A closed-loop control method and system for plasma surface parameters

Abstract

The present application relates to the technical field of plasma closed loop control, and discloses a kind of closed loop control method and system of plasma surface parameter, comprising: executing chip interval classification strategy, chip is divided into two categories according to the interval of chip on circuit board;Execute cleaning duration estimation strategy, estimate the cleaning duration of plasma cleaning pen cleaning the area to be cleaned under different cleaning distances;Single cleaning prediction strategy is executed, and the single duration of cleaning circuit board area to be cleaned is predicted by using plasma cleaning pen single cleaning area to be cleaned;Double cleaning prediction strategy is executed, and the double duration of cleaning circuit board area to be cleaned is predicted by using plasma cleaning pen twice cleaning local cleaning area;Execute isolated chip cleaning optimization strategy, based on the limit duration set, single cleaning and fractional cleaning are carried out to isolated chip, and the shortest cleaning duration is selected to clean isolated chip, improve the cleaning accuracy of circuit board, while reducing cleaning energy consumption.

Description

Technical Field

[0001] This invention relates to the field of plasma closed-loop control technology, specifically to a closed-loop control method and system for plasma surface parameters. Background Technology

[0002] Plasma cleaning pens, as non-contact micro-contaminant removal tools, offer advantages such as precision, efficiency, and no mechanical damage, making them suitable for cleaning precision chips and bare board areas on circuit boards. By exciting a high-energy particle beam, they can effectively remove organic residues and micro-dust, improving the reliability of subsequent packaging and soldering, and are particularly suitable for surface pretreatment of complex circuit boards.

[0003] Most existing plasma cleaning solutions rely on fixed distances, fixed durations, or manual experience, lacking a precise control mechanism based on the linkage between distance and particle density. In practical applications, particle density varies significantly at different cleaning distances, causing fluctuations in cleaning intensity and duration, easily leading to over- or under-cleaning. Especially in scenarios with inconsistent contaminant thickness, dense chip layouts (clusters), or widely spaced (isolated) chips, traditional cleaning strategies cannot flexibly adjust the cleaning range and duration, affecting cleaning integrity and equipment lifespan. Furthermore, existing methods lack a modeling process based on a dynamic mapping of "cleaning distance—cleaning duration," failing to predict and optimize cleaning duration for specific areas, and lacking an effective "duration limit" judgment and automatic decision-making mechanism. Therefore, with the increasing demands for precision circuit board manufacturing and high-consistency surface treatment, existing technologies can no longer meet the comprehensive requirements of flexible control, intelligent discrimination, and high-quality cleaning.

[0004] This solution 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] This invention provides a closed-loop control method and system for plasma surface parameters, which helps to solve the problems mentioned in the background art.

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

[0007] The circuit board is cleaned vertically using a plasma cleaning pen, where the plasma cleaning pen cleans a corresponding area at each cleaning distance from the circuit board.

[0008] The cleaning coverage area is a rectangular cleaning area on the circuit board by plasma.

[0009] Set the maximum and minimum cleaning distances;

[0010] A chip spacing classification strategy is implemented, which divides the chips into two categories based on the spacing between chips on the circuit board: clustered chips and isolated chips.

[0011] Obtain the rectangular area between any two adjacent cluster chips, and denote it as the area to be cleaned;

[0012] The thickness of contaminants at several measurement points is selected in each area to be cleaned, and the average thickness is calculated as the average thickness of contaminants in each area to be cleaned.

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

[0014] Implement a single-cleaning prediction strategy, use a plasma cleaning pen to clean the area to be cleaned in a single cleaning, and predict the single cleaning time of the area to be cleaned on the circuit board.

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

[0016] A dual-cleaning prediction strategy is implemented, using a plasma cleaning pen to clean the local cleaning area twice, and the duration of the two cleaning cycles for the area to be cleaned on the circuit board is predicted.

[0017] Compare the duration of a single cleaning session with the duration of two cleaning sessions, and select the cleaning method corresponding to the shorter 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] An optimized cleaning strategy for isolated chips is implemented, which involves single-cycle and multi-cycle cleaning of isolated chips based on a set time limit, and the method with the shortest cleaning time is selected.

