A PCB silver immersion production line, silver immersion solution replenishment control system and method thereof

Abstract

The present invention discloses a PCB silver immersion production line, a silver immersion solution replenishment control system and a method thereof. The silver immersion solution replenishment control system of the present invention, the plate number acquisition module, the information acquisition module and the controller control the solution replenishment module to realize the automatic replenishment of the silver immersion solution; in addition, the PCB silver immersion production line uses the silver immersion solution replenishment control system, the silver immersion tank and the transportation device to realize the automatic replenishment and production of the silver immersion process, and effectively improve the silver immersion production efficiency. Finally, in the silver immersion solution replenishment control method, by obtaining the required amount of silver corresponding to the first plate number, and then making a replenishment judgment based on the required amount of silver corresponding to the first plate number and the preset amount of silver, when the required amount of silver corresponding to the first plate number is greater than the preset amount of silver, the control is to replenish, and the silver replenishment amount is the required amount of silver corresponding to the first plate number to maintain the total amount of silver in the silver immersion tank stable, ensure the silver immersion effect, and can realize automatic replenishment, improve production efficiency.

Description

Technical Field

[0001] The invention relates to the field of PCB production, in particular to a PCB silver immersion production line, a silver immersion solution replenishment control system and a method thereof. Background Art

[0002] In order to meet the urgent requirement of the electronics industry to ban lead, the printed circuit board industry is gradually transferring the final surface treatment from lead-tin hot air leveling to other surface treatments, such as immersion silver, immersion tin, chemical immersion nickel gold and organic protective film, etc. Among them, the immersion silver process is considered to be the best choice for the final surface treatment due to its excellent performance and reasonable cost.

[0003] The PCB silver deposition process is based on the principle of replacement reaction between silver ions in the solution and metallic copper on the printed circuit board (PCB). Therefore, in the actual production process, with the increase in output and the increase in copper content, the consumption of the solution in the silver deposition tank will increase significantly, and silver ions need to be supplemented to ensure normal production. The known replenishment method is to manually replenish the silver deposition solution, which has low production efficiency, and untimely replenishment of the solution is likely to result in poor silver deposition effect. There is an urgent need to improve this technology. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, one object of the present invention is to provide a silver immersion solution supply control system for controlling the supply of silver immersion solution, and to provide a PCB silver immersion production line for completing PCB silver immersion operation.

[0005] To this end, the second object of the present invention is to provide a method for controlling the replenishment of silver immersion solution, which is used to control the replenishment of silver immersion solution and maintain the total amount of silver in the silver immersion tank stable.

[0006] The technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a silver immersion solution replenishment control system, which is applied to a PCB silver immersion production line. The PCB silver immersion production line includes a silver immersion tank filled with silver immersion solution and a transportation device, wherein the transportation device is used to transport PCB boards to the silver immersion tank. The silver immersion solution replenishment control system includes a board number acquisition module for acquiring the number of PCB boards entering the silver immersion tank, an information acquisition module for acquiring product information of PCB boards, a controller, and a solution replenishment module for replenishing the solution in the silver immersion tank. The output end of the board number acquisition module is connected to the input end of the controller, the output end of the information acquisition module is connected to the input end of the controller, and the output end of the controller is connected to the input end of the solution replenishment module.

[0008] Furthermore, the board number acquisition module includes an infrared probe, and the infrared probe is arranged on one side of the silver sink in the board feeding direction.

[0009] Furthermore, the controller includes a computer or a single chip microcomputer.

[0010] Furthermore, the information acquisition module includes a keyboard or a touch screen.

[0011] Furthermore, the medicine replenishment module includes a replenishment medicine storage device and an electric control valve, the replenishment medicine storage device is connected to the silver precipitation tank, the electric control valve is used to control whether the replenishment medicine storage device outputs replenishment medicine to the silver precipitation tank, and the output end of the controller is connected to the control end of the electric control valve.

[0012] Furthermore, the output end of the replenishing medicinal water storage device is arranged on the side of the plate inlet direction of the silver precipitation tank.

[0013] Furthermore, the medicine replenishment module also includes a heating module and / or a cooling module, the heating module is used to heat the replenishment medicine, and the cooling module is used to reduce the temperature of the replenishment medicine, and the output end of the controller is respectively connected to the input end of the heating module and the input end of the cooling module.

