Method for maintaining line width consistency of a circuit board

Abstract

The application discloses a method for keeping the consistency of the line width of a circuit board, characterized by comprising an online control system, and the keeping method comprises the following steps: S1, acquiring the copper thickness of each point of the copper line on the circuit board; S2, adjusting the VCP line tank liquid level and the floating plate height; S3, adjusting the line width design value according to the copper thickness; S4, adjusting the etching line speed range according to the copper thickness; S5, monitoring the copper ion concentration in real time; and S6, determining the adjustment means according to the copper ion concentration in the etching process. The copper thickness on the circuit board is acquired in real time, and the VCP line tank liquid level and the floating plate height are adjusted according to the difference between the copper thickness and the preset copper thickness, so that the copper thickness is accurately controlled, the etching difficulty in the subsequent process is reduced, and the consistency of the line width of the circuit board is kept. Through the accurate dynamic compensation mode, the consistency of the line width of the finally formed circuit board is maintained. The application improves the stability of the forming method of the circuit on the circuit board through the above technical means, and the CPK compliance rate of the line width of the circuit on the circuit board is 100%.

Description

Technical Field

[0001] This application relates to the field of circuit board linewidth control technology, and in particular to a method for maintaining the consistency of circuit board linewidth. Background Technology

[0002] Line width refers to the width of the lines on a circuit board. The lines on the circuit board connect various electronic components in an orderly manner to achieve the function of the circuit. The design of the lines directly determines the performance, reliability, cost, and manufacturing feasibility of the circuit board.

[0003] With the miniaturization of electronic products and the development of high-density interconnect (HDI) technology, the linewidth consistency of circuit boards has become a key factor affecting signal transmission quality and impedance matching. During the manufacturing process, linewidth deviations are mainly caused by factors such as fluctuations in etching process parameters, uneven copper thickness, and inaccurate compensation strategies.

[0004] In existing technologies, issues such as a wide range of etching line speed settings and insufficient precision in copper thickness control make it difficult to meet high-precision requirements for line width consistency, resulting in a low first-piece yield and affecting mass production stability.

[0005] Therefore, it is necessary to propose a method to maintain the consistency of circuit board line width and improve the consistency of line width, which has become an important technical problem that needs to be solved urgently. Summary of the Invention

[0006] This application provides a method for maintaining the consistency of circuit board linewidth, aiming to solve the problems of wide etching speed range and insufficient copper thickness control in the prior art, which makes it difficult to meet the high precision requirements for linewidth consistency, resulting in low first-piece yield and affecting the stability requirements of mass production.

[0007] To achieve the above objectives, this application proposes a method for maintaining the consistency of circuit board linewidth, including an online control system. The method includes the following steps: S1. After electroplating, the copper thickness at each point on the copper line on the circuit board is obtained; S2. The online control system adjusts the VCP line groove level and the float height according to the copper thickness to accurately control the copper thickness of the circuit board; S3. After electroplating, the linewidth design value is adjusted according to the copper thickness; S4. Before the etching process, the etching line speed range is adjusted according to the copper thickness; S5. During the etching process, the copper ion concentration is monitored in real time; S6. Based on the copper ion concentration during the etching process, adjustment measures are determined to maintain the stability of the etching process.

[0008] In some embodiments, the method for adjusting the VCP line groove liquid level in S2 is as follows: S21, compare the copper thickness at the upper end of the circuit board with the preset copper thickness at the upper end; S22, when the preset copper thickness at the upper end is greater than the copper thickness at the upper end, increase the VCP line groove liquid level; S23, when the preset copper thickness at the upper end is less than the copper thickness at the upper end, decrease the VCP line groove liquid level.

[0009] In some embodiments, the method for adjusting the height of the floating plate in S2 above is as follows: S24, compare the copper thickness at the bottom of the circuit board with the preset copper thickness at the bottom;

[0010] S25. When the preset copper thickness at the lower end is greater than the copper thickness at the lower end, the height of the floating plate is slightly reduced.

[0011] S26. When the preset copper thickness at the lower end is less than the copper thickness at the lower end, the height of the floating plate increases slightly.

