A method for manufacturing a flexible circuit board with a high-precision sensing circuit

Abstract

The present invention discloses a method for manufacturing a flexible circuit board with a high-precision induction circuit. The method comprises the following steps: a first coil circuit pattern and a pad pattern are manufactured from a flexible copper-clad laminate, and an AOI inspection is performed to form a first flexible core board; a window is opened in a first covering film corresponding to the pad pattern, and the covering film is attached to the first flexible core board to form an attached board; a second coil circuit pattern is manufactured from a single-sided copper-clad laminate to form a second flexible core board; the first coil circuit pattern corresponds to the second coil circuit pattern; an adhesive layer is manufactured on the second flexible core board, and the covering board is attached to the attached board to form a flexible back-attached board; an induction circuit test is performed, and post-processing is performed to form a flexible circuit board; AOI inspection is combined with a four-wire circuit tester to form a double inspection, thereby improving the comprehensiveness and accuracy of the inspection; an adhesive layer is provided to bond the second flexible core board to the attached board, thereby providing physical support for the inspection process and providing a processing basis for subsequent depth-controlled laser cutting and panel structure sub-operation.

Description

Technical Field

[0001] The present invention relates to the field of flexible circuit board manufacturing, and in particular to a method for manufacturing a flexible circuit board with a high-precision sensing circuit. Background Art

[0002] In order to achieve more convenient and efficient functions, some low-altitude aircraft and consumer electronic products have begun to widely use inductive sensing circuit modules with wireless charging and wireless touch transmission functions. Flexible circuit boards, with their thin body, high precision, flexible installation, and bendability, can meet the application of sensing circuit modules in complex environments and diverse needs. Based on this development, the design and production of flexible circuit boards for high-precision sensing circuits have been spawned.

[0003] However, there are currently the following difficulties in processing this type of product:

[0004] (1) The coil circuit of the inductor is highly precise. When etching the circuit, micro short circuits or circuit gaps are prone to occur. Currently, common circuit board electrical performance testers, such as flying probe testers and general testers, are difficult to directly measure the inductance value.

[0005] Therefore, the method of testing the circuit resistance value is generally used to indirectly replace the inductance value test: if a micro short circuit occurs in the middle of the coil circuit, the effective length of the entire coil circuit will be shortened, and the resistance value will also decrease accordingly; if there is a circuit gap, it is equivalent to the circuit becoming thinner at a certain position, and the resistance value will increase.

[0006] However, during actual testing, since copper circuits are good conductors, slight changes in circuit length or width will cause extremely small changes in resistance, which are almost imperceptible. This makes it impossible to effectively and accurately detect the electrical performance quality of high-precision inductor coil circuits, making product quality difficult to control.

[0007] (2) High-precision circuit boards are usually small in size. In order to improve processing efficiency and reduce costs, they must be processed by assembling several unit boards into a large board. After completing the component welding process (such as common welding processes such as patch or SMT), the unit boards need to be cut from the large board.

[0008] However, the cut unit boards are often scattered, which brings great inconvenience to subsequent processing links such as further testing, visual inspection and packaging. Moreover, during the process of taking and placing the unit boards and multi-layer transportation, it is very easy for the welded components to collide, which in turn causes the solder feet to loosen and affect the product quality. On the contrary, if the board structure is separated first and then welded, the operation will be more difficult due to the small size of the board, and the processing efficiency will be greatly reduced. At the same time, the processing accuracy is difficult to guarantee, which will also have an adverse effect on product production.

[0009] Therefore, in order to solve the above-mentioned problems, it is necessary to provide a method for manufacturing a flexible circuit board with a high-precision sensing circuit. Summary of the Invention

[0010] The present invention aims to solve the comprehensive problems of the prior art circuit boards with inductive circuits, such as the difficulty in detecting their inductive performance and low processing precision. A method for manufacturing a flexible circuit board with a high-precision inductive circuit is proposed. The flexible circuit board is designed and processed in a panel structure during the processing process. The panel structure is designed with a forming line. The area within the forming line is the effective area, and the other area is the ineffective area. The manufacturing method includes the following steps:

[0011] S10: Take a flexible copper clad laminate, make a first circuit pattern, and then perform AOI optical scanning inspection to form a first flexible core board;

