A method for manufacturing a single-layer circuit flexible circuit board for an intelligent vision module

Abstract

The application discloses a manufacturing method of a single-layer circuit flexible circuit board for an intelligent vision module, takes a copper layer and respectively pastes a first dry film and a protective film, a window is made on the first dry film corresponding to a hollow circuit pattern, a tin plating layer is formed, a tin plating plate is formed; a single-sided copper-clad plate is taken, a circuit pattern is made corresponding to the tin layer area, a copper pattern of the copper-clad plate is formed, a first pattern plate is formed; the tin plating plate is correspondingly pressed with the first pattern plate to form a pressed plate; the protective film in the pressed plate is removed, a circuit pattern is made, a copper layer window pattern and a hollow circuit pattern are formed, and a second pattern plate is formed; the area corresponding to the copper pattern of the copper-clad plate of the insulating medium layer in the second pattern plate is removed, then tin removal processing is performed, after processing, the hollow circuit pattern forms a hollow circuit, and a flexible circuit board is formed; the tin layer provides protection for etching, creates a release condition for the copper pattern of the copper-clad plate, and lays a foundation for uncovering the insulating layer, and finally realizes efficient and high-precision processing of the flexible circuit board.

Description

A method for fabricating a single-layer flexible circuit board for an intelligent vision module Technical Field

[0001] This invention relates to the field of flexible circuit board manufacturing, and more particularly to a method for manufacturing a single-layer flexible circuit board for intelligent vision modules. Background Technology

[0002] In applications such as industrial vision lens modules and intelligent connected vehicle camera modules, flexible circuit boards need to meet two core requirements: first, to ensure the transmission function of the circuit, and second, to avoid mutual interference between interlayer lines. Based on this, the design of flexible circuit boards with only a single layer of lines has emerged. If a plug-in soldering connection module is also required, an additional hollow plug line needs to be designed, forming a composite structure of "single layer of lines + hollow plug".

[0003] Currently, there are two main processing methods for this type of flexible circuit board, but both have significant technical defects, as follows:

[0004] (1) First processing method: Take the copper layer as the substrate, first attach a micro film to the first side of the copper layer, and then press a cover film on the second side (the cover film needs to be opened in advance in the area of ​​the cutout circuit). Make the circuit pattern, peel off the micro film, and then press the cover film on the same side (open the window in the area of ​​the cutout circuit as well). After subsequent processing and shaping, the flexible circuit board is finally obtained.

[0005] The problem with this production method is:

[0006] The entire process uses a micro-adhesive film as the carrier film in the manufacturing process. During the processing of processes such as pressing, etching, and baking, the micro-adhesive film is prone to large expansion and contraction, resulting in large expansion and contraction of the circuit pattern. This may cause problems such as attachment misalignment when attaching the cover film to the first side, reducing the overall accuracy of the flexible circuit board.

[0007] During the process of peeling off the micro-adhesive film, the perforated circuit loses the support of the micro-adhesive film, which can easily lead to problems such as skewing. Furthermore, when attaching the cover film to the first side, the perforated circuit is prone to misalignment and skewing during the pressing process, resulting in poor circuit processing.

[0008] (2) The second processing method: take a single-sided copper-clad board as the substrate, make the circuit pattern, attach a cover film to the side where the circuit pattern is located (the cover film needs to be opened in advance for the area of ​​the hollow circuit), use laser ablation to remove the material of the area of ​​the hollow circuit on the single-sided copper-clad board to form the hollow circuit, and then process and shape it through subsequent processes to obtain a flexible circuit board.

[0009] The problem with this production method is:

[0010] High cost: If the flexible circuit board requires a large number of cutout lines or a large cutout area, the laser ablation process will consume a lot of electrical energy, and the processing time will increase exponentially with the size of the cutout, which will directly lead to a significant increase in processing costs and make it difficult to meet the cost control requirements of mass production.