[0020] Optionally, the chip spacing classification strategy divides the chips into two categories based on the spacing between chips on the circuit board, including:

[0021] For any chip on the circuit board:

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

[0023] Measure the perpendicular distances between the four sides of the chip and adjacent chips to obtain... , , and ;

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

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

[0026] like If so, then the chip is a cluster chip.

[0027] Optionally, the cleaning time estimation strategy, which estimates the cleaning time of the plasma cleaning pen on the area to be cleaned at different cleaning distances, includes:

[0028] Set cleaning interval ;

[0029] From minimum cleaning distance Initially, the distance corresponding to each cleaning interval is recorded as the cleaning distance, until the cleaning distance equals the maximum cleaning distance. ;

[0030] All cleaning distances were combined into an experimental distance set. , ,in, For the i-th cleaning distance, The number of cleaning distances;

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

[0032] Traverse each cleaning distance in the experimental distance set, use a plasma cleaning pen to clean the area to be cleaned with uniform contaminant thickness once according to the cleaning distance, and measure the contaminant thickness of the area to be cleaned in real time.

[0033] Set the thickness threshold for contaminants ;

[0034] The thickness of contaminants in the area to be cleaned is measured in real time and compared with a thickness threshold. If... If the cleaning is completed, then the area to be cleaned is considered finished.

[0035] The time from the start to the end of cleaning the area to be cleaned is recorded as the cleaning time. Then the cleaning time of the area r to be cleaned at different cleaning distances can be obtained. , .

[0036] Optionally, the implementation of the single-cleaning prediction strategy, which uses a plasma cleaning pen to clean the area to be cleaned in a single cycle and predicts the single-cycle duration of cleaning the area to be cleaned on the circuit board, includes:

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

[0038] Obtain the width of the area to be cleaned, and compare the width with the width of all cleaning coverage areas. The cleaning coverage area with a width equal to the width is recorded as a single coverage area.

[0039] The cleaning distance corresponding to a 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, and divide the area to be cleaned into multiple areas of equal size to the single coverage area:

[0041] The number of regions mentioned is counted and recorded as the single quantity. , ,in, Given the length of the area to be cleaned, The length of the area covered in a single instance;

[0042] Obtain the average thickness of contaminants in the area to be cleaned, and determine the cleaning time based on the contaminant thickness and the single cleaning distance. , ;

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

[0044] Obtain the first cleaning time for all areas to be cleaned, calculate and sum them, and use the result as the predicted single cleaning time for the areas to be cleaned on the cleaning circuit board.

[0045] Optionally, the implementation of the dual-cleaning prediction strategy, which involves using a plasma cleaning pen to clean the local cleaning area twice and predicting the duration of the two cleaning cycles for the area to be cleaned on the circuit board, includes:

[0046] Obtain the width of the local cleaning area and compare it with the width of all cleaning coverage areas. The cleaning coverage area with a width equal to the width is recorded 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 into multiple areas of equal size, using the double coverage area as a unit.

[0049] Multiply the number of regions by 2 to get the double count. :

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

[0051] Obtain the average thickness of contaminants in the area to be cleaned, and determine the cleaning time based on the contaminant thickness and the distance between two cleaning passes. , ;

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

[0053] Obtain the second cleaning time for all areas to be cleaned, calculate and sum them, and use the result as the predicted double cleaning time for the areas to be cleaned on the cleaning circuit board.

