Flexible circuit board and manufacturing method thereof

Abstract

The invention provides a flexible circuit board and a manufacturing method thereof, the flexible circuit board comprises an insulating substrate, and two opposite end faces of the insulating substrate are respectively provided with a groove. The signal line is arranged in the insulating substrate, and the insulating substrate surrounds the signal line. The two layers of flexible circuit substrates are respectively arranged on two opposite surfaces of the insulating substrate, and each flexible circuit substrate comprises a conductive layer and a power supply layer. The conductive layer extends from one surface of the insulating substrate to the end face and extends into the groove along the end face. The power supply layer is located between the conductive layer and the insulating substrate and is electrically connected with the conductive layer. Wherein one conducting layer is connected with the other conducting layer in the groove, and the two conducting layers are electrically connected with each other. Therefore, the electromagnetic shielding effect of the flexible circuit board can be improved.

Description

Technical Field

[0001] The present invention relates to a flexible circuit board, and in particular to a flexible circuit board for high-frequency signal transmission and a manufacturing method thereof. Background Art

[0002] With the rapid development of wireless communication, the requirements for signal transmission speed and terminal connection density are gradually increasing, and multiple-input multiple-output (MIMO) wireless communication antenna technology has been developed. Although the existing electromagnetic shielding technology can meet the transmission signal within a specific frequency range, with the increase in high-frequency transmission requirements, for example, when the signal frequency exceeds 50GHz, the communication antenna and transmission line will be more susceptible to external signals.

[0003] On the other hand, the main way to achieve electromagnetic shielding of transmission lines or antennas is to set conductive vias between the circuit layers of the transmission line and block the signal through these conductive vias. 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 manufacturing method thereof, so as to enhance the electromagnetic shielding effect of the flexible circuit board on high-frequency signals.

[0005] A flexible circuit board provided in one embodiment of the present invention comprises an insulating substrate, and each of the two opposite end surfaces of the insulating substrate has a groove. A signal line is arranged in the insulating substrate, and the insulating substrate surrounds the signal line. Two layers of flexible circuit substrates are respectively located on two opposite surfaces of the insulating substrate, wherein each of the flexible circuit substrates comprises a conductive layer and a power layer, and the conductive layer extends from one surface of the insulating substrate toward the end surface, and extends into the groove along the end surface. 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 in 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 respectively located in the grooves, and one conductive layer is connected to the other conductive layer through the conductive structures.

[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 layer is electrically connected to the ground terminal through the welding materials, and the power supply layer is electrically connected to the ground terminal through the welding materials.

[0008] In at least one embodiment of the present invention, each conductive structure further comprises two metal materials, which are respectively located at two opposite sides of the ground terminal and at the bottom surface of the groove. The conductive layer is electrically connected to the ground terminal through the welding material and the metal material.

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

[0010] In at least one embodiment of the present invention, each flexible circuit substrate further includes an insulating layer, wherein the conductive layer and the power layer are respectively located on two opposite sides of the insulating layer, and the thickness of the power layer is greater than that 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 covering layer is further included, which is disposed on the conductive layer of the flexible circuit substrate and surrounds the insulating substrate and the flexible circuit substrate.