[0011] (B) Risk of circuit contamination and scrapping: A large amount of carbon black powder will be generated during the laser ablation process. This powder is chemically inert and difficult to remove completely by conventional cleaning methods. The residual carbon black powder will contaminate the circuit surface, which will not only interfere with the normal processing of subsequent processes, but may also cause short circuits in severe cases, ultimately causing the flexible circuit board to be scrapped.

[0012] Therefore, in order to solve the problems mentioned above, it is necessary to provide a method for manufacturing a single-layer flexible circuit board for intelligent vision modules. Summary of the Invention

[0013] This invention aims to solve the comprehensive problems of high cost and difficulty in guaranteeing processing quality in existing flexible circuit board processing methods. It proposes a method for manufacturing a single-layer flexible circuit board for intelligent vision modules. The circuit board is processed according to design data, which includes a cutout circuit pattern and forming lines. The area within the forming lines is the effective area, and the remaining area is the tool area. The cutout circuit pattern is located within the effective area. The manufacturing method includes the following steps:

[0014] S10: Take the copper layer, apply a first dry film and a protective film to the surface of the copper layer respectively, make a window in the area of ​​the first dry film corresponding to the hollow circuit pattern to form the first dry film pattern, and then electroplate a tin layer on the whole board to form a tin-plated board.

[0015] S20: Take a single-sided copper-clad board composed of an insulating dielectric layer and copper foil, and fabricate a circuit pattern on the copper foil corresponding to the tin layer to form a copper-clad board copper pattern. The whole board forms the first pattern board.

[0016] S30: Press the tin-plated plate and the first pattern plate together, with the tin layer adjacent to the copper pattern of the copper-clad laminate, and the whole plate forms a pressed plate;

[0017] S40: Remove the protective film in the laminating plate, and create a circuit pattern on the exposed copper layer. The circuit pattern includes a copper layer window pattern, which includes a hollow circuit pattern formed in the area corresponding to the tin layer. The whole board is then formed into a second pattern board.

[0018] S50: Remove the area of ​​the insulating dielectric layer in the second pattern board corresponding to the copper pattern of the copper-clad laminate, then perform desoldering, and after subsequent processing, the hollowed-out circuit pattern forms a hollowed-out circuit, and the whole board forms the flexible circuit board.

[0019] Furthermore, the copper layer has a copper thickness of <70μm, and the protective film is a micro-adhesive film.

[0020] Furthermore, the copper layer has a copper thickness of ≥70μm, and the protective film is a second dry film.

[0021] Furthermore, forming the hollow circuit pattern includes removing the protective film, taking a third dry film, creating a dry film pattern corresponding to the hollow circuit pattern, and then sequentially developing and etching to form the hollow circuit pattern; the etching is alkaline etching.

[0022] Furthermore, the size of the tin layer is larger on one side than the area of ​​the cutout circuit pattern.

[0023] Furthermore, the size of the copper pattern on the copper-clad laminate is smaller on one side than that of the tin layer.

[0024] Furthermore, the side of the copper pattern of the copper clad laminate adjacent to the effective area is ≤50μm smaller than the size of the tin layer.

[0025] Furthermore, the size of the copper layer window pattern is reduced by a second inward reduction, except for the remaining sides adjacent to the effective area.

[0026] Furthermore, the copper layer window pattern extends into the tool area from one side adjacent to the tool area.

[0027] Furthermore, the flexible circuit board is formed by using laser-controlled deep cutting to remove the area of ​​the insulating dielectric layer corresponding to the copper pattern of the copper-clad laminate, followed by laser trimming, desoldering, and subsequent processing to form the flexible circuit board.

