A method for manufacturing a pseudo large current-carrying thick copper flexible circuit board

Abstract

The application discloses a manufacturing method of a pseudo large-current thick copper flexible circuit board, which comprises the following steps: taking an insulating material plate and attaching a glue layer, taking a thick copper layer, attaching the thick copper layer to one side of the glue layer, performing first pattern processing on the thick copper layer, etching away part of the thickness, making a resin pattern on the etched pattern, electroplating a copper layer, attaching a dry film, and performing second pattern processing according to the pattern of the first pattern processing, taking a first cover film and attaching the first cover film to one side of the second pattern processing, then removing an auxiliary layer to expose the first unetched copper layer, performing third pattern processing on the first unetched copper layer, taking a second cover film and attaching the second cover film to one side of the third pattern processing, and forming the pseudo large-current thick copper flexible circuit board; the auxiliary layer is used to form support for the thick copper layer, an additive manufacturing method of a thick copper circuit pattern is adopted, the resin pattern is used to ensure the flatness of the board, the first cover film and the second cover film are attached to form a pseudo flexible circuit board structure, and the thick copper circuit pattern formed in the overall processing process has a good effect.

Description

Technical Field

[0001] This invention relates to the field of circuit board processing, and more particularly to a method for manufacturing a pseudo-high current-carrying thick copper flexible circuit board. Background Technology

[0002] For power modules such as charging piles for some intelligent connected vehicles, thick copper circuit boards with high current carrying capacity are required. For circuit boards with ultra-high current carrying capacity, the copper thickness is generally ≥105μm, or even ≥245μm.

[0003] When manufacturing thick copper circuit boards, the excessive copper thickness can lead to problems such as excessive side etching and insufficient etching factor during the pattern etching process. This results in a narrower top and wider bottom for the circuit pattern, affecting its current carrying capacity and increasing the risk of short circuits.

[0004] Currently, the common practice is to adjust etching methods, such as adjusting the etching spray or improving the characteristics of the etching solution, to solve the problem of etching thick copper lines.

[0005] However, whether adjusting the etching method or improving the characteristics of the etching solution, the effect of increasing the etching factor is limited, and it is accompanied by problems such as increased solution usage and increased pollution.

[0006] Based on the above background and problems, this paper provides a partial fabrication method that utilizes flexible circuit boards to form a fabrication method that can effectively improve the processing effect of high current-carrying thick copper circuit boards. Summary of the Invention

[0007] This invention addresses the problem of insufficient etching factor in the pattern fabrication of thick copper high-current-carrying circuit boards in existing technologies. From a processing method perspective, it provides a method for fabricating a pseudo-high-current-carrying thick copper flexible circuit board by partially utilizing flexible circuit board processing technology. The circuit board is designed with forming lines, and the area within the forming lines is the effective area, while the area outside the forming lines is the ineffective area.

[0008] The manufacturing method includes the following steps:

[0009] S10: Take an insulating material board of the same size as the circuit board, and attach an adhesive layer to one side of the board corresponding to the invalid area to form an auxiliary layer;

[0010] S20: Take a thick copper layer and attach it to one side of the adhesive layer of the auxiliary layer. Then, sequentially apply dry film, expose, develop, and perform a first etching process on the thick copper layer to form a first half-etched pattern. The first etching process is to etch away part of the thickness of the thick copper layer. The unetched thick copper layer is the first retained half copper, and the whole is formed into a first half-etched board.

[0011] S30: Silk screen resin is applied to one side of the first half-etched pattern of the first half-etched plate to fill the gaps of the first half-etched pattern. Then, curing, polishing, and copper plating are performed in sequence. After that, a dry film is applied to the copper plating layer, and exposure, development, and second etching are performed in sequence according to the pattern distribution of the first half-etched pattern to form the second half-etched pattern. The whole is formed into the second half-etched plate.

[0012] S40: Following the same manufacturing method as S30, a plurality of first-side etched patterns that are identical to the second half-etched pattern and are stacked sequentially are formed on the second half-etched plate to form a first-side pattern plate;

[0013] S50: Take the first cover film, attach the first cover film to the side of the first etched pattern of the first pattern board, and remove the auxiliary layer to expose the first retained half copper to form the first cover film pattern board.