[0012] The first circuit pattern includes a first coil circuit pattern and a pad pattern;

[0013] S20: Take the first cover film, open windows corresponding to the pad pattern to form a window cover film, and attach it to the first flexible core board to form an attached board;

[0014] S30: Take the single-sided copper clad board and make a second circuit pattern to form a second flexible core board;

[0015] The second circuit pattern includes a second coil circuit pattern;

[0016] The first coil circuit pattern corresponds to the second coil circuit pattern;

[0017] S40: forming an adhesive layer on the insulating medium surface of the second flexible core board, and then attaching it to the attachment board to form a flexible back-attached board;

[0018] S50: performing an induction circuit test and post-processing on the flexible backing plate to form the flexible circuit board.

[0019] Furthermore, the induction circuit test is as follows: the flexible backing plate is fixed to a circuit tester, the circuit tester is provided with a first probe and a second probe, which respectively contact the contacts corresponding to the beginning and the end of the first coil circuit pattern; and a third probe and a fourth probe are provided, which respectively contact the contacts corresponding to the beginning and the end of the second coil circuit pattern; a primary current is applied to the third probe and the fourth probe, so that the second coil circuit pattern generates a primary inductance, and the primary inductance is induced to the first coil circuit pattern, so that the first coil circuit pattern generates a secondary current, and then the secondary current is tested by the first probe and the second probe to form a circuit quality measurement of the first coil circuit pattern.

[0020] Furthermore, the line width of the second coil circuit pattern is greater than the line width of the first coil circuit pattern, and the line gap of the second coil circuit pattern is greater than the line gap of the first coil circuit pattern.

[0021] Furthermore, the width of the second coil circuit pattern is larger on one side than the width of the first coil circuit pattern.

[0022] Furthermore, the second coil circuit pattern is ring-shaped.

[0023] Furthermore, a second covering film is provided on the surface of the second coil line.

[0024] Furthermore, taking the single-sided copper clad laminate includes performing plasma surface treatment on the single-sided copper clad laminate.

[0025] Furthermore, the making of the adhesive layer includes: making the adhesive layer on the ineffective area corresponding to one side of the insulating medium layer of the second flexible core board.

[0026] Furthermore, the making of the adhesive layer is: making a micro-adhesive layer on the entire surface of one side of the insulating dielectric layer of the second flexible core board.

[0027] Furthermore, forming the flexible circuit board includes: performing intermittent laser-controlled deep milling or mechanical mold-controlled deep punching on the flexible back-attached board along the forming line, then performing the induction circuit test, and then performing welding components and whole board inspection, and then performing laser-controlled deep milling or mechanical mold-controlled deep punching on the uncut forming line to remove the invalid area, and remove the second flexible core board and the adhesive layer to form the flexible circuit board; the depth of the laser-controlled deep milling is from the window covering film to the adhesive layer.

[0028] The technical solution of the present invention mainly includes the following beneficial effects:

[0029] (1) By combining AOI detection with a circuit tester, a double inspection of the first coil circuit pattern is performed; first, obvious defects and errors can be quickly identified through AOI, and second, the circuit tester is used to inspect the first coil circuit through the second coil circuit to evaluate its inductance performance, effectively improving the comprehensiveness and accuracy of the inspection.

[0030] (2) The method of detecting the first coil line through the second coil line solves the problem that traditional technology is difficult to directly measure the inductor coil line accurately. It is not only easy to operate, but also greatly improves the detection accuracy.

[0031] (3) The second flexible core board is bonded to the attached board by setting a glue layer to form a flexible back-attached board for subsequent processing. It not only provides the necessary physical support for the detection process, but also provides a processing basis for the depth-controlled laser cutting of the panel structure after the subsequent welding of components. It solves the problem that the panel structure of the existing technology is easy to be scattered after processing, which brings great inconvenience to the subsequent further detection, visual inspection and packaging processing links, and the problem that the welded components are easy to collide during the placement and transportation process, resulting in loose solder feet and affecting product quality.

[0032] (4) The backing plate first provides a stable platform for the circuit tester, ensuring the accuracy of the test; secondly, as a micro-adhesive membrane, it can keep the position of components stable during the processing; in addition, it also improves the overall strength of the flexible circuit board and reduces the risk of damage that may occur during manufacturing and use.