[0012] In some embodiments, the method for determining the line width design value in S3 above is as follows:

[0013] Line width design value = Theoretical line width value + Basic compensation value + Dynamic compensation coefficient × Copper thickness deviation

[0014] Wherein: the theoretical line width value is the theoretical width of the line on the circuit board, the basic compensation value is the compensation value determined according to the theoretical line width value and the compensation table, the dynamic compensation coefficient is a variable constant, and the copper thickness deviation is the deviation value between the copper thickness on the circuit board and the preset copper thickness.

[0015] In some embodiments, S4 specifically includes the following steps: S41, establishing multiple copper thickness intervals based on the maximum and minimum copper thickness values; S42, determining the etching line speed range for each copper thickness interval; S43, determining the etching line speed range based on the copper thickness interval where the actual copper thickness is located.

[0016] In some embodiments, the method for monitoring the copper ion concentration during the etching process in S5 described above is as follows: a fixed sampling time interval and multiple sampling points are set at different intervals, and copper ion concentration is detected simultaneously at multiple sampling points at a fixed time interval.

[0017] In some embodiments, S1 specifically includes the following steps:

[0018] S11. After electroplating is completed, the part number of the circuit board is obtained through a CCD camera;

[0019] S12. Obtain the board height and copper wire height of the circuit board using a laser rangefinder;

[0020] S13. The online control system obtains the copper thickness at each point of the copper wire based on the board height and the copper wire height.

[0021] S14. The online control system stores the part number of the circuit board and the copper thickness at each point on the circuit board corresponding to that part number.

[0022] In some embodiments, it also includes:

[0023] S7. During the etching process, make the etching solution nozzles on the upper side of the circuit board mirror symmetrical to the etching solution nozzles on the lower side of the circuit board.

[0024] In some embodiments, the etching solution nozzle uses a radial fan-shaped nozzle.

[0025] In some embodiments, the pressure of the etching solution nozzle is adjusted according to the uniformity of etching.

[0026] This application proposes a method for maintaining consistent linewidth on a circuit board. The method includes an online control system and comprises the following steps: S1. After electroplating, the copper thickness at various points on the circuit board is obtained; S2. The online control system adjusts the VCP (Vacuum-Conducting Plating) level and float height based on the copper thickness to precisely control the copper thickness; S3. After electroplating, the linewidth design value is adjusted based on the copper thickness; S4. Before etching, the etching speed range is adjusted based on the copper thickness; S5. During etching, the copper ion concentration is monitored in real time; S6. The adjustment method is determined based on the copper ion concentration during etching to maintain the stability of the etching process. By obtaining the copper thickness on the circuit board in real time and adjusting the VCP level and float height based on the difference between the copper thickness and the preset copper thickness, the copper thickness is precisely controlled, reducing the difficulty of subsequent etching and maintaining consistent linewidth on the circuit board. Through precise dynamic compensation, targeted compensation is applied to different lines on the circuit board, which helps maintain the consistency of the final formed linewidth. Real-time monitoring of copper ion concentration and establishment of a mean-range control chart based on the copper ion concentration data, along with historical process data, effectively controls the stable progress of the etching process, which helps maintain the consistency of the final linewidth. This application improves the stability of the circuit board forming method through the above-mentioned technical means and enables the CPK compliance rate of the linewidth on the circuit board to reach 100%. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0028] Figure 1 This is a technical roadmap of a method for maintaining linewidth consistency on a circuit board according to an embodiment of this application;

[0029] Figure 2 This is a cross-sectional structural diagram of the VCP cable tray in one embodiment of this application;

[0030] Figure 3 This is a front view of a VCP cable tray in one embodiment of this application.

[0031] In the diagram: 1. Circuit board; 2. Upper slot; 3. Overflow hole; 4. Adjustment valve; 5. Lower slot; 6. Nozzle; 7. Float; 8. Titanium basket. Detailed Implementation

[0032] The technical solutions of the embodiments of this application 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 this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0033] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application 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 indicator will also change accordingly.

[0034] It should also be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.