[0014] In a second aspect, the present invention provides a PCB silver immersion production line, comprising a silver immersion tank filled with silver immersion solution, a transportation device and the silver immersion solution replenishment control system, wherein the transportation device is used to transport the PCB board to the silver immersion tank.

[0015] Furthermore, the PCB immersion silver production line also includes an automatic board loading device, and the automatic board loading device is used to transport the PCB board to the transportation device.

[0016] In a third aspect, the present invention provides a silver immersion solution replenishment control method, which is applied to the silver immersion solution replenishment control system, comprising:

[0017] Acquire product information of a PCB board, wherein the product information of the PCB board includes a front-side plated area, a back-side plated area, and a required silver thickness;

[0018] Obtaining the number of PCB boards entering the silver sink as a first board number;

[0019] Obtaining a corresponding required amount of silver according to the first number of boards, product information of the PCB board, and silver density;

[0020] The replenishment judgment is performed according to the required amount of silver and the preset amount of silver, wherein the preset amount of silver is less than the total amount of silver in the silver sink and greater than the required amount of silver for a single PCB board, and the required amount of silver for a single PCB board is obtained according to the product information and silver density of the PCB board;

[0021] If it is determined that the required amount of silver corresponding to the first number of boards is less than the preset amount of silver, no replenishment is performed; otherwise, liquid medicine replenishment is performed, and the amount of silver replenishment is the required amount of silver corresponding to the first number of boards. The first number of boards is cleared and the number of PCB boards entering the silver sink is continued to be obtained as the first number of boards.

[0022] The beneficial effects of the present invention are:

[0023] The silver immersion solution replenishment control system of the present invention is provided with a board number acquisition module for acquiring the number of PCB boards entering the silver immersion tank and an information acquisition module for acquiring product information of the PCB board. The board number acquisition module and the information acquisition module are combined with a controller to control the solution replenishment module to realize automatic replenishment of the silver immersion solution, thereby overcoming the technical problems that the silver immersion production process in the prior art uses manual replenishment of the solution, the production efficiency is low, and the silver immersion effect is poor; in addition, the PCB silver immersion production line uses the silver immersion solution replenishment control system, the silver immersion tank, and the transportation device to realize automatic replenishment and production of the silver immersion process, thereby effectively improving the silver immersion production efficiency. Finally, in the silver immersion solution replenishment control method, by acquiring the required amount of silver corresponding to the first board number, and then making a replenishment judgment based on the required amount of silver corresponding to the first board number and the preset amount of silver, when the required amount of silver corresponding to the first board number is greater than the preset amount of silver, the control is performed to replenish, and the silver replenishment amount is the required amount of silver corresponding to the first board number to maintain the total amount of silver in the silver immersion tank stable, ensure the silver immersion effect, and can realize automatic replenishment to improve production efficiency.

[0024] In addition, since the value of the silver deposition rate in the silver deposition tank decreases from the board feeding direction to the inside, the present invention also sets the output end of the solution supply module on the board feeding side of the silver deposition tank, that is, starting from the high silver deposition rate area, so that the solution is evenly distributed in the silver deposition tank, ensuring that the concentration of the solution is consistent everywhere in the silver deposition tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of a specific embodiment of the PCB immersion silver production line of the present invention;

[0026] Figure 2 It is a schematic diagram of the position of a board number acquisition module and a PCB board in one direction of a specific embodiment of the silver immersion solution replenishment control system of the present invention;

[0027] Figure 3 It is a schematic diagram of the position of a board number acquisition module and a PCB board in another direction of a specific embodiment of the silver immersion solution replenishment control system of the present invention;

[0028] Among them, 1-PCB board, 2-infrared probe, 3-silver sink, 4-roller, 5-paddle, 6-supply box, 7-heating module, 8-solenoid valve, 9-infrared, 10-solar flip machine, 11-pipeline, 12-outer frame. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0030] Example 1

