Flexible circuit board and manufacturing method thereof
The one-piece flexible circuit board design and fuse structure solves the problem of poor solder connection quality, improves assembly quality and production efficiency, and enhances the product's safety performance and vibration resistance.
Patent Information
- Application Number
- CN202410487365.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-22
- Publication Date
- 2025-10-24
AI Technical Summary
Existing flexible printed circuit boards are prone to problems such as poor connection quality, excessive internal resistance leading to severe heating, or incorrect connection positions when soldering functional components, resulting in poor assembly quality and reduced production efficiency.
By performing multiple patterning and molding processes on the flexible circuit board, the main circuit area and the bus connection area are formed into one piece, combined with the fuse and buffer structure to improve the product's safety performance and vibration resistance.
The assembly process is reduced, the assembly defect rate is reduced, the assembly quality and production efficiency are improved, and at the same time, the fuse can be blown in time when the safety range is exceeded, thereby enhancing the safety performance and vibration resistance of the product.
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Figure CN120835449A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a flexible circuit board and a manufacturing method thereof. BACKGROUND
[0002] In the prior art, a flexible printed circuit (FPC) connects functional elements (such as battery cells) by soldering to achieve the purpose of signal acquisition. However, during the soldering process, there are problems such as poor connection quality, excessive internal resistance leading to serious heating, or incorrect connection position, which in turn leads to poor assembly quality of the product and reduces production efficiency. Therefore, how to provide a flexible circuit board that can solve the above problems is still the goal of the people in the field to strive for. SUMMARY
[0003] Some embodiments of the present application provide a flexible circuit board and a manufacturing method thereof. The main circuit area and the bus connection area of the flexible circuit board are simultaneously manufactured by multiple patterning and molding processes, so that the main circuit area and the bus connection area are formed by one-piece molding. Compared with the prior art, this design reduces the assembly process, reduces the assembly failure rate, and improves the assembly quality and production efficiency. In addition, the fuse and the buffer structure on the flexible circuit board can melt and improve the anti-vibration ability of the product when the product exceeds the set safety range, thereby improving the safety performance of the product.
[0004] Some embodiments of the present application provide a flexible circuit board having a main circuit area and a bus connection area connected to the main circuit area. The flexible circuit board includes a first metal layer, an insulating material layer, a conductive etching stop layer, and a second metal layer. The first metal layer includes metal lines in the main circuit area and metal blocks in the bus connection area, wherein the first metal layer has opposite first and second surfaces. The insulating material layer is on the first surface of the first metal layer and covers the metal lines. The conductive etching stop layer is on the second surface of the first metal layer. The second metal layer is on the surface of the conductive etching stop layer opposite the first metal layer, wherein the conductive etching stop layer and the second metal layer are in the bus connection area and not in the main circuit area.
[0005] According to some embodiments of the present application, the flexible circuit board described above, wherein the insulating material layer contacts the side of the conductive etching stop layer facing the main circuit area.
[0006] According to some embodiments of the present application, the flexible circuit board described above, wherein the first metal layer includes a fuse connected to the metal lines, and the width of the fuse is less than the width of the metal lines.
[0007] According to some embodiments of the present application, the flexible circuit board, wherein the area of the bus connection region is less than the area of the main circuit region.
[0008] According to some embodiments of the present application, the flexible circuit board, wherein the thickness of the second metal layer is between 0.1 mm and 5 mm.
[0009] Some embodiments of the present application provide a method for manufacturing a flexible circuit board. The method comprises the following steps. A first metal layer of a patterned composite layer is patterned into metal lines and metal blocks, wherein the composite layer comprises the first metal layer, a conductive etch stop layer, and a second metal layer, the conductive etch stop layer is between the first metal layer and the second metal layer. A first portion of the second metal layer is removed, wherein the metal lines of the first metal layer overlap the first portion of the second metal layer. An insulating material layer is disposed on the first metal layer to cover the metal lines. A molding process is performed on the composite layer to form a main circuit region and a bus connection region connecting the main circuit region, wherein the metal lines are in the main circuit region, the metal blocks and a second portion of the second metal layer are in the bus connection region.
[0010] According to some embodiments of the present application, the method, wherein the second metal layer is an aluminum layer.
[0011] According to some embodiments of the present application, the method, wherein the removing the first portion of the second metal layer exposes a first surface of the conductive etch stop layer.
[0012] According to some embodiments of the present application, the method, wherein the patterning the first metal layer of the composite layer exposes a second surface of the conductive etch stop layer.