[0035] Furthermore, the use of terms such as "first" and "second" in this application is 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. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0036] See Figure 1 As shown, this application proposes a method for maintaining the linewidth consistency of circuit board 1, including an online control system, preferably a CPU. The online control system is used to read information and issue instructions based on the information to adjust the parameters of the circuit board 1 production line in real time to ensure the linewidth consistency on circuit board 1. The forming method of the circuit on circuit board 1 includes electroplating, circuit pretreatment, molding, exposure, development, etching, first inspection, and final AOI inspection. The method for maintaining the linewidth consistency of circuit board 1 proposed in this application refers to optimizing the key nodes affecting the linewidth in the above-mentioned forming method of the circuit on circuit board 1 to maintain the consistency of the final formed linewidth. The specific method includes the following steps:

[0037] S1. After electroplating, the copper thickness at each point on the circuit board is obtained. The copper thickness deviation caused by uneven copper thickness is the main factor affecting the consistency of the line width on circuit board 1. After electroplating, the copper thickness at each point on the circuit board is obtained by a laser rangefinder. The copper thickness at each point on the circuit board is stored in the online control system. The online control system adjusts the parameters of the circuit board 1 production line based on the copper thickness at each point on the copper line to ensure the consistency of the line width on circuit board 1.

[0038] S2. The online control system adjusts the VCP line tray level and the height of the float plate 7 based on the copper thickness to precisely control the copper thickness of the circuit board. Copper thickness is a key factor affecting linewidth consistency. If the copper thickness at the top and bottom of the circuit board 1 is not precisely controlled, it can easily lead to inconsistent linewidth during subsequent etching. By adjusting the VCP line tray level and the height of the float plate 7, the copper thickness can be precisely controlled, which helps reduce the difficulty of subsequent etching and maintain the linewidth consistency of the circuit board 1. Specifically, adjusting the VCP line tray level can change the number and density of electric field lines at the top of the circuit board 1, thereby adjusting the copper thickness at the top of the circuit board 1. The float plate 7 is located between the anode and cathode of the electroplating process, which can both block excessive electric field lines and excessive jetting at the bottom. Adjusting the height of the float plate 7 can adjust the copper thickness at the bottom of the circuit board 1. Simultaneously adjusting the VCP line tray level and the height of the float plate 7 to precisely control the copper thickness at the top and bottom of the circuit board 1 helps maintain the linewidth consistency of the final formed circuit.

[0039] S3. After electroplating, adjust the line width design value according to the copper thickness; determine the line width compensation value based on the line spacing on the production draft and the difference between the measured copper thickness of circuit board 1 and the preset copper thickness; determine the final line width design value based on the line width compensation value and the theoretical line width value. Through the above precise dynamic compensation method, targeted compensation is performed on different lines on circuit board 1, which helps to maintain the consistency of the final formed line width.

[0040] S4. Before the etching process, adjust the etching line speed range according to the copper thickness; determine multiple copper thickness ranges based on the range of copper thickness, and each copper thickness range corresponds to an etching line speed range. The corresponding etching line speed range can be selected according to the actual copper thickness on the circuit board, which reduces the parameter fluctuation range, improves the first-pass yield, and helps to improve the stability of the etching process.

[0041] S5. Monitor the copper ion concentration in real time during the etching process; S6. Determine adjustment measures based on the copper ion concentration during the etching process to maintain its stability. Real-time monitoring of the copper ion concentration and establishment of a mean-range control chart based on the data, along with determining control limits based on historical process data, are crucial. When the mean or range of the copper ion concentration data exceeds the corresponding control limit, timely adjustment measures are determined to maintain the stability of the etching process. Ensuring the stability of the etching process helps maintain the consistency of the final linewidth.

[0042] Specifically, the copper thickness on the circuit board is acquired in real time, and the VCP line groove level and the height of the float 7 are adjusted based on the difference between the copper thickness and the preset copper thickness. This allows for precise control of the copper thickness, reducing the difficulty of subsequent etching and maintaining the consistency of the linewidth on the circuit board 1. Through precise dynamic compensation, different lines on the circuit board 1 are compensated specifically, which helps maintain the consistency of the final formed linewidth. Real-time monitoring of copper ion concentration and the establishment of a mean-range control chart based on the copper ion concentration data, combined with historical process data, effectively controls the stable progress of the etching process, further contributing to the consistency of the final formed linewidth. This application improves the stability of the line forming method on the circuit board 1 through the above technical means, and enables a 100% CPK compliance rate for the linewidth on the circuit board 1.