[0028] The technical solution of this invention has the following main advantages:

[0029] (1) The process of “electroplated tin layer → copper pattern on copper-clad laminate → copper layer window pattern to expose copper layer → alkaline etching of copper layer to create circuit pattern → tin stripping” is used to construct the production path of the hollow circuit pattern:

[0030] By electroplating a tin layer onto the copper layer, it can replace the micro-adhesive film to provide a load-bearing function and provide stable support for the cutout lines during etching and peeling processes. This avoids the expansion and contraction of the micro-adhesive film during pressing and etching, which can cause the lines to shift. It also solves the problems of skewed cutout lines and poor line processing that can easily occur after the micro-adhesive film is removed. On the other hand, it is beneficial to effectively prevent the seepage of etching chemicals in subsequent processing processes and ensure the integrity of the line pattern.

[0031] By using alkaline etching to create differentiated processing, the copper layer corresponding to the cutout lines can be precisely preserved, completely avoiding the carbon black powder pollution caused by laser ablation, which can lead to problems such as short circuits and scrapping of the lines. At the same time, the processing time and power consumption do not increase with the complexity of the cutout lines.

[0032] Furthermore, alkaline etching simultaneously completes the fabrication of copper layer window patterns and hollow circuit patterns, achieving a synergistic effect of "one-time dry film positioning, simultaneous forming of copper layer window patterns and hollow circuit patterns." This can effectively improve the processing accuracy of circuit patterns, and the processing time and cost do not increase significantly with the increase of the hollow scale, making it suitable for large-scale mass production needs.

[0033] The desoldering solution only dissolves the tin layer without damaging the copper layer circuitry. After desoldering, the hollowed-out circuit structure remains intact, which not only does not affect the conductivity of the circuitry but also avoids plug-in compatibility issues caused by residual tin layers, thus meeting the functional requirements of hollowed-out plugs for industrial vision lenses and automotive camera modules.

[0034] (2) Based on the size coordination relationship between the copper layer window pattern, the tin layer, and the copper pattern of the copper-clad laminate, the etching solution seepage is eliminated, which is suitable for thick copper and high current carrying scenarios. A comprehensive sealing and adaptation system is formed, so that the cover film and the copper layer and the insulating dielectric layer form a gapless closed structure at the edge position, which completely blocks the path of etching solution seepage from the edge of the line, avoids the copper layer in non-target areas from being corroded, and ensures the integrity of the line pattern; solves the problem of etching solution seepage.

[0035] (3) Through the differentiated protective film design, it has good adaptability to the processing of flexible circuit boards with different copper thicknesses. It can meet the processing requirements of conventional thin copper flexible circuit boards and adapt to the processing requirements of thick copper high current-carrying flexible circuit boards. It solves the problem of "thick copper processing is prone to insufficient precision due to micro-adhesive film expansion and contraction or laser ablation damage" in the existing technology, and ensures that the high current carrying capacity of thick copper boards and the line accuracy are taken into account.

[0036] (4) The technical points are related. The tin layer not only provides protection for etching, but also creates release conditions for the copper pattern of the copper-clad laminate and lays the foundation for the insulation layer to be uncovered. The dimensional relationship between the "copper layer window pattern, tin layer and copper pattern of copper-clad laminate" ensures the sealing of the lamination and supports the precision of etching and the integrity of finishing. Each link supports each other to achieve efficient and high-precision processing of flexible circuit boards. Attached Figure Description

[0037] 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.

[0038] Figure 1 is a schematic diagram of the process flow of an embodiment of the present invention;

[0039] Figure 2 is a cross-sectional schematic diagram of the tin-plated plate according to an embodiment of the present invention;

[0040] Figure 3 is a cross-sectional schematic diagram of the first graphic plate according to an embodiment of the present invention;

[0041] Figure 4 is a cross-sectional schematic diagram of the pressing plate according to an embodiment of the present invention;

[0042] Figure 5 is a plan view of the second graphic plate according to an embodiment of the present invention;

[0043] Figure 6 is a schematic diagram of section AA in Figure 5;

[0044] Figure 7 is a schematic diagram of the BB cross section in Figure 5;

[0045] Figure 8 is a plan view of the covering film plate according to an embodiment of the present invention;

[0046] Figure 9 is a schematic diagram of the CC section of Figure 5;

[0047] Figure 10 is a cross-sectional schematic diagram of the cover plate according to an embodiment of the present invention;

[0048] Figure 11 is a cross-sectional schematic diagram of the desoldering plate according to an embodiment of the present invention;

[0049] Figure 12 is a cross-sectional schematic diagram of the flexible circuit board according to an embodiment of the present invention;

[0050] Figure 13 is a planar schematic diagram of the flexible circuit board according to an embodiment of the present invention.