[0033] (5) The overall processing flow is simple, feasible and highly correlated. The early inspection steps provide quality assurance for subsequent processing, and the design of the back plate facilitates the subsequent welding and cutting processes, which not only optimizes production efficiency but also greatly improves the final quality of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0035] Figure 1 Schematic diagram of the process flow of an embodiment of the present invention;

[0036] Figure 2 A schematic plan view of a panel structure according to an embodiment of the present invention;

[0037] Figure 3 A schematic plan view of a first flexible core board according to an embodiment of the present invention;

[0038] Figure 4 for Figure 3 AA cross-sectional diagram of ;

[0039] Figure 5 for Figure 3 Design data diagram;

[0040] Figure 6 is a schematic cross-sectional view of an attachment plate according to an embodiment of the present invention;

[0041] Figure 7Schematic diagram of a plan view of a flexible backing plate according to an embodiment of the present invention;

[0042] Figure 8 for Figure 7 BB cross-section diagram;

[0043] Figure 9 A schematic cross-sectional view of a milling plate according to an embodiment of the present invention;

[0044] Figure 10 for Figure 9 Schematic diagram of CC cross section;

[0045] Figure 11 is a schematic cross-sectional view of a split-plate structure according to an embodiment of the present invention;

[0046] Figure 12 Schematic cross-sectional view of a flexible circuit board according to an embodiment of the present invention.

[0047] Explanation of the accompanying numbers: 10, panel structure; 1010, molding line; 1020, effective area; 1030, invalid area; FD, local enlargement area; 20, first flexible core board; 2010, first coil circuit pattern; 2020, pad pattern; 2030, PI layer; 30, attached board; 40, second flexible core board; 4010, second coil circuit pattern; 50, flexible back-attached board; 5010, adhesive layer; 60, milling board; 6010, milling groove; 6020, components; 70, sub-board structure; 80, flexible circuit board.

[0048] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0050] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, inside, outside, etc.) are only used to explain the relative position relationship and movement status of the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0051] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0052] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0053] See also Figure 1 , Figure 1 Schematic diagram of the process flow of an embodiment of the present invention.

[0054] The manufacturing process of the embodiment of the present invention includes using Figure 1 The following will implement the various steps in the process Figure 1 Each step in the process is further explained step by step.

[0055] See also Figure 2 、 Figure 3 、 Figure 4 and Figure 5 , Figure 2 A schematic plan view of a panel structure according to an embodiment of the present invention; Figure 3 A schematic plan view of a first flexible core board according to an embodiment of the present invention; Figure 4 for Figure 3 AA cross-sectional diagram of ; Figure 5 for Figure 3 Design information diagram.

[0056] The flexible circuit board 80 with a high-precision sensing circuit in this embodiment is designed and processed in the form of a panel structure 10 during the processing. The panel structure 10 is designed with a forming line 1010. The area within the forming line 1010 is an effective area 1020, and the other areas are invalid areas 1030. The manufacturing method includes the following steps.

[0057] The technical solution of this embodiment will be specifically described below by partially enlarging the region FD.

[0058] Step S10:

[0059] A flexible copper clad laminate is taken to make a first circuit pattern, which is then subjected to AOI optical scanning inspection to form a first flexible core board 20 ; the first circuit pattern includes a first coil circuit pattern 2010 and a pad pattern 2020 .

[0060] Optical scanning is performed using AOI technology to ensure that the first circuit pattern is consistent with the designed standard template. At the same time, abnormal conditions such as open circuit, short circuit or pattern deviation that affect the inductor performance can also be checked, so that the formed first flexible core board 20 (including PI layer 2030) can provide a processing basis for subsequent flexible back-attached board 50 bonding and induction circuit testing and other processes.

[0061] See also Figure 6 , Figure 6 Schematic cross-sectional view of an attachment plate according to an embodiment of the present invention.

[0062] Step S20:

[0063] Take the first covering film, open windows corresponding to the pad pattern 2020 to form a window covering film 3010, and attach it to the first flexible core board 20 to form an attached board 30.