[0031] refer to Figure 1 , Figure 1 Schematic diagram of a specific embodiment of the PCB silver immersion production line in the present invention; the PCB silver immersion production line includes an automatic board loading device, a silver immersion tank 3 filled with silver immersion solution, a transportation device and a silver immersion solution replenishment control system, the automatic board loading device is used to transport the PCB board 1 to the transportation device; the transportation device is used to transport the PCB board 1 to the silver immersion tank 3. In this embodiment, the transportation device is used to transport the PCB board 1 through the silver immersion tank 3, that is, from the board inlet direction of the silver immersion tank 3 to the board outlet direction of the silver immersion tank 3. After the PCB board 1 passes through the silver immersion tank 3, the silver immersion operation will be completed; the silver immersion solution replenishment control system includes a control system for obtaining A board number acquisition module for obtaining the number of PCB boards 1 entering the silver sinking tank, an information acquisition module for obtaining product information of the PCB boards, a controller and a medicine solution supply module for replenishing medicine solution into the silver sinking tank 3. The product information of the PCB boards includes board size, PCB board thickness, front plated area, back plated area, required silver thickness, etc. The output end of the medicine solution supply module is set on one side of the board feeding direction of the silver sinking tank 3, the output end of the board number acquisition module is connected to the input end of the controller, the output end of the information acquisition module is connected to the input end of the controller, and the output end of the controller is connected to the input end of the medicine solution supply module.

[0032] In the silver immersion solution replenishment control system, the board number acquisition module and the information acquisition module are combined with the controller to control the solution replenishment module to realize the automatic replenishment of the silver immersion solution, which overcomes the technical problems in the prior art that the silver immersion production process uses manual replenishment of the solution, the production efficiency is low and the silver immersion effect is not good; in addition, since the value of the silver immersion rate in the silver immersion tank decreases from the board inlet direction to the board outlet direction, the output end of the solution replenishment module is set on the board inlet direction side of the silver immersion tank in the present invention, that is, the replenishment starts from the high silver immersion rate area of ​​the silver immersion tank, so that the solution is evenly distributed in the silver immersion tank, ensuring that the concentration of the solution in each place in the silver immersion tank is consistent, and the silver immersion effect of the PCB board is effectively guaranteed. The PCB silver immersion production line uses the silver immersion solution replenishment control system, the silver immersion tank and the transportation device to realize the automatic replenishment and production of the silver immersion process, effectively improving the silver immersion production efficiency.

[0033] refer to Figures 1 to 3 , Figure 2This is a schematic diagram of the position of a specific embodiment of the board number acquisition module and the PCB board in one direction of the silver immersion solution supply control system of the present invention. Figure 3 This is a schematic diagram of the position of a specific embodiment of the board number acquisition module and the PCB board in another direction of the silver immersion solution replenishment control system in the present invention; the PCB silver immersion production line is specifically described below:

[0034] In this embodiment, the automatic board loading device adopts a solar-type flipper 10. The gap of the clamping plate of the solar-type flipper 10 can be adjusted according to different PCB board thickness information, and the PCB board 1 can be stably clamped; its flipping speed (rotation speed) can be adjusted, and the distance between the front and rear two PCB boards 1 can be customized according to the size of the flipping speed. The solar-type flipper 10 transports the PCB board 1 to the transportation device, wherein the transportation device includes a conveyor belt composed of a plurality of conveying rollers 4 for realizing the transmission of items. The conveying rollers 4 rotate to drive the PCB board 1 to move linearly to realize forward transmission, wherein the upper and lower parts of the conveying rollers 4 are included. The medicine will have buoyancy to float the PCB board, and the upper part of the conveying roller 4 is used to press the board surface; on the other hand, the transmission stability is increased, and the upper and lower conveying rollers 4 are driven, and the speed is better controlled and stable. The board number acquisition module includes an infrared probe 2, and the infrared probe 2 is arranged on the side of the silver sinking tank 3 in the board feeding direction. Specifically, the infrared probe 2 is arranged on the side of the silver sinking tank 3 (board feeding direction) to realize the counting of the PCB board 1 entering the silver sinking tank 3. It is worth noting that the transport device further includes a paddle 5 and a paddle control device (not shown). The paddle control device includes a manipulator or a cylinder. Before the infrared probe collects the signal of the PCB board, the paddle control device controls the paddles 5 on both sides to move toward the middle to adjust the PCB board 1 to the center of the transport belt. Then, the infrared rays 9 emitted by the infrared probe 2 can cover the complete outline of the PCB board 1 to achieve the counting of the PCB board 1. Figure 1 The outer periphery of the silver immersion tank 3 is also covered with an outer frame 12, which is used to prevent external dust or polluting gas from entering the silver immersion tank 3, avoiding pollution and damage to the silver immersion environment and affecting the silver immersion quality of the PCB board.