[0013] According to some embodiments of the present application, the method further comprises the following step. After the disposing the insulating material layer, a portion of the conductive etch stop layer is removed, wherein the metal lines of the first metal layer overlap the portion of the conductive etch stop layer. BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1A is a top view of a flexible circuit board according to some embodiments of the present application.
[0015] FIG. 1B is a perspective view of FIG. 1A is a cross-sectional view along line A-A’.
[0016] FIG. 1C is a perspective view of FIG. 1A
[0017] FIG. 2 is a flow chart of a method for manufacturing a flexible circuit board according to some embodiments of the present application.
[0018] FIG. 3A to FIG. 3J FIG. 4 is a schematic diagram of a flexible circuit board according to an embodiment of the present application at various stages of a process. DETAILED DESCRIPTION
[0019] Embodiments of the present application are discussed in detail below. It should be appreciated, however, that the embodiments provide many applicable concepts that can be embodied in a wide variety of specific contexts. The embodiments discussed, disclosed, and taught herein are merely for illustration and are not intended to limit the scope of the application. With reference to the use of "first," "second," etc., in this and other descriptions of the application, these terms are used, and are intended to embrace different and / or different combination of the claimed elements. There are many applications for the application beyond those described herein, which will become apparent to one skilled in the art.
[0020] In addition, spatially relative terms, such as "beneath", "below", "lower", "above", "upper", and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The devices can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. As used herein, the terms "about", "approximately", "substantially", or "essentially" generally mean within 20% of a given value or range, or within 10% of a given value or range, or within 5% of a given value or range. Numerical quantities given herein are approximate, meaning that the term "about", "approximately", "substantially", or "essentially" can be inferred if not expressly specified.
[0021] FIG. 1A FIG. 1 is a top view of a flexible circuit board 100 according to an embodiment of the present application. The flexible circuit board 100 can have a primary circuit region PR and a bus connection region CR connecting the primary circuit region PR. The primary circuit region PR and the bus connection region CR can be fabricated by a one-piece formation. The shape and number of the bus connection region CR can be varied according to functional requirements. For example, the bus connection region CR can be rectangular, circular, or other suitable shapes. In the present embodiment, the number of the bus connection region CR is four. In other embodiments, the bus connection region CR can take other suitable numbers without being limited thereto. In the present embodiment, the area of the bus connection region CR is smaller than the area of the primary circuit region PR. In other embodiments, the area of the bus connection region CR can take any suitable configuration without being limited thereto.
[0022] FIG. 1B FIG. 2 is a perspective view of the flexible circuit board 100 of FIG. 1. FIG. 1A FIG. 3 is a cross-sectional view along line A-A' of FIG. 1. FIG. 1C FIG. 4 is a schematic diagram of a flexible circuit board according to an embodiment of the present application at various stages of a process. FIG. 1A FIG. 5 is a perspective view of the flexible circuit board of FIG. 4. FIG. 1B FIG. 6 is a cross-sectional view along line B-B' of FIG. 5. FIG. 1CThe flexible circuit board 100 can include a first metal layer 120, a conductive etch stop layer 140, a second metal layer 160, an insulating material layer 180, and a buffer structure 190.
[0023] In some embodiments, the first metal layer 120 includes metal traces 121 in the primary circuit region PR and metal blocks 122 in the connection region CR, wherein the first metal layer 120 has a first surface 120A and a second surface 120B. The first metal layer 120 can be any suitable metal. For example, in the present embodiment, the first metal layer 120 is copper. However, it should be noted that the first metal layer 120 can employ any suitable metal material without limitation.
[0024] In some embodiments, the first metal layer 120 can further include a fuse 125. The fuse 125 is located on and connected to the metal traces 121 of the first metal layer 120. The width of the fuse 125 can be varied according to functional requirements. For example, in the present embodiment, the width of the fuse 125 is less than the width of the metal traces 121, such that the flexible circuit board 100 can be fused in time when exceeding a set safety range, thereby improving the safety of the product. However, it should be noted that the fuse 125 can employ any suitable configuration without limitation.
[0025] In some embodiments, the first metal layer 120, the conductive etch stop layer 140, and the second metal layer 160 can further include a positioning hole H1. The positioning hole H1 is used to assist in positioning when connecting other functional elements (such as battery cells) in the connection region CR.