[0043] See Figure 2 As shown, in some embodiments, the VCP cable tray includes an upper tray 2 and a lower tray 5, with an overflow hole 3 on the upper tray 2. Figure 2 The arrows shown indicate the overflow direction of the chemicals in the VCP line trough. An adjusting valve 4 is installed between the upper trough 2 and the lower trough 5. A circulating pump pumps the chemicals from the lower trough 5 to the upper trough 2. The upper trough 2 has an overflow port to ensure the liquid level is maintained at a relatively fixed position. The liquid level in the upper trough 2 can be adjusted appropriately using the adjusting valve 4 between the upper trough 2 and the lower trough 5. Opening the adjusting valve 4 lowers the liquid level in the upper trough 2, and closing the adjusting valve 4 raises the liquid level in the upper trough 2. The adjustment method for the VCP line trough liquid level in S2 is as follows: S21, compare the copper thickness at the top of the circuit board 1 with the preset copper thickness at the top; S22, when the preset copper thickness at the top is greater than the actual copper thickness, increase the VCP line trough liquid level; closing the adjusting valve 4 increases the liquid level in the upper trough 2, which increases the number and density of electric field lines at the top of the circuit board 1, thus increasing the copper thickness at the top of the circuit board 1; S23, when the preset copper thickness at the top is less than the actual copper thickness, decrease the VCP line trough liquid level. Opening the adjusting valve 4 and lowering the liquid level in the upper tank 2 can reduce the number and density of electric field lines at the top of the circuit board 1, thereby reducing the copper thickness at the top of the circuit board 1.

[0044] See Figure 3As shown, in some embodiments, the circuit board 1 extends into the upper tank 2, which is also equipped with a nozzle 6, a float 7, and a titanium basket 8. The titanium basket 8 is used to place the anode material, the nozzle 6 is used to perform electroplating on the circuit board 1, and the float 7 is located between the anode and cathode of the electroplating process. It can both block excessive electric field lines at the lower end and block excessive jets at the lower end. Adjusting the height of the float 7 can adjust the copper thickness at the lower end of the circuit board 1. Slightly adjusting the float 7 upwards can reduce the copper thickness at the lower end of the circuit board 1; slightly adjusting the float 7 downwards can increase the copper thickness at the lower end of the circuit board 1. The method for adjusting the height of the float 7 in S2 above is as follows: S24, compare the copper thickness at the lower end of the circuit board 1 with the preset copper thickness at the lower end; S25, when the preset copper thickness at the lower end is greater than the copper thickness at the lower end, slightly decrease the height of the float 7; S26, when the preset copper thickness at the lower end is less than the copper thickness at the lower end, slightly increase the height of the float 7.

[0045] In this embodiment, the copper thickness can be precisely controlled through the above-mentioned adjustment methods, effectively reducing the copper thickness variation on circuit board 1. This helps to reduce the difficulty of subsequent etching and maintain the linewidth consistency of circuit board 1. Specifically, before the adjustment, the copper thickness variation on circuit board 1 was 5um-10um, and after the adjustment, the copper thickness variation on circuit board 1 was 3um-5um, effectively improving the uniformity of copper thickness.

[0046] In some embodiments, the method for determining the line width design value in S2 above is as follows:

[0047] Line width design value = Theoretical line width value + Basic compensation value + Dynamic compensation coefficient × Copper thickness deviation

[0048] Wherein: the theoretical linewidth value is the theoretical width of the line on the circuit board; the basic compensation value is the compensation value determined based on the copper thickness and the compensation table; the dynamic compensation coefficient is a variable constant; and the copper thickness deviation is the deviation between the copper thickness on the circuit board and the preset copper thickness. Since the basic compensation value is determined based on the preset copper thickness, it becomes inaccurate when there is a copper thickness deviation. The dynamic compensation coefficient is determined according to the dynamic compensation rule table, which is established based on process experiments and measurement data. The dynamic compensation rule table specifies the dynamic compensation coefficients corresponding to different copper thickness deviations. Adjusting the basic compensation value in conjunction with the copper thickness deviation, and accurately compensating for the linewidth, helps maintain the consistency of the final formed linewidth.

