Circuit board etching solution concentration control method and system

Abstract

The invention relates to the technical field of integrated circuit manufacturing, in particular to a circuit board etching solution concentration control method and system, and the method comprises the following steps: monitoring a circuit board etching solution in real time, obtaining a conductivity reading and a temperature reading, comparing a preset conductivity range and a preset temperature range of a circuit board etching process, and verifying and screening data. And establishing an effective etching parameter set. According to the invention, the conductivity and temperature values of the circuit board etching liquid are monitored in real time, an effective etching parameter set is established, data verification and screening are realized, the monitoring precision is improved, the interference of data abnormity is reduced, and the reliability of etching liquid concentration estimation is ensured; the concentration is calculated and corrected in real time by using a conductivity and etching agent concentration reference relation curve, correction and probability analysis are performed in combination with the prior aging characteristics of the etching solution and the drift probability of the sensor, and the accuracy and stability of concentration estimation are enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit manufacturing, and in particular to a method and system for controlling the concentration of etching liquid for a circuit board. Background Art

[0002] The field of integrated circuit manufacturing technology is one of the core technology areas in the electronics industry. This field covers the use of microelectronics processing technology to manufacture precision structures at the micron or even nanometer scale on semiconductor wafers, substrates, and related base materials. Specifically, it includes multiple key steps such as photolithography, thin film deposition, etching, doping diffusion, chemical mechanical polishing (CMP), cleaning, and packaging testing to manufacture integrated circuit chips or electronic components with specific electrical functions.

[0003] Existing technologies in the integrated circuit manufacturing process primarily rely on periodic spot checks to manage etching solution concentration. This lacks real-time measurement of parameters such as conductivity and temperature, making it difficult to promptly and effectively identify and correct abnormal concentration fluctuations caused by sensor drift or etching solution aging. This, in turn, makes it difficult to accurately assess the real-time reactivity of the etching solution under actual operating conditions. Therefore, improvements are needed. Summary of the Invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a method and system for controlling the concentration of etching solution for a circuit board.

[0005] In order to achieve the above object, the present invention adopts the following technical solution, a method for controlling the concentration of a circuit board etching solution, comprising the following steps: Monitor the PCB etching solution in real time, obtain conductivity and temperature readings, compare them with the preset conductivity and temperature ranges of the PCB etching process, verify and filter the data, and establish an effective etching parameter set; Based on the effective etching parameter set, calling the conductivity value and combining it with a reference relationship curve between conductivity and etchant concentration to infer the etchant concentration and generate an etchant concentration estimation result; based on the etchant concentration estimation result, combined with the prior aging characteristics of the circuit board etching solution and the inherent drift probability of the sensor, establish an etchant concentration probability distribution; Based on the probability distribution of the etching agent concentration and the temperature value in the effective etching parameter set, the reaction activity of the current solution is evaluated to obtain the current activity of the etching solution; based on the current activity of the etching solution, the degree of solution performance attenuation is determined to obtain a comprehensive performance probability point set of the etching solution; Based on the comprehensive performance probability point set of the etching solution, the performance probability point is compared with the minimum acceptable performance threshold and the optimal performance target interval for circuit board etching, the deviation state of the performance probability point and the threshold or interval is identified, and an identification result of the risk point exceeding the threshold is obtained. Based on the identification result of the risk point exceeding the threshold, the risk level of the circuit board manufacturing process is matched, and an etching process deviation warning code is generated.

[0006] Preferably, the steps of obtaining the effective etching parameter set are: Collect the conductivity readings and temperature readings of the circuit board etching solution, match the time tags to synchronize the conductivity readings and temperature readings point by point, and generate a synchronized pairing group of conductivity readings and temperature readings; Based on the synchronous pairing group of conductivity readings and temperature readings, and comparing the preset conductivity range and temperature range of the circuit board etching process, each group of conductivity readings and temperature readings in the synchronous pairing group is interval-checked item by item, and the synchronous pairing groups that fall within the preset conductivity range and temperature range are screened to obtain the screened pairing groups that meet the preset process conditions; Based on the screened paired groups that meet the preset process conditions, all conductivity readings and temperature readings in the screened paired groups are extracted and packaged into structured records to obtain an effective etching parameter set.

[0007] Preferably, the steps of obtaining the etching agent concentration estimation result are: Based on the valid etching parameter set, the conductivity value field in each record is extracted, and after reading the corresponding numerical value, linear interpolation is performed to fill the missing points to generate a continuous and complete conductivity value sequence, and each conductivity value is bound to its own timestamp and temperature fields to generate a conductivity reading record set containing the conductivity value, timestamp, and temperature fields; According to the conductivity reading record set, a calibrated conductivity-etchant concentration reference relationship curve is called, each conductivity value is used as an input value to look up a table to obtain a concentration output node, if the conductivity value does not directly hit the reference relationship node, quadratic interpolation is performed between adjacent nodes to fit and generate a corresponding concentration value, the obtained concentration value is merged with the corresponding timestamp and temperature field and written into a concentration fitting result record set, thereby generating an etchant concentration fitting result set; Based on the set of etchant concentration fitting results, outlier detection is performed on the concentration values ​​in all records, and a 3-times standard deviation screening mechanism is used to exclude concentration anomalies that deviate from the mean. At the same time, the temperature field in the timestamp corresponding to the fitted concentration value is checked to see if it falls within the effective temperature fluctuation range. Only record entries that meet the conditions are retained, and the concentration values ​​that pass the check are output in chronological order as the final concentration estimation sequence to generate the etchant concentration estimation result.

[0008] Preferably, the steps for obtaining the etching agent concentration probability distribution are: Based on the etchant concentration estimation result, extracting the aging days and relative humidity value of each record, calling the sensor number matching to obtain the maximum drift in the last 30 days and recording it as the drift intensity value, dividing the stirring speed by the reference speed to obtain the stirring ratio, dividing the aging days by the maximum aging days to obtain the normalized aging factor, integrating the normalized aging factor, the relative humidity value, the drift intensity value and the stirring ratio to generate a correction parameter set; Calculating an etchant concentration correction value based on the correction parameter set; Based on the etchant concentration correction value, all etchant concentration correction values ​​are numerically segmented with a fixed interval starting step of 0.1 mol / L. The total number of entries of the etchant concentration correction value contained in each segmented interval is counted in turn, and the ratio of the number of entries in each segment to the total number of entries is calculated as the concentration probability value of the interval. Each concentration segmented interval is paired with the corresponding concentration probability value one by one and output as an ordered concentration-probability combination sequence to generate an etchant concentration probability distribution.

[0009] Preferably, the step of obtaining the current activity of the etching solution is: Based on the etching agent concentration probability distribution, all etching agent concentration intervals and corresponding concentration probability values ​​are extracted, each etching agent concentration interval is used as an index parameter, and the temperature value corresponding to the same timestamp in the valid etching parameter set is matched. A triple set consisting of the etching agent concentration interval, the concentration probability value and the corresponding temperature value is constructed to generate a matching record set; Based on the matching record set, each combination of concentration value and temperature value is read one by one, and a matching or interval-fitted standard etching rate value is searched in a standard copper foil etching rate reference table, and the found standard etching rate value is combined with the corresponding concentration probability value in the original triplet into a four-tuple record to obtain a concentration-temperature-probability-rate matching combination set; Based on the concentration-temperature-probability-rate matching combination set, the probability average level of the rate values ​​in all combinations is calculated, and the weighted average rate value is extracted as the etching reaction ability performance value of the current solution under the current concentration and temperature conditions to generate the current etching solution activity.

[0010] Preferably, the steps for obtaining the etching solution comprehensive performance probability point set are: Based on the current activity of the etching solution, extracting a standard interval value corresponding to the current activity of the etching solution, and synchronously reading the number of processed circuit board batches in the current batch statistical record, forming a one-to-one correspondence between the activity interval and the batch number, establishing an activity-batch number comparison set under the condition of consistent time tags, and generating an etching activity batch comparison set; Calculating the etching solution efficiency decay ratio of each group based on the etching activity batch control set; It is determined in turn whether each etching solution efficiency attenuation ratio exceeds a set attenuation identification threshold, and the corresponding etching solution activity is extracted from the records greater than the attenuation identification threshold. The occurrence probability points of the etching solution activity in the time dimension are constructed to generate a comprehensive etching solution efficiency probability point set.

[0011] Preferably, the steps for obtaining the identification result of the risk point exceeding the threshold are: Based on the comprehensive performance probability point set of the etching solution, each etching solution performance probability point is merged with the minimum acceptable performance threshold of the circuit board etching and the two end points of the optimal performance target interval, and each probability point, the minimum threshold, the lower limit and the upper limit of the optimal target interval are bound into a four-element relationship to generate a performance reference comparison set; Calculating a deviation index for each efficacy probability point based on the efficacy reference comparison set; Based on the deviation index, each deviation index is compared with the deviation index, the efficiency probability point number where the deviation index is greater than the deviation judgment threshold is marked, and the time label and efficiency value are output as the record result to generate the risk point identification result exceeding the threshold.