[0014] S60: The first retained half-copper is sequentially subjected to dry film application, exposure, development, and third etching to form a third half-etched pattern. Following the same manufacturing method as in S30, a fourth half-etched pattern identical to and stacked with the third half-etched pattern is formed on the third half-etched pattern, and several stacked second-side etched patterns are also formed. A second cover film is taken and attached to one side of the second-side etched pattern to form the pseudo-high current-carrying thick copper flexible circuit board.

[0015] Optionally, an insulating material board of the same size as the circuit board is taken, and a cover film layer is taken. The cover film layer is attached to the surface of the insulating material board, and an adhesive layer is attached to the surface of the cover film layer corresponding to the ineffective area to form the auxiliary layer.

[0016] Optionally, the insulating material board is an FR-4 board, a PP board, a PET board, or a PTFE board.

[0017] Optionally, the adhesive layer is an acrylic adhesive or an epoxy resin adhesive.

[0018] Optionally, the adhesive layer is attached inward along the edge of the circuit board, and the attachment width of the adhesive layer is smaller than the width from the edge to the molding line.

[0019] Optionally, forming the first cover film pattern plate includes, after forming the second half-etched pattern, screen printing resin onto one side of the second half-etched pattern to fill the gaps in the second half-etched pattern, then performing curing and polishing processes in sequence, and then attaching the first cover film onto one side of the second half-etched pattern to form the first cover film pattern plate as a whole.

[0020] Optionally, the resin is solder resist ink or via-filling resin.

[0021] Optionally, removing the auxiliary layer involves milling the circuit board along the edge of the adhesive layer extending into the invalid area to remove the auxiliary layer; or, removing the auxiliary layer involves laser ablation of the insulating material board along the contour of the adhesive layer to remove the insulating material board, and then polishing the adhesive layer.

[0022] Optionally, the width of the second half-etched pattern is smaller on one side than that of the first half-etched pattern.

[0023] The width of several first-side etched patterns decreases sequentially outward from the first half-etched pattern.

[0024] Optionally, the width of the fourth half-etched pattern is smaller on each side than that of the third half-etched pattern.

[0025] The width of several second-side etched patterns decreases sequentially outward from the third half-etched pattern.

[0026] This invention provides excellent support for the first-side circuit pattern processing of the thick copper layer by utilizing an auxiliary layer to support the thick copper layer and an adhesive layer to seal and adhere the thick copper layer to the auxiliary layer. The thick copper layer, acting as a base layer, is used to create a first semi-etched pattern through a semi-etching process. This is followed by an electroplating process to create another first semi-etched pattern, and so on, using the same additive method to form a multi-layered thick copper circuit pattern. The second side is fabricated in the same way, using screen printing resin to create a resin pattern. This fills the height difference between the circuit gaps and provides a plating base for the copper layer, ensuring the reliability of the circuit pattern fabrication. The application of a first cover film, similar to that used in flexible circuit boards, provides a supporting foundation for the second-side circuit pattern fabrication, preventing the difficulty of providing a foundation for the second-side processing when using rigid boards to create solder mask patterns. The application of the first and second cover films creates a pseudo-flexible circuit board structure, further improving the overall structural reliability of the circuit board. The entire processing forms a streamlined, matching process, providing an effective and feasible manufacturing method for thick copper circuit boards. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0028] Figure 1 This is a flowchart illustrating the main processes included in the embodiments of the present invention;

[0029] Figure 2 This is a schematic diagram of the cross-sectional structure of the auxiliary layer in this embodiment;

[0030] Figure 3 This is a schematic diagram of the cross-sectional structure of another auxiliary layer in this embodiment;

[0031] Figure 4 This is a cross-sectional schematic diagram of the first half-etched plate in this embodiment;

[0032] Figure 5 This is a cross-sectional schematic diagram of the first resin graphic plate of this embodiment;

[0033] Figure 6 This is a cross-sectional schematic diagram of the second half of the etched plate in this embodiment;

[0034] Figure 7 This is a cross-sectional schematic diagram of the first cover film attachment plate in this embodiment;

[0035] Figure 8 This is a cross-sectional schematic diagram of another first cover film attachment plate in this embodiment;

[0036] Figure 9 This is a cross-sectional schematic diagram of the first cover film graphic plate of this embodiment;

[0037] Figure 10 This is a cross-sectional schematic diagram of the third half-etched plate in this embodiment;

[0038] Figure 11 This is a schematic cross-sectional view of the pseudo-high current-carrying thick copper flexible circuit board of this embodiment;

[0039] Figure 12 This is a physical image of the pseudo-high current-carrying thick copper flexible circuit board of this embodiment.

