Closed-loop control method and system for plasma surface parameters

Abstract

The invention relates to the technical field of plasma closed-loop control, and discloses a closed-loop control method and system for plasma surface parameters, and the method comprises the steps: executing a chip interval classification strategy, and dividing chips into two types according to the intervals of the chips on a circuit board; executing a cleaning duration estimation strategy, and estimating the cleaning duration of cleaning the to-be-cleaned area by the plasma cleaning pen under different cleaning distances; executing a single-time cleaning prediction strategy, cleaning the to-be-cleaned area once by using a plasma cleaning pen, and predicting the single-time duration of cleaning the to-be-cleaned area of the circuit board; a double-cleaning prediction strategy is executed, the plasma cleaning pen is used for cleaning the local cleaning area twice, and the double-time duration of cleaning the to-be-cleaned area of the circuit board is predicted; according to the method, an isolated chip cleaning optimization strategy is executed, single-time cleaning and multi-time cleaning are performed on the isolated chip based on the set limit duration, and the isolated chip is cleaned in a mode with the shortest cleaning duration, so that the cleaning precision of the circuit board is improved, and meanwhile, the cleaning energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of plasma closed-loop control, and in particular to a closed-loop control method and system for plasma surface parameters. Background Art

[0002] As a non-contact tool for removing micro-pollutants, the plasma cleaning pen offers advantages such as precision, efficiency, and a lack of mechanical damage. It is suitable for cleaning delicate chips and bare board areas on circuit boards. By stimulating a high-energy particle beam, it effectively removes organic residue and fine dust, improving the reliability of subsequent packaging and soldering. It is particularly suitable for surface pretreatment of complex circuit boards.

[0003] Most existing plasma cleaning solutions rely on fixed distances, fixed durations, or manual experience for operation, lacking a precise control mechanism based on the linked changes in distance and particle density. In actual applications, there are significant differences in particle density at different cleaning distances, which causes the cleaning intensity and duration to fluctuate with distance, easily resulting in over- or under-cleaning. Especially when faced with scenarios such as inconsistent contaminant thickness, dense chip layouts (clusters), or long intervals (isolation), traditional cleaning strategies cannot flexibly adjust the cleaning range and duration, affecting cleaning integrity and equipment life. In addition, existing methods lack a modeling process based on the dynamic mapping of "cleaning distance-cleaning duration", making it impossible to predict the cleaning duration and optimize the strategy for specific areas, nor has an effective "limited duration" judgment and automatic decision-making mechanism been established. Therefore, against the backdrop of increasingly sophisticated circuit board manufacturing and high-consistency surface treatment requirements, existing technologies can no longer meet the comprehensive needs of flexible control, intelligent judgment, and high-quality cleaning.

[0004] This proposal proposes a closed-loop control method and system for plasma surface parameters. Based on the closed-loop control method of cleaning distance-particle density-duration, combined with chip spacing classification and multi-strategy selection mechanism, it can accurately control the action path and duration of the plasma cleaning pen in different areas. Summary of the Invention

[0005] The present invention provides a closed-loop control method and system for plasma surface parameters, which are used to promote the solution of the problems mentioned in the above background technology.

[0006] The present invention provides the following technical solution: a closed-loop control method for plasma surface parameters, comprising:

[0007] Use a plasma cleaning pen to vertically clean the circuit board, wherein the plasma cleaning pen has a corresponding cleaning coverage area at each cleaning distance from the circuit board;

[0008] The cleaning coverage area is a rectangular cleaning area of ​​the plasma on the circuit board;

[0009] Set the maximum cleaning distance and the minimum cleaning distance;

[0010] Implement chip spacing classification strategy to classify chips into two categories based on the spacing of chips on the circuit board: cluster chips and isolated chips;

[0011] Get the rectangular area between any two adjacent cluster chips and record it as the area to be cleaned;

[0012] Select several points on each area to be cleaned to measure the thickness of the contaminants at the points, and calculate the average thickness as the average thickness of the contaminants in each area to be cleaned;

[0013] Execute the cleaning time estimation strategy to estimate the cleaning time of the plasma cleaning pen cleaning the area to be cleaned at different cleaning distances;

[0014] Execute a single cleaning prediction strategy, use a plasma cleaning pen to clean the area to be cleaned once, and predict the single cleaning time of the circuit board area to be cleaned;

[0015] Divide the area to be cleaned into two local cleaning areas according to a straight line perpendicular to the width;

[0016] Execute the double cleaning prediction strategy, use the plasma cleaning pen to clean the local cleaning area twice, and predict the double cleaning time of the circuit board area to be cleaned;

[0017] Compare the single-time duration and the double-time duration, and use the cleaning method corresponding to the smaller duration as the cleaning method for the area to be cleaned;

[0018] Set the time limit for the plasma cleaning pen to irradiate the chip;

[0019] Execute the isolated chip cleaning optimization strategy, perform single cleaning and batch cleaning on the isolated chip based on the set limit time, and choose the method with the shortest cleaning time to clean the isolated chip.