[0064] A window is opened corresponding to the pad pattern 2020 to provide a window for subsequent welding of the component 6020, thereby ensuring a reliable connection between the pad pattern 2020 and the component 6020.

[0065] See also Figure 7 and Figure 8 , Figure 7 Schematic diagram of a plan view of a flexible backing plate according to an embodiment of the present invention; Figure 8 for Figure 7 BB cross-section diagram.

[0066] Step S30:

[0067] A single-sided copper clad laminate is used to make a second circuit pattern to form a second flexible core board 40 ; the second circuit pattern includes a second coil circuit pattern 4010 ; the first coil circuit pattern 2010 corresponds to the second coil circuit pattern 4010 .

[0068] The detection of the first coil circuit pattern 2010 is converted into the detection of the second coil circuit pattern 4010. The two coil circuit patterns maintain a corresponding setting relationship in design. The electromagnetic coupling relationship between the first coil circuit pattern 2010 and the second coil circuit pattern 4010 is utilized to indirectly verify the circuit condition of the first coil circuit pattern 2010 by detecting the second coil circuit pattern 4010, ensuring that the inductance performance meets the design requirements, thereby improving the detection efficiency and accuracy in the manufacturing process of the flexible circuit board 80.

[0069] Furthermore, the line width of the second coil circuit pattern 4010 is greater than the line width of the first coil circuit pattern 2010 , and the line gap of the second coil circuit pattern 4010 is greater than the line gap of the first coil circuit pattern 2010 .

[0070] Larger line widths and line gaps mean that the precision requirements for the manufacturing process are relatively lower, which can provide more error tolerance, thereby improving the speed and efficiency of the production line and reducing the scrap rate; setting the line width and line gap of the second coil circuit pattern 4010 to be larger makes it easier to process, and the probability of its own processing errors is lower, providing a more reliable reference basis for the first coil circuit pattern 2010.

[0071] The formula for self-inductance is: L=(μSN²) / l

[0072] Where:

[0073] L: inductance of the coil;

[0074] μ: magnetic permeability;

[0075] S: coil cross-sectional area;

[0076] N: total number of coil turns;

[0077] l: coil length.

[0078] The inductance of a coil is directly proportional to the coil's cross-sectional area S (i.e., the cross-sectional area of ​​the second coil circuit pattern 4010) and the square of the total number of coil turns N (i.e., the number of turns in the second coil circuit pattern 4010), and inversely proportional to the coil length l. Therefore, increasing the line width and line gap of the second coil circuit pattern 4010 is equivalent to increasing the coil's cross-sectional area S while reducing the total number of coil turns N and the coil length l. This does not necessarily increase the coil's inductance L. However, larger line widths and line gaps can reduce the difficulty of circuit pattern processing, making the coil's inductance L easier to control and measure, thereby making the induced current easier to measure.

[0079] The second coil circuit pattern 4010 adopts a design with larger line width and line gap, making the second coil circuit pattern 4010 easier to process and test than the first coil circuit pattern 2010. This not only helps to simplify the manufacturing process and improve detection accuracy, but also enhances the durability and reliability of the product.

[0080] Optionally, the line width of the first coil circuit pattern 2010 is ≥50 μm, and the line gap is ≥50 μm; the line width of the second coil circuit pattern 4010 is ≥100 μm, and the line gap is ≥100 μm.

[0081] For example, the line width / line gap of the first coil circuit pattern 2010 is 50 μm / 50 μm, and the line width / line gap of the second coil circuit pattern 4010 is 125 μm / 125 μm.

[0082] Furthermore, the width of the second coil circuit pattern 4010 is larger than the width of the first coil circuit pattern 2010 on one side, preferably, larger than 30 μm to 3.0 mm.

[0083] When viewed from a vertical direction, the edge of the second coil circuit pattern 4010 extends beyond the area of ​​the first coil circuit pattern 2010, increasing the magnetic field coverage effect, thereby enhancing the coupling between the second coil circuit pattern 4010 and the first coil circuit pattern 2010. At the same time, it can also effectively guide the magnetic lines of force to concentrate between the second coil circuit pattern 4010 and the first coil circuit pattern 2010, reducing external interference and improving inductance efficiency.

[0084] Furthermore, the second coil circuit pattern 4010 is ring-shaped.

