please refer to... Figure 3C In this embodiment, after the patterned metal layer 324, a cover layer 160 can be bonded to the conductive layer 122 by thermoforming. This cover layer 160 covers a portion of the conductive layer 122, and also covers a portion of the power supply line 124p and each ground line 124g.

[0054] Please return Figure 2E In this embodiment, the manufacturing method of the flexible circuit board 10 may further include removing another portion of the substrate 200 to form recessed regions 206 on surfaces 200f and 200s of the substrate 200. Surfaces 200f and 200s of the substrate 200 have two second boundaries A2 (or two second boundaries B2) between them and one of the end faces 200a (or 200b). Specifically, end face 200a has one second boundary A2 between it and surface 200f, and also has one second boundary A2 between it and surface 200s. The other end face 200b has one second boundary B2 between it and surface 200f, and also has one second boundary B2 between it and surface 200s.

[0055] Please refer to Figure 4 After removing part of the substrate 200, two flexible circuit boards 120 are respectively disposed on two opposite surfaces 200f and 200s of the substrate 200, such that the power layer 124 of the flexible circuit board 120 is located between the conductive layer 122 and the substrate 200, that is, the power layer 124 of the two flexible circuit boards 120 both face the substrate 200.

[0056] In this embodiment, the metal block 324b of the flexible circuit board 120 can be aligned with the recessed region 206 and disposed on the substrate 200, with the metal block 324b located within the recessed region 206 of the substrate 200. Notably, before disposing the flexible circuit board 120 on the substrate 200, a bonding layer 110 can be disposed on the power layer 124 of the flexible circuit board 120, covering the surface of the power layer 124 (and the metal block 324b). After disposing the bonding layer 110, the flexible circuit board 120 is then disposed on the substrate 200 by thermoforming.

[0057] Please refer to Figure 5 After a flexible circuit board 120 is formed on the substrate 200, one of the flexible circuit boards 120 is bent along the second boundary A2 and the second boundary B2, respectively, and along the first boundary A1 and the first boundary B1, respectively, by hot pressing. This causes one conductive layer 122 (i.e., the conductive layer 122 of one flexible circuit board 120) to connect to another conductive layer 122 (i.e., the conductive layer 122 of the other flexible circuit board 120) within the groove 104. Alternatively, two cover layers 160 can be connected by hot pressing to form a protective layer surrounding the substrate 200 and the two flexible circuit boards 120.

[0058] It is worth mentioning that the two conductive layers 122 are electrically connected to each other after bending. In this embodiment, the two conductive layers 122 are respectively connected to the ground terminal 142 by solder material 144. Before the flexible circuit board 120 is provided on the substrate 200, these solder materials 144 can be provided on the ground terminal 142 and the metal material 146 by, for example, tin spraying. When the flexible circuit board 120 is bent by hot pressing, the conductive layers 122 also bend and come into contact with the solder material 144 in the groove 104. Then, the solder material 144 can be heated and melted by, for example, laser heating, thereby connecting the conductive layers 122 to the ground terminal 142. Thus, a structure such as Figure 1 The flexible circuit board 10 is shown.

[0059] In summary, the materials of the insulating layer and the insulating substrate in the flexible circuit board include materials with good thermoplastic properties (such as liquid crystal polymers and modified polyimide). These thermoplastic properties allow the two ends of the flexible circuit board to bend along the boundary of the insulating substrate, connecting the flexible circuit boards located on opposite sides of the insulating substrate. In this way, the flexible circuit board surrounds the outside of the insulating substrate, and the conductive layer within the flexible circuit board also surrounds the outside of the insulating substrate. Because the two conductive layers are electrically connected, a fully shielded electromagnetic shielding layer can be formed in the flexible circuit board, protecting the signal lines from the influence of external high-frequency signals.

[0060] In addition, because the insulating layer material in the flexible circuit board has good thermoplastic properties, it can adhere more tightly to the outside of the insulating substrate when the flexible circuit board is bent under heat and pressure. Therefore, it can reduce the occurrence of bubbles or breakage of the flexible circuit board during the process, thereby improving the yield of flexible circuit boards.

[0061] Although the embodiments of the present invention have been disclosed above, they are not intended to limit the embodiments of the present invention. Any person skilled in the art can make some modifications and refinements without departing from the spirit and scope of the embodiments of the present invention. Therefore, the protection scope of the embodiments of the present invention shall be determined by the appended claims.

[0062] [Symbol Explanation]

[0063] 10: Flexible Circuit Board

[0064] 100: Insulating substrate

[0065] 102: Signal line

[0066] 100a, 100b, 200a, 200b: End face

[0067] 100f, 100s, 102s, 200f, 200s, 212s: Surface

[0068] 104: Groove

[0069] 104w: Sidewall

[0070] 110: Bonding layer

[0071] 120: Flexible Circuit Board

[0072] 122: Conductive layer

[0073] 124: Power Layer

[0074] 124g: Grounding wire

[0075] 124p: Power supply cable

[0076] 126,212: Insulation layer

[0077] 140: Conductive structure

[0078] 142: Grounding terminal

[0079] 144: Welding materials

[0080] 146: Metallic Materials

[0081] 160: Overlay

[0082] 200:Substrate

[0083] 205: Copper Foil

[0084] 210: Initial substrate

[0085] 212p: Opening

[0086] 214, 324: Metallic layer

[0087] 220: Flexible copper foil substrate

[0088] 222: Insulating materials

[0089] 324b: Metal block

[0090] A1, B1: First boundary

[0091] A2, B2: Second boundary.