[0040] Explanation of icon numbers:

[0041]

[0042] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0044] It should be noted that all directional indications (such as up, down, left, right, front, back, inside, outside, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0045] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0046] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0047] Please see Figure 1 ; Figure 1 This is a flowchart illustrating the main processes involved in an embodiment of the present invention.

[0048] The method for fabricating a pseudo-high current-carrying thick copper flexible circuit board according to an embodiment of the present invention includes: Figure 1 The main manufacturing process is explained in detail step by step below.

[0049] Please see Figure 2 and Figure 3 ; Figure 2 This is a schematic diagram of the cross-sectional structure of the auxiliary layer in this embodiment; Figure 3 This is a schematic diagram of the cross-sectional structure of another auxiliary layer in this embodiment.

[0050] The pseudo-high current-carrying thick copper flexible circuit board of the present invention is designed with a forming line 100. The area within the forming line is the effective area, and the area outside the forming line is the ineffective area.

[0051] Step S10:

[0052] Take an insulating material board 100 of the same size as the circuit board, and attach an adhesive layer 120 to one side corresponding to the ineffective area to form an auxiliary layer 10 (e.g., Figure 2 (As shown).

[0053] Since this embodiment uses a single-layer thick copper layer 200 to create the circuit pattern, it is necessary to provide support for the single-layer thick copper layer 200. Therefore, an auxiliary layer 10 is made as a support. The auxiliary layer 10 is an auxiliary structure in the processing, rather than a structure retained in the finished circuit board. Therefore, the adhesive layer 120 can be used to bond the auxiliary layer 10 and the thick copper layer 200 together through high temperature and high pressure pressing, and can ensure that the areas without the adhesive layer 120 do not adhere, making it easy to remove later.

[0054] In this embodiment, an insulating material board 100 of the same size as the circuit board is taken, and a cover film layer 130 is taken. The cover film layer 130 is attached to the surface of the insulating material board 100, and an adhesive layer 120 is attached to the surface of the cover film layer 130 corresponding to the ineffective area, forming an auxiliary layer 10A (e.g., Figure 3 (As shown).

[0055] The covering film 130 is generally made of polyimide, which has good inertness. Compared with the good adhesion effect of the thick copper layer 200 and the adhesive layer 120 under the pressure conditions, the bonding force between polyimide and the thick copper layer 200 is poor, forming a release effect, which facilitates the subsequent removal of the effective area and the auxiliary layer 10A.

[0056] In this embodiment, the insulating material board 110 is an FR-4 board, PP board, PET board or PTFE board. Preferably, the thickness of the insulating material board 110 is 1.0 mm to 3.0 mm, and more preferably 1.6 mm or 2.0 mm.

[0057] Generally, FR-4 board with similar properties to the insulating dielectric layer material of the circuit board itself is used as the insulating material board 110. Other materials can also be used when the requirements for processing precision are not strict.

[0058] In this embodiment, the adhesive layer 120 is an acrylic adhesive or an epoxy resin adhesive; both adhesive layers have relatively good adhesion to the thick copper layer 200.

[0059] In this embodiment, the adhesive layer 120 is attached inward along the edge of the circuit board, and the attachment width of the adhesive layer 120 is less than the width from the edge to the molding line 100.

[0060] The width of the adhesive layer 120 must completely cover the ineffective area, achieving a width that effectively bonds the auxiliary layer 10 or auxiliary layer 10A to the thick copper layer 200 at their edges, preventing issues such as chemical seepage during subsequent processing, and facilitating complete separation from the effective area later.

[0061] Preferably, the tool pattern distributed in the invalid area is set in the area not covered by the adhesive layer 120 to prevent the tool pattern from being removed after the auxiliary layer 10A is removed. However, the tool hole can be left unset and made after the auxiliary layer 10 or auxiliary layer 10A is removed to prevent the adhesive layer 120 from cracking and leaking due to the making of the tool hole.

[0062] Please see Figure 4 ; Figure 4 This is a cross-sectional schematic diagram of the first half-etched plate in this embodiment.