[0051] Explanation of reference numerals: 100, Cutout circuit pattern; 200, Forming line; 300, Effective area; 400, Tool area; 500, Auxiliary alignment hole; 10, Tin plate; 1010, Copper layer; 1020, First dry film; 1030, Protective film; 1040, First dry film pattern; 1050, Tin layer; 20, First pattern board; 2010, Single-sided copper clad laminate; 2020, Copper pattern of copper clad laminate; 30, Lamination board; 40, Second pattern board; 4010, Circuit pattern; 4020, Opening pattern of copper layer; 50, Cover film board; 5010, Opening pattern of cover film; 5020, Opening cover film; 60, Removal board; 70, Desoldering board; 80, Flexible circuit board; 8010, Cutout circuit.

[0052] 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

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] Please refer to Figure 1. Figure 1 is a schematic diagram of the process flow of an embodiment of the present invention.

[0058] The flexible circuit board 80 of this embodiment is processed according to design data, which includes a cutout circuit pattern 100 and a forming line 200. The area within the forming line 200 is the effective area 300, and the remaining area is the tool area 400. The cutout circuit pattern 100 is located in the effective area 300. The manufacturing method includes the following steps.

[0059] Please refer to Figure 2, which is a cross-sectional schematic diagram of the tin-plated plate according to an embodiment of the present invention.

[0060] Step S10:

[0061] Take the copper layer 1010, apply the first dry film 1020 and the protective film 1030 to the surface of the copper layer 1010 respectively, make a window in the area of ​​the first dry film 1020 corresponding to the hollow circuit pattern 100 to form the first dry film pattern 1040, and then electroplate the whole board with a tin layer 1050 to form a tin-plated board 10.

[0062] Optionally, the copper layer 1010 is laid on a steel plate larger than itself, fixed by adhesive edge bonding, and then processed in step S10.

[0063] By attaching a first dry film 1020 and a protective film 1030 to both sides of the copper layer 1010, the first dry film pattern 1040 provides a basis for the processing pattern of the electroplated tin layer 1050, while the protective film 1030 protects the copper layer 1010 during the electroplating process and provides a processing basis for the subsequent process of making the circuit pattern 4010.

[0064] The functions of the tin layer 1050 include: allowing it to bond tightly with the copper layer 1010 through electroplating, effectively preventing etching solution from seeping into the subsequent process of processing the cutout circuit 8010, thus ensuring the integrity of the circuit pattern 4010; the tin layer 1050 can replace the protective film 1030 in the etching process, providing rigid support for the circuit pattern 4010, preventing the circuit from skewing due to lack of support, and reducing the circuit defect rate; the tin layer 1050 and the copper pattern 2020 of the copper-clad laminate produced in step S20 have the characteristic of mutual release, providing feasible structural conditions for the peeling process in step S50, ensuring that the insulating dielectric layer can be accurately peeled off without damaging the circuit.

[0065] Optionally, the copper layer 1010 has a copper thickness of <70μm, and the protective film 1030 is a micro-adhesive film.

[0066] Optionally, the copper layer 1010 has a copper thickness of ≥70μm, and the protective film 1030 is a second dry film.