[0026] In some embodiments, the conductive etch stop layer 140 can be located on the second surface 120B of the first metal layer 120. The conductive etch stop layer 140 is located in the connection region CR of the flexible circuit board 100, but not in the primary circuit region PR. The shape and position of the conductive etch stop layer 140 can be varied according to functional requirements. For example, in the present embodiment, the first metal block 122 overlaps the conductive etch stop layer 140. In some embodiments, the length of the conductive etch stop layer 140 is the same as the length of the first metal block 122. However, it should be noted that the conductive etch stop layer 140 can employ any suitable configuration without limitation.
[0027] In some embodiments, the second metal layer 160 can be located on the surface of the conductive etch stop layer 140 opposite to the first metal layer 120. The second metal layer 160 is located in the conductive connection region CR of the flexible circuit board 100, but not in the primary line region PR. The second metal layer 160 can be any suitable metal. For example, in the present embodiment, the second metal layer 160 is aluminum. The thickness of the second metal layer 160 can be varied according to functional requirements. For example, in the present embodiment, the thickness of the second metal layer 160 is between 0.1 mm and 5 mm. Furthermore, the shape and location of the second metal layer 160 can be varied according to functional requirements. In the present embodiment, the conductive etch stop layer 140 overlaps the second metal layer 160. In the present embodiment, the length of the second metal layer 160 is the same as the length of the conductive etch stop layer 140. However, it should be noted that the second metal layer 160 can employ any suitable material and configuration without being limited thereto.
[0028] In some embodiments, the second metal layer 160 further includes openings 160O. The openings 160O extend from the first surface 160A to the second surface 160B of the second metal layer 160, and correspond to the plurality of metal lines 121 of the first metal layer 120. In some embodiments, the openings 160O can prevent short circuits from being formed when the flexible circuit board 100 is integrated with a battery cell (not shown), thereby improving the stability of the product.
[0029] In some embodiments, the insulating material layer 180 can be located on the first surface 120A of the first metal layer 120 and cover the metal lines 121, wherein the insulating material layer 180 contacts the side of the conductive etch stop layer 140 facing the primary line region PR. The number of insulating material layers 180 can be varied according to functional requirements. For example, in the present embodiment, the insulating material layer 180 has a first insulating material layer 182 and a second insulating material layer 184. The first insulating material layer 182 can be any suitable insulating material, such as polyimide (PI). The second insulating material layer 184 can be any suitable adhesive, such as epoxy. The location of the insulating material layer 180 can be varied according to functional requirements. However, it should be noted that the insulating material layer 180 can employ any suitable material and configuration without being limited thereto.
[0030] In some embodiments, the buffer structure 190 is located in the primary line region PR and adjacent to the metal lines 121 of the first metal layer 120. The buffer structure 190 can be used to increase the amount of expansion of the flexible circuit board 100, thereby improving the anti-expansion and anti-vibration capabilities of the product.
[0031] FIG. 2 A flowchart of a method for manufacturing a flexible circuit board 100 according to some embodiments of the present application.FIG. 3A to FIG. 3J FIG. 8 is a flowchart of a method 200 for manufacturing a flexible circuit board 100 according to an embodiment of the present application. The description is merely an example and is not intended to further limit the contents of the present application. The method 200 includes steps 210-280. It should be understood that additional steps can be added before, during, and after steps 210-280, and some of the steps mentioned below can be replaced or removed for another implementation of the method. The order of the steps / processes can be changed.
[0032] First, refer to FIG. 2 and FIG. 3A . The composite layer 300 is provided.
[0033] The composite layer 300 includes the first metal layer 120, the conductive etch stop layer 140, and the second metal layer 160, wherein the conductive etch stop layer 140 is located between the first metal layer 120 and the second metal layer 160. The first metal layer 120, the conductive etch stop layer 140, and the second metal layer 160 can be laminated together by any suitable process, such as a compression process. However, it should be noted that the composite layer 300 can be configured in any suitable manner without being limited thereto.
[0034] Next, refer to FIG. 2 and FIG. 3B . The method 200 proceeds to step 210. In the composite layer 300, the positioning holes H1 are formed. For example, in the present embodiment, a drilling process, such as a machine drilling process, is performed on both sides of the composite layer 300 to form the positioning holes H1. However, it should be noted that the positioning holes H1 can be formed by any suitable drilling process without being limited thereto.
[0035] Next, refer to FIG. 2 and FIG. 3C . The method 200 proceeds to step 220. On both sides of the composite layer 300, the first film 320 is formed. In some embodiments, the material of the first film 320 can be Polyethylene Terephthalate or Polyethylene. For example, in the present embodiment, the first film 320 can be formed on the first metal layer 120 and the second metal layer 160 of the composite layer 300 by a compression molding process. However, it should be noted that the first film 320 can be formed by any suitable material and process without being limited thereto.