[0063] Step S20:

[0064] A thick copper layer 200, typically ≥105μm thick, is attached to one side of the adhesive layer 120 of the auxiliary layer 10. The thick copper layer 200 is then subjected to a series of processes: dry film application, exposure, development, and first etching, forming a first half-etched pattern 210. This first half-etching process involves etching away a portion of the thick copper layer 200; the unetched thick copper layer 200 is the first retained half-copper 220. The entire process forms the first half-etched board 20 (e.g., ...). Figure 4 (As shown).

[0065] This embodiment uses an additive pattern overlay method of "half-etch + half-etch + ..." to form the final high-precision thick copper layer pattern; the thickness of the first half-etch pattern 210 is 1 / 3 to 3 / 5 of the thickness of the thick copper layer 200.

[0066] Please see Figure 5 and Figure 6 ; Figure 5 This is a cross-sectional schematic diagram of the first resin graphic plate of this embodiment; Figure 6 This is a cross-sectional schematic diagram of the second half of the etched plate in this embodiment.

[0067] Step S30:

[0068] One side of the first half-etched pattern 210 of the first half-etched plate 20 is sequentially screen-printed with resin, cured, and polished to form the first resin layer 310, thus forming the first resin pattern plate 30 (e.g., Figure 5 (As shown), then a copper layer is electroplated, and a dry film is applied to the electroplated copper layer. Following the pattern distribution of the first half-etched pattern 210, exposure, development, and second etching processes are performed sequentially to form the second half-etched pattern 410, thus forming the second half-etched board 40 (as shown). Figure 6 (As shown).

[0069] By using screen printing resin to create resin patterns, the gaps in the first half-etched pattern 210 are filled, reducing the height difference of the thick copper layer and providing a plating base for subsequent copper plating. It also provides a base for attaching the first cover film 610 and the second cover film 830 and filling the gaps in the circuit. The screen printing resin can use a dotted screen printing method, and the resin is only screen printed into the gaps between the first half-etched patterns 210. The thickness of the first resin layer 310 is less than or equal to the thickness of the first half-etched pattern 210. During screen printing, a small amount of resin can be screen printed, and it is not necessary to screen print the same thickness as the first half-etched pattern 210. Otherwise, a lot of resin will overflow onto the surface of the first half-etched pattern 210, causing problems with polishing.

[0070] The thickness of the electroplated copper layer is determined by the number of times the required final copper thickness is divided. Generally, the electroplating thickness is 25μm to 50μm, preferably 35μm. The electroplated copper layer is etched to form a second half-etched pattern 410 superimposed on the surface of the first half-etched pattern 210, thus forming a thicker copper circuit pattern overall.

[0071] Step S40:

[0072] Following the same manufacturing method as step S30, a plurality of first-side etched patterns (not shown in the figure) that are identical to the second-side etched pattern 410 and are stacked sequentially are formed on the second half-etched plate 40 to form a first-side pattern plate.

[0073] If, after the second half-etched pattern 410 is completed, it is necessary to continue forming a stacked circuit pattern, then the stacking process is further carried out in the manner described above. That is, one side of the second half-etched pattern 410 of the second half-etched board 40 is screen-printed with resin, cured, and polished in sequence to form a stacked resin layer. Then, a copper layer is electroplated, and a dry film is applied. The exposure, development, and etching processes are carried out in sequence according to the pattern distribution of the second half-etched pattern 410 to form a stacked etched pattern.

[0074] In this embodiment, the width of the second half-etched pattern 410 is smaller on one side than that of the first half-etched pattern 210, and the width of the plurality of first-side etched patterns decreases sequentially from the first half-etched pattern 210 outwards.

[0075] Due to the influence of the expansion and contraction of the board during the processing, as well as the exposure error of the copper layer in each stack, there may be a deviation between the second half etched pattern 410 and the first half etched pattern 210. Using a stacking method with progressively decreasing width is beneficial to eliminate processing deviations. Generally, the width decreases by 5μm to 10μm on each side.

[0076] Please see Figure 7 , Figure 8 and Figure 9 ; Figure 7 This is a cross-sectional schematic diagram of the first cover film attachment plate in this embodiment; Figure 8 This is a cross-sectional schematic diagram of another first cover film attachment plate in this embodiment; Figure 9 This is a cross-sectional schematic diagram of the first cover film graphic plate in this embodiment.