[0067] Different types of protective films 1030 are adapted to copper layers 1010 with different copper thicknesses. When the copper thickness is ≥70μm, its own thickness already provides support and rigidity, so there is no need to use micro-adhesive films to provide further support. When the copper thickness is <70μm, the support characteristics of the micro-adhesive film can meet the rigidity requirements when processing thin copper. Moreover, the micro-adhesive film will be removed in the subsequent process of fabricating circuit patterns 4010, and the support will be provided by the tin layer 1050 electroplated in the previous process. This can effectively solve the problems of dimensional expansion and contraction caused by the use of micro-adhesive films throughout the entire process in the existing technology.

[0068] This manufacturing method, through the design of a differentiated protective film 1030, has good adaptability to the processing of flexible circuit boards 80 with different copper thicknesses. It can meet the processing requirements of both conventional thin copper flexible circuit boards 80 and thick copper high current-carrying flexible circuit boards 80.

[0069] In this embodiment, both the micro-adhesive film and the second dry film can effectively protect the copper layer 1010 during the tin plating process, preventing the plating solution or other impurities from damaging the surface of the copper layer 1010, and providing a substrate for the subsequent fabrication of the circuit pattern 4010.

[0070] Please refer to Figure 3, which is a cross-sectional schematic diagram of the first graphic plate according to an embodiment of the present invention.

[0071] Step S20:

[0072] Take a single-sided copper-clad laminate 2010 composed of an insulating dielectric layer and copper foil, and fabricate a circuit pattern 4010 on the tin layer 1050 corresponding to the copper foil to form a copper pattern 2020 of the copper-clad laminate. The whole board forms the first pattern board 20.

[0073] The copper pattern 2020 of the copper clad laminate corresponds in size to the tin layer 1050, providing a processing prerequisite for the two to form a non-adhesive release state after subsequent lamination. At the same time, after etching, the other areas of the single-sided copper clad laminate 2010 expose the insulating dielectric layer, which can act as a cover film, tightly adhering to the copper layer 1010 and the tin layer 1050, effectively avoiding the positioning deviation of traditional bonding processes. Meanwhile, the adhesiveness of the insulating dielectric layer can ensure a gapless bond between the tin layer 1050 and the copper layer 1010, effectively preventing the seepage of etching chemicals in subsequent processes.

[0074] Furthermore, the dimensions of the copper pattern 2020 on the copper clad laminate are smaller on one side than the tin layer 1050.

[0075] The tin layer 1050 extends beyond the copper pattern 2020 of the copper clad laminate. During the subsequent lamination process, it forms a "sealed barrier" around the copper pattern 2020, blocking the path of the etching solution from seeping in from the edge, ensuring that the circuit is not corroded during the etching process, and improving the circuit processing yield.

[0076] Furthermore, the size of one side of the copper pattern 2020 adjacent to the effective area 300 of the copper clad laminate is ≤50μm smaller than that of the tin layer 1050.

[0077] A 50μm size difference can maximize the layout space of the effective area 300, avoiding excessive occupation of the effective area 300. This ensures that the tin layer 1050 on the side of the copper pattern 2020 of the copper clad laminate adjacent to the effective area 300 can form a stable seal with the insulating dielectric layer, and also ensures the integrity of the circuit design of the effective area 300.

[0078] Please refer to Figure 4, which is a cross-sectional schematic diagram of the pressing plate according to an embodiment of the present invention.

[0079] Step S30:

[0080] The tin-plated plate 10 is pressed together with the first pattern plate 20, and the tin layer 1050 is adjacent to the copper pattern 2020 of the copper-clad laminate, forming the entire plate 30.

[0081] The tin-plated board 10 made in the previous two steps is pressed together with the first pattern board 20 to form an integral whole, and the tin layer 1050 is adjacent to the copper pattern 2020 of the copper clad laminate. The release characteristics of the tin layer 1050 and the copper pattern 2020 of the copper clad laminate are used to provide the processing premise for the peeling process of removing the "insulating dielectric layer" in the subsequent process S50.

[0082] Optionally, the tin-plated plate 10 and the first pattern plate 20 can be precisely aligned by means of auxiliary alignment holes 500.