[0020] Optionally, the chip spacing classification strategy is implemented to classify the chips into two categories according to the spacing of the chips on the circuit board, including:

[0021] For any chip on the circuit board:

[0022] Get the maximum cleaning distance of the plasma cleaning pen The width of the corresponding cleaning coverage area ;

[0023] Measure the four sides of the chip and the vertical distance between adjacent chips to obtain , , and ;

[0024] Compare four vertical distances and upper limit width;

[0025] If , the chip is an isolated chip;

[0026] If , the chip is a cluster chip.

[0027] Optionally, the execution of the cleaning duration estimation strategy estimates the cleaning duration of the plasma cleaning pen in cleaning the to-be-cleaned area under different cleaning distances, including:

[0028] Set the cleaning distance interval ;

[0029] From the minimum cleaning distance , every interval corresponding to the cleaning distance is recorded as the cleaning distance until the cleaning distance is equal to the maximum cleaning distance ;

[0030] All cleaning distances form an experimental distance set , , wherein is the ith cleaning distance, and is the number of cleaning distances.

[0031] For any to-be-cleaned area r, obtain the average thickness of the contaminants in the to-be-cleaned area ;

[0032] Iterate through each cleaning distance in the experimental distance set, and use the plasma cleaning pen to clean the to-be-cleaned area with the average thickness of the contaminants once according to the cleaning distance, and measure the thickness of the contaminants in the to-be-cleaned area in real time.

[0033] Set the thickness threshold of the contaminants ;

[0034] Compare the real-time measured thickness of the contaminants in the to-be-cleaned area with the thickness threshold, if , it is determined that the cleaning of the to-be-cleaned area is completed.

[0035] The duration from the start of cleaning to the end of cleaning the to-be-cleaned area is recorded as the cleaning duration , the cleaning duration of the to-be-cleaned area r under different cleaning distances is obtained , .

[0036] Optionally, the execution of the single cleaning prediction strategy uses the plasma cleaning pen to clean the to-be-cleaned area once to predict the single duration of cleaning the to-be-cleaned area of the circuit board, including:

[0037] Obtain the cleaning coverage area corresponding to each cleaning distance in the experimental distance set.

[0038] Obtaining the width of the area to be cleaned, and comparing the width with the widths of all cleaning coverage areas, and recording the cleaning coverage area with a width equal to the width as a single coverage area;

[0039] The cleaning distance corresponding to the single coverage area is recorded as the single cleaning distance ;

[0040] Align the width of the area to be cleaned with the width of the single coverage area, divide the area to be cleaned evenly based on the single coverage area, and divide the area to be cleaned into multiple areas of the same size as the single coverage area:

[0041] Count the number of the areas mentioned and record it as a single number , ,in, is the length of the area to be cleaned, is the length of the single coverage area;

[0042] Get the average thickness of the pollutants in the area to be cleaned, and get the cleaning time under the pollutant thickness and single cleaning distance , ;

[0043] Predict the first cleaning time of the area to be cleaned , ;

[0044] The first cleaning durations of all the areas to be cleaned are obtained, and the sum is calculated and used as the predicted single cleaning duration of the areas to be cleaned on the circuit board.

[0045] Optionally, the double cleaning prediction strategy is executed, using a plasma cleaning pen to clean the local cleaning area twice, and predicting the double cleaning time of the area to be cleaned of the circuit board, including:

[0046] Obtaining the width of the local cleaning area, and comparing the width with the width of all cleaning coverage areas, and recording the cleaning coverage area with a width equal to the width as a double coverage area;

[0047] The cleaning distance corresponding to the double coverage area is recorded as the double cleaning distance ;

[0048] Align the width of the local cleaning area with the width of the double coverage area, divide the local cleaning area equally based on the double coverage area, and divide the local cleaning area into multiple areas of equal size to the local cleaning area;

[0049] Count the number of areas and multiply by 2 to record it as double number :

[0050] ,in, is the length of the double coverage area;

[0051] Get the average thickness of the pollutants in the area to be cleaned, and get the cleaning time under the pollutant thickness and double cleaning distance , ;

[0052] Predict the second cleaning time of the area to be cleaned , ;

[0053] The second cleaning time of all the areas to be cleaned is obtained, and the sum is calculated and used as the predicted double cleaning time of the areas to be cleaned on the circuit board.

[0054] Optionally, executing the isolated chip cleaning optimization strategy, performing single cleaning and multiple cleaning on the isolated chip based on a set time limit, and selecting a method with the shortest cleaning time to clean the isolated chip, includes:

[0055] The method of single cleaning of isolated chips is:

[0056] Select multiple points on the bare board area of ​​the circuit board to measure the thickness of the contaminant, calculate the average thickness, and record the result as the bare board contaminant average thickness ;

[0057] The obtained contaminant thickness is equal to the average thickness of the bare board contaminants and the cleaning time is equal to the limit time The cleaning distance is calculated, and the cleaning coverage area corresponding to the cleaning distance is obtained, which is recorded as the restricted coverage area;

[0058] calculate ,in, is the marking distance;

[0059] The cleaning coverage area corresponding to the mark distance is obtained and recorded as the mark coverage area;

[0060] The length and width of the marked area are recorded as the mark length and marker width ;

[0061] Traverse each isolated chip and record the length and width of the isolated chip as the isolated length and isolated width ;

[0062] calculate , Cleaning the head for safety;

[0063] calculate , For safe cleaning of the total width;

[0064] The length and width of the restricted coverage area are respectively recorded as the restricted length and limit width ;

[0065] like and , then the isolated chip is recorded as the target chip;

[0066] Align the center of the restricted coverage area with the center of the target chip;

[0067] The width of the restricted coverage area is controlled to be parallel to the width of the target chip, the length of the restricted coverage area is controlled to be parallel to the length of the target chip, and the cleaning time of the target chip is limited.