[0054] Optionally, the isolated chip cleaning optimization strategy involves performing single-cycle and multi-cycle cleaning on the isolated chip based on a set time limit, and selecting the method with the shortest cleaning time to clean the isolated chip, including:

[0055] The method for cleaning isolated chips in a single operation is as follows:

[0056] Multiple points are selected in the bare area of ​​the circuit board to measure the thickness of the contaminants, and the average thickness is calculated. The result is recorded as the average thickness of the bare board contaminants. ;

[0057] The contaminant thickness is equal to the average contaminant thickness on the bare plate, and the cleaning time is equal to the specified time. The cleaning distance is determined, and the cleaning coverage area corresponding to the cleaning distance is obtained, which is denoted as the restricted coverage area;

[0058] calculate ,in, Mark the distance;

[0059] The cleaning coverage area corresponding to the marked distance is recorded as the marked coverage area;

[0060] The length and width of the area covered by the marker are denoted as the marker length. and mark width ;

[0061] Iterate through each isolated chip, and record the length and width of the isolated chip as the isolated length. and isolated width ;

[0062] calculate , For safe cleaning of the total length;

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

[0064] The length and width of the restricted coverage area are denoted as the restriction length. and restrictions ;

[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 control and restriction coverage area is parallel to the width of the target chip, the length of the control and restriction coverage area is parallel to the length of the target chip, and the cleaning time of the target chip is limited.

[0068] Optionally, the isolated chip cleaning optimization strategy involves performing single-cycle and multi-cycle cleaning on the isolated chip based on a set time limit, and selecting the method with the shortest cleaning time to clean the isolated chip, including:

[0069] The specific method of multiple cleaning steps is as follows:

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

[0071] The cleaning time corresponding to a contaminant thickness equal to the average contaminant thickness on the bare plate and a cleaning distance equal to the marked distance is recorded as the third cleaning time. , ;

[0072] calculate The result is recorded as the number of fractions. ;

[0073] calculate , The duration is divided into several sessions;

[0074] like Then, isolated chips are cleaned in a single operation.

[0075] like Then, isolated chips are cleaned in stages;

[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 includes:

[0078] The parameter initialization module is used to set the minimum and maximum cleaning distances, generate rectangular coverage areas at different cleaning distances, and record the width and length of each rectangular coverage area.

[0079] The chip spacing classification module measures the distance between each chip and surrounding chips in four perpendicular directions, and classifies the chips based on the comparison with the maximum cleaning distance.

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

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

[0082] The 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 equally sized areas, and calculate the single cleaning duration.

[0083] The dual-cleaning prediction module is used to divide the area to be cleaned into two local cleaning areas along the vertical direction, divide each local cleaning area, and calculate the duration of the two cleaning cycles.

[0084] An isolated chip cleaning module is used to determine and operate a single or multi-stage cleaning scheme for isolated chips, including a single cleaning unit and a multi-stage cleaning unit.

[0085] The single-cleaning unit is used to detect when the total length and width of the safe cleaning are both smaller than the length and width of the restricted coverage area, then center-align the isolated chip and perform a single cleaning.

[0086] The segmented cleaning unit is used to divide the area into blocks according to the marked area, calculate the number of segments and the duration of each segment, and control the plasma pen to complete the segmented cleaning sequentially when the duration of each segment is less than the limit duration.

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

[0088] 1. This closed-loop control method for plasma surface parameters measures the vertical distances in four directions between each chip on the circuit board and its surrounding chips. This distance is compared to the coverage width of the plasma cleaning pen at the maximum cleaning distance. This distinguishes between isolated chips and clustered chips, providing fundamental support for differentiated subsequent regional cleaning strategies and avoiding inefficient or over-cleaning issues caused by a one-size-fits-all approach. It avoids unnecessary repetitive judgment logic, has clear operation steps, is suitable for automated identification processes on large-scale circuit boards, and facilitates modular integration.

[0089] 2. The closed-loop control method for plasma surface parameters constructs a dataset containing multiple experimental distances by setting a step interval between the minimum and maximum cleaning distances. At each distance, the actual cleaning time required to reach the cleaning threshold 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 trials and calculations. It provides input data for single-cleaning and multi-cleaning time prediction modules, improving the overall response speed and adaptability of the closed-loop control system.

[0090] 3. The closed-loop control method for plasma surface parameters determines the appropriate single-cleaning distance by comparing the matching relationship between the width of the area to be cleaned and the width of the coverage area at various cleaning distances. It then divides the entire area into several equally divided regions, achieving a standardized processing method for time prediction. This allows for rapid calculation of the total cleaning time without increasing the measurement burden, providing a predictable time reference for the control system. By using existing contamination thickness and duration estimation data, cleaning scheduling can be completed without real-time and repeated monitoring of contamination changes, reducing sensor load and improving the overall system's time control accuracy and scheduling efficiency.