[0083] Please refer to Figures 5, 6 and 7. Figure 5 is a plan view of the second graphic plate according to an embodiment of the present invention; Figure 6 is a cross-sectional view of AA in Figure 5; and Figure 7 is a cross-sectional view of BB in Figure 5.

[0084] Step S40:

[0085] Remove the protective film 1030 from the laminating plate 30, and create a circuit pattern 4010 on the exposed copper layer 1010. The circuit pattern 4010 includes a copper layer window pattern 4020, which includes a hollow circuit pattern 100 formed in the area corresponding to the tin layer 1050. The entire board is then used to form a second pattern board 40.

[0086] Furthermore, forming the hollow circuit pattern 100 includes removing the protective film 1030, taking a third dry film (not shown in the attached figure), making a dry film pattern corresponding to the hollow circuit pattern 100, and then performing development and etching in sequence to form the hollow circuit pattern 100; the etching is alkaline etching.

[0087] Since the second dry film in step S10 needs to be exposed in order to protect the copper layer 1010 in the electroplating process, regardless of whether the protective film 1030 is a micro-adhesive film or a second dry film, when making the circuit pattern 4010 in step S40, the micro-adhesive film or the second dry film needs to be peeled off first, and then the third dry film 4030 is used to make the dry film pattern.

[0088] Etching the copper layer 1010 forms a copper layer window pattern 4020 and a hollow circuit pattern 100. The hollow circuit pattern 100 is located within the area of ​​the copper layer window pattern 4020. During the etching process of the copper layer 1010, the etching solution only acts on the copper layer window pattern 4020 and does not etch the non-window areas in the copper layer 1010 and tin layer 1050, effectively ensuring the processing accuracy and integrity of the circuit pattern 4010.

[0089] This embodiment utilizes an etching process to simultaneously create the copper layer window pattern 4020 and the hollow circuit pattern 100, achieving a synergistic effect of "one-time dry film positioning and synchronous molding". This can effectively improve the processing accuracy of the circuit pattern 4010, and the processing time and cost do not increase significantly with the increase in the scale of the hollow circuit pattern 100, thus meeting the needs of large-scale mass production.

[0090] It is worth noting that alkaline etching utilizes the differences in material properties to achieve "selective and precise etching." The alkaline etching solution is corrosive to the copper layer 1010 but inert to the tin layer 1050. After development, the copper layer 1010 in the corresponding area of ​​the cutout circuit pattern 100 is etched away, while the non-cutout areas and the copper pattern 2020 of the copper-clad laminate protected by the tin layer 1050 are preserved. This effectively avoids the risk of carbon black contamination and short circuits that can easily occur when using laser ablation to create the circuit pattern 4010 in existing technologies.

[0091] Optionally, the size of the copper layer window pattern 4020 is reduced by a second inward, except for the edges adjacent to the effective area 300.

[0092] By designing an inward-shrinking pattern, the edge of the copper layer window pattern 4020 is always within the coverage area of ​​the tin layer 1050, effectively avoiding the risk of etching solution seeping in from the side of the tool area 400.

[0093] Optionally, the copper layer window pattern 4020 extends into the tool area 400 from one side adjacent to the tool area 400.

[0094] The copper layer window pattern 4020 extends to the tool area 400, so that the forming line 200 is located within the extension of the copper layer window pattern 4020, and the extended side is still smaller than the edge of the tin layer 1050. This ensures that the copper layer window pattern 4020 extending to the tool area 400 is always covered by the tin layer 1050. During etching, only the copper layer 1010 in the window area is etched, without damaging the copper pattern 2020 of the copper clad laminate and the non-window area, thus ensuring the regularity and precision of the edge of the cutout circuit pattern 100.

[0095] Optionally, the size of the tin layer 1050 is larger on one side than the area of ​​the cutout pattern 100.

