Smt paste printing stability and patch offset collaborative correction method and system

Abstract

The application discloses a kind of SMT tin paste printing stability and patch offset collaborative correction method and system, it is related to surface mount technology (SMT) production process quality control technical field.The method comprises: obtaining the coordinates of pad design center, tin paste actual center and device terminal projection center;In the unified coordinate system, the tin paste offset and device offset of tin paste actual center and device terminal projection center are calculated relative to pad design center respectively;Based on the center deviation and preset criterion, determine and output collaborative correction action.The application solves the problem that tin paste printing detection and patch precision control are independent of each other and cannot handle offset superposition effect collaboratively, by comprehensively analyzing the offset of tin paste and device, the welding risk can be accurately predicted, and the welding yield and production process stability are improved.

Description

Technical Field

[0001] This invention relates to the field of surface mount technology (SMT) production process quality control technology, and in particular to a method and system for co-correcting SMT solder paste printing stability and component misalignment. Background Technology

[0002] In surface mount technology (SMT) manufacturing, the quality of solder paste printing and the precision of component placement are two key factors determining the final soldering quality. For precision placement scenarios such as fine-pitch integrated circuits (ICs), micro-components (such as 0201 / 01005), QFN packages, and connectors with narrow pads, even the slightest positional misalignment can lead to soldering defects, such as insufficient solder, cold solder joints, bridging, tombstoning, or component misalignment.

[0003] Existing technologies typically perform separate process quality control for solder paste printing and component placement. For example, Solder Paste Printing Inspection (SPI) equipment can detect data such as the volume, area, height, and X / Y coordinate offset of the solder paste and determine whether the printing process is under control. However, it mainly focuses on the quality of the printing process itself and does not correlate the actual position of the solder paste with subsequent placement actions. On the other hand, pick-and-place machines usually have visual positioning and offset correction functions, which can correct the placement position based on the reference points of the circuit board and the visual inspection results of the components. However, its correction target is usually the pad design coordinates defined in the circuit board design file (Gerber), rather than actively referring to the actual position of the solder paste detected by SPI.

[0004] Therefore, existing technologies have the following drawbacks: First, solder paste printing inspection and component placement calibration operate under their respective coordinate systems and evaluation standards, lacking a unified coordination mechanism. Second, when solder paste offset and component offset coexist, existing technologies cannot determine whether they cancel each other out or are superimposed in the same direction, easily leading to missed soldering risks. For example, individual solder paste and component offsets may not exceed limits, but their combined effects can cause defects. Third, if the placement machine does not consider the actual position of the solder paste during calibration, even if the component is precisely placed in the center of the designed pad, solder paste offset may reduce the effective overlap area between the component terminals and the solder paste, affecting soldering quality. Finally, due to the lack of collaborative analysis, when anomalies occur, engineers find it difficult to quickly identify the root cause of the problem and cannot determine whether to adjust the printer, clean the stencil, or correct the placement coordinates. Summary of the Invention

[0005] The purpose of this application is to provide a method and system for co-correcting SMT solder paste printing stability and component misalignment, so as to solve the problem in the prior art that it is difficult to comprehensively judge the risk of misalignment superposition and cannot perform effective co-correction because solder paste printing detection and component positioning are independent of each other.

[0006] To achieve the above objectives, this application provides the following solution: Firstly, this application provides a method for co-correcting SMT solder paste printing stability and component misalignment, including: The system acquires the design outline data and design center coordinates of multiple target pads on the current circuit board, the actual outline data and actual center coordinates of multiple solder pastes obtained through solder paste detection, and the projected outline data and projected center coordinates of multiple device terminals obtained through chip mounting. In a unified coordinate system, a set of center deviations is calculated based on the design center coordinates, the actual center coordinates of the solder paste, and the projected center coordinates of the device terminals. The set of center deviations includes: the solder paste offset of the actual center coordinates of the solder paste relative to the design center coordinates, and the device offset of the projected center coordinates of the device terminals relative to the design center coordinates. Based on the center deviation and the preset criteria, a collaborative correction action is determined and output.