[0091] 4. The closed-loop control method for plasma surface parameters shows that when the cleaning pen is close to the circuit board, the plasma particle density is higher and the effect is more concentrated, allowing for faster removal of contaminants per unit time. However, when the cleaning distance is greater, the particle density decreases, and although the coverage area expands, the cleaning speed slows down, resulting in a longer total cleaning time. Based on this physical characteristic, the area to be cleaned is divided into two local areas along the vertical direction, and each area is treated with two cleaning operations with narrower coverage widths and closer distances. Compared to a single cleaning method using long-distance coverage, this method can accelerate the removal of contaminants in each local area while maintaining coverage integrity, thus effectively shortening the overall cleaning time. However, the number of cleaning operations increases, so the final cleaning method needs to be determined by considering the combined duration of a single operation and the duration of two operations.

[0092] 5. The closed-loop control method for plasma surface parameters considers the potential thermal, electrical, or structural effects of direct irradiation of the chip body by the plasma cleaning pen when cleaning isolated chips. Therefore, a limited irradiation time is set to ensure that the cleaning operation is completed within a safe range. The operation is performed by constructing a cleaning frame around the chip. A marked distance is used as the standard cleaning distance for the bare chip area, ensuring moderate particle density and high coverage accuracy. Then, based on the marked coverage area corresponding to this marked distance, the maximum safe cleaning range achievable in a single operation is calculated by matching it with the size expansion value of the target chip, i.e., the total safe cleaning length and total safe cleaning width. If the expanded cleaning frame size falls within the set limited coverage area, it is considered to meet the single-operation cleaning conditions, and a one-time cleaning operation is performed using a center-aligned method. This method can efficiently remove surrounding contaminants without damaging the chip structure, avoiding repetitive path planning and batch control command generation, and has advantages such as short execution path, fast response speed, and clear parameter control.

[0093] 6. This closed-loop control method for plasma surface parameters provides a phased cleaning scheme implemented by controlling variables when an isolated chip, due to its excessive size or complex structural edges, cannot be cleaned in one go within a set time limit. This scheme does not directly irradiate the chip body; instead, it uses the bare area around the chip as the cleaning target and uses the cleaning coverage area corresponding to the "marking distance" (i.e., the marked coverage area) as the basic unit to control the range and particle density of local cleaning. By fixing the cleaning parameters and adjusting only the spatial size of the target cleaning area, it ensures that each cleaning is performed under the same physical conditions, effectively avoiding instability caused by frequent adjustments to distance or energy parameters. Based on the proportional relationship between the size of the limited coverage area and the marked coverage area, the number of cleaning phases required is calculated, and the total phase duration is estimated by combining the cleaning time of a single area. By comparing this result with the time limit, it intelligently determines whether to adopt the phased cleaning method, which can significantly improve the flexibility and control accuracy of cleaning the chip's surrounding area. Attached Figure Description

[0094] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0095] Figure 2 This is a schematic diagram of the system modules 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 This is a schematic diagram illustrating the restricted coverage area of ​​the present invention. Detailed Implementation

[0098] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort 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 generate high-energy plasma by exciting gas. The active particles in the plasma then physically bombard, chemically react with, and ultraviolet-degrade contaminants on the circuit board surface, achieving complete removal of these contaminants. They offer advantages such as non-contact operation, localized control, and adaptability to complex structures, making them particularly suitable for micro-contamination treatment and surface activation of delicate circuit boards.

[0101] Because plasma has a strong energy output and the ability to bombard active particles, prolonged direct contact with the chip can easily cause problems such as localized overheating, corrosion damage, and charge accumulation, and in severe cases, even device failure. Therefore, when cleaning circuit boards with plasma, it is necessary to control the cleaning distance and duration, avoid direct irradiation of the chip, or adopt a short-time, multi-stage processing strategy to ensure the safety and reliability of the chip structure and function.