[0096] The tin layer 1050 completely covers all edges of the hollow circuit pattern 100. On the one hand, this ensures that external forces during processing will not directly act on the edges of the tin layer 1050, fundamentally eliminating the risk of cracks or peeling of the tin layer 1050 and ensuring the structural integrity of the tin layer 1050 before the desoldering process. On the other hand, it ensures that all copper layers 1010 that need to be retained during etching are within the protection range of the tin layer 1050, avoiding the loss of protection and etching of local copper layers 1010 due to dimensional deviations, thereby improving the forming accuracy and integrity of the hollow circuit pattern 100.

[0097] Please refer to Figures 8, 9, 10, 11, 12, and 13. Figure 8 is a plan view of the cover plate according to an embodiment of the present invention; Figure 9 is a cross-sectional view of the CC section of Figure 5; Figure 10 is a cross-sectional view of the cover plate according to an embodiment of the present invention; Figure 11 is a cross-sectional view of the desoldering plate according to an embodiment of the present invention; Figure 12 is a cross-sectional view of the flexible circuit board according to an embodiment of the present invention; and Figure 13 is a plan view of the flexible circuit board according to an embodiment of the present invention.

[0098] Step S50:

[0099] Remove the insulating dielectric layer in the second pattern board 40 corresponding to the copper pattern 2020 of the copper clad laminate to form a cover board 60 (Figure 10). Then perform desoldering to form a desoldering board 70 (Figure 11). After subsequent processing, the cutout circuit pattern 100 forms a cutout circuit 8010, and the whole board forms a flexible circuit board 80 (Figures 12 and 13).

[0100] Before removing the insulating dielectric layer in the second graphic board 40, a cover film is taken out, and a cover film window pattern 5010 is made in the area corresponding to the hollowed-out circuit pattern 100 to form a windowed cover film 5020, forming a cover film board 50 (Figures 8 and 9), which protects the area that does not need to be covered.

[0101] Due to the release structure design formed between the tin layer 1050 in the previous process and the copper pattern 2020 of the copper clad laminate, the copper pattern 2020 of the copper clad laminate can be directly peeled off when the insulating dielectric layer in the corresponding area is removed in step S50, thus meeting the requirements of high-precision processing.

[0102] The desoldering process uses a special desoldering solution (which only dissolves the tin layer 1050 and does not corrode the copper layer 1010). This solution can remove the tin layer 1050 from the previous process, thus avoiding the risk of poor conductivity or short circuit caused by residual tin layer 1050, while also completely preserving the cutout circuit pattern 100, ensuring good circuit transmission performance of the flexible circuit board 80.

[0103] After subsequent molding processes, the hollowed-out circuit pattern 100 is transformed into a hollowed-out circuit 8010, making the flexible circuit board 80 form a composite structure of "single-layer functional circuit + hollowed-out plug", which is suitable for the design requirements of the flexible circuit board 80 to have both signal transmission and plug-in soldering capabilities.

[0104] Furthermore, to form the flexible circuit board 80, the area corresponding to the copper pattern 2020 of the copper clad laminate is removed by laser deep cutting, and then laser trimming and desoldering are performed. After subsequent processing, the flexible circuit board 80 is formed.

[0105] Since the size of the copper pattern 2020 on one side is smaller than that of the copper layer window pattern 4020, the copper pattern 2020 can be peeled off when the insulating layer of the copper layer window pattern 4020 area is cut off. At this time, the side of the hollow circuit pattern 100 facing the effective area 300 still has the inward tin layer 1050 and the insulating dielectric layer attached to its surface. Therefore, it is necessary to use a laser to ablate and repair the inward tin layer 1050 and the insulating dielectric layer.

[0106] Laser cutting and laser ablation create differentiated paths. The side of the cutter with the hollowed-out circuit pattern 100 facing the effective area 300 is not actually a straight line. The area without the hollowed-out circuit pattern 8010 is cut along the forming line 200, while the area with the hollowed-out circuit pattern 100 is cut along the edge of the copper layer window pattern 4020 area. Then, laser ablation is used to burn off the insulating layer at that location, ensuring that the underlying copper layer 1010 (including the hollowed-out circuit pattern 100) is not damaged.