[0013] The present invention also provides a method for manufacturing a flexible circuit board, comprising providing a substrate, the substrate comprising a signal line and two grounding ends, and the signal line is located between the grounding ends; removing part of the substrate to form a groove on each of the two opposite end surfaces of the substrate and expose a part of the grounding end, and two first boundaries are provided between one of the grooves and one of the end surfaces; providing two flexible circuit substrates, each of the flexible circuit substrates comprising a conductive layer and a power layer, and the conductive layer is electrically connected to the power layer; after removing part of the substrate, the flexible circuit substrates are respectively arranged on the two opposite surfaces of the substrate, and the power layer is located between the conductive layer and the substrate, and two second boundaries are provided between the surface of the substrate and one of the end surfaces; and after the flexible circuit substrate is arranged on the substrate, the opposite ends of one of the flexible circuit substrates are respectively bent along the second boundaries and respectively bent along the first boundaries, so that one of the conductive layers is connected to the other conductive layer in the 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, which includes an insulating layer and a metal layer, which are respectively located on opposite sides of the initial substrate; forming two metal materials on opposite sides of the initial substrate; patterning the metal layer to form a signal line and a ground terminal separated from each other, and the metal materials are respectively located on the ground terminal and electrically connected to the ground terminal; and after forming the ground terminal and the signal line, respectively setting insulating materials on the insulating layer and the signal line to form a substrate, wherein the insulating layer, the ground terminal and the signal line are located between the two insulating materials, and the insulating material covers the signal line and the ground terminal.

[0015] In at least one embodiment of the present invention, providing one of the flexible circuit substrates includes providing an initial flexible circuit substrate, the initial flexible circuit substrate including 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 substrate including a power layer. The power layer includes a power supply line and two grounding lines, and the power supply line is located between the two grounding lines, and the metal block is 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 areas on the surface of the substrate; and aligning the metal blocks of the flexible circuit substrate with the recessed areas and disposing them on the substrate.

[0017] In at least one embodiment of the present invention, providing one of the flexible circuit substrates further includes laminating a covering layer on the conductive layer after patterning the metal layer, wherein the covering layer covers a portion of the power supply line and each ground line.

[0018] Based on the above, the flexible circuit substrate extends along the surface and end surface of the insulating substrate, and extends into the groove on the end surface of the insulating substrate, so that the conductive layer of the flexible circuit substrate is connected to each other in the groove. In this way, the conductive layer surrounds the outer side 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. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

[0025] The present invention will be described in detail with the following examples. It should be noted that the following description of the embodiments of the present invention is only for illustration and is not intended to exhaustively disclose all embodiments or to limit the specific embodiments of the present invention. For example, the description of "a first feature formed on a second feature" includes multiple implementations, including the first feature being in direct contact with the second feature, and also including additional features being formed between the first feature and the second feature so that the two are not in direct contact. In addition, the same element symbols used in the drawings and the specification will represent the same or similar elements as much as possible.

[0026] Spatially relative terms, such as "lower," "below," "beneath," "above," and related terms, are used herein to simply describe the relationship of an element or feature as shown in the figures to another element or feature. These spatially relative terms also cover different orientations when using or operating the device in addition to the orientation depicted in the figures. In addition, when the element is rotatable (rotated 90 degrees or other angles), the spatially relative descriptors used herein can also be interpreted accordingly.

[0027] In the following text, in order to clearly present the technical features of the present invention, the dimensions (such as length, width, thickness and depth) of the elements (such as layers, films, substrates and regions, etc.) in the drawings will be enlarged in unequal proportions. 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 the dimensions, shapes and deviations thereof caused by actual processes and / or tolerances. For example, the flat surface shown in the drawings may have rough and / or nonlinear features, and the acute angles shown in the drawings may be replaced with obtuse angles. Therefore, the elements presented in the drawings of the present invention are mainly for illustration, and are not intended to accurately depict the actual shape of the elements, nor are they intended to limit the claims of the present invention.

[0028] Furthermore, the words "about", "approximately" or "substantially" appearing in the present case not only cover the numerical values ​​and numerical ranges clearly recorded, but also cover the permissible deviation range that can be understood by a person with ordinary knowledge in the technical field to which the invention belongs, wherein the deviation range can be determined by the error generated during measurement, and the error is caused by, for example, the limitation of the measurement system or process conditions. In addition, "about" can mean within one or more standard deviations of the above numerical values, such as ±30%, ±20%, ±10% or ±5%. The words "about", "approximately" or "substantially" appearing in the present text can select the acceptable deviation range or standard deviation according to the optical properties, etching properties, mechanical properties or other properties, and not just one standard deviation can be applied to all the above optical properties, etching properties, mechanical properties and other properties.