[0077] Step S50:

[0078] Take the first covering film 510 and apply it to the first graphic plate (used in the attached drawing). Figure 6 (As illustrated in the second half-etched plate 40) The first cover film 510 is attached to the side of the first etched pattern of the second half-etched plate 40 to form the first cover film attachment plate 50 (e.g., ...). Figure 7 (as shown), and remove the auxiliary layer 10 to expose the first retained half-copper, forming the first cover film pattern plate (as shown). Figure 9 (As shown).

[0079] This embodiment uses the method of attaching a first cover film 510 for processing. On the one hand, it can effectively fill the gaps between the lines of the second half-etched pattern 410 and form a good surface protective layer. On the other hand, the first cover film 510 can form a board surface support for subsequent processing of the second side, so that after the auxiliary layer 10 is removed, the board surface can still form a solid processable board surface by combining the first cover film 510 with the first resin layer 310 and the first half-etched pattern 210 and the second half-etched pattern 410.

[0080] In this embodiment, forming the second half-etched plate further includes sequentially screen printing resin, curing, and polishing one side of the second half-etched pattern 410 to form another first cover film pattern plate 50A (e.g., Figure 8 (As shown).

[0081] In one embodiment, resin can also be used to fill the line gaps of the second half-etched pattern 410 to reduce the height difference of the line gaps of the second half-etched pattern 410.

[0082] In this embodiment, the resin is either solder resist ink or via-filling resin; both resin materials can form good filling, and via-filling resin has higher reliability than solder resist ink.

[0083] In this embodiment, removing the auxiliary layer 10 involves milling the circuit board along the edge of the adhesive layer 120 extending into the invalid area to remove the auxiliary layer 10.

[0084] Since the adhesive layer 120 covers the edge of the circuit board, the edge can be cut off directly to remove the auxiliary layer 10. That is, the board edge area corresponding to the adhesive layer 120 is the area where the design size of the circuit board is pre-enlarged.

[0085] In one embodiment, removing the auxiliary layer 10 involves laser ablation of the insulating material board 110 along the contour of the adhesive layer 120 to remove the insulating material board 110, and then grinding the adhesive layer 120.

[0086] If the width of the adhesive layer 120 is narrow and the thickness of the insulating material board 110 is thin, the adhesive layer 120 can be set in an ineffective area between the effective board of the panel. When removing it, laser ablation can be used to perform controlled-depth ablation, followed by grinding.

[0087] Please see Figure 10 , Figure 11 and Figure 12 ; Figure 10 This is a cross-sectional schematic diagram of the third half-etched plate in this embodiment; Figure 11 This is a schematic cross-sectional view of the pseudo-high current-carrying thick copper flexible circuit board of this embodiment; Figure 12 This is a physical image of the pseudo-high current-carrying thick copper flexible circuit board of this embodiment.

[0088] Step S60:

[0089] The first half-copper 220 is sequentially subjected to dry film lamination, exposure, development, and third etching to form the third half-etched pattern 710 (e.g., Figure 10 As shown), following the same fabrication method as step S30, a fourth half-etched pattern 810, identical to and stacked with the third half-etched pattern 710, is fabricated on the third half-etched pattern 710, and several stacked second-side etched patterns (not shown in the attached figure) are fabricated; the second cover film 830 is taken, and a second-side etched pattern (used in the attached figure) is etched onto it. Figure 11 (For illustration) A second cover film 830 is attached to one side, forming a pseudo-high current-carrying thick copper flexible circuit board 80 (e.g. Figure 11 (As shown).

[0090] In this embodiment, the width of the fourth half-etched pattern is smaller on each side than that of the third half-etched pattern, and the width of the several second-side etched patterns decreases sequentially from the third half-etched pattern outwards.

[0091] The second side is processed using the same method as the first side, forming a thick copper circuit pattern with multiple layers. It is worth noting that the application of the first cover film 510 and the second cover film 830 makes the circuit board a pseudo-flexible circuit board.