[0107] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for manufacturing a single-layer flexible circuit board for an intelligent vision module, wherein the circuit board is processed according to design data, the design data including a cutout circuit pattern and forming lines, the area within the forming lines being the effective area, the remaining area being the tool area, and the cutout circuit pattern being located within the effective area, characterized in that, The manufacturing method includes the following steps: S10: Take a copper layer, apply a first dry film and a protective film to the surface of the copper layer respectively, create windows in the area of ​​the first dry film corresponding to the hollow circuit pattern to form a first dry film pattern, and then electroplate a tin layer onto the entire board to form a tin-plated board; S20: Take a single-sided copper-clad laminate composed of an insulating dielectric layer and a copper foil, create a circuit pattern on the copper foil corresponding to the tin layer to form a copper-clad laminate copper pattern, and form a first pattern board from the entire board; S30: Press the tin-plated board and the first pattern board together, and press the tin layer and the copper-clad laminate together. The copper patterns are adjacent, and the whole board is formed into a lamination board; S40: Remove the protective film in the lamination board, and make a circuit pattern on the exposed copper layer. The circuit pattern includes a copper layer window pattern, and the copper layer window pattern includes a hollow circuit pattern formed in the area corresponding to the tin layer. The whole board is formed into a second pattern board; S50: Remove the insulating dielectric layer in the second pattern board in the area corresponding to the copper pattern of the copper clad laminate, and then perform desoldering. After subsequent processing, the hollow circuit pattern forms a hollow circuit, and the whole board is formed into the flexible circuit board.

2. The method for manufacturing a single-layer flexible circuit board for an intelligent vision module as described in claim 1, characterized in that, The copper layer has a copper thickness of <70μm, and the protective film is a micro-adhesive film.

3. The method for manufacturing a single-layer flexible circuit board for an intelligent vision module as described in claim 1, characterized in that, The copper layer has a copper thickness of ≥70μm, and the protective film is a second dry film.

4. A method for manufacturing a single-layer flexible circuit board for an intelligent vision module as described in claim 2 or 3, characterized in that, The process of forming the hollow circuit pattern includes removing the protective film, taking a third dry film, making a dry film pattern corresponding to the hollow circuit pattern, and then performing development and etching sequentially to form the hollow circuit pattern. The etching is an alkaline etching.

5. The method for manufacturing a single-layer flexible circuit board for an intelligent vision module as described in claim 1, characterized in that, The size of the tin layer is larger on one side than the area of ​​the cut-out circuit pattern.

6. The method for manufacturing a single-layer flexible circuit board for an intelligent vision module as described in claim 1, characterized in that, The copper pattern on the copper-clad laminate is smaller on one side than the tin layer.

7. The method for manufacturing a single-layer flexible circuit board for an intelligent vision module as described in claim 6, characterized in that, The copper pattern of the copper clad laminate adjacent to the effective area is smaller than the size of the tin layer by ≤50μm.

8. The method for manufacturing a single-layer flexible circuit board for an intelligent vision module as described in claim 7, characterized in that, The dimensions of the copper layer window pattern are reduced by a second inward reduction, except for the remaining sides adjacent to the effective area.

9. A method for manufacturing a single-layer flexible circuit board for an intelligent vision module as described in claim 1 or 8, characterized in that, The copper layer window pattern extends into the tool area from one side adjacent to the tool area.

10. The method for manufacturing a single-layer flexible circuit board for an intelligent vision module as described in claim 1, characterized in that, The flexible circuit board is formed by using laser-controlled deep cutting to remove the area of ​​the insulating dielectric layer corresponding to the copper pattern of the copper-clad laminate, followed by laser trimming, desoldering, and subsequent processing to form the flexible circuit board.

Images