[0029] The present invention discloses a flexible circuit board. Figure 1 , the flexible circuit board 10 includes an insulating substrate 100, a signal line 102 and two layers of flexible circuit substrates 120. The signal line 102 is disposed in the insulating substrate 100, and the insulating substrate 100 surrounds the signal line 102. The flexible circuit substrates 120 are respectively located on two opposite surfaces of the insulating substrate 100. Specifically, one layer of the flexible circuit substrate 120 is located on the surface 100f of the insulating substrate 100, and the other layer of the flexible circuit substrate 120 is located on the surface 100s of the insulating substrate 100. In this embodiment, the material of the insulating substrate 100 may include, for example, liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE) or polyetheretherketone (PEEK) with better thermoplasticity. In addition, since the above materials have lower dielectric constants and loss coefficients, they are helpful for 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 periphery of the signal line 102, the signal line 102 is separated from the two layers of the flexible circuit substrate 120. Figure 1 As shown, the insulating substrate 100 has a groove 104 on each of the two opposite end surfaces 100a and 100b. In addition, each flexible circuit substrate 120 includes a conductive layer 122. The conductive layer 122 of the flexible circuit substrate 120 located on the surface 100f extends from the surface 100f of the insulating substrate 100 toward the end surface 100a and the end surface 100b, and extends into the two grooves 104 along the end surface 100a and the end surface 100b. The conductive layer 122 of the flexible circuit substrate 120 located on the surface 100s extends from the surface 100s of the insulating substrate 100 toward the end surface 100a and the end surface 100b, and extends into the two grooves 104 along the end surface 100a and the end surface 100b.

[0031] Specifically, opposite sides of each conductive layer 122 extend from one surface (eg, surface 100f or surface 100s) of the insulating substrate 100 toward the end surface 100a and the end surface 100b, and extend along the end surface 100a and the end surface 100b to the sidewall 104w of the groove 104.

[0032] One of the conductive layers 122 is connected to the other conductive layer 122 in 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 in the two grooves 104, and because the two conductive layers 122 are electrically connected to each other, an electromagnetic shielding layer surrounding the insulating substrate 100 (and surrounding the signal line 102) is formed. In particular, one of the conductive layers 122 does not necessarily need to directly contact the other conductive layer 122, and one of the conductive layers 122 can also be connected (and electrically connected) to the other conductive layer 122 through other elements.

[0033] Each flexible circuit substrate 120 includes a power layer 124, which is 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 substrate 120 also includes an insulating layer 126, and the conductive layer 122 and the power layer 124 are respectively located on opposite sides of the insulating layer 126. The materials of the conductive layer 122 and the power layer 124 can include conductive materials such as copper, and the material of the insulating layer 126 can include organic resin materials such as modified polyimide (Modified PI; MPI) or fluorinated polyimide or the like. It is worth mentioning that 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 can fall within the range of 18μm to 90μm, and the thickness of the conductive layer 122 can fall within the range of 0.2μm to 12μm.

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

[0035] In this embodiment, the flexible circuit board 10 may further include two conductive structures 140, each located in the groove 104 of the insulating substrate 100. One conductive layer 122 is connected to another conductive layer 122 through the conductive structure 140, and the two conductive layers 122 are electrically connected to each other through 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 the 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 the 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 respectively located on two opposite sides of the ground terminal 142, and the two conductive layers 122 located on two opposite sides of the conductive structure 140 are respectively 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 soldering material 144 electrically connects the upper conductive layer 122 and the ground terminal 142 , while the lower soldering material 144 electrically connects the lower conductive layer 122 and the ground terminal 142 .