[0068] Optionally, executing the isolated chip cleaning optimization strategy, performing single cleaning and multiple cleaning on the isolated chip based on a set time limit, and selecting a method with the shortest cleaning time to clean the isolated chip, includes:

[0069] The specific method of the stepwise cleaning is as follows:

[0070] The length of the control marker coverage area is parallel to the length and width of the target chip;

[0071] Get the cleaning time corresponding to the contaminant thickness being equal to the average thickness of the bare board contaminants and the cleaning distance being equal to the marked distance, and record it as the third cleaning time , ;

[0072] calculate , the result is recorded as the number of times ;

[0073] calculate , The duration of each session;

[0074] like , then the isolated chip is cleaned once;

[0075] like , then the isolated chip is cleaned in batches;

[0076] Control the plasma cleaning pen to clean the bare board area of ​​the circuit board according to the marked coverage area.

[0077] A closed-loop control system for plasma surface parameters, comprising:

[0078] Parameter initialization module, used to set the minimum cleaning distance and the maximum cleaning distance, generate rectangular coverage areas under different cleaning distances, and record the width and length of each rectangular coverage area;

[0079] The chip spacing classification module is used to measure the four vertical distances between each chip and the surrounding chips, and mark the chip category based on the comparison results with the maximum cleaning distance;

[0080] The pollution thickness sampling module is used to select multiple points in the area to be cleaned to measure the thickness of the pollution, and calculate the average thickness of all the measuring points as the average thickness of the pollution in the area to be cleaned;

[0081] The cleaning time modeling module is used to perform successive cleaning according to different cleaning distances, detect the thickness of pollutants in real time, and record the time from the start of cleaning to reaching the thickness threshold;

[0082] A single cleaning prediction module is used to match a cleaning coverage area with the same width as the area to be cleaned, divide the area to be cleaned into multiple equal-sized areas, and calculate the duration of a single cleaning;

[0083] The double cleaning prediction module is used to divide the area to be cleaned into two local cleaning areas in the vertical direction, divide each local cleaning area, and calculate the double cleaning time of the two times;

[0084] An isolated chip cleaning module is used to determine and operate a single or multiple cleaning scheme for an isolated chip, including a single cleaning unit and a multiple cleaning unit;

[0085] The single cleaning unit is used to detect that when the total length of safe cleaning and the total length and width of safe cleaning are both smaller than the length and width of the restricted coverage area, the isolated chip is centered and a single cleaning is performed;

[0086] The step-by-step cleaning unit is used to divide the marking area into blocks, calculate the number of steps and the step-by-step cleaning time, and control the plasma pen to complete the step-by-step cleaning in sequence when the step-by-step cleaning time is less than the limit time.

[0087] The present invention has the following beneficial effects:

[0088] 1. This closed-loop control method for plasma surface parameters distinguishes isolated chips from clustered chips by measuring the vertical distance between each chip on the circuit board and its surrounding chips in four directions and comparing this distance with the coverage width of the plasma cleaning pen at the maximum cleaning distance. This provides a foundation for differentiated regional cleaning strategies and avoids the problems of inefficiency or excessive cleaning caused by a one-size-fits-all cleaning process. This method avoids unnecessary repetitive judgment logic, provides clear operational steps, and is suitable for the automatic identification process of large-scale circuit boards, facilitating modular integration.

[0089] 2. The closed-loop control method for plasma surface parameters constructs a data set containing multiple experimental distances by setting the step interval between the minimum cleaning distance and the maximum cleaning distance. The actual cleaning time required to reach the cleaning threshold at each distance is measured, forming an "empirical time database" covering multiple distances and contamination thickness conditions. This database is used to quickly estimate the time required for subsequent cleaning areas, avoiding repeated experiments and repeated calculations, and providing input data for the single cleaning and multi-cleaning time prediction modules, thereby improving the overall response speed and adaptability of the closed-loop control system.

[0090] 3. This closed-loop control method for plasma surface parameters determines the appropriate single cleaning distance by comparing the width of the area to be cleaned with the width of the coverage area at each cleaning distance. The method then divides the entire area into several equal sections, creating a standardized approach to time prediction. This method rapidly calculates the total cleaning time without increasing the measurement burden, providing a predictable time benchmark for the control system. By utilizing existing contamination thickness and duration estimation data, cleaning scheduling can be completed without the need for repeated real-time monitoring of contamination changes, reducing the burden on sensors and improving the time control accuracy and scheduling efficiency of the entire system.