[0007] Secondly, this application provides a collaborative correction system for SMT solder paste printing stability and component misalignment, including: The data acquisition module is used to acquire the design outline data and design center coordinates of multiple target pads on the circuit board, the actual outline data and actual center coordinates of multiple solder pastes obtained through solder paste detection, and the projection outline data and projection center coordinates of multiple device terminals obtained through chip positioning. The deviation calculation module is used to calculate a set of center deviations in a unified coordinate system based on the design center coordinates, the actual center coordinates of the solder paste, and the projected center coordinates of the device terminals. The center deviations include: the solder paste offset of the actual center coordinates of the solder paste relative to the design center coordinates, and the device offset of the projected center coordinates of the device terminals relative to the design center coordinates. The action output module is used to determine and output a coordinated correction action based on the center deviation and a preset criterion.

[0008] Thirdly, this application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the SMT solder paste printing stability and chip offset co-correction method described in any one of the above.

[0009] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the SMT solder paste printing stability and component offset co-correction method described above.

[0010] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the SMT solder paste printing stability and chip offset collaborative correction method described above.

[0011] According to the specific embodiments provided in this application, the following technical effects are disclosed: 1. By comprehensively analyzing solder paste offset and device offset under a unified coordinate system, the superposition effect of the two can be accurately identified and quantified, thereby predicting and avoiding soldering defects such as insufficient solder, cold solder joints, and bridging caused by offset superposition, which significantly improves the final soldering yield.

[0012] 2. By introducing the overlap area between device terminals and pads, between device terminals and solder paste, and the spacing between adjacent pads as the basis for judgment, the correction decision is closer to the actual situation of physical soldering, avoiding misjudgment that may be caused by relying solely on center point offset, and improving the accuracy and reliability of the decision.

[0013] 3. By distinguishing between overall offset and local offset, more targeted correction actions can be output (such as adjusting the printing press alignment or suggesting cleaning the stencil), achieving precise location and handling of the root cause of the problem, improving correction efficiency and speed of solving process problems.

[0014] 4. By establishing a closed-loop update mechanism based on continuous production data and adopting statistical process control analysis methods, the system can adaptively respond to process drift and dynamically optimize correction criteria, thereby helping to ensure the long-term stability of the production process. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart illustrating a method for co-correcting SMT solder paste printing stability and component offset in one embodiment of this application. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] This application provides a method for collaboratively correcting SMT solder paste printing stability and component placement misalignment, aiming to solve the technical problem in the prior art where solder paste printing inspection (SPI) and pick-and-place machine visual positioning are performed independently, leading to missed or false judgments of misalignment risks. The core of this method lies in establishing a unified coordinate system and evaluation standard to collaboratively analyze and correct printing misalignment and component placement misalignment.

[0020] Reference Figure 1 The SMT solder paste printing stability and component offset co-correction method provided in this application embodiment specifically includes: Step S110: Obtain the design outline data and design center coordinates of multiple target pads on the current circuit board, the actual outline data and actual center coordinates of multiple solder pastes obtained through solder paste detection, and the projection outline data and projection center coordinates of multiple device terminals obtained through chip positioning.

[0021] Step S120: In a unified coordinate system, a set of center deviations is calculated based on the design center coordinates, the actual solder paste center coordinates, and the projected center coordinates of the device terminals. The set of center deviations includes: the solder paste offset of the actual solder paste center coordinates relative to the design center coordinates, and the device offset of the projected center coordinates of the device terminals relative to the design center coordinates.

[0022] Step S130: Based on the center deviation and preset criteria, determine and output the collaborative correction action.

[0023] This method first requires acquiring the design contour data and design center coordinates of multiple target pads on the current circuit board, the actual contour data and actual center coordinates of multiple solder pastes obtained through solder paste inspection, and the projected contour data and projected center coordinates of multiple device terminals obtained through chip mounting positioning. This step is crucial for building a unified analysis foundation. Its design aims to break down the data barriers between SPI and the chip mounter, integrating the quality data of the two previously isolated processes into the same data dimension. By acquiring these three sets of key geometric and positional information, the method overcomes the deficiency in existing technologies where the lack of a unified coordinate system prevents accurate assessment of offset superposition effects, providing complete and reliable data input for subsequent collaborative analysis.