[0012] Preferably, the steps for obtaining the etching process deviation warning code are: Based on the above-threshold risk point identification results, the time tag, concentration value, temperature value, and deviation index value corresponding to each identified efficiency probability point are extracted, and the etching condition combinations corresponding to the concentration values ​​and temperature values ​​are read one by one to generate an etching condition deviation feature set. Based on the etching condition deviation feature set, the concentration value and temperature value combination of each record is mapped to the circuit board manufacturing process risk level comparison table, the matching interval or adjacent level is searched and the risk level code is marked, all records are bound to the risk level code that matches them, and a process risk level matching result is generated; Based on the process risk level matching results, corresponding warning information templates are set according to different risk levels, and text warning content with time tags and risk level identifiers is constructed. The content is then uniformly encoded into an output identifier of a standard structure to generate an etching process deviation warning code.

[0013] The present invention provides an etching solution concentration control system, comprising: Parameter acquisition module: monitors the PCB etching solution in real time, obtains conductivity and temperature readings, verifies and filters the data against the preset conductivity and temperature ranges of the PCB etching process, and establishes a valid etching parameter set; Concentration estimation module: Based on the effective etching parameter set, the conductivity value is called and combined with the conductivity and etchant concentration reference curve to infer the etchant concentration and generate an etchant concentration estimation result. Based on the etchant concentration estimation result, combined with the prior aging characteristics of the circuit board etching solution and the inherent drift probability of the sensor, an etchant concentration probability distribution is established; Activity analysis module: based on the probability distribution of the etching agent concentration and the temperature value in the effective etching parameter set, evaluates the reaction activity of the current solution, obtains the current activity of the etching solution, determines the degree of solution performance attenuation based on the current activity of the etching solution, and obtains the probability point set of the comprehensive performance of the etching solution; Deviation warning module: Based on the comprehensive performance probability point set of the etching solution, the performance probability point is compared with the minimum acceptable performance threshold and the optimal performance target interval of the circuit board etching, the deviation state of the performance probability point and the threshold or interval is identified, and the identification result of the risk point exceeding the threshold is obtained. Based on the identification result of the risk point exceeding the threshold, the circuit board manufacturing process risk level is matched and an etching process deviation warning code is generated.

[0014] Compared with the prior art, the advantages and positive effects of the present invention are: The present invention establishes an effective etching parameter set by real-time monitoring of the conductivity and temperature values ​​of the circuit board etching solution, realizes data verification and screening, improves monitoring accuracy, reduces interference from data anomalies, and ensures the reliability of etching solution concentration estimation; uses a conductivity-etchant concentration reference relationship curve to calculate and correct the concentration in real time, and combines the prior aging characteristics of the etching solution and the drift probability of the sensor to perform correction and probability analysis, thereby enhancing the accuracy and stability of the concentration estimation; evaluates the real-time reaction activity of the etching solution through the etchant concentration probability and temperature value, captures the real-time state changes during the etching process, and further accurately determines the degree of attenuation of the etching solution's efficiency based on the real-time activity, which is conducive to foreseeing and mastering the performance fluctuations of the etching solution in advance; based on the comparison of the efficiency attenuation probability point with the minimum efficiency threshold and the optimal target range, the efficiency state is clearly quantified and potential risk points are quickly identified. After matching the manufacturing process risk level, a targeted etching process deviation warning code is dynamically generated, and proactive intervention and adjustment suggestions are provided in a timely manner, thereby reducing the risk probability of the circuit board etching process and improving the process stability and product consistency during the circuit board manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the steps of the present invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] See also Figure 1 The present invention provides a technical solution, a method for controlling the concentration of a circuit board etching solution, comprising the following steps: Monitor the PCB etching solution in real time, obtain conductivity and temperature readings, compare them with the preset conductivity and temperature ranges of the PCB etching process, verify and filter the data, and establish an effective etching parameter set; Based on the effective etching parameter set, the conductivity value is called and combined with the conductivity and etchant concentration benchmark curve to infer the etchant concentration and generate an etchant concentration estimation result. Based on the etchant concentration estimation result, combined with the prior aging characteristics of the circuit board etching solution and the inherent drift probability of the sensor, the etchant concentration probability distribution is established; Based on the probability distribution of the etchant concentration and the temperature value in the effective etching parameter set, the reaction activity of the current solution is evaluated to obtain the current activity of the etching solution. Based on the current activity of the etching solution, the degree of solution performance attenuation is determined to obtain the probability point set of the comprehensive performance of the etching solution. Based on the comprehensive performance probability point set of the etching solution, the performance probability point is compared with the minimum acceptable performance threshold and the optimal performance target range of the circuit board etching, and the deviation state of the performance probability point and the threshold or range is identified to obtain the identification result of the risk point exceeding the threshold. Based on the identification result of the risk point exceeding the threshold, the risk level of the circuit board manufacturing process is matched and an etching process deviation warning code is generated.

[0018] The steps to obtain a valid etching parameter set are: Collect the conductivity readings and temperature readings of the circuit board etching solution, match the time tags to synchronize the conductivity readings and temperature readings point by point, and generate a synchronized pairing group of conductivity readings and temperature readings; Based on the synchronous pairing of conductivity readings and temperature readings, each set of conductivity readings and temperature readings in the synchronous pairing group is interval-checked against the preset conductivity range and temperature range of the circuit board etching process, and the synchronous pairing groups that fall within the preset conductivity range and temperature range are screened to obtain the screened pairing groups that meet the preset process conditions; Based on the screened paired groups that meet the preset process conditions, all conductivity readings and temperature readings in the screened paired groups are extracted and packaged into structured records to obtain an effective etching parameter set.

[0019] Specifically, the conductivity readings and temperature readings of the etching solution of the circuit board are collected. Specifically, the online conductivity sensor and temperature sensor deployed in the etching tank continuously obtain the conductivity analog signal and temperature analog signal of the etching solution at a preset sampling frequency, for example, 10 times per second. These analog signals are then converted into digital quantities by the built-in or external analog-to-digital converters of each sensor, namely the raw conductivity reading and the raw temperature reading. At the same time, a standard clock built into the system or synchronized through the network time protocol is assigned a high-precision time tag to each raw reading. The time tag records the exact moment of data collection, for example, 2023-10-26T10:30:05.123. Then, in order to associate the separated conductivity reading stream and temperature reading stream, all collected conductivity readings are traversed and the temperature reading with the closest time tag is found. A time synchronization tolerance window is set. The tolerance window is empirically set based on the response speed of the sensor and the data transmission delay, for example, set to 50 milliseconds. The specific calculation method is: if the conductivity reading The time label is , temperature reading The time label is , then when the condition is met When If the preset time synchronization tolerance window (e.g. 50 milliseconds) is and The conductivity readings and temperature readings that meet this condition are synchronized. If a conductivity reading with a time tag can match multiple temperature readings within the tolerance window, the one with the smallest time difference is selected for pairing. Vice versa, for any single data point that cannot find a corresponding reading within this tolerance window, it is marked as unpaired and temporarily shelved or processed according to a preset strategy (such as subsequent interpolation or discarding). Through this point-by-point timestamp comparison and pairing mechanism, conductivity readings and temperature readings with similar acquisition times are combined into data pairs, ultimately forming a collection of multiple data units consisting of conductivity values, corresponding temperature values, and shared time tags, generating a synchronized pairing group of conductivity and temperature readings.

[0020] Based on the simultaneous pairing of conductivity readings and temperature readings, we will then conduct a validity check on these preliminary paired data. The core basis is the specific requirements of the circuit board etching process for conductivity and temperature. These requirements are reflected in the preset conductivity range and the preset temperature range. The setting of these two ranges is crucial. For example, the preset conductivity range is defined based on the statistical analysis of historical production data and the etching process instruction manual for the specific circuit board model. For example, for the currently processed board, by analyzing the data of the past 200 successful etching batches and eliminating obvious outliers, the conductivity mean is calculated to be , the standard deviation is , then the preset conductivity range may be set to the mean plus or minus two standard deviations, that is, to The preset temperature range is mainly determined by the chemical specifications provided by the etching solution supplier and a large number of process verification test results. For example, the optimal operating temperature range of a commonly used acid copper chloride etching solution is verified to be to Exceeding this range may cause the etching rate to be too fast or too slow, or even damage the plate, so the preset temperature range is set to this value. The verification process is to traverse each set of data in the conductivity reading and temperature reading synchronization pairing group one by one. For each synchronization pairing group, its conductivity reading and temperature reading are taken out at the same time, and its conductivity reading value is compared with the preset conductivity range (for example to ) and compares its temperature reading with a preset temperature range (e.g. to ) is compared, only when the conductivity readings and temperature readings in a synchronization pairing group are strictly within their respective preset valid ranges, for example, a group of readings is (conductivity ,temperature ),because and , so the data set is considered valid and the synchronization pairing set is screened out. If any value exceeds its corresponding preset range, for example (conductivity ,temperature ) or (conductivity ,temperature ), the synchronous pairing group will be judged as not meeting the process conditions and will be eliminated. All synchronous pairing groups that have passed this double interval verification are gathered together to obtain the screened pairing group that meets the preset process conditions.