[0091] 4. The closed-loop control method of the plasma surface parameters: when the cleaning pen is close to the circuit board, the plasma particle density is higher and the effect is concentrated, which can remove pollutants faster per unit time; when the cleaning distance is farther, the particle density decreases. Although the coverage area is expanded, the cleaning speed is slowed down, resulting in a longer total cleaning time. Based on this physical property, the area to be cleaned is divided into two local areas in the vertical direction, and two cleaning operations with narrower coverage widths and closer distances are used for each treatment. Compared with the one-time long-distance coverage cleaning method, it can maintain the coverage integrity while speeding up the removal of pollutants in each local area, thereby effectively shortening the overall cleaning time. However, the number of cleaning times increases, so the final cleaning method needs to be determined by considering the size of the single and double cleaning times.

[0092] 5. This closed-loop control method for plasma surface parameters considers the potential thermal, electrical, or structural impacts of direct plasma pen exposure to the chip body when cleaning isolated chips. Therefore, a limited exposure time is set to ensure that the cleaning operation is completed within a safe range. This operation is performed by constructing a cleaning frame surrounding the chip. A marked distance is used as the standard cleaning distance for cleaning the bare board area, ensuring a moderate cleaning particle density and high coverage accuracy. The marked coverage area corresponding to the marked distance is then matched with the target chip's dimensional expansion value to calculate the maximum safe cleaning range for a single pass, namely, the safe total length and width. If the expanded cleaning frame dimensions fall within the set restricted coverage area, the single-pass cleaning conditions are considered met, and a one-shot cleaning operation is performed using center alignment. This method efficiently removes surrounding contaminants without damaging the chip structure, avoiding repeated path planning and batch control command generation. It offers advantages such as a short execution path, fast response, and clear parameter control.

[0093] 6. This closed-loop control method for plasma surface parameters provides a step-by-step cleaning solution using controlled variables when isolated chips, due to their large size or complex edge structures, cannot be cleaned in a single pass within the set time limit. This solution does not directly irradiate the chip itself, but instead targets the bare substrate area surrounding the chip. The cleaning coverage area corresponding to the "marker distance" (i.e., the marked coverage area) is used as the basic unit to control the scope and particle density of the local cleaning. By fixing the cleaning parameters and adjusting only the spatial size of the target cleaning area, each cleaning run is performed under the same physical conditions, effectively avoiding instabilities caused by frequent adjustments to distance or energy parameters. Based on the ratio between the size of the restricted coverage area and the marked coverage area, the number of cleaning passes required is calculated, and the total cleaning time is estimated based on the cleaning time of each individual area. By comparing this result with the time limit, an intelligent decision is made whether to use a step-by-step cleaning approach, significantly improving the flexibility and control accuracy of cleaning the chip periphery. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] Figure 1 Schematic diagram of the process of the present invention.

[0095] Figure 2 Schematic diagram of the system module of the present invention.

[0096] Figure 3 This is a schematic diagram of the area to be cleaned according to the present invention;

[0097] Figure 4 Schematic diagram of the limited coverage area of ​​the present invention. DETAILED DESCRIPTION

[0098] 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0099] Example 1, refer to Figure 1 , a closed-loop control method for plasma surface parameters, comprising:

[0100] Plasma cleaning pens excite gases to form high-energy plasma, using active particles in the plasma to physically bombard, chemically react, and degrade contaminants on the circuit board surface through ultraviolet light, effectively removing them. These pens offer advantages such as non-contact, localized controllability, and adaptability to complex structures, making them particularly suitable for micro-contamination treatment and surface activation on refined circuit boards.

[0101] Because plasma has high energy output and active particle bombardment capabilities, prolonged exposure to the chip itself can easily cause localized overheating, corrosion damage, charge accumulation, and even device failure. Therefore, when plasma cleaning circuit boards, it is necessary to control the cleaning distance and duration, avoid direct exposure to the chip itself, or adopt a short, multi-step treatment strategy to ensure the safety and reliability of the chip structure and function.

[0102] Use a plasma cleaning pen to vertically clean the circuit board, wherein the plasma cleaning pen has a corresponding cleaning coverage area at each cleaning distance from the circuit board;

[0103] The cleaning coverage area is a rectangular cleaning area of ​​the plasma on the circuit board;

[0104] Set the maximum cleaning distance and the minimum cleaning distance;

[0105] Implement a chip spacing classification strategy to classify chips into two categories based on their spacing on the circuit board: cluster chips and isolated chips, including:

[0106] There are three chips on the circuit board: Chip A, Chip B, and Chip C. The length and width dimensions of Chip A and Chip B are 5mm x 5mm.