[0085] The magnetic field generated by the toroidal coil is relatively more uniform and the processing is relatively simpler.

[0086] Furthermore, a second covering film is provided on the surface of the second coil circuit pattern 4010 .

[0087] The second covering film is provided to provide a protective layer for the second coil circuit pattern 4010 , thereby effectively preventing the copper surface from being oxidized or physically damaged by scratches during transportation, thereby effectively protecting the flexible circuit board 80 .

[0088] Furthermore, taking the single-sided copper clad laminate includes performing plasma surface treatment on the single-sided copper clad laminate.

[0089] The single-sided copper clad laminate is plasma treated to make the surface of the PI layer 2030 of the second flexible core board 40 formed thereby rougher, which can improve the bonding strength between the adhesive layer 5010 and the PI layer 2030 of the second flexible core board 40 in subsequent processing steps. In comparison, its adhesion strength is higher than the adhesion strength between the adhesive layer 5010 and the attached board 30, which is conducive to making it easier to remove the flexible circuit board 80 with components 6020 from the second flexible core board 40 after completing the welding process, effectively avoiding the risk of the adhesive layer 5010 being torn off along with the flexible circuit board 80.

[0090] Please refer again Figure 7 and Figure 8 .

[0091] Step S40:

[0092] An adhesive layer 5010 is formed on one side of the insulating medium layer of the second flexible core board 40 , and then attached to the attachment board 30 to form the flexible back-attachment board 50 .

[0093] The second coil circuit pattern 4010 is attached to the attachment plate 30 through the adhesive layer 5010, forming a corresponding positional relationship between the second coil circuit pattern 4010 and the first coil circuit pattern 2010, providing a processing basis for the subsequent process to use the inductive coupling principle to realize the detection of the first coil circuit pattern 2010.

[0094] In addition, the attached second flexible core board 40 can also provide important back support for the attached board 30, which is beneficial to ensure the integrity of the flexible circuit board 80 after the circuit board is processed into the sub-board structure 70 after the components 6020 are welded. It not only enhances the mechanical strength and supporting force of the entire circuit board, but also ensures the structural stability of the circuit board during subsequent processing.

[0095] Furthermore, since the overall rigidity of the board is enhanced, the positioning of the probe contact points during circuit testing is more accurate, thereby effectively reducing the missed detection rate caused by poor contact or position deviation, enabling higher accuracy to be achieved when using a circuit tester for electrical characteristics testing.

[0096] Furthermore, the adhesive layer 5010 is formed by forming the adhesive layer 5010 on the inactive area 1030 on one side of the insulating medium layer of the second flexible core board 40 .

[0097] When the subsequent flexible circuit board 80 needs to be molded separately and packaged for shipment, the adhesive layer 5010 is made in the invalid area 1030 to ensure that there is no residual adhesive layer 5010 in the effective area 1020. Therefore, in the subsequent molding process, the flexible circuit board 80 can be separated from the panel structure 10, and the adhesive layer 5010 can be removed together with the invalid area 1030, which simplifies the production process and improves production efficiency.

[0098] Furthermore, the adhesive layer 5010 is made by forming a micro-adhesive layer on the entire surface of the insulating medium layer of the second flexible core board 40 .

[0099] The entire surface of the adhesive layer 5010 can only use a slightly adhesive layer, which can temporarily fix the second flexible core board 40 on the flexible backing board 50 while facilitating the separation operation during subsequent processing.

[0100] After the components 6020 are welded, the cutting depth is precisely controlled to ensure that only the ineffective area 1030 is removed without damaging the effective area 1020, thereby forming a split board structure 70. At this time, the flexible circuit board 80 with the components 6020 welded remains on the flexible backing board 50, while the ineffective area 1030 is removed.

[0101] The panel splitting process to form the panel splitting structure 70 is equivalent to semi-forming the panel splitting structure 10. Since the flexible circuit board 80 is still fixed on the flexible back plate 50, it prevents possible damage or deformation during subsequent testing, packaging and transportation, which not only improves the operational convenience and efficiency of the production process, but also ensures the integrity and reliability of the product in the final use stage.

[0102] Optionally, the material of the micro-adhesive layer is acrylic or epoxy resin.

[0103] The performance of this type of colloid component can be better matched to the processing process of the flexible circuit board 80.