[0102] The circuit board is cleaned vertically using a plasma cleaning pen, where the plasma cleaning pen cleans a corresponding area at each cleaning distance from the circuit board.

[0103] The cleaning coverage area is a rectangular cleaning area on the circuit board by plasma.

[0104] Set the maximum and minimum cleaning distances;

[0105] A chip spacing classification strategy is implemented, dividing chips into two categories based on their spacing on the circuit board: clustered chips and isolated chips, including:

[0106] There are a total of 3 chips on the circuit board: chip A, chip B and chip C. The length × width dimensions of chip A and chip B are 5mm × 5mm.

[0107] In this embodiment, the dimensions of all chips are defined by the boundaries of the pins around the chip, meaning that the chip dimensions include the length of the pins.

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

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

[0110] Chip A center: (10mm, 10mm);

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

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

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

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

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

[0116] Both chip B and chip A are cluster chips;

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

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

[0119] The thickness of contaminants at several measurement points is selected in each area to be cleaned, and the average thickness is calculated as the average thickness of contaminants in each area to be cleaned.

[0120] In this embodiment, the thickness of the contaminant is measured using existing elliptic deflection technology, as detailed below:

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

[0122] Applications: Suitable for measuring transparent or semi-transparent contamination layers ranging from a few nanometers to a few micrometers.

[0123] Advantages: Non-contact, high precision, and can monitor online in real time.

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

[0125] Set cleaning interval ;

[0126] From minimum cleaning distance Initially, the distance corresponding to each cleaning interval is recorded as the cleaning distance, until the cleaning distance equals the maximum cleaning distance. ;

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

[0128] n=4;

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

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

[0131] Set the thickness threshold for contaminants ;

[0132] The thickness of contaminants in the area to be cleaned is measured in real time and compared with a thickness threshold. If... If the cleaning is completed, then the area to be cleaned is considered finished.

[0133] Experimental results (cleaning time for 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, the cleaning time measured during the actual experiment is the cleaning time measured by cleaning the area to be cleaned once using a plasma cleaning pen.

[0140] A single-cycle cleaning prediction strategy is implemented, using a plasma cleaning pen to clean the area to be cleaned in a single cycle, predicting the duration of a single cycle for cleaning 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 1.2 mm and the length is 2.4 mm. The width is compared with the width of all cleaning coverage areas. The cleaning coverage area with a width equal to the width is recorded as a single coverage area.

[0143] The coverage area dimensions corresponding to an 8mm cleaning distance are: 1.2 mm wide and 0.8 mm long.

[0144] The cleaning distance corresponding to a 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, and divide the area to be cleaned into multiple areas of equal size to the single coverage area:

[0146] The number of regions mentioned is counted and recorded as the single quantity. , ,in, Given the length of the area to be cleaned, The length of the area covered in a single instance;

[0147] Obtain cleaning time based on contaminant thickness and single cleaning distance. ;

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

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

[0150] A dual-cleaning prediction strategy is implemented, using a plasma cleaning pen to clean the localized cleaning area twice, predicting the duration of each cleaning cycle for the area to be cleaned on the circuit board, including:

[0151] The width of the local cleaning area is 0.6 mm, and the length of the local cleaning area 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 double coverage area.

[0152] When the cleaning distance is 4mm, the dimensions of the double-coverage area are: width 0.6mm and length 0.6mm.

[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 into multiple areas of equal size, using the double coverage area as a unit.

[0155] Multiply the number of regions by 2 to get the double count. :

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

[0157] Obtain the cleaning time under the specified contaminant thickness and double cleaning distance. ;

[0158] Predict the duration of two cleaning sessions for the area to be cleaned. , .

[0159] By comparing the duration of a single cleaning session with the duration of two cleaning sessions, the cleaning method corresponding to the duration of a single cleaning session is selected as the cleaning method for the area to be cleaned.