[0021] Based on the screened paired groups that meet the preset process conditions, these verified data are further processed. First, from each data pair in the screened paired groups that meet the preset process conditions, the confirmed valid conductivity readings and the paired valid temperature readings are extracted, while retaining their original or synchronously confirmed shared time tags. This extraction process ensures that the data points used in subsequent analysis are collected within the parameter window allowed by the process. Then, in order to facilitate subsequent calculations, storage and model input, these extracted, scattered valid data points (i.e., time tag, conductivity reading, temperature reading triplets) need to be uniformly structured and encapsulated. In specific implementation, a standardized data record structure can be created for each valid data point. For example, a record format containing the following fields is defined: Field one is "acquisition timestamp", the data type is a high-precision time format (such as ISO8601 string or Unix timestamp), used for Records the precise moment of data collection; Field 2 is the "Effective Conductivity Value," a floating-point number with units of mS / cm, which stores the verified conductivity measurement results; Field 3 is the "Effective Temperature Value," a floating-point number with units of degrees Celsius (°C), which stores the verified temperature measurement results. The system will traverse all data pairs in the filtered paired group and generate corresponding records one by one according to the structured record format defined above. For example, if a data pair in the filtered paired group is {time: "2023-10-26T10:31:00.500", conductivity: 21.2, temperature: 50.5}, it will be converted into a structured record containing these three specific values. All of these generated structured records are organized into an ordered set (usually sorted by timestamp). This set is the final required data compilation containing all relevant measurement information under the valid process parameter conditions, resulting in a valid etching parameter set.

[0022] The steps to obtain the etchant concentration estimation result are: Based on the valid etching parameter set, the conductivity value field in each record is extracted, and after reading the corresponding numerical value, linear interpolation is performed to fill in the missing points to generate a continuous and complete conductivity value sequence. Each conductivity value is bound to its own timestamp and temperature fields to generate a conductivity reading record set containing the conductivity value, timestamp, and temperature fields. Based on the conductivity reading record set, the calibrated conductivity and etchant concentration benchmark relationship curve is called, and each conductivity value is used as an input value to look up the table to obtain the concentration output node. If the conductivity value does not directly hit the benchmark relationship node, quadratic interpolation is performed between adjacent nodes to fit and generate the corresponding concentration value. The obtained concentration value is merged with the corresponding timestamp and temperature fields and written into the concentration fitting result record set to generate the etchant concentration fitting result set; Based on the set of etchant concentration fitting results, outlier detection is performed on the concentration values ​​in all records, and a 3-times standard deviation screening mechanism is used to exclude concentration anomalies that deviate from the mean. At the same time, the temperature field in the timestamp corresponding to the fitted concentration value is checked to see if it falls within the effective temperature fluctuation range. Only record entries that meet the conditions are retained, and the concentration values ​​that pass the verification are output in chronological order as the final concentration estimation sequence to generate the etchant concentration estimation result.

[0023] Specifically, based on the valid etching parameter set, the system first traverses each structured record in this parameter set, and extracts the value of the 'valid conductivity value' field, as well as the associated 'acquisition timestamp' and 'valid temperature value' fields from each record. Since conductivity readings may be missing at certain time points during the actual acquisition process due to transient sensor failure, signal transmission loss, or failure to fully meet the synchronization tolerance window in the previous processing, in order to obtain a temporally continuous conductivity data stream, the system will perform linear interpolation to fill these missing points. The specific operation is to first sort all valid conductivity values ​​according to timestamps, and then detect whether there are expected conductivity data point gaps between consecutive timestamps. The expectation here is based on the normal sampling frequency, for example, 10 points per second corresponds to one point every 100 milliseconds. If there is a gap between two valid data points ( )and( ), according to the timestamp and And preset sampling interval, judge that there should be one or more data points but are actually missing, then interpolate these missing points. The execution of interpolation has a prerequisite, that is, the time interval between two known data points cannot exceed a "maximum interpolation interval threshold". The threshold is set according to the stability of the process and the acceptable data quality loss, for example, it is set to 500 milliseconds. If the interval is less than or equal to this threshold, for the (in ) of the missing conductivity values , which is calculated as In this way, all missing points within the allowable range are filled one by one, thus forming a continuous and complete conductivity value sequence without breakpoints on the time axis. For the original valid conductivity value, its corresponding timestamp and temperature value are directly retained. For the conductivity value newly generated by linear interpolation, its timestamp is the timestamp of the interpolation point itself. , and its corresponding temperature value also uses a similar linear interpolation method, using and The effective temperature value at the moment is interpolated, or the distance is directly used The temperature value recorded at the most recent valid data point. If the temperature change is relatively slow, reassemble each conductivity value (whether original or interpolated) with its corresponding timestamp and temperature field into a new record to generate a conductivity reading record set containing conductivity value, timestamp and temperature fields.

[0024] Based on the conductivity reading record set, the system then converts these processed conductivity data into etchant concentration information. This conversion process relies on a core reference tool, namely the "calibrated conductivity and etchant concentration benchmark curve". This benchmark curve is pre-established through systematic experiments in a controlled laboratory environment. The specific establishment process includes preparing a series of known different precise concentrations (for example, determined by weighing and titration), and the concentration range covers all possible situations that may be encountered in the actual process, such as from arrive ,interval ) of the etching solution standard sample, and then at a constant temperature consistent with the actual process conditions (for example, the center temperature required by the process specification ), use a high-precision conductivity meter to measure the conductivity values ​​of these standard samples, thereby obtaining a set of "conductivity-concentration" paired data points, such as ( , )、( , )、( , ) and so on. These data points are then fitted using numerical fitting methods (such as least squares polynomial curve fitting or piecewise linear connection) to form a reference relationship curve. During processing, each record in the conductivity reading record set is traversed, and the conductivity value therein is used as input to find the corresponding etchant concentration on the reference relationship curve. If the input conductivity value is exactly the same as the conductivity value of a calibration node on the curve, the concentration value of the node is directly taken as the output. However, the more common situation is that the input conductivity value is between two calibration nodes. At this time, if the conductivity value does not directly hit the reference relationship node, quadratic interpolation is performed, which refers to the calibration nodes on the two nearest reference relationship curves on both sides of the input conductivity value (set as node 1: conductivity). ,concentration ; Node 2: Conductivity ,concentration ) to fit and generate the corresponding concentration value. The calculation formula is: ,in, is the conductivity value entered, It is the corresponding concentration value obtained by calculation. Each concentration value obtained in this way is merged together with the timestamp and temperature fields in its original record to create a new record entry. These new entries are written into a set sequentially to generate an etchant concentration fitting result set.

[0025] Based on the set of etchant concentration fitting results, this preliminary concentration data is further cleaned and verified. First, outlier detection is performed to identify and eliminate unreliable concentration estimates caused by accidental interference or transient sensor anomalies. Specifically, a 3x standard deviation screening mechanism is used. The operating process of this mechanism is to select all concentration values ​​within a sliding window (for example, the most recently collected or calculated 100 concentration data points) or a fixed batch, and calculate the arithmetic mean of these concentration values ​​( ) and standard deviation ( ), and then traverse each concentration record in the window or batch. If the concentration value of a record Meet the conditions , then the concentration value of the record is judged to be abnormal and is removed from the data set. For example, if the average concentration is , the standard deviation is , then any value less than or greater than The concentration values ​​of the fitted concentration values ​​will be regarded as outliers. After completing the outlier screening of the concentration values, the system will also perform an association check, that is, to check whether the temperature field of these fitted concentration values ​​at the corresponding timestamp is within a reasonable, preset "temperature effective fluctuation range". This range is usually narrower than the initial process window and is based on the statistical analysis of the temperature data of the highly stable and excellent etching effect stage in the historical production. For example, if the target temperature during normal stable etching is , then the effective temperature fluctuation range may be set to arrive The basis for setting this range is to ensure the accuracy of concentration estimation, because drastic temperature fluctuations themselves may indicate process abnormalities or affect the existing relationship between conductivity and concentration. Only those record entries whose concentration values ​​pass the 3 times standard deviation test and whose corresponding temperature values ​​also fall within this preset temperature effective fluctuation range are finally retained. All concentration values ​​that pass the above double verification are strictly arranged in the order of their original timestamps to form a time series. This sequence is the concentration estimation data finally used for subsequent analysis to generate the etchant concentration estimation result.