[0104] See also Figure 9 、 Figure 10 、 Figure 11 and Figure 12 , Figure 9 A schematic cross-sectional view of a milling plate according to an embodiment of the present invention; Figure 10 for Figure 9 Schematic diagram of CC cross section; Figure 11 is a schematic cross-sectional view of a split-plate structure according to an embodiment of the present invention; Figure 12 Schematic cross-sectional view of a flexible circuit board according to an embodiment of the present invention.

[0105] Step S50:

[0106] The flexible backing plate 50 is subjected to an induction circuit test and post-processing to form a flexible circuit board 80 .

[0107] Furthermore, the induction circuit test is as follows: the flexible backing plate 50 is fixed to a circuit tester, the circuit tester includes a first probe and a second probe, which respectively contact the contacts at the beginning and the end of the first coil circuit pattern 2010; and a third probe and a fourth probe are provided, which respectively contact the contacts at the beginning and the end of the second coil circuit pattern 4010; a primary current is applied to the third probe and the fourth probe, so that the second coil circuit pattern 4010 generates a primary inductance, and the primary inductance is induced to the first coil circuit pattern 2010, so that the first coil circuit pattern 2010 generates a secondary current, and then the secondary current is tested by the first probe and the second probe to form a circuit quality measurement of the first coil circuit pattern 2010.

[0108] Optionally, the secondary voltage generated by the second coil circuit pattern 4010 may also be tested, and the testing principle is the same as the above principle.

[0109] Optionally, the circuit tester is a flying probe tester or a universal tester, and both testers can meet the above test requirements.

[0110] During the actual measurement process, a suitably larger current value is used for the first probe and the second probe, for example, a current value of 0.3A to 0.5A is used to make the second coil circuit pattern 4010 produce a more obvious inductance, which is more conducive to making the first coil circuit pattern 2010 produce a more obvious secondary current, facilitating comparison of test results.

[0111] The manufacturing method of this embodiment can form a process of detecting the first coil circuit pattern 2010 through the second coil circuit pattern 4010 using the principle of electromagnetic coupling, effectively avoiding the inaccuracy of resistance detection using existing technologies, and solving the problem of being unable to effectively and accurately detect the electrical performance quality of high-precision inductor coil circuits.

[0112] The current mutual inductance formula is: I1 / I2=N2 / N1

[0113] Where:

[0114] I1 primary current;

[0115] I2 secondary current;

[0116] N1 is the number of turns of the primary coil (i.e., the number of turns of the second coil circuit pattern 4010 in this embodiment);

[0117] N2 is the number of turns of the secondary coil (ie, the number of turns of the coil of the first coil circuit pattern 2010 in this embodiment).

[0118] If the first coil circuit pattern 2010 is short-circuited, it is equivalent to the number of turns N2 decreasing, and the current I2 increasing. Therefore, if the measured secondary current of the first coil circuit pattern 2010 increases relatively, it indicates that there is a possibility of a short circuit, which requires further confirmation or scrapping.

[0119] Furthermore, forming the flexible circuit board 80 includes: intermittently performing laser-controlled depth milling or mechanical mold-controlled deep punching on the flexible back-attached board 50 along the forming line 1010 to form a milling groove 6010, and forming a milling board 60 on the entire board, and then performing an induction circuit test, and then performing welding components 6020 and whole-board inspection to form a sub-board structure 70, and then performing laser-controlled depth milling or mechanical mold-controlled deep punching on the uncut forming line 1010 to remove the invalid area 1030, and remove the second flexible core board 40 and the glue layer 5010 to form a flexible circuit board 80; the depth of the laser-controlled depth milling is from the window covering film 3010 to the glue layer 5010.

[0120] By first performing controlled-depth cutting on part of the forming line 1010 and then cleaning it, the amount of carbon powder generated by subsequent large-scale cutting can be significantly reduced, thereby reducing the risk of short circuit. If, after welding the components 6020, the forming line 1010 is then subjected to laser controlled-depth milling to form the panel structure 70, the amount of cutting will be relatively large, and the amount of carbon powder generated will be relatively large. Moreover, after welding the components 6020, it will be inconvenient to clean the panel body, so the carbon powder remaining on the panel body will increase the probability of short circuit.