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

[0038] It is worth mentioning that, in this embodiment, each conductive structure 140 further includes two metal materials 146, which are respectively located on two opposite sides of the ground terminal 142, wherein the metal material 146 may include copper. Figure 1 As shown, the metal material 146 is located on the bottom surface (not shown) of the groove 104, and the welding material 144 is located between the metal material 146 and the flexible circuit substrate 120. Further, the conductive layer 122 of the flexible circuit substrate 120 can be electrically connected to the ground terminal 142 through the welding material 144 and the metal material 146, and the power layer 124 of the flexible circuit substrate 120 can also be electrically connected to the ground terminal 142 through the welding material 144 and the metal material 146.

[0039] Since the conductive layer 122 and the power layer 124 of the flexible circuit substrate 120 are respectively connected to the welding material 144, in this embodiment, the power layer 124 is electrically connected to the conductive layer 122 through the welding material 144. However, the present invention is not limited thereto, for example, in other embodiments, a conductive through hole 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 through hole.

[0040] In the present embodiment, the power layer 124 further includes two grounding wires 124g and a power supply wire 124p. A portion of each grounding wire 124g is respectively located in the groove 104 and is connected to the conductive structure 140. In detail, the grounding wire 124g located in the groove 104 is electrically connected to the ground terminal 142 through the welding material 144. On the other hand, the power supply wire 124p is located between the two grounding wires 124g and is electrically connected to the grounding wire 124g. It is particularly mentioned that 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 (such as Figure 1 The central area of ​​the power supply line 124p is used to increase the current carrying capacity of the power supply layer 124.

[0041] The flexible circuit board 10 may further include a covering 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 covering layer 160 covers the outer surfaces of the two flexible circuit substrates 120 and envelops the flexible circuit substrate 120 and the insulating substrate 100, so that the flexible circuit substrate 120 is isolated from the outside. The material of the covering layer 160 may include an insulating material such as resin to protect the flexible circuit substrate 120 from being affected by external substances and producing reactions such as oxidation.

[0042] The present invention discloses a method for manufacturing a flexible circuit board. Taking the above-mentioned flexible circuit board 10 as an example, the manufacturing method may include the following steps: FIG. 2A to FIG. 2E , FIG. 3A to FIG. 3C , Figure 4 and Figure 5 In this embodiment, first, a substrate 200 (indicated at Figure 2E ), and the detailed steps of providing the substrate 200 are referred to FIG. 2A to FIG. 2E .like Figure 2A As shown, an initial substrate 210 is provided, and the initial substrate 210 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 clad laminate (FCCL) including a liquid crystal polymer material, wherein the insulating layer 212 and the metal layer 214 are located on opposite sides of the initial substrate 210, respectively.

[0043] Next, please refer to Figure 2BAt least two openings 212p can be formed on the insulating layer 212 by, for example, laser ablation or similar methods. The metal layer 214 covers one side of the opening 212p, that is, the opening 212p does not connect the opposite sides of the insulating layer 212. After the opening 212p is formed, a photoresist layer (not shown) is disposed on the insulating layer 212 and the metal layer 214, respectively, and the photoresist layer is patterned by a photolithography process of exposure and development to form a plurality of openings (not shown) on the photoresist layer, and the openings on the photoresist layer overlap with the opening 212p of the insulating layer 212.

[0044] Please refer to Figure 2A and Figure 2B After the openings are formed in the photoresist layer, two metal materials 146 can be formed on opposite sides of the initial substrate 210 by, for example, electroplating. The metal materials 146 are formed in the openings of the photoresist layer on both sides, and the openings overlap with the openings 212p of the insulating layer 212, so that two of the metal materials 146 overlap with one of the openings 212p, and the other two metal materials 146 overlap with the other opening 212p.

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

[0046] After forming the ground terminal 142 and the signal line 102, please refer to Figure 2D , insulating materials 222 are respectively disposed on the insulating layer 212 and the signal line 102 to form a substrate 200 (indicated at Figure 2E In detail, 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, so 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 also covers the metal material 146.