[0107] In this embodiment, the size of all chips is the boundary of the pins around the chip, that is, the size of the chip includes the length of the pins;

[0108] Set up a two-dimensional coordinate system on the circuit board;

[0109] The center coordinates of the three chips are:

[0110] Center of chip A: (10mm, 10mm);

[0111] Chip B center: (16.2mm, 10mm);

[0112] Chip C center: (100mm, 100mm);

[0113] Get the maximum cleaning distance of the plasma cleaning pen The width of the corresponding cleaning coverage area ;

[0114] For chip A, calculate the center distance between chip A and chip B: 16.2-10 = 6.2 mm;

[0115] The edge distance is 6.2−5=1.2mm, 1.2mm<2mm, so chip A is a cluster chip;

[0116] Chip B and chip A are both cluster chips;

[0117] If the distance between chip C and any other chip A or chip B is greater than 2 mm on all four sides and between adjacent chips, then chip C is an isolated chip.

[0118] Obtain the rectangular area between any two adjacent cluster chips. In this embodiment, refer to Figure 3 , is the area to be cleaned between chip A and chip B;

[0119] Select several points on each area to be cleaned to measure the thickness of the contaminants at the points, and calculate the average thickness as the average thickness of the contaminants in each area to be cleaned;

[0120] In this embodiment, the existing ellipsometry technology is used to measure the thickness of the contaminant, as described below:

[0121] Principle: The film thickness is measured based on the changes in reflection and refraction of polarized light on the pollutant film.

[0122] Scope of application: Suitable for measuring transparent or semi-transparent pollution layers between a few nanometers and a few microns.

[0123] Advantages: non-contact, high precision, and real-time online monitoring.

[0124] Execute the cleaning time estimation strategy to estimate the cleaning time of the plasma cleaning pen cleaning the area to be cleaned at different cleaning distances, including:

[0125] Set cleaning distance interval ;

[0126] From the minimum cleaning distance At the beginning, the distance corresponding to each cleaning distance interval is recorded as the cleaning distance until the cleaning distance is equal to the maximum cleaning distance ;

[0127] All cleaning distances are combined into an experimental distance set ;

[0128] , n=4;

[0129] For the area to be cleaned between chip A and chip B, obtain the average thickness of the contaminants in the area to be cleaned. ;

[0130] Traverse each cleaning distance in the experimental distance set, use the plasma cleaning pen to clean the area to be cleaned with uniform thickness of contaminants according to the cleaning distance, and measure the thickness of contaminants in the area to be cleaned in real time;

[0131] Setting the thickness threshold for contaminants ;

[0132] Compare the real-time measured contaminant thickness of the area to be cleaned with the thickness threshold. , it is determined that the cleaning of the area to be cleaned is completed;

[0133] Experimental results (cleaning time at each distance):

[0134] Cleaning distance 2mm: cleaning time 6s;

[0135] Cleaning distance 4mm: cleaning time 9s;

[0136] Cleaning distance 6mm: cleaning time 12s;

[0137] Cleaning distance 8mm: cleaning time 15s;

[0138] Cleaning distance 10mm: cleaning time 18s.

[0139] In this embodiment, during the actual experiment, the cleaning time measured is the cleaning time obtained by using a plasma cleaning pen to clean the area to be cleaned once;

[0140] Execute a single cleaning prediction strategy, use a plasma cleaning pen to clean the area to be cleaned once, and predict the single cleaning time of the circuit board area to be cleaned, including:

[0141] Obtain the cleaning coverage area corresponding to each cleaning distance in the experimental distance set;

[0142] The width of the area to be cleaned is obtained as 1.2 mm and the length is 2.4 mm. The width is compared with the width of all cleaning coverage areas, and the cleaning coverage area with a width equal to the width is recorded as a single coverage area;

[0143] The coverage area size corresponding to the 8mm cleaning distance is: 1.2 mm wide and 0.8 mm long;

[0144] The cleaning distance corresponding to the single coverage area is recorded as the single cleaning distance =8mm;

[0145] Align the width of the area to be cleaned with the width of the single coverage area, divide the area to be cleaned evenly based on the single coverage area, and divide the area to be cleaned into multiple areas of the same size as the single coverage area:

[0146] Count the number of the areas mentioned and record it as a single number , ,in, is the length of the area to be cleaned, is the length of the single coverage area;

[0147] Get the cleaning time under the condition of pollutant thickness and single cleaning distance ;

[0148] Predict the duration of a single cleaning of the area to be cleaned , .

[0149] Divide the area to be cleaned into two local cleaning areas according to a straight line perpendicular to the width;

[0150] Execute the double cleaning prediction strategy, use the plasma cleaning pen to clean the local cleaning area twice, and predict the double cleaning time of the circuit board area to be cleaned, including:

[0151] Obtain a local cleaning area width of 0.6 mm and a local cleaning area length of 2.4 mm, compare the width with the width of all cleaning coverage areas, and record the cleaning coverage area with a width equal to the width as a double coverage area;

[0152] When the cleaning distance is 4mm, the double coverage area size is: 0.6mm wide and 0.6mm long;

[0153] The cleaning distance corresponding to the double coverage area is recorded as the double cleaning distance ;

[0154] Align the width of the local cleaning area with the width of the double coverage area, divide the local cleaning area equally based on the double coverage area, and divide the local cleaning area into multiple areas of equal size to the local cleaning area;

[0155] Count the number of areas and multiply by 2 to record it as double number :

[0156] ,in, is the length of the double coverage area;

[0157] Get the cleaning time under the given contaminant thickness and double cleaning distance ;

[0158] Predict the double cleaning time of the area to be cleaned , .