[0024] Next, in a unified coordinate system, a set of center deviations is calculated based on the design center coordinates, the actual solder paste center coordinates, and the projected center coordinates of the device terminals. Specifically, these center deviations include the solder paste offset relative to the design center coordinates, and the device offset relative to the design center coordinates. The principle behind this step is to compare all actual measured values ​​with theoretical design values, thereby quantifying the degree and direction of offset in each process. By calculating these two core offset vectors, the deviations introduced by the printing process and the placement process can be intuitively revealed, solving the problems of indistinguishable offset sources and unclear responsibility boundaries in the background technology, and achieving precise quantification of deviations in each process.

[0025] Finally, based on at least one of the center deviations and a preset criterion, a collaborative correction action is determined and output. This step is the core of the closed-loop control achieved by this invention. Its design aims to go beyond mere detection and alarm; it intelligently decides on the most appropriate response strategy based on quantified deviation data and preset engineering rules. By outputting actions based on deviations and criteria, it solves the problem in existing technologies that can only perform single-process alarms or optimizations, but cannot perform cross-process collaborative processing. This achieves a leap from passive monitoring to proactive intervention, significantly improving the production line's responsiveness and adaptability to process fluctuations.

[0026] Furthermore, in a preferred embodiment, the collaborative correction action can be at least one of a correction action targeting the printing side, a compensation action targeting the surface mount side, or an action to intercept the current circuit board. This definition concretizes the higher-level "collaborative correction action" into three core industrial operations, enhancing the feasibility of the solution. The principle is to take different levels of countermeasures based on the nature and severity of the problem. For example, minor, controllable offsets can be absorbed through surface mount compensation; systemic offsets require correction at the source (printing side); while severe offsets that may lead to batch defects must be intercepted immediately. By providing these three explicit action options, the problem of single and inflexible response strategies in existing technologies is solved, enabling differentiated and precise handling of different risk levels.

[0027] Furthermore, the correction action on the printing side involves adjusting the printing position of subsequent circuit boards; the compensation action on the surface mount side involves adjusting the placement coordinates of components on the current circuit board. This further clarifies the specific meanings of printing-side correction and surface mount compensation. Its design aims to distinguish between "stopgap" and "cure" operations: "Surface mount compensation" is a "stopgap" measure for the current board, adjusting the placement coordinates to adapt to the solder paste misalignment that has occurred, aiming to salvage the current board; while "printing-side correction" is a "cure" measure for subsequent boards, adjusting the alignment parameters of the printer to eliminate the source of misalignment at its root. This clear distinction resolves the confusion among engineers when faced with misalignment, who often don't know whether to adjust the current board or the equipment, achieving an organic combination of short-term remediation and long-term optimization.

[0028] In one alternative implementation, when solder paste offset is within a preset compensable range, the coordinated correction action is determined to be a compensation action targeting the surface mount side. This criterion clarifies the prerequisite for triggering "surface mount side compensation." The principle is that not all solder paste offsets are suitable for compensation via surface mount technology. Compensation is only safe and effective when the offset is small and compensation will not cause new problems (such as excessive terminal misalignment from the pad). By setting a "compensable range," the problem of blind compensation potentially leading to unintended consequences is solved, ensuring the effectiveness and safety of the compensation action and helping to avoid secondary defects.

[0029] Furthermore, to make the correction actions more targeted, the correction actions on the printing side can be determined based on whether the solder paste offset is a board-wide offset or a localized offset. The technical principle is that different types of offsets usually correspond to different root causes. Board-wide offsets often point to overall alignment problems of the printer, while localized offsets may be related to localized stencil blockage, contamination, or localized deformation of the substrate. By adding this diagnostic step, the previous "one-size-fits-all" adjustment of printer parameters may be ineffective or exacerbate localized problems, achieving precise location of the root cause of the problem. This allows for more targeted measures, such as adjusting the overall alignment of the printer or guiding manual cleaning of specific stencil areas.

[0030] Preferably, when the differentiation result is a full-plate offset, the coordinated correction action is determined to be a correction action targeting the printing side. This solidifies the above-mentioned diagnosis-action logic. Its design aims to establish a clear rule: once the system identifies a problem as systemic and globally impactful (i.e., a full-plate offset), adjustments to the upstream core equipment (printing press) should be triggered. By establishing this direct causal link, it avoids erroneously intercepting individual plates or performing ineffective local compensation when facing a full-plate offset, ensuring the effective use of correction resources and achieving rapid response and effective resolution of systemic problems.