[0036] Next, refer to FIG. 2 , FIG. 3D and FIG. 3E , wherein FIG. 3E is FIG. 3D. Method 200 proceeds to step 230. The first metal layer 120 of the patterned composite layer 300 becomes the metal line 121 and the metal block 122. For example, the first metal layer 120 can be patterned by a photolithography process and an etching process. The photolithography process can include exposing and developing the first film 320 on the first metal layer 120. The etching process can include etching the first metal layer 120 using the first film 320 on the first metal layer 120 as an etching mask. Patterning the first metal layer 120 can expose the surface 140A of the conductive etching stop layer 140. After the photolithography process, the first film 320 on the second metal layer 160 can protect the second metal layer 160 in subsequent processes. For example, in this embodiment, the first metal layer 120 uses copper and the second metal layer 160 uses aluminum. The first film 320 on the second metal layer 160 can protect the aluminum layer in the subsequent etching process to prevent the aluminum layer from being damaged due to the different etching rates of copper and aluminum.
[0037] Furthermore, the buffer structure 190 and the fuse 125 can be formed using appropriate methods. For example, the buffer structure 190 and the fuse 125 can be formed using the same process as the metal lines 121 and the metal blocks 122, such as by patterning the first metal layer 120 of the composite layer 300. However, it should be noted that the buffer structure 190 and the fuse 125 can be formed using any appropriate process, without limitation. After patterning the first metal layer 120, the first film 320 on the first metal layer 120 and the second metal layer 160 can be stripped. For example, the first film 320 can be removed using a chemical agent, such as a stripping solution.
[0038] Receiver, reference FIG. 2 as well as FIG. 3F . Method 200 proceeds to step 240. A second film 340 is formed on both sides of the composite layer 300. In some embodiments, the material of the second film 340 may be polyethylene terephthalate (PET) or polyethylene (PE). For example, in this embodiment, the second film 340 may be formed on the first metal layer 120 and the second metal layer 160 of the composite layer 300 by a molding process, wherein the second film 340 covers the metal circuit 121 of the first metal layer 120. However, it should be noted that the second film 340 may be made of any appropriate material and process, without limitation thereto.
[0039] Receiver, reference FIG. 2 、 FIG. 3G as well as FIG. 3H ,in FIG. 3H for FIG. 3G. The method 200 proceeds to step 250 to remove the portion 162 of the second metal layer 160. For example, in this embodiment, the second metal layer 160 can be patterned by a photolithography process and an etching process. The photolithography process can include exposing and developing the second film 340 on the second metal layer 160. The etching process can include etching the second metal layer 160 using the second film 340 on the second metal layer 160 as an etching mask. This etching process removes the portion 162 of the second metal layer 160 and forms an opening 160O. The opening 160O overlaps the metal line 121 of the first metal layer 120. After this removal step, the remaining portions 164 and 166 of the second metal layer 160 are separated by the opening 160O, wherein the metal line 121 is located in the main circuit region PR, and the metal block 122 and the portions 164 and 166 of the second metal layer 160 are located in the bus connection region CR. In this embodiment, the removal of the portion 162 of the second metal layer exposes the surface 140B of the conductive etch stop layer 140. After the photolithography process, the first film 320 on the first metal layer 120 can protect the first metal layer 120 in subsequent processes.
[0040] After patterning the first metal layer 120, the second film 340 on the first metal layer 120 and the second metal layer 160 may be stripped. For example, the second film 340 may be removed using a chemical agent, such as a stripping solution.
[0041] Receiver, reference FIG. 2 as well as FIG. 3I Method 200 proceeds to step 260. An insulating material layer 180 is disposed on the first metal layer 120 to cover the metal line 121. For example, the insulating material layer 180 can be formed on the first metal layer 120 by any suitable process. In this embodiment, the insulating material layer 180 can protect the first metal layer 120 from being exposed to air, thereby preventing the first metal layer 120 from oxidizing.
[0042] In some embodiments, method 200 proceeds to step 270 to remove a portion of the conductive etch stop layer 140. For example, in this embodiment, after providing the insulating material layer 180, a laser treatment process is used to remove the portion of the conductive etch stop layer 140 exposed by the opening 160O of the second metal layer 160. In other words, step 270 removes the portion of the conductive etch stop layer 140 that overlaps the metal line 121. This design can prevent short circuits when integrating with other components, such as battery cells. However, it should be noted that the removal of the conductive etch stop layer 140 can be performed using any suitable process, and is not limited to this process.