[0159] Compare the single time duration and the double time duration, and use the cleaning method corresponding to the single time duration as the cleaning method for cleaning the area to be cleaned.

[0160] Set the time limit for the plasma cleaning pen to irradiate the chip;

[0161] Execute the isolated chip cleaning optimization strategy, perform single cleaning and batch cleaning on the isolated chip based on the set time limit, and choose the method with the shortest cleaning time to clean the isolated chip, including:

[0162] The method of single cleaning of isolated chips is:

[0163] Select multiple points on the bare board area of ​​the circuit board to measure the thickness of the contaminant, calculate the average thickness, and record the result as the bare board contaminant average thickness ;

[0164] The obtained contaminant thickness is equal to the average thickness of the bare board contaminants and the cleaning time is equal to the limit time The cleaning distance is calculated, and the cleaning coverage area corresponding to the cleaning distance is obtained, which is recorded as the restricted coverage area;

[0165] ;

[0166] The length × width dimensions of chip C are 0.3 mm × 1 mm;

[0167] In this embodiment, refer to Figure 4 , the limited coverage area is the cleaning coverage area corresponding to the 10mm cleaning distance, length: 1.3mm, width: 2mm;

[0168] calculate ,in, is the marking distance;

[0169] The cleaning coverage area corresponding to the mark distance is obtained and recorded as the mark coverage area;

[0170] The length and width of the marked area are recorded as the mark length and marker width ;

[0171] Traverse each isolated chip and record the length and width of the isolated chip as the isolated length and isolated width ;

[0172] calculate , Cleaning the head for safety;

[0173] calculate , For safe cleaning of the total width;

[0174] The length and width of the restricted coverage area are respectively recorded as the restricted length and limit width ;

[0175] and , then the isolated chip C is recorded as the target chip;

[0176] Align the center of the restricted coverage area with the center of the target chip;

[0177] The width of the restricted coverage area is controlled to be parallel to the width of the target chip, the length of the restricted coverage area is controlled to be parallel to the length of the target chip, and the cleaning time of the target chip is limited.

[0178] The specific method of the stepwise cleaning is as follows:

[0179] The length of the control marker coverage area is parallel to the length and width of the target chip;

[0180] Get the cleaning time corresponding to the contaminant thickness being equal to the average thickness of the bare board contaminants and the cleaning distance being equal to the marked distance, and record it as the third cleaning time , ;

[0181] calculate , the result is recorded as the number of times The reason for adding 4 here is that the bare board area contacted by the four corners of the target chip may not be cleaned, so the bare board area contacted by each corner is cleaned once using a plasma cleaning pen. However, in this embodiment, there is no bare board area contacted by each corner that is not cleaned, so there is no need to add 4.

[0182] calculate , The duration of each session;

[0183] like , then the isolated chip is cleaned once;

[0184] Controlling the plasma cleaning pen to clean the bare board area of ​​the PCB according to the marked coverage area simplifies the cleaning parameter determination process and expands the strategy's applicability. By selecting the cleaning coverage area corresponding to the marked distance (i.e., the average of the minimum and maximum cleaning distances), the bare board area is cleaned uniformly, eliminating the need to distinguish between particle density differences at different distances. This provides a neutral cleaning intensity reference point, balancing cleaning efficiency and chip protection requirements, and serves as a key basis for subsequent judgment of cleaning capacity and time allocation for the target area.

[0185] Example 2, refer to Figure 2 , a closed-loop control system for plasma surface parameters, comprising:

[0186] Parameter initialization module, used to set the minimum cleaning distance and the maximum cleaning distance, generate rectangular coverage areas under different cleaning distances, and record the width and length of each rectangular coverage area;

[0187] The chip spacing classification module is used to measure the four vertical distances between each chip and the surrounding chips, and mark the chip category based on the comparison results with the maximum cleaning distance;

[0188] The pollution thickness sampling module is used to select multiple points in the area to be cleaned to measure the thickness of the pollution, and calculate the average thickness of all the measuring points as the average thickness of the pollution in the area to be cleaned;

[0189] The cleaning time modeling module is used to perform successive cleaning according to different cleaning distances, detect the thickness of pollutants in real time, and record the time from the start of cleaning to reaching the thickness threshold;

[0190] A single cleaning prediction module is used to match a cleaning coverage area with the same width as the area to be cleaned, divide the area to be cleaned into multiple equal-sized areas, and calculate the duration of a single cleaning;

[0191] The double cleaning prediction module is used to divide the area to be cleaned into two local cleaning areas in the vertical direction, divide each local cleaning area, and calculate the double cleaning time of the two times;

[0192] An isolated chip cleaning module is used to determine and operate a single or multiple cleaning scheme for an isolated chip, including a single cleaning unit and a multiple cleaning unit;

[0193] The single cleaning unit is used to detect that when the total length of safe cleaning and the total length and width of safe cleaning are both smaller than the length and width of the restricted coverage area, the isolated chip is centered and a single cleaning is performed;

[0194] The step-by-step cleaning unit is used to divide the marking area into blocks, calculate the number of steps and the step-by-step cleaning time, and control the plasma pen to complete the step-by-step cleaning in sequence when the step-by-step cleaning time is less than the limit time.