[0026] The steps to obtain the probability distribution of etchant concentration are: Based on the etchant concentration estimation results, the aging days and relative humidity values ​​of each record are extracted. The maximum drift in the last 30 days is obtained by calling the sensor number matching method and recorded as the drift intensity value. The stirring speed is divided by the reference speed to obtain the stirring ratio. The aging days are divided by the maximum aging days to obtain the normalized aging factor. The normalized aging factor, relative humidity value, drift intensity value and stirring ratio are integrated to generate a correction parameter set. Based on the correction parameter set, the etchant concentration correction value is calculated using the following formula: ; in, For the Corrected value of etching agent concentration recorded (unit: mol / L), For the Etchant concentration estimate (mol / L) for each record. For the Record normalized aging factor (dimensionless, aging days divided by the maximum aging days of the system), For the Record relative humidity values ​​(dimensionless, raw percentage divided by 100), For the Record drift intensity values ​​(unit mol / L), For the records the stirring ratio (dimensionless, stirring rate divided by reference rate), Set the buffer constant (dimensionless) for experience; Based on the etchant concentration correction value, all etchant concentration correction values ​​are numerically segmented with a fixed interval starting step of 0.1 mol / L. The total number of entries of the etchant concentration correction value contained in each segmented interval is counted in turn, and the ratio of the number of entries in each segment to the total number of entries is calculated as the concentration probability value of the interval. Each concentration segmented interval is paired with the corresponding concentration probability value one by one and output as an ordered concentration-probability combination sequence to generate the etchant concentration probability distribution.

[0027] Specifically, based on the etchant concentration estimation result, which is a series of etchant concentration estimation values ​​with timestamps, the system further collects and calculates the auxiliary parameters required for correction for each record. First, for the extraction of aging days, the system will query the activation date or the last replacement date of the current etching solution batch, for example, the record is 08:00 on May 1, 2025, and then subtract the activation date from the timestamp of the current record (for example, 10:30 on May 8, 2025) to obtain the actual aging days, which is 7 days and 2.5 hours here, rounded or accurately recorded as 7.1 days. Secondly, the relative humidity value is obtained through the environmental monitoring system deployed near the etching equipment on the production line. The environmental monitoring sensor collects data in real time. For example, the sensor reports data once every minute. The system matches the valid humidity reading at the same time point or the most recent time point based on the timestamp recorded by the current etchant concentration estimation result. For example, the relative humidity is obtained to be 65%. Furthermore, the sensor number matching is called to obtain the maximum drift in the last 30 days. This means that the unique number of the conductivity sensor from which the current concentration estimation value comes is used to search the sensor maintenance and calibration history database for the maximum absolute deviation value when the sensor is compared with the standard concentration solution in the past 30 working days. This value is recorded as the drift intensity value. For example, for the sensor numbered SN007, the maximum drift recorded is , which is the drift intensity value. Next, the actual operating speed of the agitator in the current etching tank, for example, 95 revolutions per minute read through the device interface, is divided by the preset reference speed of the process standard, for example, 100 revolutions per minute, to obtain the stirring ratio, which is 0.95 in this case. Then, the aging days obtained previously (7.1 days) are divided by the preset maximum aging days of the system, for example, set to 14 days. The maximum aging days is the upper limit of the cycle at which the etching solution must be replaced based on the chemical stability of the etching solution and historical experience. The two are divided to obtain the normalized aging factor. In this case, 7.1 divided by 14 is approximately equal to 0.507. Finally, the calculated normalized aging factor (0.507), the relative humidity value obtained previously (65%, which needs to be converted to 0.65 for use), and the drift intensity value ( ) and the stirring ratio (0.95), and a complete set of correction factors is provided for each etchant concentration estimation result record to generate a correction parameter set.

[0028] formula: The benefit of the formula lies in that it comprehensively considers various factors that affect the accuracy of concentration measurement in actual production, such as the aging of the etching solution itself, the impact of external environmental humidity on the sensor, the inherent drift of the sensor itself, and the stirring state of the solution. The original concentration estimate is corrected through a structured mathematical model. The numerator uses the square root of the sum of squares to aggregate the combined effects of aging, humidity, and drift, while the denominator introduces the stirring effect and empirical constant for adjustment, making the correction more in line with actual working conditions, thereby improving the accuracy and reliability of etching agent concentration monitoring and providing more accurate data support for subsequent process control and decision-making; For the The steps for obtaining the etchant concentration estimate for the record are as follows: This parameter comes directly from the output sequence of the previous step "Generate Etchant Concentration Estimation Results". It is a concentration estimate based on conductivity and temperature readings, converted through a reference curve, and processed after preliminary outlier processing. It represents the etchant concentration without further correction for environmental factors and aging effects. For example, for the kth record currently being processed, the corresponding concentration value read from the "Etchant Concentration Estimation Results" is ,therefore .

[0029] For the The steps to obtain the normalized aging factor of each record are as follows: This parameter is calculated by first obtaining the actual "aging days" of the current etching solution batch since it was activated or last replaced, and then obtaining a preset "system maximum aging days". The actual "aging days" is the time from the etching solution replacement time recorded in the production management system (for example, 08:00 on May 1, 2025) to the current batch. The time elapsed from the timestamp of the record (for example, 12:00 on May 10, 2025) is calculated to be 9 days and 4 hours, that is, Days. The "maximum system aging days" is a fixed value set based on the chemical properties of the etching solution, supplier recommendations, and the critical usage time during long-term production practice when etching efficiency significantly decreases or quality does not meet standards. For example, it is set at 15 days. This value ensures that the etching solution is replaced before it becomes ineffective. The calculation formula for the normalized aging factor is: .

[0030] For the The steps for obtaining the relative humidity value of the record are as follows: This parameter is obtained by reading the relative humidity sensor installed in the operating area of ​​the etching equipment. The relative humidity sensor usually sends readings to the data acquisition system regularly (for example, every minute). The system matches the closest humidity record based on the timestamp. The raw relative humidity obtained is a percentage value. For example, in the At the time of the record, the relative humidity sensor measured a humidity of 58%. To convert it into a dimensionless value for formula calculation, it needs to be divided by 100. .

[0031] For the The steps to obtain the drift intensity value of the record are as follows: This parameter represents the maximum measurement deviation of the sensor (usually a conductivity sensor) used to measure the current etching solution concentration in the recent period. The method to obtain it is: first identify the sensor that produces the first The sensor number that records the raw data is then queried for the historical calibration and maintenance record database of the sensor. The maximum absolute deviation value recorded when the sensor is compared and calibrated with a standard etching solution of known concentration in the past 30 natural days is extracted. This deviation value is the drift intensity value. For example, for sensor number SCD-003, the highest calibration deviation in the past 30 days is recorded as being higher than the standard value. ,but .

[0032] For the The steps to obtain the stirring ratio (dimensionless) are as follows: This parameter reflects the comparison between the actual state and the ideal state of solution stirring during the etching process. The actual operating speed of the stirrer in the etching tank at the corresponding time point is recorded and divided by a preset "reference stirring rate". The "reference stirring rate" is the optimal stirring rate that can ensure etching uniformity and efficiency according to the process document regulations or experimental optimization. For example, it is set to 120 revolutions per minute (RPM). If the current At the time of recording, the actual speed sensor reading of the stirrer is 110 revolutions per minute, so the calculation formula of the stirring ratio is: .

[0033] The steps for obtaining the empirically set buffer constant are as follows: This parameter is a constant obtained through experiments and long-term application experience adjustment. Its function is to adjust the sensitivity of the entire correction term, prevent the correction amplitude from being too large or oscillating due to parameter fluctuations, and ensure the stability of the correction model. Its setting is usually in the system debugging stage, by comparing the degree of agreement between the concentration values ​​before and after correction and the offline test values, and observing the stability of the correction system in continuous operation to gradually optimize. For example, the initial setting is 0.1. If it is found that the concentration value after correction fluctuates greatly, it is appropriately increased. value (for example, adjust it to 0.15 or 0.2) to enhance the buffering effect; on the contrary, if the correction response is slow, you can reduce it appropriately. In this case, after long-term operation data analysis and process verification, it is determined The system performs most stably and accurately when

[0034] Calculation process: For the Records, the setting values ​​of each parameter are as follows: ; Substituting these values ​​into the formula: ; Evaluate the terms in the numerator: ; Square root of the sum of the squares of the numerators: ; Evaluate the terms in the denominator: Denominator = ; Calculate the correction term: Correction term = ; Calculate the final : ; The result (Keep three decimal places) is The etchant concentration value after comprehensive correction is recorded. This value represents the result of fine-tuning the original concentration estimate after considering various factors such as the aging degree of the etching solution, the current ambient humidity, the inherent drift of the sensor, and the stirring efficiency. It is better than the original ( ) decreased, indicating that under the currently set parameter conditions, the combined effect of these factors led to an overestimation of the original estimated value, and the corrected concentration value was closer to the actual active concentration of the etching solution.