[0031] To achieve automatic determination of offset types, the differentiation steps may include: calculating the average offset vector of multiple solder paste offsets; if the magnitude of the average offset vector is greater than a first preset threshold, and the dispersion of each solder paste offset from the average offset vector is less than a second preset threshold, then it is determined to be a board-wide offset. This provides a concrete and operable algorithm. The principle is that if a board-wide offset exists, then the solder paste offset vectors on most pads will exhibit a high degree of consistency in direction and magnitude. The magnitude of the average offset vector being greater than the first threshold ensures that the offset is significant rather than random noise; while the dispersion being less than the second threshold ensures that this offset is a "collective behavior" rather than individual actions. This dual-threshold algorithm solves the problems of subjective and inefficient manual judgment of offset types, achieving rapid, objective, and automated classification of offset patterns.

[0032] To further improve the accuracy of the judgment, in another preferred embodiment, the method also includes calculating the overlap area between the device terminal and the target pad, the overlap area between the device terminal and the solder paste, and the spacing between the solder paste on two adjacent target pads. The principle behind introducing these physical quantities is that center point deviation is only an indirect indicator, while the final determination of soldering quality lies in the effective physical contact area and the presence of short-circuit risk. By directly calculating these physical quantities that are strongly correlated with the soldering result, the problem of relying solely on center deviation potentially being out of sync with the actual soldering effect is solved, making the decision-making basis closer to the physical reality and significantly improving the accuracy of risk assessment.

[0033] Based on this, the specific steps for determining and outputting collaborative correction actions can be optimized as follows: decisions are made based on center deviation, the overlap area between the device terminal and the target pad, the overlap area between the device terminal and the solder paste, the spacing between the solder paste on two adjacent target pads, and preset criteria. When the overlap area between the device terminal and the target pad, the overlap area between the device terminal and the solder paste, and the spacing between the solder paste on two adjacent target pads are all greater than their respective thresholds, it indicates that the basic soldering conditions and safety clearances are guaranteed. At this time, correction actions for the printed side or compensation actions for the surface mount side can be output based on the center deviation. Otherwise, if any condition is not met, it means that there is an unacceptable soldering risk (such as open circuit or short circuit), and the system should output an action to intercept the current circuit board. This decision logic solves the problem of misjudgment or omission that may be caused by a single criterion through multi-dimensional threshold judgment, builds a more robust decision model, and ensures that compensation or correction is only performed when safety is confirmed; otherwise, the action to intercept the current circuit board is output, thereby significantly improving the yield of the final product.

[0034] To enable the system to adapt and learn, the method in this embodiment of the invention further includes updating the criteria used to determine the collaborative correction action based on the center deviation of multiple consecutive circuit boards. This is designed to address slow process drift that may occur during production, such as equipment thermal expansion and contraction, and batch differences in materials. By continuously learning from recent data, the system can dynamically adjust its internal criteria (such as the threshold of the compensation range). This solves the problem that static parameters gradually become ineffective in the face of dynamically changing production environments, enabling the system to have adaptive optimization capabilities.

[0035] Specifically, the steps for updating the criteria may include: performing statistical process control (SPC) analysis on the center deviation of multiple consecutive circuit boards to obtain at least one of the moving average, standard deviation, or process capability index Cpk as the analysis result; and then updating the criteria based on the analysis result. The principle is that SPC tools can identify systematic trends or anomalies from seemingly random fluctuations. For example, if the moving average continuously deviates from the target, it indicates a systematic deviation; if the standard deviation or Cpk index deteriorates, it indicates a decrease in process stability. By feeding these statistical analysis results back into the decision-making system, such as dynamically adjusting compensation thresholds or interception criteria, the limitation of not being able to discern long-term trends from a single measurement is overcome, realizing a shift from passive response to predictive maintenance and proactive process optimization.

[0036] This application also provides a system for coordinated correction of SMT solder paste printing stability and component misalignment. The system includes a data acquisition module, a deviation calculation module, and an action output module. The data acquisition module performs the aforementioned data acquisition steps and can be integrated with or connected to SPI devices and pick-and-place machines on the production line to capture the required contour and coordinate data in real time. The deviation calculation module performs the aforementioned deviation calculation steps and includes logic for coordinate transformation and vector calculation to ensure accurate calculation of solder paste and component misalignment in a unified coordinate system. The action output module is responsible for performing the aforementioned steps of determining and outputting coordinated correction actions. Based on the results of the deviation calculation module and a built-in criterion library, it generates and sends specific control commands to the printer, pick-and-place machine, or manufacturing execution system (MES).