[0195] It is to be noted that, in the present text, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0196] The above description is only the preferred embodiment of the present application, it should be pointed out that for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and refinements can also be made, which should be considered as the protection scope of the present application.

Claims

1. A closed-loop control method for plasma surface parameters, characterized in that: include: Use a plasma cleaning pen to vertically clean the circuit board, wherein the plasma cleaning pen has a corresponding cleaning coverage area at each cleaning distance from the circuit board; The cleaning coverage area is a rectangular cleaning area of ​​the plasma on the circuit board; Set the maximum cleaning distance and the minimum cleaning distance; Implement chip spacing classification strategy to classify chips into two categories based on the spacing of chips on the circuit board: cluster chips and isolated chips; Get the rectangular area between any two adjacent cluster chips and record it as the area to be cleaned; Select several points on each area to be cleaned to measure the thickness of the contaminants at the points, and calculate the average thickness as the average thickness of the contaminants in each area to be cleaned; Execute the cleaning time estimation strategy to estimate the cleaning time of the plasma cleaning pen cleaning the area to be cleaned at different cleaning distances; Execute a single cleaning prediction strategy, use a plasma cleaning pen to clean the area to be cleaned once, and predict the single cleaning time of the circuit board area to be cleaned; Divide the area to be cleaned into two local cleaning areas according to a straight line perpendicular to the width; Execute the double cleaning prediction strategy, use the plasma cleaning pen to clean the local cleaning area twice, and predict the double cleaning time of the circuit board area to be cleaned; Compare the single-time duration and the double-time duration, and use the cleaning method corresponding to the smaller duration as the cleaning method for the area to be cleaned; Set the time limit for the plasma cleaning pen to irradiate the chip; Execute the isolated chip cleaning optimization strategy, perform single cleaning and batch cleaning on the isolated chip based on the set limit time, and choose the method with the shortest cleaning time to clean the isolated chip.

2. The closed-loop control method for plasma surface parameters according to claim 1, characterized in that: The chip spacing classification strategy is implemented to classify chips into two categories according to the spacing of chips on the circuit board, including: For any chip on the circuit board: Get the maximum cleaning distance of the plasma cleaning pen The width of the corresponding cleaning coverage area ; Measure the four sides of the chip and the vertical distance between the adjacent chips to obtain , , and ; Compare the four vertical distances to the upper width; like , then the chip is an isolated chip; like , then the chip is a cluster chip.

3. The closed-loop control method of plasma surface parameters according to claim 1, characterized in that: The cleaning time estimation strategy is executed to estimate the cleaning time of the plasma cleaning pen cleaning the area to be cleaned at different cleaning distances, including: Set cleaning distance interval ; From the minimum cleaning distance At the beginning, the distance corresponding to each cleaning distance interval is recorded as the cleaning distance until the cleaning distance is equal to the maximum cleaning distance ; All cleaning distances are combined into an experimental distance set , ,in, is the i-th cleaning distance, is the number of cleaning distances; For any area to be cleaned r, obtain the average thickness of the pollutants in the area to be cleaned ; Traverse each cleaning distance in the experimental distance set, use the plasma cleaning pen to clean the area to be cleaned with uniform thickness of contaminants according to the cleaning distance, and measure the thickness of contaminants in the area to be cleaned in real time; Setting the contaminant thickness threshold ; Compare the real-time measured contaminant thickness of the area to be cleaned with the thickness threshold. , it is determined that the cleaning of the area to be cleaned is completed; The time from the start of cleaning to the end of cleaning the area to be cleaned is recorded as the cleaning time , then the cleaning time of the area to be cleaned r at different cleaning distances is obtained , .

4. The closed-loop control method for plasma surface parameters according to claim 3, characterized in that: The single cleaning prediction strategy is executed, the plasma cleaning pen is used to clean the area to be cleaned once, and the single cleaning time of the area to be cleaned of the circuit board is predicted, including: Obtain the cleaning coverage area corresponding to each cleaning distance in the experimental distance set; Obtaining the width of the area to be cleaned, and comparing the width with the widths of all cleaning coverage areas, and recording the cleaning coverage area with a width equal to the width as a single coverage area; The cleaning distance corresponding to the single coverage area is recorded as the single cleaning distance ; Align the width of the area to be cleaned with the width of the single coverage area, divide the area to be cleaned evenly based on the single coverage area, and divide the area to be cleaned into multiple areas of the same size as the single coverage area: Count the number of the areas mentioned and record it as a single number , ,in, is the length of the area to be cleaned, is the length of the single coverage area; Get the average thickness of the pollutants in the area to be cleaned, and get the cleaning time under the pollutant thickness and single cleaning distance , ; Predict the first cleaning time of the area to be cleaned , ; The first cleaning durations of all the areas to be cleaned are obtained, and the sum is calculated and used as the predicted single cleaning duration of the areas to be cleaned on the circuit board.