[0035] Based on a series of calculated etchant concentration correction values, such as the one calculated in the previous paragraph The system then converts these discrete concentration values ​​into a statistically significant probability distribution. First, a fixed concentration interval step size is determined, which is set here as The choice of this step size is based on the consideration of the etching process accuracy requirements and the fluctuation range of historical data. A moderate step size can avoid data being too sparse while ensuring resolution. For example, if the concentration correction value is mainly distributed in arrive , then the numerical segmentation will produce 、 , until After a series of continuous concentration intervals, the system will traverse all the etching agent concentration correction values, classify each value into the concentration segment interval to which it belongs, and accumulate the number of correction value entries that fall into each interval. For example, after statistics, it is found that There are 150 concentration correction values ​​for the interval, and the total number of valid etching agent concentration correction value entries in the entire data set is 1000. Next, calculate the ratio of the number of entries in each segmented interval to the total number of entries. This ratio is defined as the "concentration probability value" of the concentration interval. In the above example, the interval The concentration probability value is 150 divided by 1000, which is 0.15. The system performs this calculation for all concentration segment intervals. Finally, each concentration segment interval (for example, the midpoint or lower limit of the interval is used as a representative) is paired with its corresponding calculated concentration probability value to form an ordered combination sequence that can reflect the probability of occurrence of different concentration levels, for example (" ”, 0.02), (“ ”, 0.05),…, (“ ”, 0.15),…, this sequence is what we need, which can quantitatively characterize the etchant concentration probability distribution of the current etchant concentration state.

[0036] The steps to obtain the current etching solution activity are: Based on the probability distribution of etchant concentration, all etchant concentration intervals and corresponding concentration probability values ​​are extracted. Each etchant concentration interval is used as an index parameter to match the temperature value corresponding to the same timestamp in the valid etching parameter set. A set of triplets consisting of etchant concentration interval, concentration probability value and corresponding temperature value is constructed to generate a matching record set. Based on the matching record set, each combination of concentration value and temperature value is read one by one, and the matching or interval-fitted standard etching rate value is searched in the standard copper foil etching rate reference table. The found standard etching rate value and the corresponding concentration probability value in the original triplet are combined into a four-tuple record to obtain a concentration-temperature-probability-rate matching combination set; Based on the concentration-temperature-probability-rate matching combination set, the probability average level of the rate values ​​in all combinations is calculated, and the weighted average rate value is extracted as the etching reaction ability performance value of the current solution under the current concentration and temperature conditions to generate the current etching solution activity.

[0037] Specifically, based on the probability distribution of etchant concentration, the distribution consists of a series of paired etchant concentration intervals and their corresponding concentration probability values, for example, including ( , probability 0.15) and other items, the system first extracts each etchant concentration range and its accompanying concentration probability value from this probability distribution one by one. Next, for each extracted etchant concentration range, the system needs to match it with a representative process temperature value at that concentration level. This temperature value comes from the "effective etching parameter set" established in the previous step. The parameter set contains timestamp records synchronized with the original effective conductivity readings and effective temperature readings. The specific matching logic is as follows: For the currently processed etchant concentration range (for example ), the system will review all the "etchant concentration correction value" sequences that fall into this concentration interval when generating the probability contribution of this concentration interval. Each such "etchant concentration correction value" retains its original acquisition timestamp. Using these timestamps, the system searches and extracts the "effective temperature values" that are exactly the same as these timestamps in the "effective etching parameter set". If there are multiple "etchant concentration correction value" contributions in a concentration interval, multiple effective temperature values ​​at that time will be obtained. The system then calculates the arithmetic mean of these temperature values ​​and uses this average temperature (for example, if the corresponding temperatures are 、 、 , then the average temperature is ) as the representative temperature associated with the current etchant concentration range. Through this operation, the original concentration range and concentration probability value are expanded and the corresponding average temperature value is added, thereby constructing a triple for each concentration range, which includes the etchant concentration range itself, the concentration probability value of the range, and the calculated corresponding representative average temperature value. For example, ( , 0.15, ), all these triples together form a new set, generating a set of matching records.

[0038] Based on the matching record set, each record is a triple consisting of an etchant concentration range, a concentration probability value, and a corresponding representative average temperature value. The system then processes these records one by one to query the etching rate of standard copper foil under specific concentration and temperature conditions. This query operation relies on a pre-established "standard copper foil etching rate reference table". The establishment of this reference table is completed through rigorous laboratory calibration work: copper foil of uniform specifications (for example, 1 ounce thickness, 99.9% purity) is selected as the standard sample, and a series of different etchant concentration gradients (for example, from Increment to , every a gradient point) and different operating temperature gradients (e.g., from Increment to , every A timed etching experiment is conducted under the combination conditions of a gradient point. By measuring the weight loss of the copper foil before and after etching or observing the change in the thickness of the copper layer under a microscope, the average etching rate (for example, in microns / minute) under each specific concentration and temperature combination is calculated. After sorting, statistical analysis and necessary smoothing, these experimental data points are compiled into a two-dimensional lookup table or fitted into a computable empirical model as a "standard copper foil etching rate reference table". When processing each triple in the matching record set, the system extracts the etchant concentration range (usually the midpoint value of the range is used as the query input, for example, for the range ,use ) and the corresponding representative mean temperature values ​​(e.g. ), use these two values ​​as indexes to look up the corresponding standard etching rate value in the reference table. If the input value does not completely match the calibration point in the reference table, a numerical method such as bilinear interpolation is used to estimate the standard etching rate under the current conditions based on the adjacent calibration point data. For example, if the standard etching rate is 25 microns per minute after table lookup and interpolation calculation, the system will then merge this standard etching rate value with the existing etchant concentration range, representative average temperature value, and concentration probability value in the original triple record to form a four-tuple record containing the etchant concentration range, representative average temperature value, concentration probability value, and the standard etching rate value. For example, ( , , 0.15, 25 μm / min), all of these newly generated four-tuple records are aggregated to obtain a set of concentration-temperature-probability-rate matching combinations.

[0039] Based on the concentration-temperature-probability-rate matching combination set, which contains multiple four-tuple records consisting of the etchant concentration range, the representative average temperature value, the concentration probability value, and the standard etching rate value found under the concentration and temperature conditions, the system then performs calculations to evaluate the comprehensive etching reaction ability of the entire etching solution under all possible concentration and temperature combinations. The specific calculation process is to obtain the probability weighted average of all standard etching rate values. In operation, the system will traverse each four-tuple record in the concentration-temperature-probability-rate matching combination set and extract the standard etching rate value (denoted as ) and the corresponding concentration probability value (denoted as ), multiplying these two values ​​together gives the weighted contribution of the etching rate to the overall average rate under that particular condition ( ), for example, for a record ( , , 0.15, 25 μm / min), its weighted contribution is 25 μm / min multiplied by 0.15, which is equal to 3.75 (μm / min) probability unit. The system performs this multiplication operation on all four-tuple records in the set, and then accumulates all the calculated weighted contribution values. Since the probability value of each concentration interval is It is derived from a complete probability distribution. In theory, all The sum of the total weighted contributions is 1, so this cumulative sum itself represents the expected etching rate of the entire etching solution under the current state. The final calculated weighted average rate value, for example, if the cumulative total weighted contribution value is 28.5 μm / min, then this value is extracted and recorded as a single indicator of the etching reaction ability of the current solution under the current overall concentration distribution and corresponding temperature conditions, generating the current etching solution activity.

[0040] The steps for obtaining the probability point set of the comprehensive performance of the etching solution are as follows: Based on the current etching solution activity, the standard interval value corresponding to the current etching solution activity is extracted, and the number of processed circuit board batches in the current batch statistical record is simultaneously read. The activity interval and the batch number are formed into a one-to-one correspondence group, and an activity-batch number comparison set is established under the condition of consistent time tags to generate an etching activity batch comparison set; Based on the etching activity batch control set, the etching solution efficiency attenuation ratio of each group was calculated using the following formula: ; in, For the The etching solution performance attenuation ratio corresponding to the group of samples is For the Initial etching solution activity of each sample (unit: mol / s·cm²), For the Estimated current activity of the sample group under the influence of the number of processed circuit board batches (in mol / s·cm²); The system determines whether each etching solution's efficiency attenuation ratio exceeds the set attenuation recognition threshold in turn. The corresponding etching solution activity is extracted from the records that are greater than the attenuation recognition threshold. The occurrence probability points of the etching solution activity in the time dimension are constructed to generate a set of etching solution comprehensive efficiency probability points.