[0121] Laser controlled deep milling is suitable for scenarios with high precision requirements. Although the speed may be lower than the processing efficiency of mechanical punching, it can provide higher precision and will not cause vibration or impact to the welded components.

[0122] Mechanical die-controlled deep punching is more efficient and less costly for mass production, but long-term operation may lead to decreased accuracy and increase the risk of damage to soldered components.

[0123] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's description and drawings, or direct / indirect applications in other related technical fields, within the scope of the present invention are included in the patent protection scope of the present invention.

Claims

1. A method for manufacturing a flexible circuit board with a high-precision sensing circuit, wherein the flexible circuit board is designed and processed in a panel structure during the processing process, the panel structure is designed with a forming line, the area within the forming line is the effective area, and the other area is the ineffective area, characterized in that: The production method comprises the following steps: S10: Take a flexible copper clad laminate, make a first circuit pattern, and then perform AOI optical scanning inspection to form a first flexible core board; The first circuit pattern includes a first coil circuit pattern and a pad pattern; S20: Take the first cover film, open windows corresponding to the pad pattern to form a window cover film, and attach it to the first flexible core board to form an attached board; S30: Take the single-sided copper clad board and make a second circuit pattern to form a second flexible core board; The second circuit pattern includes a second coil circuit pattern; The first coil circuit pattern corresponds to the second coil circuit pattern; S40: forming an adhesive layer on the insulating medium surface of the second flexible core board, and then attaching it to the attachment board to form a flexible back-attached board; S50: performing an induction circuit test and post-processing on the flexible backing plate to form the flexible circuit board; The induction circuit test is performed by fixing the flexible backing plate to a circuit tester, wherein the circuit tester is provided with a first probe and a second probe, which are respectively contacted with the contact points at the beginning and the end of the first coil circuit pattern; and a third probe and a fourth probe, which are respectively contacted with the contact points at the beginning and the end of the second coil circuit pattern; Applying a primary current to the third probe and the fourth probe to generate a primary inductance in the second coil circuit pattern, which is then induced into the first coil circuit pattern to generate a secondary current in the first coil circuit pattern. The secondary current is then measured by the first probe and the second probe to form a line quality measurement of the first coil circuit pattern. Forming the flexible circuit board includes: intermittent laser-controlled deep milling or mechanical mold-controlled deep punching of the flexible back-attached board along the forming line, then performing the induction circuit test, welding components and whole-board inspection, and then performing laser-controlled deep milling or mechanical mold-controlled deep punching on the uncut forming line to remove the invalid area, and remove the second flexible core board and the adhesive layer to form the flexible circuit board; the depth of the laser-controlled deep milling is from the window covering film to the adhesive layer.

2. The method for manufacturing a flexible circuit board with a high-precision sensing circuit according to claim 1, wherein: The line width of the second coil circuit pattern is greater than the line width of the first coil circuit pattern, and the line gap of the second coil circuit pattern is greater than the line gap of the first coil circuit pattern.

3. The method for manufacturing a flexible circuit board with a high-precision sensing circuit according to claim 1, wherein: The width of the second coil circuit pattern is larger than the width of the first coil circuit pattern on one side.

4. A method for manufacturing a flexible circuit board with a high-precision sensing circuit according to claim 1 or 2, characterized in that: The second coil circuit pattern is ring-shaped.

5. A method for manufacturing a flexible circuit board with a high-precision sensing circuit according to claim 1 or 2, characterized in that: A second cover film is provided on the surface of the second coil line.

6. The method for manufacturing a flexible circuit board with a high-precision sensing circuit according to claim 1, wherein: Taking the single-sided copper clad laminate includes performing plasma surface treatment on the single-sided copper clad laminate.

7. The method for manufacturing a flexible circuit board with a high-precision sensing circuit according to claim 1, wherein: The step of making the adhesive layer comprises: making the adhesive layer on the ineffective area corresponding to one side of the insulating medium layer of the second flexible core board.

8. The method for manufacturing a flexible circuit board with a high-precision sensing circuit according to claim 1, wherein: The step of making the adhesive layer is to make a micro-adhesive layer on the entire surface of one side of the insulating medium layer of the second flexible core board.

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