[0047] It is worth mentioning that in this embodiment, the insulating material 222 may include materials with good thermoplasticity such as liquid crystal polymer, polytetrafluoroethylene or polyetheretherketone. The steps of respectively setting the insulating material 222 on the insulating layer 212 and the signal line 102 are as follows: two flexible copper foil substrates 220 including the insulating material 222 are respectively set on the insulating layer 212 and the signal line 102 by hot pressing. Then, the copper foil 205 on the flexible copper foil substrate 220 is removed by etching.

[0048] Please refer to Figure 2E After insulating materials 222 are disposed on the insulating layer 212 and the signal line 102, a portion of the substrate 200 is removed to form grooves 104 on two opposite end surfaces 200a and 200b of the substrate 200, respectively, and to expose a portion of each metal material 146 and a portion of the grounding terminal 142. Two first boundaries A1 are formed between one of the grooves 104 and the end surface 200a, and another two first boundaries B1 are formed between the other groove 104 and the end surface 200b.

[0049] Next, two flexible circuit substrates 120 are provided. Each flexible circuit substrate 120 includes 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 of providing one of the flexible circuit substrates 120, please refer to FIG. 3A to FIG. 3C First, if Figure 3A As shown, an initial flexible circuit substrate 120 ′ is provided. The initial flexible circuit substrate 120 ′ includes a conductive layer 122 and a metal layer 324 , and the conductive layer 122 and the metal layer 324 are respectively located on two opposite sides of the insulating layer 126 .

[0050] It is worth mentioning that the initial flexible circuit substrate 120' can be a flexible copper foil substrate containing liquid crystal polymer material, that is, the material of the conductive layer 122 and the metal layer 324 can include copper foil, and the material of the insulating layer 126 can include 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 to this.

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

[0052] After the metal block 324b is formed, the metal layer 324 may be patterned by, for example, chemical etching to form the flexible circuit substrate 120 including the power layer 124. Figure 3B As shown, the power layer 124 includes a power supply line 124p and two grounding lines 124g, and the power supply line 124p is located between the two grounding lines 124g. In particular, the 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 forming the metal block 324b, the present invention is not limited thereto. In other embodiments, the metal layer 324 may also be patterned before forming the metal block 324b.

[0053] At this point, a flexible circuit substrate 120 is formed, and the manufacturing steps of the two flexible circuit substrates 120 in the present invention can be as described above. Figure 3C In this embodiment, after the metal layer 324 is patterned, a covering layer 160 may be attached to the conductive layer 122 by thermal compression bonding. The covering layer 160 covers a portion of the conductive layer 122. In addition, the covering layer 160 covers a portion of the power supply line 124p and each ground line 124g.

[0054] Please go back 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 a recessed area 206 on the surface 200f and the surface 200s of the substrate 200. There are two second boundaries A2 (or two second boundaries B2) between the surface 200f and the surface 200s of the substrate 200 and one of the end surfaces 200a (or the end surface 200b). In detail, there is a second boundary A2 between the end surface 200a and the surface 200f, and there is also a second boundary A2 between the end surface 200a and the surface 200s. The other end surface 200b has a second boundary B2 between the surface 200f and the surface 200s, and there is also a second boundary B2 between the end surface 200b and the surface 200f.

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

[0056] In this embodiment, the metal block 324b of the flexible circuit substrate 120 can be aligned with the recessed area 206 and arranged on the substrate 200, and the metal block 324b is located in the recessed area 206 of the substrate 200. In particular, before the flexible circuit substrate 120 is arranged on the substrate 200, a bonding layer 110 can be arranged on the power layer 124 of the flexible circuit substrate 120, and the bonding layer 110 covers the surface of the power layer 124 (and the metal block 324b). After the bonding layer 110 is arranged, the flexible circuit substrate 120 is arranged on the substrate 200 by thermal compression bonding.