[0092] It is worth noting that, due to the high precision of the circuit boards in the actual design and manufacturing process, the actual structural diagrams and dimensions such as the thickness of each layer and the width of the lines are at the micrometer level. For example, the thickness of each layer is generally between 5μm and 50μm. If the accompanying drawings in the instruction manual are made according to the actual scale, there will be a problem of unclear illustrations. Therefore, in order to more clearly show the implementation process of the manufacturing method, the accompanying drawings in this embodiment are all enlarged schematic diagrams of the technical features, and do not represent the size of the actual structural diagram, nor do they represent enlarged views of the actual structural diagram at the same scale.

[0093] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural transformations made using the contents of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. A method for manufacturing a pseudo-high current-carrying thick copper flexible circuit board, wherein the circuit board is designed with forming lines, the area within the range of the forming lines is the effective area, and the area outside the forming lines is the ineffective area; Its features are, The manufacturing method includes the following steps: S10: Take an insulating material board of the same size as the circuit board, and attach an adhesive layer to one side of the board corresponding to the invalid area to form an auxiliary layer; S20: Take a thick copper layer and attach it to one side of the adhesive layer of the auxiliary layer. Then, sequentially apply dry film, expose, develop, and perform a first etching process on the thick copper layer to form a first half-etched pattern. The first etching process is to etch away part of the thickness of the thick copper layer. The unetched thick copper layer is the first retained half copper, and the whole is formed into a first half-etched board. S30: Silk screen resin is applied to one side of the first half-etched pattern of the first half-etched plate to fill the gaps of the first half-etched pattern. Then, curing, polishing, and copper plating are performed in sequence. After that, a dry film is applied to the copper plating layer, and exposure, development, and second etching are performed in sequence according to the pattern distribution of the first half-etched pattern to form the second half-etched pattern. The whole is formed into the second half-etched plate. S40: Following the same manufacturing method as S30, a plurality of first-side etched patterns that are identical to the second half-etched pattern and are stacked sequentially are formed on the second half-etched plate to form a first-side pattern plate; The width of the second half-etched pattern is smaller on one side than that of the first half-etched pattern, and the width of several first-face etched patterns decreases sequentially from the first half-etched pattern outwards. S50: Take the first cover film, attach the first cover film to the side of the first etched pattern of the first pattern board, and remove the auxiliary layer to expose the first retained half copper to form the first cover film pattern board. S60: The first retained half-copper is sequentially subjected to dry film lamination, exposure, development, and third etching to form a third half-etched pattern. Following the same manufacturing method as in S30, a fourth half-etched pattern identical to and stacked with the third half-etched pattern is formed on the third half-etched pattern, and several stacked second-side etched patterns are also formed. A second cover film is taken and attached to one side of the second-side etched pattern to form the pseudo high current-carrying thick copper flexible circuit board. The width of the fourth half-etched pattern is smaller on one side than that of the third half-etched pattern, and the width of the several second-side etched patterns decreases sequentially from the third half-etched pattern outwards.

2. The manufacturing method as described in claim 1, characterized in that, The auxiliary layer is formed by taking an insulating material board with the same dimensions as the circuit board. Then, take the cover film layer, attach the cover film layer to the surface of the insulating material board, and attach an adhesive layer to the surface of the cover film layer corresponding to the ineffective area to form the auxiliary layer.

3. The manufacturing method as described in claim 1 or 2, characterized in that, The insulating material board is an FR-4 board, PP board, PET board, or PTFE board.

4. The manufacturing method as described in claim 1 or 2, characterized in that, The adhesive layer is an acrylic adhesive or an epoxy resin adhesive.

5. The manufacturing method as described in claim 1 or 2, characterized in that, The adhesive layer is attached inward along the edge of the circuit board, and the attachment width of the adhesive layer is less than the width from the edge to the molding line.

6. The manufacturing method as described in claim 1, characterized in that, The process of forming the second half-etched plate also includes, after forming the second half-etched pattern, screen printing resin onto one side of the second half-etched pattern to fill the gaps in the second half-etched pattern, followed by curing and polishing.

7. The manufacturing method as described in claim 1 or 6, characterized in that, The resin is solder resist ink or pore-filling resin.

8. The manufacturing method as described in claim 1, characterized in that, Removing the auxiliary layer involves milling the circuit board along the edge of the adhesive layer extending into the invalid area to remove the auxiliary layer. Alternatively, the insulating material board can be laser-ablated along the contour of the adhesive layer to remove the insulating material board, and the adhesive layer can be polished.

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