[0035] Furthermore, the controller includes a computer or a single-chip microcomputer to realize data processing and replenishment control, and the information acquisition module may correspond to a keyboard or a touch screen for realizing data input. The medicine replenishment module includes a replenishment medicine storage device, a pump and an electric control valve. The electric control valve is used to control whether the replenishment medicine storage device outputs replenishment medicine to the silver precipitation tank. The output end of the controller is connected to the control end of the electric control valve to control the operation of the electric control valve. When replenishment medicine is needed, the controller controls the electric control valve to open and the pump draws replenishment medicine from the replenishment medicine storage device to make it flow into the silver precipitation tank. Reference Figure 1In this embodiment, the replenishing medicine storage device is a replenishing box 6, and the electric control valve is realized by a solenoid valve 8. The replenishing box 6 is connected to the silver precipitation tank 3 through a pipe 11, and the outlet of the pipe 11 is arranged at the front of the silver precipitation tank 3 (the area with the highest silver precipitation rate), and the replenishing medicine directly touches the board surface of the PCB board 1. The outlet of the pipe 11 is arranged in the high silver precipitation rate area of ​​the silver precipitation tank 3 (the area where the medicine is consumed faster), and the medicine components around the board surface of the PCB board are directly adjusted to maintain a stable level of the surrounding concentration, so that the medicine concentration at each position of the silver precipitation tank 3 is evenly distributed, ensuring the silver precipitation effect of the PCB board; in addition, since the silver precipitation rate depends on the reduction rate of silver ions, the silver precipitation rate increases with the increase of silver ion concentration, solution stirring and temperature. In order to enable the replenishing medicine to quickly participate in the PCB board surface reaction without reducing the rate of the copper-silver replacement reaction, the medicine replenishment module also includes a heating module and / or a cooling module. The heating module is used to heat the replenishing medicine, and the cooling module is used to reduce the temperature of the replenishing medicine. The output end of the controller is connected to the input end of the heating module and the input end of the cooling module respectively. The heating module and the cooling module are set so that the replenishing medicine can be maintained at a certain temperature, so that the temperature of the replenishing medicine and the silver-immersing medicine in the silver-immersing tank are consistent. Specifically, the heating module 7 can be implemented by a heating tube, and the cooling module can be implemented by a cooling tube. When the medicine replenishment module does not include a heating module but includes a cooling module, the cooling tube can be set at the position of the heating module 7. Similarly, in order to prevent the addition of the replenishing medicine from causing the concentration of the medicine in the silver-immersing tank to exceed the standard and change the silver-immersing rate, it is necessary to configure a silver-immersing medicine of a suitable concentration as the replenishing medicine, and the concentration of the replenishing medicine is greater than or equal to the concentration of the medicine in the silver-immersing tank to ensure that the concentration of the medicine in the silver-immersing tank after replenishment is stable.

[0036] Example 2

[0037] A silver immersion solution replenishment control method, applied to the silver immersion solution replenishment control system described in Example 1, comprising:

[0038] S1. Obtain product information of the PCB board, which includes the front-side plated area, the back-side plated area and the required silver thickness;

[0039] S2, obtaining the number of PCB boards entering the silver immersion tank as the first board number;

[0040] S3. Obtain the corresponding required amount of silver according to the first board number, the product information of the PCB board and the silver density, and the calculation formula is:

[0041] The required amount of silver corresponding to the first number of boards = the first number of boards * (front plated area + back plated area) * required silver thickness * silver density. The required amount of silver is the amount of silver required for the PCB board to reach the required silver thickness;

[0042] S4. Make replenishment judgment based on the required amount of silver and the preset amount of silver. The preset amount of silver is less than the total amount of silver in the silver sink and greater than the required amount of silver for a single PCB. The preset amount of silver is used to control the timing of replenishment, ensuring that replenishment is done in advance so that the concentration of the silver sink remains at a stable level to ensure the silver sinking effect. The required amount of silver for a single PCB is obtained based on the product information and silver density of the PCB. Similarly, the calculation formula for the required amount of silver for a single PCB is:

[0043] The required amount of silver for a single PCB board = (front plated area + back plated area) * required silver thickness * silver density;

[0044] S5. If the required amount of silver corresponding to the first number of boards is less than the preset amount of silver, no replenishment is performed and the first number of boards is continued to be counted; otherwise, the liquid medicine is replenished, and the amount of silver replenished is the required amount of silver corresponding to the first number of boards. The first number of boards is cleared and the process returns to step S2 to continue to obtain the number of PCB boards entering the silver sink as the first number of boards, and continue to execute steps S3, S4 and S5. For example, when the first number of boards is 2, the corresponding required amount of silver is greater than the preset amount of silver, and the consumption of boards 1 and 2 (that is, the required amount of silver corresponding to the first number of boards) is replenished to the silver sink in advance, so that when board 3 enters the silver sink, the liquid medicine concentration level of the original silver sink is reached. After boards 1 and 2 pass through, the consumption is reset to zero and the replenishment judgment is compared.

[0045] In the silver immersion solution replenishment control method, the control principle is that the concentration of the solution in the silver immersion tank gradually decreases. When the replenishment condition is reached, the solution replenishment starts in advance to adjust the concentration of the solution in the silver immersion tank back to the original level, so as to achieve the stability of the solution in the silver immersion tank, the process is stable, and the solution can be automatically replenished to improve production efficiency. The replenishment purpose is to replenish as much as consumed in advance to maintain the stable concentration level of the solution in the silver immersion tank. In this way, when multiple models are continuously mass-produced, the stable solution supply can be maintained, and the stability of the solution concentration can still be accurately controlled to achieve the purpose of stable production, avoiding the problem of uneven distribution of solution concentration at various positions of the silver immersion tank when multiple models are continuously produced. In this embodiment, the tank liquid temperature of the silver immersion tank is stable, and the silver concentration of the silver immersion tank is stable, then the silver immersion rate is stable. Therefore, the requirements for the silver thickness of different types of PCB boards can be achieved by changing the linear speed of the transport device (i.e., the residence time of the PCB board in the silver immersion tank).

[0046] In actual production, the controller automatically calculates the required amount of silver corresponding to the first plate number of different models to complete the replenishment judgment. In order to improve the speed of replenishment judgment, in this embodiment, the following replenishment judgment method is adopted:

[0047] The required silver thickness of different products is a, in cm, according to the chemical equation Cu+2Ag + =2Ag+Cu2 +, 63.5g of copper can replace 216g of silver. 216g is the preset amount of silver, and the specific value can be adjusted. In the actual production process, the content of copper is much higher than the content of Ag ions, and the amount involved in the reaction is sufficient. Theoretically, the density of silver is 10.536g / cm 3 , 216g of silver generates a cm thick silver that can cover an area of ​​20.5 / a cm 2 , with 20.5 / a cm 2 As the preset area, the replenishment judgment rule is that when the current total plating area Vtotal is greater than or equal to 20.5 / a, the controller sends a replenishment instruction to the medicine supply module, and the current total plating area Vtotal = the first plate number n*(the front plating area of ​​the single plate + the back plating area of ​​the single plate); the replenishment amount is the required amount of silver corresponding to the first plate number n; when Vtotal is greater than or equal to 20.5 / a, no replenishment is performed.

[0048] refer to Figure 1 The description of Example 1 is as follows, taking the actual production process as an example, the silver immersion solution replenishment control method is specifically described:

[0049] 1. Product information entry

[0050] Input the board size, PCB thickness, front plated area, back plated area, and required silver thickness of different PCB models into the controller. At this point, the total amount of silver in the silver sink is known, and the required amount of silver for a single PCB can be calculated, so the preset silver amount for different models can be calculated, set, and adjusted on the controller.

[0051] 2. Set the production order

[0052] Set the production order of different models on the controller, as shown in the following table:

[0053] Production Order model Silver thickness requirements 1 A X 2 B Y … … …

[0054] 3. Start the solar panel turning machine 10. The clamps of the solar panel turning machine 10 start to rotate in a fixed direction. At this time, the PCB board 1 to be produced is placed between the clamps. The PCB board 1 is brought onto the conveying roller 4 by the clamps. At this time, the paddle of the transport device starts to move toward the middle, and the transport path of the PCB board is adjusted to the center of the conveyor belt.