[0057] Please refer to Figure 5 After the flexible circuit substrate 120 is disposed on the substrate 200, the two opposite ends of one of the flexible circuit substrates 120 are bent along the second boundary A2 and the second boundary B2, and are bent along the first boundary A1 and the first boundary B1, respectively, by means of thermoforming, so that one of the conductive layers 122 (i.e., the conductive layer 122 of one of the flexible circuit substrates 120) is connected to the other conductive layer 122 (i.e., the conductive layer 122 of the other flexible circuit substrate 120) in the groove 104. On the other hand, the two cover layers 160 can also be connected by thermoforming to form a protective layer surrounding the substrate 200 and the two flexible circuit substrates 120.

[0058] It is worth mentioning that the two conductive layers 122 are electrically connected to each other after being bent. In the present embodiment, the two conductive layers 122 are respectively connected to the ground terminal 142 through the welding materials 144. Before the flexible circuit substrate 120 is set on the substrate 200, these welding materials 144 can be set on the ground terminal 142 and the metal material 146 by, for example, spraying tin. When the flexible circuit substrate 120 is bent by hot pressing, the conductive layer 122 is also bent and contacts the welding material 144 in the groove 104. Then, the welding material 144 can be heated and melted by, for example, laser heating, and the conductive layer 122 is connected to the ground terminal 142. At this point, a structure such as the following can be formed. Figure 1 The flexible circuit board 10 is shown.

[0059] In summary, the material of the insulating layer and the material of the insulating substrate in the flexible circuit substrate include materials with good thermoplastic properties (such as liquid crystal polymer materials and modified polyimide). Through the thermoplastic properties of this material, the two ends of the flexible circuit substrate can be bent along the boundary of the insulating substrate, and the flexible circuit substrates located on opposite sides of the insulating substrate are connected to each other. In this way, the flexible circuit substrate surrounds the outside of the insulating substrate, and the conductive layer in the flexible circuit substrate also surrounds the outside of the insulating substrate. Since the two conductive layers are electrically connected to each other, a fully shielded electromagnetic shielding layer can be formed in the flexible circuit board, so that the signal line is not affected by external high-frequency signals.

[0060] In addition, since the material of the insulating layer in the flexible circuit substrate has good thermoplastic properties, when the flexible circuit substrate is bent by heat and pressure, it can be more closely attached to the outer side of the insulating substrate. Therefore, it can reduce the occurrence of bubbles or fractures of the flexible circuit substrate during the process, thereby improving the yield of the flexible circuit board.

[0061] Although the embodiments of the present invention have been disclosed as above, they are not intended to limit the embodiments of the present invention. Any technician in the relevant technical field can make some changes and modifications 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 definition of the attached claims.

[0062]

Explanation of symbols

[0063] 10: Flexible circuit board

[0064] 100: Insulation 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 substrate

[0072] 122: Conductive layer

[0073] 124: Power layer

[0074] 124g: Ground wire

[0075] 124p: Power supply line

[0076] 126,212: Insulation layer

[0077] 140: Conductive structure

[0078] 142: Ground terminal

[0079] 144: Welding materials

[0080] 146:Metal Materials

[0081] 160: Covering layer

[0082] 200:Substrate

[0083] 205: Copper foil

[0084] 210: Initial substrate

[0085] 212p: Opening

[0086] 214,324:Metal layer

[0087] 220: Flexible copper foil substrate

[0088] 222: Insulation material

[0089] 324b: Metal Block

[0090] A1,B1: First boundary

[0091] A2, B2: Second boundary.

Claims

1. A flexible circuit board, characterized in that: Include: An insulating substrate, wherein two opposite end surfaces of the insulating substrate each have a groove; A signal line is disposed in the insulating substrate, and the insulating substrate surrounds the signal line; and Two layers of flexible circuit substrates are respectively located on two opposite 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 groove; and A power supply layer, located between the conductive layer and the insulating substrate, and electrically connected to the conductive layer; One of the conductive layers is connected to another of the conductive layers in the groove, and the conductive layers are electrically connected to each other.