[0043] Receiver, reference FIG. 2 as well as FIG. 3JMethod 200 proceeds to step 280. A molding process is performed on composite layer 300 to form the primary circuit region PR and the bus connection region CR connecting the primary circuit region PR. For example, composite layer 300 can be cut to the desired primary circuit region PR and bus connection region CR by a laser, die cutting, or the like. It should be noted, however, that composite layer 300 can be formed by any suitable process without being limited thereto.
[0044] Some embodiments of the present application provide a flexible circuit board and a manufacturing method thereof. The flexible circuit board and the manufacturing method thereof can simultaneously form a primary circuit region and a bus connection region of the flexible circuit board by a plurality of patterning processes and a molding process, so that the primary circuit region and the bus connection region are formed by an integral molding process. This design reduces assembly procedures, reduces assembly failure rate, and improves assembly quality and production efficiency compared to the prior art. In addition, this design can also melt the fuse on the flexible circuit board or improve the anti-vibration capability of the product when the product exceeds the set safety range, thereby improving the safety performance of the product.
[0045] The foregoing outlines features of several embodiments so that those skilled in the art can better understand the various aspects of the present application. Those skilled in the art should appreciate that they can readily use the present application as a basis for designing or modifying other processes and structures for carrying out the same purposes and / or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present application and that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the present application.
[0046] [SYMBOL DESCRIPTION]
[0047] 100: flexible circuit board
[0048] 120: first metal layer
[0049] 121: metal circuit
[0050] 122: metal block
[0051] 120A, 160A: first surface
[0052] 120B, 160B: second surface
[0053] 125: fuse
[0054] H1: positioning hole
[0055] 140: conductive etch stop layer
[0056] 160: second metal layer
[0057] 160O: opening
[0058] 162, 164: portion
[0059] 180: layer of insulating material
[0060] 182: first layer of insulating material
[0061] 184: second layer of insulating material
[0062] 190: buffer structure
[0063] 200: method
[0064] 210, 220, 230, 240, 250, 260, 270, 280: step 300: composite layer
[0065] 320: first film
[0066] 340: second film
[0067] PR: primary line region
[0068] CR: confluence connection region
Claims
1. A flexible circuit board having a main circuit area and a bus connection area connecting the main circuit area, characterized by, The flexible circuit board comprises: a first metal layer comprising metal traces in the main trace area and a metal block in the bus connection area, wherein the first metal layer has a first surface and a second surface opposite to the first surface; an insulating material layer on the first surface of the first metal layer and covering the metal traces; a conductive etch stop layer on the second surface of the first metal layer; and a second metal layer on the surface of the conductive etch stop layer opposite to the first metal layer, wherein the conductive etch stop layer and the second metal layer are in the bus connection area and not in the main trace area.
2. The flexible circuit board of claim 1, wherein, The insulating material layer contacts a side of the conductive etch stop layer facing the main trace area.
3. The flexible circuit board of claim 1, wherein, The first metal layer comprises fuses connected to the metal traces, and the width of the fuses is less than the width of the metal traces.
4. The flexible circuit board of claim 1, wherein, The area of the bus connection area is less than the area of the main trace area.
5. The flexible circuit board of claim 1, wherein, The thickness of the second metal layer is between 0.1 mm and 5 mm.
6. A method of manufacturing a flexible circuit board, characterized by, The method comprises: patterning a first metal layer of a composite layer to be metal traces and a metal block, wherein the composite layer comprises the first metal layer, a conductive etch stop layer, and a second metal layer, the conductive etch stop layer being between the first metal layer and the second metal layer; removing a first portion of the second metal layer, wherein the metal traces of the first metal layer overlap the first portion of the second metal layer; providing an insulating material layer on the first metal layer to cover the metal traces; and performing a forming process on the composite layer to form a main trace area and a bus connection area connected to the main trace area, wherein the metal traces are in the main trace area, the metal block and a second portion of the second metal layer are in the bus connection area. The second metal layer is an aluminum layer.
7. The method of claim 6, wherein, The removing of the first portion of the second metal layer exposes a first surface of the conductive etch stop layer.
8. The method of claim 6, wherein, The patterning of the first metal layer of the composite layer exposes a second surface of the conductive etch stop layer.
9. The method of claim 6, wherein, The method further comprises:
10. The method of claim 6, wherein, after providing the insulating material layer, removing a portion of the conductive etch stop layer, wherein the metal traces of the first metal layer overlap the portion of the conductive etch stop layer.