[0041] Specifically, based on the current etching solution activity, this is a single value that characterizes the overall reaction capacity of the current etching solution. For example, the activity calculated in the previous step is , the system first needs to classify this specific activity value into a predefined standard activity range, such as the "high activity range" ( ), “medium activity range” ( to ), "low activity range" ( ), are determined based on long-term statistical analysis of production data, combined with etching quality standards and process windows. They reflect the general impact of different activity levels on production results. For example, if the current etching solution activity is , the corresponding standard interval value is the "high activity interval." Simultaneously, the system reads from the production batch management system the number of PCB batches that have been processed for the currently processed etching solution batch since it was activated. For example, if the system records show that the current etching solution has processed 25 batches of PCBs, the system then groups the extracted standard interval value corresponding to the current etching solution activity (the "high activity interval") with the number of processed PCB batches (25 batches) into a corresponding pair. To track the change in etching solution activity as the number of processing batches increases, the system repeats the above extraction and matching process each time a new current etching solution activity value is calculated (usually associated with a certain monitoring cycle or specific production event and with a time stamp). The resulting (activity interval, batch number) pair is recorded along with the corresponding time stamp. By continuously accumulating these records, a data set containing the corresponding relationship between activity intervals and the number of processed batches at multiple time points, provided the time stamps are consistent, is established. This set is the etching activity batch reference set.

[0042] formula: The benefit of the formula is that it provides a method to quantitatively evaluate the degree of attenuation of etching solution performance. It not only considers the absolute difference between the current activity and the initial activity, but also considers the square operation. This formula amplifies the situation where the activity decreases significantly, making the attenuation effect more sensitive. The term, on the one hand, performs some form of normalization on the attenuation degree based on the initial activity, and on the other hand, by adding "1", ensures that the denominator is It is always positive when it exists, avoiding the risk of dividing by zero and Smaller values ​​provide a certain buffer, making The value can stably reflect the relative loss of performance; For the The steps for obtaining the initial etching solution activity of a group of samples are as follows: This parameter represents the baseline etching capacity of a specific batch of etching solution when it is brand new or just replaced, that is, when the number of processed circuit board batches is zero. Its value is determined by measuring the newly configured etching solution using the same method as the calculation of the "current etching solution activity" (that is, by monitoring its conductivity and temperature, estimating the concentration distribution, and then combining the weighted average etching rate calculated from the standard etching rate table). This initial activity is measured and recorded when the etching solution batch is replaced, and serves as the benchmark for attenuation comparison throughout the life cycle of the batch. For example, for the newly replaced etching solution in the current large tank, the initial etching solution activity measured before it is put into use (when the number of processed batches is 0) is , then for all sample points belonging to this large tank of etching solution ,That The values ​​are all adopted .

[0043] For the The steps for obtaining the current activity estimate of the sample group under the influence of the number of batches of processed circuit boards are as follows: This parameter is the "current etching solution activity" calculated in the previous step, which reflects the etching solution's current activity at a specific sampling or evaluation time point after processing a certain number of circuit board batches. The actual etching capacity performance of the sample is extracted from the "etching activity batch reference set". In this reference set, each record contains the "current etching solution activity" at a certain point in time and the "number of processed circuit board batches" at that time. For example, for the The sample group corresponds to an evaluation point after 25 batches of circuit boards have been processed. At this time, the "current etching solution activity" obtained from the "etching activity batch control set" or directly calculated in the previous step is ,but .

[0044] Calculation process: For the The setting values ​​of each parameter for group samples are as follows: ; Substituting these values ​​into the formula: ; Evaluate the terms in the numerator: ; Calculate the terms in the denominator: Denominator = ; The result It is The etching solution performance attenuation ratio corresponding to the group of samples.

[0045] The performance attenuation ratio of each etching solution calculated based on the etching activity batch control set, such as the one calculated in the previous paragraph The system will then evaluate these attenuation ratios one by one to determine whether they exceed a pre-set "attenuation recognition threshold". The setting of this "attenuation recognition threshold" is based on the accumulation of production experience and the specific requirements for product quality. For example, through long-term production data monitoring and analysis, it is found that when the etching solution efficiency attenuation ratio is achieve (The threshold here is the same as the above When the calculation result is matched), the etching uniformity of the circuit board begins to show an observable decline, or the scrap rate has a slight upward trend. Considering the economic benefits and quality control, the process engineer will set this value Set as the critical point to judge whether the etching solution performance has significantly decreased. When judging, the system will calculate each The value is compared with this threshold, if Values ​​greater than this "attenuation identification threshold" (e.g. ), then it is considered that The etching solution state corresponding to the value has shown significant performance degradation. For these records identified as having significant performance degradation, the system will extract the "current etching solution activity" when it occurs (i.e. calculate the current etching solution activity). Used when The activity values ​​of the etching solution in the state of performance attenuation collected in the time dimension and their corresponding timestamps are combined. These combinations (timestamp, etching solution activity at significant attenuation) constitute a series of "points" marked on the time axis. These points together depict the historical trajectory and distribution of the activity of the etching solution when it reaches the significant attenuation state, thereby forming a set of probability points for the comprehensive performance of the etching solution.

[0046] The steps to obtain the identification results of risk points exceeding the threshold are as follows: Based on the comprehensive performance probability point set of the etching solution, each etching solution performance probability point is merged with the minimum acceptable performance threshold of the circuit board etching and the two end points of the optimal performance target interval. Each probability point, the minimum threshold, the lower limit and the upper limit of the optimal target interval are bound into a four-element relationship to generate a performance reference comparison set; Based on the efficacy reference comparison set, the deviation index of each efficacy probability point is calculated using the following formula: ; in, For the The deviation index of the efficiency probability point, For the The effectiveness value of the effectiveness probability point, The minimum acceptable performance threshold for circuit board etching. is the median value of the optimal performance target range; Based on the deviation index, each deviation index is compared with the deviation index, and the efficiency probability point number where the deviation index is greater than the deviation judgment threshold is marked. The time label and efficiency value are output as the record result to generate the identification result of the risk point exceeding the threshold.

[0047] Specifically, based on the comprehensive efficiency probability point set of the etching solution, the set consists of a series of paired timestamps and the etching solution efficiency values ​​(i.e., "current etching solution activity") marked at the timestamp due to significant efficiency degradation, for example, including ("2025-05-10 14:00:00", ) records, the system will then equip each performance probability point in the set (i.e., each performance value and its timestamp) with a set of reference benchmarks for risk assessment. These benchmarks include the "minimum acceptable performance threshold for circuit board etching" and the upper and lower limits of the "optimal performance target range". First, the setting of the "minimum acceptable performance threshold for circuit board etching" is determined based on strict process bottom lines and product quality standards. For example, through a large amount of production practice and failure analysis, it is confirmed that when the activity of the etching solution is lower than When the etching rate is too low, the risk of fatal defects such as circuit pattern incompleteness and open circuit increases sharply, and the production cycle is unacceptably extended. The lowest acceptable performance threshold is set. Secondly, the setting of the "optimal performance target range" aims to define an ideal etching solution activity range that can achieve the best product quality, the highest production efficiency and the most economical operating cost. For example, the process department conducted statistical regression analysis on historical batch data and combined it with small batch verification experiments and found that when the etching solution activity is maintained at to When the etching uniformity of the circuit board is the best, the defective rate is the lowest and the agent consumption rate is within the economic range, this interval is set as the optimal performance target interval, and its lower limit is , the upper limit is , then, the system traverses each efficiency probability point in the “etching solution comprehensive efficiency probability point set” (assuming its efficiency value is ), the performance value , the minimum acceptable performance threshold set above ( ), the lower limit of the optimal performance target range ( ) and the upper limit of the optimal performance target range ( ) bind these four values ​​to form a four-tuple relationship group, while retaining All of these four-tuple relationship groups (with associated timestamps) are collected together to generate a performance reference comparison set.

[0048] formula: The formula is useful in that it provides an effective means for quantitatively evaluating the comprehensive deviation of the etching solution performance state at a specific moment from its ideal state and the minimum acceptable state. It calculates the performance value Minimum acceptable performance threshold and the median of the optimal performance target range The average of the sum of the absolute distances can simultaneously reflect the extent to which the current performance deviates from both the "safety bottom line" and the "optimal target". The use of absolute values ​​ensures that the direction of deviation does not affect the measurement of the deviation size. The sum and average gives a comprehensive deviation index. The larger the value, the further the current performance status is from the ideal and safe area, and the higher the potential process risk; For the The steps for obtaining the efficiency value of each efficiency probability point are as follows: This parameter comes from the "etching solution comprehensive efficiency probability point set" generated in the previous step. Each point in the point set contains a timestamp and an efficiency value of the etching solution that is identified as having significant efficiency degradation at that time point. That is the first Such an efficiency value, for example, select the first value from the "etching liquid comprehensive efficiency probability point set" points, and the recorded performance value is ,but .