[0049] In some embodiments, S4 specifically includes the following steps: S41. Establishing multiple copper thickness intervals based on the maximum and minimum copper thickness values; the copper thickness interval closer to the minimum copper thickness value is smaller, and the copper thickness interval closer to the maximum copper thickness value is larger, thereby increasing the number of copper thickness intervals. S42. Determining the etching line speed range for each copper thickness interval; each copper thickness interval corresponds to an etching line speed range. Increasing the number of copper thickness intervals can refine the etching line speed range, reduce parameter fluctuation range, and improve the first-pass yield. S43. Determining the etching line speed range based on the actual copper thickness within the specified copper thickness interval.

[0050] In this application, the method for defining the copper thickness range and the corresponding etching line speed range for each copper thickness range are shown in Table 1:

[0051]

[0052] Table 1

[0053] In some embodiments, the method for monitoring copper ion concentration during the etching process in S5 described above is as follows: a fixed sampling time interval and multiple sampling points with intervals are set, and copper ion concentration is detected simultaneously at multiple sampling points at a fixed time interval. The sampling time interval can be selected according to the etching process, and can be 10s, 15s, or 30s. No specific limitation is made here, and it can be selected according to actual needs.

[0054] In this embodiment, S6 further includes the following steps: S61, calculating the mean of copper ion concentrations measured at multiple sampling points at the same time; the mean is the average of the copper ion concentrations at multiple sampling points, and the mean is used to reflect the central value of copper ions; S62, calculating the range of copper ion concentrations measured at multiple sampling points at the same time; the range is the difference between the maximum and minimum values ​​of copper ion concentrations at multiple sampling points, and the range is used to monitor the dispersion of copper ion concentrations; S63, when the mean or range exceeds the control value, corresponding adjustment measures are taken. Different control lines are determined based on historical data, such as etching solution replenishment control lines, etching time adjustment control lines, temperature adjustment control lines, specific gravity adjustment control lines, etc. Once a parameter exceeds the corresponding control line, the corresponding parameter needs to be adjusted. For example, when the parameter exceeds the upper etching time adjustment control line, the etching time needs to be increased; when the parameter exceeds the lower etching time adjustment control line, the etching time needs to be decreased. The above control methods ensure the stability of the etching process. The more stable the etching process, the better it is for improving the uniformity of etching.

[0055] In some embodiments, the method further includes: S7, during the etching process, making the etching solution nozzles on the upper side of the circuit board 1 and the lower side of the circuit board 1 mirror-symmetrical. The mirror-symmetrical arrangement of the etching solution nozzles helps to balance the pressure on the upper and lower sides of the circuit board 1 and improve the uniformity of etching. The etching solution nozzles use radial fan-shaped nozzles. The pressure of the etching solution nozzles is adjusted according to the uniformity of etching. It is also possible to judge whether the etching solution nozzles have problems such as nozzle orifice enlargement, local blockage, or nozzle deformation based on the uniformity feedback of etching. During the etching process, the etching solution nozzles can also be visually inspected for problems such as nozzle orifice enlargement, local blockage, or nozzle deformation. By balancing the pressure on the upper and lower sides of the circuit board 1 using the above method, the etching uniformity is improved from 90% to over 95%.

[0056] The above description is only a part or preferred embodiment of this application. Neither the text nor the drawings should limit the scope of protection of this application. All equivalent structural transformations made using the content of this application's specification and drawings under the overall concept of this application, or direct / indirect applications in other related technical fields, are included within the scope of protection of this application.