Claims

1. A flexible circuit board, characterized by, Comprising: an insulating substrate, and each of opposite two end surfaces of the insulating substrate has a recess; a signal line disposed in the insulating substrate, and the insulating substrate surrounds the signal line; and two flexible circuit substrates respectively located on the opposite two surfaces of the insulating substrate, wherein each of the flexible circuit substrates comprises: a conductive layer extending from one of the surfaces of the insulating substrate toward the end surface and extending along the end surface into the recess; and a power supply layer located between the conductive layer and the insulating substrate and electrically connected to the conductive layer; wherein one of the conductive layers is connected to the other one of the conductive layers in the recess, and the conductive layers are electrically connected to each other.

2. The flexible circuit board of claim 1, wherein, Further comprising: two conductive structures respectively located in the recess, and one of the conductive layers is connected to the other one of the conductive layers through the conductive structures.

3. The flexible circuit board of claim 2, wherein each of the conductive structures comprises: a ground terminal; and two solder materials respectively located on opposite sides of the ground terminal, wherein the conductive layer is electrically connected to the ground terminal through the solder materials, and the power supply layer is electrically connected to the ground terminal through the solder materials.

4. The flexible circuit board of claim 3, wherein each of the conductive structures further comprises: two metal materials respectively located on opposite sides of the ground terminal and on a bottom surface of the recess, wherein the conductive layer is electrically connected to the ground terminal through the solder materials and the metal materials.

5. The flexible circuit board of claim 2, wherein the power supply layer comprises: two ground lines, and a portion of each of the ground lines is respectively located in the recess and connected to the conductive structure; and a supply line located between the ground lines and electrically connected to the ground lines.

6. The flexible circuit board of claim 1, wherein each of the flexible circuit substrates further comprises: an insulating layer, wherein the conductive layer and the power supply layer are respectively located on opposite sides of the insulating layer, and the thickness of the power supply layer is greater than the thickness of the conductive layer.

7. The flexible circuit board of claim 1, wherein the insulating substrate comprises liquid crystal polymer material.

8. The flexible circuit board of claim 1, wherein, Further comprising: a cover layer disposed on the conductive layer of the flexible circuit substrate and surrounding the insulating substrate and the flexible circuit substrate.

9. A method of manufacturing a flexible circuit board, characterized by, Comprising: providing a substrate comprising a signal line and two ground terminals, and the signal line is located between the ground terminals; removing a portion of the substrate to form a recess on each of opposite two end surfaces of the substrate and expose a portion of the ground terminals, and one of the recesses and one of the end surfaces have two first boundaries therebetween; providing two flexible circuit substrates, each of the flexible circuit substrates comprises a conductive layer and a power supply layer, and the conductive layer is electrically connected to the power supply layer; After removing a portion of the substrate, the flexible circuit substrate is disposed on opposite surfaces of the substrate, respectively, with the power layer between the conductive layer and the substrate, wherein two second boundaries are formed between the surfaces of the substrate and one of the end surfaces; and After disposing the flexible circuit substrate on the substrate, opposite ends of one of the flexible circuit substrates are bent along the second boundaries, respectively, and are bent along the first boundaries, respectively, such that one of the conductive layers connects the other conductive layer in the groove, and the conductive layers are electrically connected to each other.

10. The method of claim 9, wherein, Providing the substrate includes: providing an initial substrate including an insulating layer and a metal layer on opposite sides of the initial substrate, respectively; forming two metal materials on the opposite sides of the initial substrate, respectively; patterning the metal layer to form the signal lines and the ground terminals separated from each other, with the metal materials on the ground terminals, respectively, and electrically connected to the ground terminals; and after forming the ground terminals and the signal lines, disposing an insulating material on the insulating layer and the signal lines, respectively, to form the substrate, wherein the insulating layer, the ground terminals, and the signal lines are between the insulating materials, and the insulating materials cover the signal lines and the ground terminals.

11. The method of claim 9, wherein, Providing one of the flexible circuit substrates includes: providing an initial flexible circuit substrate including the conductive layer and a metal layer, wherein a thickness of the conductive layer is less than a thickness of the metal layer; forming a metal block on the metal layer; and patterning the metal layer to form the flexible circuit substrate including the power layer. The power layer includes a power line and two ground lines, with the power line between the ground lines, wherein the metal block is on the power line. Further includes:

12. The method of claim 11, wherein, removing another portion of the substrate to form recessed areas on the surfaces of the substrate, respectively; and disposing the metal block of the flexible circuit substrate on the substrate in alignment with the recessed areas. Providing one of the flexible circuit substrates further includes:

13. The method of claim 11, wherein, after patterning the metal layer, adhering a cover layer on the conductive layer, wherein the cover layer covers a portion of each of the power line and the ground lines. ​

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