[0055] 4. First board number collection

[0056] When each PCB board passes through the area under the infrared probe, it will feedback the "board to station" signal to the controller. Similarly, when each PCB board leaves the area under the infrared probe, it will also feedback the "board leaves the station" information. After collecting these two signals, the controller automatically counts the first board number n.

[0057] 5. Supply Judgment

[0058] The replenishment judgment is made according to the first plate number n and the preset silver amount. During actual production, the replenishment judgment is made according to the total plated area and the preset area. When replenishment is needed, the first plate number n is cleared, and the first plate number collection step is returned to continue production.

[0059] When different models are produced continuously, the controller controls the replenishment according to different preset silver amounts and the required amount of silver corresponding to the first number of plates; and because of the replenishment operation, the silver immersion tank still maintains the original potion concentration level after the previous model is produced. Therefore, the production of different models before and after does not affect each other.

[0060] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A silver immersion solution replenishment control system, applied to a PCB silver immersion production line, the PCB silver immersion production line comprises a silver immersion tank filled with silver immersion solution and a transport device, the transport device is used to transport the PCB board to the silver immersion tank, characterized in that: The silver immersion liquid medicine supply control system includes a board number acquisition module for acquiring the number of PCB boards entering the silver immersion tank, an information acquisition module for acquiring product information of PCB boards, a controller, and a liquid medicine supply module for replenishing liquid medicine into the silver immersion tank, wherein the output end of the board number acquisition module is connected to the input end of the controller, the output end of the information acquisition module is connected to the input end of the controller, and the output end of the controller is connected to the input end of the liquid medicine supply module; The board number acquisition module includes an infrared probe, which is arranged on one side of the silver sink in the board feeding direction; The medicine replenishment module includes a replenishment medicine storage device, an electric control valve and a pipeline, the replenishment medicine storage device is connected to the silver sink, the replenishment medicine storage device outputs replenishment medicine to the silver sink through the pipeline, the electric control valve is used to control whether the replenishment medicine storage device outputs replenishment medicine to the silver sink, the output end of the controller is connected to the control end of the electric control valve, and the output end of the replenishment medicine storage device is arranged on the side of the plate inlet direction of the silver sink; The medicine replenishment module also includes a heating module and a cooling module. The heating module is used to heat the replenishment medicine, and the cooling module is used to reduce the temperature of the replenishment medicine. The output end of the controller is connected to the input end of the heating module and the input end of the cooling module respectively.

2. The silver immersion solution supply control system according to claim 1, characterized in that: The controller includes a computer or a single chip microcomputer.

3. The silver immersion solution supply control system according to claim 1, characterized in that: The information acquisition module includes a keyboard or a touch screen.

4. A PCB immersion silver production line, characterized in that: It comprises a silver immersion tank filled with silver immersion solution, a transportation device and the silver immersion solution replenishment control system according to any one of claims 1 to 3, wherein the transportation device is used to transport a PCB board into the silver immersion tank.

5. The PCB immersion silver production line according to claim 4, characterized in that: The PCB silver immersion production line also includes an automatic board loading device, which is used to transport the PCB board to the transportation device.

6. A method for controlling the replenishment of silver immersion solution, applied to the silver immersion solution replenishment control system according to any one of claims 1 to 3, characterized in that: include: Acquire product information of a PCB board, wherein the product information of the PCB board includes a front-side plated area, a back-side plated area, and a required silver thickness; Obtaining the number of PCB boards entering the silver sink as a first board number; Obtaining a corresponding required amount of silver according to the first number of boards, product information of the PCB board, and silver density; The replenishment judgment is performed according to the required amount of silver and the preset amount of silver, wherein the preset amount of silver is less than the total amount of silver in the silver sink and greater than the required amount of silver for a single PCB board, and the required amount of silver for a single PCB board is obtained according to the product information and silver density of the PCB board, wherein the preset amount of silver is used to control the replenishment timing; If it is determined that the required amount of silver corresponding to the first number of boards is less than the preset amount of silver, no replenishment is performed; otherwise, liquid medicine replenishment is performed, and the amount of silver replenishment is the required amount of silver corresponding to the first number of boards. The first number of boards is cleared and the number of PCB boards entering the silver sink is continued to be obtained as the first number of boards.

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