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

[0161] An optimized cleaning strategy for isolated chips is implemented, involving single-cycle and multi-cycle cleaning of isolated chips based on set time limits, and selecting the method with the shortest cleaning time. This includes:

[0162] The method for cleaning isolated chips in a single operation is as follows:

[0163] Multiple points are selected in the bare area of ​​the circuit board to measure the thickness of the contaminants, and the average thickness is calculated. The result is recorded as the average thickness of the bare board contaminants. ;

[0164] The contaminant thickness is equal to the average contaminant thickness on the bare plate, and the cleaning time is equal to the specified time. The cleaning distance is determined, and the cleaning coverage area corresponding to the cleaning distance is obtained, which is denoted as the restricted coverage area;

[0165] ;

[0166] The dimensions of chip C are 0.3mm x 1mm (length x width).

[0167] In this embodiment, refer to Figure 4 The coverage area is limited to the cleaning area corresponding to a 10mm cleaning distance, with a length of 1.3mm and a width of 2mm.

[0168] calculate ,in, Mark the distance;

[0169] The cleaning coverage area corresponding to the marked distance is recorded as the marked coverage area;

[0170] The length and width of the area covered by the marker are denoted as the marker length. and mark width ;

[0171] Iterate through each isolated chip, and record the length and width of the isolated chip as the isolated length. and isolated width ;

[0172] calculate , For safe cleaning of the total length;

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

[0174] The length and width of the restricted coverage area are denoted as the restriction length. and restrictions ;

[0175] and Then, the isolated chip C is denoted 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 control and restriction coverage area is parallel to the width of the target chip, the length of the control and restriction coverage area is parallel to the length of the target chip, and the cleaning time of the target chip is limited.

[0178] The specific method of multiple cleaning steps is as follows:

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

[0180] The cleaning time corresponding to a contaminant thickness equal to the average contaminant thickness on the bare plate and a cleaning distance equal to the marked distance is recorded as the third cleaning time. , ;

[0181] calculate The result is recorded as the number of fractions. The reason for adding 4 here is that the bare board areas at the four corners of the target chip may not have been cleaned. Therefore, each corner contact bare board area is cleaned again with a plasma cleaning pen. However, in this embodiment, there are no uncleaned corner contact bare board areas, so there is no need to add 4.

[0182] calculate , The duration is divided into several sessions;

[0183] like Then, isolated chips are cleaned in a single operation.

[0184] Controlling the plasma cleaning pen to clean the bare board area of ​​the circuit board according to the marked coverage area simplifies the process of determining cleaning parameters and expands the applicability of the strategy. 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 uniformly cleaned without needing 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 is an important basis for subsequent judgment of the cleaning capability 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] The parameter initialization module is used to set the minimum and maximum cleaning distances, generate rectangular coverage areas at different cleaning distances, and record the width and length of each rectangular coverage area.

[0187] The chip spacing classification module measures the distance between each chip and surrounding chips in four perpendicular directions, and classifies the chips based on the comparison with the maximum cleaning distance.

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

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

[0190] The 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 equally sized areas, and calculate the single cleaning duration.

[0191] The dual-cleaning prediction module is used to divide the area to be cleaned into two local cleaning areas along the vertical direction, divide each local cleaning area, and calculate the duration of the two cleaning cycles.

[0192] An isolated chip cleaning module is used to determine and operate a single or multi-stage cleaning scheme for isolated chips, including a single cleaning unit and a multi-stage cleaning unit.

[0193] The single-cleaning unit is used to detect when the total length and width of the safe cleaning are both smaller than the length and width of the restricted coverage area, then center-align the isolated chip and perform a single cleaning.

[0194] The segmented cleaning unit is used to divide the area into blocks according to the marked area, calculate the number of segments and the duration of each segment, and control the plasma pen to complete the segmented cleaning sequentially when the duration of each segment is less than the limit duration.