[0037] The following describes in more detail the SMT solder paste printing stability and component offset collaborative correction method and system provided in this application through a more specific embodiment.

[0038] In one embodiment, the SMT solder paste printing stability and component misalignment co-correction method is implemented on an SMT production line equipped with a solder paste printer, SPI inspection equipment, and a vision-positioning component placement machine. First, the system's data acquisition module retrieves the design contour data (e.g., pad shape and size defined in Gerber data) and design center coordinates P for all target pads on the currently produced circuit board from the production preparation file. This data forms the benchmark for all subsequent comparisons.

[0039] When the circuit board passes through the solder paste printer and is transferred to the SPI inspection device, the data acquisition module drives the SPI to perform a full-board scan of the circuit board, acquiring the actual contour data and actual center coordinates S of the solder paste printed on each target pad. These data reflect the actual quality of the printing process.

[0040] Subsequently, when the same circuit board is conveyed to the pick-and-place machine, before the components are placed, the machine's flying or fixed camera takes pictures of the picked-up components. The data acquisition module obtains the projected contour data of each terminal on the component and the coordinates T of the component terminal projection center from the pick-and-place machine's vision system. This data reflects the actual position and orientation of the component after it has been picked up.

[0041] After acquiring the above three sets of data, the system's deviation calculation module begins operation. This module processes the data within a unified device coordinate system. It calculates solder paste offset and component offset. Solder paste offset is the offset vector of the actual center coordinates S of the solder paste relative to the design center coordinates P of the pad. Component offset is the offset vector of the projected center coordinates T of the component terminal relative to the design center coordinates P of the pad. These two vectors clearly quantify the magnitude and direction of the deviations introduced by the printing and placement processes, respectively.

[0042] Finally, the action output module makes a decision based on the results obtained from the deviation calculation module and preset criteria. For example, a simple criterion could be: if the magnitude of the solder paste offset is less than a preset primary threshold (e.g., 10% of the pad width), it is considered acceptable, and a "release" action is output; if it is greater than the threshold, an "alarm" action is output, prompting manual inspection. This basic embodiment solves the problem of isolated SPI and pick-and-place machine data and the inability to coordinate judgment in the background technology by establishing a unified coordinate system and quantifying the deviation. It realizes unified monitoring and preliminary decision-making for printing and placement offsets, laying the foundation for subsequent more complex collaborative correction strategies.

[0043] In this embodiment, the collaborative correction action is specified into three types: correction action for the printed side, compensation action for the surface mount side, or action to intercept the current circuit board. This refinement makes the system output no longer a simple "alarm," but an operational instruction with clear guidance. Its technical advantage lies in providing differentiated solutions for different offset situations, making the processing flow more efficient and accurate. For example, for a slight offset, the system can choose the relatively low-cost "surface mount side compensation" to resolve it without stopping the machine or reprinting, thereby significantly improving production efficiency while ensuring quality.

[0044] Furthermore, the correction action on the printing side involves adjusting the printing position of subsequent circuit boards, while the compensation action on the surface mount side involves adjusting the surface mount coordinates of components on the current circuit board. This distinction clarifies the target and timing of the two core operations. "Surface mount side compensation" is immediate, acting on the current board, and its advantage lies in its ability to immediately salvage work-in-process with compensable defects, preventing them from becoming scrap. "Printing side correction," on the other hand, is forward-looking, acting on subsequent boards, and its advantage lies in its ability to eliminate systematic misalignment at its source, preventing the same problem from recurring in subsequent production. By combining these two actions, this invention achieves an intelligent control strategy that combines "short-term remediation" with "long-term optimization."

[0045] In this embodiment, the system determines whether to perform surface mount compensation based on a key criterion: the collaborative correction action is only considered surface mount compensation if the calculated solder paste offset is within a preset, considered safe and effective "compensable range." For example, this range can be set to ±15% of the pad width. The technical advantage of introducing this criterion is that it sets a "safety gate" for enabling surface mount compensation, preventing improper compensation for excessive or dangerous offsets. This avoids excessive deviation of device terminals from the pad center to accommodate solder paste, which could lead to new soldering defects (such as decreased reliability or cold solder joints), ensuring the reliability of the compensation operation itself.