[0049] The steps to obtain the minimum acceptable performance threshold for circuit board etching are as follows: This parameter is the key process parameter defined in the previous step. Its value is set based on the minimum etching quality requirements of the specific model of circuit boards on the production line and the absolute bottom line of the process operation. It is combined with the critical etching solution activity when etching defects (such as incomplete etching, excessive side etching, etc.) appear in historical production data, and is determined after process verification. For example, in the above, this value has been set to ,therefore, .

[0050] The steps for obtaining the median value of the optimal performance target range are as follows: This parameter represents the center point of the most ideal etching solution performance state expected to be achieved in the process, and its calculation depends on the lower limit of the "optimal performance target range" defined in the previous step of this method ( ) and upper limit ( ), for example, in the above, the lower limit of the optimal performance target range is set to , the upper limit is set to , then the median value of the optimal performance target interval .

[0051] Calculation process: For the selected The setting values ​​of each parameter are as follows: ; Substituting these values ​​into the deviation index In the calculation formula: ; Calculate the absolute value of each item: The absolute value of the first item: , the absolute value of the second term: ; Calculate the sum of absolute values: Sum = ; Calculating deviation indicators : ; The result It is The deviation index value of each efficiency probability point, which comprehensively measures the current efficiency value Deviating from the minimum acceptable threshold and the optimal target median The average degree of ( ) is below the minimum threshold ( ), and is far below the optimal median value ( ), the calculated deviation index The value is This value will be used to compare with the "deviation judgment threshold" to determine the risk level of the current performance point. The larger it is, the higher the risk.

[0052] The deviation index of each efficacy probability point calculated based on the efficacy reference comparison set, such as the deviation index of the first Deviation Indicator The system will then evaluate each such deviation indicator. The core operation is to compare each calculated deviation indicator with a preset "deviation judgment threshold". This "deviation judgment threshold" is a key parameter used to define the risk level in process management. Its setting combines the requirements for production stability, the acceptable fluctuation range of product quality, and the statistical correlation between deviation indicators in historical data and actual process problems. For example, through a review and analysis of historical data, the process team found that under similar unit systems, when the deviation indicator The value exceeds When the quality problem occurs in the subsequent production batches, the probability of quality problems will increase significantly, or the frequency of manual intervention adjustment will increase significantly. Set as this "deviation judgment threshold", the system will read the deviation index corresponding to each performance probability point one by one when making a judgment and compare it with this threshold ( ) for comparison, if the deviation index of a certain efficiency probability point is Greater than the “deviation judgment threshold” (e.g., ), the system will mark the efficiency probability point as having a high risk. Subsequently, the system will extract the original information corresponding to all efficiency probability points marked as high risk, that is, the time label of their occurrence and the actual efficiency value at that time (i.e. These time tags and performance values ​​are output as a set of records. These records together constitute a risk event set indicating that the performance of the etching solution has exceeded the acceptable deviation range, generating an identification result of the risk point exceeding the threshold.

[0053] The steps to obtain the etching process deviation warning code are as follows: Based on the identification results of risk points exceeding the threshold, the time tag, concentration value, temperature value, and deviation index value corresponding to each identified efficiency probability point are extracted, and sorted according to the order of occurrence and source records. The etching condition combinations corresponding to the concentration values ​​and temperature values ​​are read one by one to generate the etching condition deviation feature set; Based on the etching condition deviation feature set, the concentration value and temperature value combination of each record is mapped to the circuit board manufacturing process risk level comparison table. The matching interval or adjacent level is found and marked with the risk level code. All records are bound to the matching risk level code to generate the process risk level matching result. Based on the process risk level matching results, corresponding warning information templates are set according to different risk levels, and text warning content with time tags and risk level identifiers is constructed. Then, it is uniformly encoded into an output identifier with a standard structure to generate an etching process deviation warning code.

[0054] Specifically, based on the identification result of the risk point exceeding the threshold, the result is a series of efficiency probability points that are judged to have higher process risks, each point contains at least a time label and a corresponding efficiency value ( ), and the deviation indicator value that led to its identification ( ), the system first extracts the respective time tags and deviation index values ​​from these risk point records, and the efficiency value corresponding to each risk point ( , that is, the "current etching solution activity" at that time), the system needs to trace back and extract the representative etching solution concentration value and temperature value based on which the performance value is calculated. These concentration values ​​and temperature values ​​are the parameters that best characterize the overall state of the etching solution at that time. For example, when calculating the "current etching solution activity", the midpoint value of the concentration interval with the highest probability is selected from the "etchant concentration probability distribution" as the representative concentration, and the representative average temperature corresponding to the concentration interval is matched. For example, the time tag is "2025-05-1015:30:00", and the representative concentration value is , the representative temperature value is , the performance value is , the deviation index value is The system will collect this complete set of data (time label, representative concentration value, representative temperature value, efficiency value) for each identified risk point. , deviation from index value ), and then sort all these collected risk point data records in the order of occurrence of their time tags. If the record also contains data source information (such as a specific production line number or equipment number), it can also be used as a secondary sorting basis. After the sorting is completed, the system obtains a list of risk events that evolves over time and contains detailed working condition parameters. The combination of the representative concentration value and the representative temperature value in each record constitutes the specific etching condition combination at that time. The collection of these combinations forms the etching condition deviation feature set.

[0055] According to the etching condition deviation feature set, each record describes in detail the etching conditions (representative concentration and temperature) at an identified risk moment and the related performance and deviation evaluation results. The system will then compare these actual deviation conditions with the preset risk standards. The core basis is a "circuit board manufacturing process risk level comparison table". This comparison table is pre-compiled by the process management department based on a large amount of historical production data, product defect analysis reports, process experiment results and the experience judgment of senior engineers. Its content defines in detail the process risk levels that may be caused by different etching solution concentration ranges and temperature range combinations. For example, the table stipulates: when the etching solution concentration is lower than and the temperature is higher than When the concentration is to Range, temperature to When the concentration is to , the temperature is to When it belongs to the ideal process window, the risk level is "low" (code L01). The system will traverse each record in the etching condition deviation feature set, extract its representative concentration value and representative temperature value, and then use this combination as the query condition to search in the "Circuit Board Manufacturing Process Risk Level Comparison Table". The system will give priority to trying to match the exact interval. If the exact match fails, it will determine the most appropriate risk level based on the preset proximity logic (for example, select the minimum risk interval containing the point, or if the point is at the intersection of multiple intervals, take the higher risk level), and mark the code corresponding to the risk level (such as H03, M02, L01) to the currently processed record. After completing the binding of the risk level codes of all records, the process risk level matching result is generated.

[0056] Based on the process risk level matching results, the corresponding risk level code is added to each record in the "etching condition deviation feature set". The system will then generate specific warning prompts based on this information. First, the system has preset standardized "warning information templates" for different risk level codes. These templates are designed based on the possible consequences of each risk level, the recommended response measures, and the key information that needs to be conveyed. For example, for the risk level code "H03" (high risk), the template may be: "Serious warning! Time: {time label}, etching solution status high risk (H03), current concentration: {concentration value} mol / L, temperature: {temperature value} °C, efficiency Energy value: {efficiency value}, deviation index: {deviation index value}. This state is very likely to cause excessive side etching. Please check the etching parameters immediately, suspend production and adjust the solution if necessary! "For the medium risk "M02", the template may be: "Note: Time: {time label}, etching solution state medium risk (M02), current concentration: {concentration value} mol / L, temperature: {temperature value} °C. The etching rate may be slow. Please pay attention to the quality of subsequent batches and prepare for inspection. "The system will traverse each record in the process risk level matching result, select the corresponding warning information template according to its risk level code, and then add the time label, representative concentration value, representative temperature value, efficiency value ( ), deviation index value ( ) and other specific data are filled into the corresponding placeholders in the template to construct a complete text warning content with time information and risk level identification. Finally, in order to facilitate automated processing and interaction between different systems, these generated text warning contents will be further encapsulated or converted into a unified coded standard structure output identifier, such as a JSON object or XML record containing specific fields (such as alarm level, timestamp, message body, parameter details, etc.). This standard structured output is the final generated etching process deviation warning code.

[0057] The above are merely preferred embodiments of the present invention and do not limit the present invention in any other form. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for controlling the concentration of a circuit board etching solution, characterized in that: The following steps are involved: Monitor the PCB etching solution in real time, obtain conductivity and temperature readings, compare them with the preset conductivity and temperature ranges of the PCB etching process, verify and filter the data, and establish an effective etching parameter set; Based on the effective etching parameter set, calling the conductivity value and combining it with a reference relationship curve between conductivity and etchant concentration to infer the etchant concentration and generate an etchant concentration estimation result; based on the etchant concentration estimation result, combined with the prior aging characteristics of the circuit board etching solution and the inherent drift probability of the sensor, establish an etchant concentration probability distribution; Based on the probability distribution of the etching agent concentration and the temperature value in the effective etching parameter set, the reaction activity of the current solution is evaluated to obtain the current activity of the etching solution; based on the current activity of the etching solution, the degree of solution performance attenuation is determined to obtain a comprehensive performance probability point set of the etching solution; Based on the comprehensive performance probability point set of the etching solution, the performance probability point is compared with the minimum acceptable performance threshold and the optimal performance target interval for circuit board etching, the deviation state of the performance probability point and the threshold or interval is identified, and an identification result of the risk point exceeding the threshold is obtained. Based on the identification result of the risk point exceeding the threshold, the risk level of the circuit board manufacturing process is matched, and an etching process deviation warning code is generated.