Claims

1. A method for maintaining consistent linewidth on a circuit board, characterized in that, Including online control systems, the method of maintaining includes the following steps: S1. After electroplating is completed, obtain the copper thickness at each point of the copper wire on the circuit board; S2. The online control system adjusts the VCP line groove liquid level and float height according to the copper thickness to accurately control the copper thickness of the circuit board; S3. After electroplating is completed, adjust the line width design value according to the copper thickness; S4. Before the etching process, adjust the etching line speed range according to the copper thickness. S5. During the etching process, monitor the copper ion concentration in real time; S6. Determine adjustment methods based on the copper ion concentration during the etching process to maintain the stability of the etching process; In S3 above, the method for determining the line width design value is as follows: Line width design value = Theoretical line width value + Basic compensation value + Dynamic compensation coefficient × Copper thickness deviation Wherein: the theoretical line width value is the theoretical width of the line on the circuit board, the basic compensation value is the compensation value determined according to the theoretical line width value and the compensation table, the dynamic compensation coefficient is a variable constant, and the copper thickness deviation is the deviation value between the copper thickness on the circuit board and the preset copper thickness. The above-mentioned S6 also includes the following steps: S61, calculating the mean of the copper ion concentration measured at multiple sampling points at the same time; the mean is the average value of the copper ion concentration at multiple sampling points, and the mean is used to reflect the central value of copper ions; S62, calculating the range of the copper ion concentration measured at multiple sampling points at the same time; the range is the difference between the maximum and minimum values ​​of the copper ion concentration at multiple sampling points, and the range is used to monitor the dispersion of copper ion concentration; S63, when the mean or range exceeds the control value, making corresponding adjustment measures.

2. The method for maintaining consistent linewidth on a circuit board according to claim 1, characterized in that, The method for adjusting the VCP line tank level described in S2 above is as follows: S21. Compare the copper thickness at the upper end of the circuit board with the preset copper thickness at the upper end; S22. When the upper preset copper thickness is greater than the upper copper thickness, increase the liquid level of the VCP line groove; S23. When the upper preset copper thickness is less than the upper copper thickness, reduce the VCP line groove liquid level.

3. The method for maintaining consistent linewidth on a circuit board according to claim 1, characterized in that, The method for adjusting the height of the float as described in S2 above is as follows: S24. Compare the copper thickness at the lower end of the circuit board with the preset copper thickness at the lower end; S25. When the preset copper thickness at the lower end is greater than the copper thickness at the lower end, the height of the floating plate is slightly reduced. S26. When the preset copper thickness at the lower end is less than the copper thickness at the lower end, the height of the floating plate increases slightly.

4. The method for maintaining consistent linewidth on a circuit board according to claim 1, characterized in that, The above S4 specifically includes the following steps: S41. Establish multiple copper thickness intervals based on the maximum and minimum copper thickness values; S42. Determine the etching line speed range for each of the copper thickness intervals; S43. Determine the etching line speed range based on the actual copper thickness range.

5. The method for maintaining consistent linewidth on a circuit board according to claim 1, characterized in that, In S5 above, the method for monitoring the copper ion concentration during the etching process is as follows: a fixed sampling time interval and multiple sampling points with different intervals are set, and copper ion concentration is detected simultaneously at multiple sampling points at a fixed time interval.

6. The method for maintaining consistent linewidth on a circuit board according to claim 1, characterized in that, The above S1 specifically includes the following steps: S11. After electroplating is completed, the part number of the circuit board is obtained by using a CCD camera; S12. Obtain the board surface height and copper wire height of the circuit board using a laser rangefinder; S13. The online control system obtains the copper thickness at each point of the copper wire based on the board height and the copper wire height. S14. The online control system stores the part number of the circuit board and the copper thickness at each point of the circuit board corresponding to the part number.

7. A method for maintaining consistent linewidth on a circuit board according to claim 1, characterized in that, Also includes: S7. During the etching process, the etching nozzle on the upper side of the circuit board is mirror-symmetrical to the etching nozzle on the lower side of the circuit board.

8. A method for maintaining consistent linewidth on a circuit board according to claim 7, characterized in that, The etching solution nozzle uses a radial fan-shaped nozzle.

9. A method for maintaining consistent linewidth on a circuit board according to claim 7, characterized in that, The pressure of the etching solution nozzle is adjusted according to the uniformity of the etching.

Images