[0195] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0196] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A closed-loop control method for plasma surface parameters, characterized in that, include: The circuit board is cleaned vertically using a plasma cleaning pen, where the plasma cleaning pen covers a corresponding area at each cleaning distance from the circuit board. The cleaning coverage area is a rectangular cleaning area on the circuit board by plasma. Set the maximum and minimum cleaning distances; A chip spacing classification strategy is implemented, which divides the chips into two categories based on the spacing between chips on the circuit board: clustered chips and isolated chips. Obtain the rectangular area between any two adjacent cluster chips, and denote it as the area to be cleaned; The thickness of contaminants at several measurement points is selected in each area to be cleaned, and the average thickness is calculated as the average thickness of contaminants in each area to be cleaned. Implement a cleaning time estimation strategy to estimate the cleaning time of the plasma cleaning pen on the area to be cleaned at different cleaning distances; Implement a single-cleaning prediction strategy, use a plasma cleaning pen to clean the area to be cleaned in a single cleaning, and predict the single cleaning time of the area to be cleaned on the circuit board. Divide the area to be cleaned into two local cleaning areas along a straight line perpendicular to the width; A dual-cleaning prediction strategy is implemented, using a plasma cleaning pen to clean the local cleaning area twice, and the duration of the two cleaning cycles for the area to be cleaned on the circuit board is predicted. Compare the duration of a single cleaning session with the duration of two cleaning sessions, and select the cleaning method corresponding to the shorter duration as the cleaning method for the area to be cleaned. Set the time limit for the plasma cleaning pen to irradiate the chip; An optimized cleaning strategy for isolated chips is implemented, which involves single-cycle and multi-cycle cleaning of isolated chips based on a set time limit, and the method with the shortest cleaning time is selected.

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

3. The closed-loop control method for plasma surface parameters according to claim 1, characterized in that, The cleaning time estimation strategy estimates the cleaning time of the plasma cleaning pen on the area to be cleaned at different cleaning distances, including: Set cleaning interval ; From minimum cleaning distance Initially, the distance corresponding to each cleaning interval is recorded as the cleaning distance, until the cleaning distance equals the maximum cleaning distance. ; All cleaning distances were combined into an experimental distance set. , ,in, For the i-th cleaning distance, The number of cleaning distances; For any area r to be cleaned, obtain the average thickness of contaminants in the area to be cleaned. ; Traverse each cleaning distance in the experimental distance set, use a plasma cleaning pen to clean the area to be cleaned with uniform contaminant thickness once according to the cleaning distance, and measure the contaminant thickness of the area to be cleaned in real time. Set the thickness threshold for contaminants ; The thickness of contaminants in the area to be cleaned is measured in real time and compared with a thickness threshold. If... If the cleaning is completed, then the area to be cleaned is considered finished. The time from the start 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 can be obtained. , .

4. The closed-loop control method for plasma surface parameters according to claim 3, characterized in that, The single-cycle cleaning prediction strategy, which uses a plasma cleaning pen to clean the area to be cleaned in a single cycle, predicts the duration of a single cleaning cycle for the circuit board area to be cleaned, including: Obtain the cleaning coverage area corresponding to each cleaning distance in the experimental distance set; Obtain the width of the area to be cleaned, and compare the width with the width of all cleaning coverage areas. The cleaning coverage area with a width equal to the width is recorded as a single coverage area. The cleaning distance corresponding to a 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, and divide the area to be cleaned into multiple areas of equal size to the single coverage area: The number of regions is counted and recorded as the single quantity. , ,in, Given the length of the area to be cleaned, The length of the area covered in a single instance; Obtain the average thickness of contaminants in the area to be cleaned, and determine the cleaning time based on the contaminant thickness and the single cleaning distance. , ; Predict the first cleaning time for the area to be cleaned. , ; Obtain the first cleaning time for all areas to be cleaned, calculate and sum them, and use the result as the predicted single cleaning time for the areas to be cleaned on the cleaning circuit board.

5. The closed-loop control method for plasma surface parameters according to claim 4, characterized in that, The dual-cleaning prediction strategy involves using a plasma cleaning pen to clean a localized cleaning area twice, predicting the duration of each cleaning cycle for the area to be cleaned on the circuit board. This includes: Obtain the width of the local cleaning area and compare it with the width of all cleaning coverage areas. The cleaning coverage area with a width equal to the width is recorded 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 into multiple areas of equal size, using the double coverage area as a unit. Multiply the number of regions mentioned above by 2, and record this as the double count. : ,in, The length of the double-coverage area; Obtain the average thickness of contaminants in the area to be cleaned, and determine the cleaning time based on the contaminant thickness and the distance between two cleaning passes. , ; Predict the second cleaning time for the area to be cleaned. , ; Obtain the second cleaning time for all areas to be cleaned, calculate and sum them, and use the result as the predicted double cleaning time for the areas to be cleaned on the cleaning circuit board.