2. The method for controlling the concentration of the circuit board etching solution according to claim 1, wherein: The steps for obtaining the effective etching parameter set are: Collect the conductivity readings and temperature readings of the circuit board etching solution, match the time tags to synchronize the conductivity readings and temperature readings point by point, and generate a synchronized pairing group of conductivity readings and temperature readings; Based on the synchronous pairing group of conductivity readings and temperature readings, and comparing the preset conductivity range and temperature range of the circuit board etching process, each group of conductivity readings and temperature readings in the synchronous pairing group is interval-checked item by item, and the synchronous pairing groups that fall within the preset conductivity range and temperature range are screened to obtain the screened pairing groups that meet the preset process conditions; Based on the screened paired groups that meet the preset process conditions, all conductivity readings and temperature readings in the screened paired groups are extracted and packaged into structured records to obtain an effective etching parameter set.

3. The method for controlling the concentration of the circuit board etching solution according to claim 1, wherein: The steps for obtaining the etching agent concentration estimation result are: Based on the valid etching parameter set, the conductivity value field in each record is extracted, and after reading the corresponding numerical value, linear interpolation is performed to fill the missing points to generate a continuous and complete conductivity value sequence, and each conductivity value is bound to its own timestamp and temperature fields to generate a conductivity reading record set containing the conductivity value, timestamp, and temperature fields; According to the conductivity reading record set, a calibrated conductivity-etchant concentration reference relationship curve is called, each conductivity value is used as an input value to look up a table to obtain a concentration output node, if the conductivity value does not directly hit the reference relationship node, quadratic interpolation is performed between adjacent nodes to fit and generate a corresponding concentration value, the obtained concentration value is merged with the corresponding timestamp and temperature field and written into a concentration fitting result record set, thereby generating an etchant concentration fitting result set; Based on the set of etchant concentration fitting results, outlier detection is performed on the concentration values ​​in all records, and a 3-times standard deviation screening mechanism is used to exclude concentration anomalies that deviate from the mean. At the same time, the temperature field in the timestamp corresponding to the fitted concentration value is checked to see if it falls within the effective temperature fluctuation range. Only record entries that meet the conditions are retained, and the concentration values ​​that pass the check are output in chronological order as the final concentration estimation sequence to generate the etchant concentration estimation result.

4. The method for controlling the concentration of the circuit board etching solution according to claim 1, wherein: The steps for obtaining the etching agent concentration probability distribution are: Based on the etchant concentration estimation result, extracting the aging days and relative humidity value of each record, calling the sensor number matching to obtain the maximum drift in the last 30 days and recording it as the drift intensity value, dividing the stirring speed by the reference speed to obtain the stirring ratio, dividing the aging days by the maximum aging days to obtain the normalized aging factor, integrating the normalized aging factor, the relative humidity value, the drift intensity value and the stirring ratio to generate a correction parameter set; Calculating an etchant concentration correction value based on the correction parameter set; Based on the etchant concentration correction value, all etchant concentration correction values ​​are numerically segmented with a fixed interval starting step of 0.1 mol / L. The total number of entries of the etchant concentration correction value contained in each segmented interval is counted in turn, and the ratio of the number of entries in each segment to the total number of entries is calculated as the concentration probability value of the interval. Each concentration segmented interval is paired with the corresponding concentration probability value one by one and output as an ordered concentration-probability combination sequence to generate an etchant concentration probability distribution.

5. The method for controlling the concentration of the circuit board etching solution according to claim 1, wherein: The steps for obtaining the current activity of the etching solution are: Based on the etching agent concentration probability distribution, all etching agent concentration intervals and corresponding concentration probability values ​​are extracted, each etching agent concentration interval is used as an index parameter, and the temperature value corresponding to the same timestamp in the valid etching parameter set is matched. A triple set consisting of the etching agent concentration interval, the concentration probability value and the corresponding temperature value is constructed to generate a matching record set; Based on the matching record set, each combination of concentration value and temperature value is read one by one, and a matching or interval-fitted standard etching rate value is searched in a standard copper foil etching rate reference table, and the found standard etching rate value is combined with the corresponding concentration probability value in the original triplet into a four-tuple record to obtain a concentration-temperature-probability-rate matching combination set; Based on the concentration-temperature-probability-rate matching combination set, the probability average level of the rate values ​​in all combinations is calculated, and the weighted average rate value is extracted as the etching reaction ability performance value of the current solution under the current concentration and temperature conditions to generate the current etching solution activity.

6. The method for controlling the concentration of the circuit board etching solution according to claim 1, wherein: The steps for obtaining the comprehensive efficiency probability point set of the etching solution are as follows: Based on the current activity of the etching solution, extracting a standard interval value corresponding to the current activity of the etching solution, and synchronously reading the number of processed circuit board batches in the current batch statistical record, forming a one-to-one correspondence between the activity interval and the batch number, establishing an activity-batch number comparison set under the condition of consistent time tags, and generating an etching activity batch comparison set; Calculating the etching solution efficiency decay ratio of each group based on the etching activity batch control set; It is determined in turn whether each etching solution efficiency attenuation ratio exceeds a set attenuation identification threshold, and the corresponding etching solution activity is extracted from the records greater than the attenuation identification threshold. The occurrence probability points of the etching solution activity in the time dimension are constructed to generate a comprehensive etching solution efficiency probability point set.

7. The method for controlling the concentration of the circuit board etching solution according to claim 1, wherein: The steps for obtaining the identification result of the risk point exceeding the threshold are: Based on the comprehensive performance probability point set of the etching solution, each etching solution performance probability point is merged with the minimum acceptable performance threshold of the circuit board etching and the two end points of the optimal performance target interval, and each probability point, the minimum threshold, the lower limit and the upper limit of the optimal target interval are bound into a four-element relationship to generate a performance reference comparison set; Calculating a deviation index for each efficacy probability point based on the efficacy reference comparison set; Based on the deviation index, each deviation index is compared with the deviation index, the efficiency probability point number where the deviation index is greater than the deviation judgment threshold is marked, and the time label and efficiency value are output as the record result to generate the risk point identification result exceeding the threshold.

8. The method for controlling the concentration of the circuit board etching solution according to claim 1, wherein: The steps for obtaining the etching process deviation warning code are as follows: Based on the above-threshold risk point identification results, the time tag, concentration value, temperature value, and deviation index value corresponding to each identified efficiency probability point are extracted, and the etching condition combinations corresponding to the concentration values ​​and temperature values ​​are read one by one to generate an etching condition deviation feature set. Based on the etching condition deviation feature set, the concentration value and temperature value combination of each record is mapped to the circuit board manufacturing process risk level comparison table, the matching interval or adjacent level is searched and the risk level code is marked, all records are bound to the risk level code that matches them, and a process risk level matching result is generated; Based on the process risk level matching results, corresponding warning information templates are set according to different risk levels, and text warning content with time tags and risk level identifiers is constructed. The content is then uniformly encoded into an output identifier of a standard structure to generate an etching process deviation warning code.

9. The etching solution concentration control system of the circuit board etching solution concentration control method according to any one of claims 1 to 8, characterized in that: include: Parameter acquisition module: monitors the PCB etching solution in real time, obtains conductivity and temperature readings, verifies and filters the data against the preset conductivity and temperature ranges of the PCB etching process, and establishes a valid etching parameter set; Concentration estimation module: Based on the effective etching parameter set, the conductivity value is called and combined with the conductivity and etchant concentration reference curve to infer the etchant concentration and generate an etchant concentration estimation result. Based on the etchant concentration estimation result, combined with the prior aging characteristics of the circuit board etching solution and the inherent drift probability of the sensor, an etchant concentration probability distribution is established; Activity analysis module: based on the probability distribution of the etching agent concentration and the temperature value in the effective etching parameter set, evaluates the reaction activity of the current solution, obtains the current activity of the etching solution, determines the degree of solution performance attenuation based on the current activity of the etching solution, and obtains the probability point set of the comprehensive performance of the etching solution; Deviation warning module: Based on the comprehensive performance probability point set of the etching solution, the performance probability point is compared with the minimum acceptable performance threshold and the optimal performance target interval of the circuit board etching, the deviation state of the performance probability point and the threshold or interval is identified, and the identification result of the risk point exceeding the threshold is obtained. Based on the identification result of the risk point exceeding the threshold, the circuit board manufacturing process risk level is matched and an etching process deviation warning code is generated.

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