2. The flexible circuit board according to claim 1, wherein: Also includes: Two conductive structures are respectively located in the grooves, and one of the conductive layers is connected to the other of the conductive layers through the conductive structures.

3. The flexible circuit board according to claim 2, wherein each of the conductive structures comprises: ground terminal; and Two welding materials are respectively located at two opposite sides of the ground end, wherein the conductive layer is electrically connected to the ground end through the welding materials, and the power supply layer is electrically connected to the ground end through the welding materials.

4. The flexible circuit board according to claim 3, wherein each of the conductive structures further comprises: Two metal materials are respectively located at two opposite sides of the grounding end and at the bottom surface of the groove, wherein the conductive layer is electrically connected to the grounding end through the welding material and the metal material.

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

6. The flexible circuit board according to claim 1, wherein each of the flexible circuit substrates further comprises: The insulating layer, wherein the conductive layer and the power layer are respectively located on two opposite sides of the insulating layer, and the thickness of the power layer is greater than the thickness of the conductive layer. 7 . The flexible circuit board according to claim 1 , wherein the insulating substrate comprises a liquid crystal polymer material.

8. The flexible circuit board according to claim 1, wherein: Also includes: The covering layer is disposed on the conductive layer of the flexible circuit substrate and surrounds the insulating substrate and the flexible circuit substrate.

9. A method for manufacturing a flexible circuit board, characterized in that: Include: Providing a substrate, comprising a signal line and two ground terminals, wherein the signal line is located between the ground terminals; Removing a portion of the substrate to form a groove on each of two opposite end surfaces of the substrate and expose a portion of the ground terminal, wherein two first boundaries are provided between one of the grooves and one of the end surfaces; Providing two flexible circuit substrates, each of the flexible circuit substrates comprises a conductive layer and a power layer, and the conductive layer is electrically connected to the power layer; After removing part of the substrate, the flexible circuit substrate is disposed on two opposite surfaces of the substrate, and the power layer is located between the conductive layer and the substrate, wherein two second boundaries are provided between the surface of the substrate and one of the end surfaces; and After the flexible circuit substrate is set on the substrate, the opposite ends of one of the flexible circuit substrates are bent along the second boundary and the first boundary respectively, so that one of the conductive layers is connected to the other conductive layer in the groove, and the conductive layers are electrically connected to each other.

10. The method according to claim 9, wherein: Providing the substrate comprises: Providing an initial substrate, wherein the initial substrate comprises an insulating layer and a metal layer, which are respectively located on two opposite sides of the initial substrate; forming two metal materials on opposite sides of the initial substrate; Patterning the metal layer to form the signal line and the ground terminal separated from each other, and the metal material is respectively located on the ground terminal and electrically connected to the ground terminal; as well as After forming the ground terminal and the signal line, insulating materials are respectively disposed on the insulating layer and the signal line to form the substrate, wherein the insulating layer, the ground terminal and the signal line are located between the insulating materials, and the insulating material covers the signal line and the ground terminal.

11. The method according to claim 9, wherein: Providing one of the flexible circuit substrates includes: Providing an initial flexible circuit substrate, comprising the conductive layer and the metal layer, wherein the thickness of the conductive layer is smaller than the thickness of the metal layer; forming a metal block on the metal layer; as well as Patterning the metal layer to form the flexible circuit substrate including the power layer; The power layer includes a power supply line and two grounding lines, and the power supply line is located between the two grounding lines, and the metal block is located on the power supply line.

12. The method according to claim 11, wherein: Also includes: removing another portion of the substrate to respectively form recessed areas on the surface of the substrate; and The metal block of the flexible circuit substrate is aligned with the recessed area and disposed on the substrate.

13. The method according to claim 11, wherein: One of the flexible circuit substrates further includes: After patterning the metal layer, a covering layer is attached on the conductive layer, wherein the covering layer covers a portion of each of the power supply line and the ground line.

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