5. The closed-loop control method for plasma surface parameters according to claim 4, characterized in that: The double cleaning prediction strategy is implemented, using a plasma cleaning pen to clean the local cleaning area twice, and predicting the double cleaning time of the circuit board area to be cleaned, including: Obtaining the width of the local cleaning area, and comparing the width with the width of all cleaning coverage areas, and recording the cleaning coverage area with a width equal to the width as a double coverage area; The cleaning distance corresponding to the double coverage area is recorded as the double cleaning distance ; Align the width of the local cleaning area with the width of the double coverage area, divide the local cleaning area equally based on the double coverage area, and divide the local cleaning area into multiple areas of equal size to the local cleaning area; Count the number of areas and multiply by 2 to record it as double number : ,in, is the length of the double coverage area; Get the average thickness of the pollutants in the area to be cleaned, and get the cleaning time under the pollutant thickness and double cleaning distance , ; Predict the second cleaning time of the area to be cleaned , ; The second cleaning time of all the areas to be cleaned is obtained, and the sum is calculated and used as the predicted double cleaning time of the areas to be cleaned on the circuit board.

6. The closed-loop control method of plasma surface parameters according to claim 1, characterized in that: The isolated chip cleaning optimization strategy is executed to perform single cleaning and multiple cleaning on the isolated chip based on the set time limit, and the method with the shortest cleaning time is selected to clean the isolated chip, including: The method of single cleaning of isolated chips is: Select multiple points on the bare board area of ​​the circuit board to measure the thickness of the contaminant, calculate the average thickness, and record the result as the bare board contaminant average thickness ; The obtained contaminant thickness is equal to the average thickness of the bare board contaminants and the cleaning time is equal to the limit time The cleaning distance is calculated, and the cleaning coverage area corresponding to the cleaning distance is obtained, which is recorded as the restricted coverage area; calculate ,in, is the marking distance; The cleaning coverage area corresponding to the mark distance is obtained and recorded as the mark coverage area; The length and width of the marked area are recorded as the mark length and marker width ; Traverse each isolated chip and record the length and width of the isolated chip as the isolated length and isolated width ; calculate , Cleaning the head for safety; calculate , For safe cleaning of the total width; The length and width of the restricted coverage area are respectively recorded as the restricted length and limit width ; like and , then the isolated chip is recorded as the target chip; Align the center of the restricted coverage area with the center of the target chip; The width of the restricted coverage area is controlled to be parallel to the width of the target chip, the length of the restricted coverage area is controlled to be parallel to the length of the target chip, and the cleaning time of the target chip is limited.

7. The closed-loop control method of plasma surface parameters according to claim 6, characterized in that: The isolated chip cleaning optimization strategy is executed to perform single cleaning and multiple cleaning on the isolated chip based on the set time limit, and the method with the shortest cleaning time is selected to clean the isolated chip, including: The specific method of the stepwise cleaning is as follows: The length of the control marker coverage area is parallel to the length and width of the target chip; Get the cleaning time corresponding to the contaminant thickness being equal to the average thickness of the bare board contaminants and the cleaning distance being equal to the marked distance, and record it as the third cleaning time , ; calculate , the result is recorded as the number of times ; calculate , The duration of each session; like , then the isolated chip is cleaned once; like , then the isolated chip is cleaned in batches; Control the plasma cleaning pen to clean the bare board area of ​​the circuit board according to the marked coverage area.

8. A closed-loop control system for plasma surface parameters, applied to the closed-loop control method for plasma surface parameters according to claims 1-7, characterized in that: include: Parameter initialization module, used to set the minimum cleaning distance and the maximum cleaning distance, generate rectangular coverage areas under different cleaning distances, and record the width and length of each rectangular coverage area; The chip spacing classification module is used to measure the four vertical distances between each chip and the surrounding chips, and mark the chip category based on the comparison results with the maximum cleaning distance; The pollution thickness sampling module is used to select multiple points in the area to be cleaned to measure the thickness of the pollution, and calculate the average thickness of all the measuring points as the average thickness of the pollution in the area to be cleaned; The cleaning time modeling module is used to perform successive cleaning according to different cleaning distances, detect the thickness of pollutants in real time, and record the time from the start of cleaning to reaching the thickness threshold; A single cleaning prediction module is used to match a cleaning coverage area with the same width as the area to be cleaned, divide the area to be cleaned into multiple equal-sized areas, and calculate the duration of a single cleaning; The double cleaning prediction module is used to divide the area to be cleaned into two local cleaning areas in the vertical direction, divide each local cleaning area, and calculate the double cleaning time of the two times; An isolated chip cleaning module is used to determine and operate a single or multiple cleaning scheme for an isolated chip, including a single cleaning unit and a multiple cleaning unit; The single cleaning unit is used to detect that when the total length of safe cleaning and the total length and width of safe cleaning are both less than the length and width of the restricted coverage area, the isolated chip is centered and a single cleaning is performed; The step-by-step cleaning unit is used to divide the marking area into blocks, calculate the number of steps and the step-by-step cleaning time, and control the plasma pen to complete the step-by-step cleaning in sequence when the step-by-step cleaning time is less than the limit time.

Images