6. The closed-loop control method for plasma surface parameters according to claim 1, characterized in that, The isolated chip cleaning optimization strategy involves performing single-cycle and multi-cycle cleaning on isolated chips based on a set time limit, and selecting the method with the shortest cleaning time. This includes: The method for cleaning isolated chips in a single operation is as follows: Multiple points are selected in the bare area of ​​the circuit board to measure the thickness of the contaminants, and the average thickness is calculated. The result is recorded as the average thickness of the bare board contaminants. ; The contaminant thickness is equal to the average contaminant thickness on the bare plate, and the cleaning time is equal to the specified time. The cleaning distance is determined, and the cleaning coverage area corresponding to the cleaning distance is obtained, which is denoted as the restricted coverage area; calculate ,in, Mark the distance; The cleaning coverage area corresponding to the marked distance is recorded as the marked coverage area; The length and width of the area covered by the marker are respectively denoted as the marker length. and mark width ; Iterate through each isolated chip, and record the length and width of the isolated chip as the isolated length. and isolated width ; calculate , For safe cleaning of the total length; calculate , For safe cleaning of the total width; The length and width of the restricted coverage area are denoted as the restriction length. and restrictions ; 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 control and restriction coverage area is parallel to the width of the target chip, the length of the control and restriction coverage area is parallel to the length of the target chip, and the cleaning time of the target chip is limited.

7. The closed-loop control method for plasma surface parameters according to claim 6, characterized in that, The isolated chip cleaning optimization strategy involves performing single-cycle and multi-cycle cleaning on isolated chips based on a set time limit, and selecting the method with the shortest cleaning time. This includes: The specific method of multiple cleaning steps is as follows: The length of the control mark coverage area is parallel to the length and width of the target chip, respectively; The cleaning time corresponding to a contaminant thickness equal to the average contaminant thickness on the bare plate and a cleaning distance equal to the marked distance is recorded as the third cleaning time. , ; calculate The result is recorded as the number of fractions. ; calculate , The duration is divided into several sessions; like Then, isolated chips are cleaned in a single operation. like The isolated chip is then cleaned in stages. 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 any one of claims 1-7, characterized in that, include: The parameter initialization module is used to set the minimum and maximum cleaning distances, generate rectangular coverage areas at different cleaning distances, and record the width and length of each rectangular coverage area. The chip spacing classification module measures the distance between each chip and surrounding chips in four perpendicular directions, and classifies the chips based on the comparison with the maximum cleaning distance. The contamination thickness sampling module is used to select multiple points in the area to be cleaned to measure the contamination thickness, and calculate the average thickness of all measuring points as the average contamination thickness of the area to be cleaned. The cleaning time modeling module is used to perform sequential cleaning according to different cleaning distances, detect the thickness of contaminants in real time, and record the time from the start of cleaning to reaching the thickness threshold. The 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 equally sized areas, and calculate the single cleaning duration. The dual-cleaning prediction module is used to divide the area to be cleaned into two local cleaning areas along the vertical direction, divide each local cleaning area, and calculate the duration of the two cleaning cycles. An isolated chip cleaning module is used to determine and operate a single or multi-stage cleaning scheme for isolated chips, including a single cleaning unit and a multi-stage cleaning unit. The single-cleaning unit is used to detect when the total length and width of the safe cleaning are both smaller than the length and width of the restricted coverage area, then center-align the isolated chip and perform a single cleaning. The segmented cleaning unit is used to divide the area into blocks according to the marked area, calculate the number of segments and the duration of each segment, and control the plasma pen to complete the segmented cleaning sequentially when the duration of each segment is less than the limit duration.

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