[0046] To ensure more precise calibration, this embodiment diagnoses the solder paste offset type before deciding whether to perform printing-side calibration, distinguishing between board-wide and localized offsets. Board-wide offsets typically mean that most solder paste dots on the entire circuit board are offset in similar directions and distances, often indicating a problem with the overall alignment of the printer. Localized offsets, on the other hand, are limited to a specific area of ​​the circuit board and may be caused by localized stencil blockage or contamination. The advantage of this differentiation is that it allows for targeted solutions. Without differentiation, making global adjustments to a localized problem (such as adjusting printer alignment) not only fails to solve the problem but may even cause new offsets in other previously normal areas. By differentiating the offset type, the system can precisely direct calibration commands to the root cause of the problem.

[0047] Specifically, when the system determines through analysis that the offset is a board-wide offset, it determines that the collaborative correction action is a correction action targeting the printing side. This rule directly links the diagnostic results with specific actions. The resulting technical effect is that once a systemic problem is confirmed, adjustments to systemic parameters are immediately triggered, achieving a rapid and accurate response to significant process offsets, thereby efficiently restoring the stability of the entire production process.

[0048] To achieve this automated diagnosis, this embodiment provides a specific algorithm: First, the average offset vector of all detected solder pastes on the board is calculated to obtain an "average offset vector". Then, it is determined whether the magnitude of this average offset vector is greater than a preset first threshold (e.g., 50 micrometers), and simultaneously, whether the dispersion between the actual offset vector of each solder paste and this average offset vector (e.g., measured by the standard deviation of the angle between all vectors and the average vector) is less than a preset second threshold. Only when the "collective trend" of the offset is sufficiently obvious (the magnitude is large enough) and the "pacing" is sufficiently consistent (the dispersion is small enough) is it determined to be a board-wide offset. The technical effect of this algorithm is that it transforms a complex pattern recognition problem into a clear, quantifiable mathematical judgment, enabling the computer to reliably and repeatedly perform offset type classification, greatly improving the objectivity and efficiency of diagnosis.

[0049] To make the system's decisions closer to the final soldering physical results, a crucial improvement is the introduction of calculations for "overlap area" and "safety gap" during the decision-making process. The system not only calculates the center point deviation but also the overlap area (Apt) between the device terminal and the target pad, the overlap area (Ast) between the device terminal and the solder paste, and the spacing between the solder paste on adjacent target pads, which serves as the safety gap. Simple center point alignment does not equate to a good solder joint; sufficient overlap area is the physical basis for forming a reliable solder joint, and sufficient safety gap is the guarantee against bridging and short circuits. Therefore, introducing these physical quantities upgrades the decision model from a purely geometric position comparison to a comprehensive evaluation based on physical soldering conditions, significantly improving the accuracy of risk prediction.

[0050] Based on this richer physical information, the decision-making process becomes more refined and reliable. In this embodiment, the system first checks whether three key physical quantities—Apt, Ast, and the solder paste spacing on adjacent pads—meet their respective preset minimum thresholds. For example, Apt must be greater than 70% of the theoretical contact area, Ast must be greater than 80%, and the spacing between adjacent solder paste pads must not be less than 50 micrometers. If any of these requirements are not met, it means there is an unacceptable risk of open or short circuit, and the system will immediately output the action of "intercepting the current circuit board" and will no longer attempt any compensation. Only when all three basic requirements are met will the system proceed to the subsequent correction or compensation logic based on center deviation. This "precondition" judgment process has the technical effect of building a solid "safety bottom line," ensuring that all subsequent optimization actions are carried out on the basis of guaranteeing basic soldering quality and safety, thereby effectively preventing catastrophic defects caused by improper compensation.

[0051] To enable the system to adapt to long-term, slow drift in production line processes, this embodiment also introduces a closed-loop update mechanism. The system continuously records and analyzes the center deviation data of multiple consecutive circuit boards and updates the decision-making criteria based on the analysis results. For example, if the system finds that the average solder paste offset is continuously shifting positively along the X-axis on five consecutive boards, even if the offset amount is small each time, the system will identify this as a process drift trend. The technical effect of this mechanism is that it gives the system the ability to "learn" and "adapt," enabling it to discern long-term trends from historical data that cannot be detected by a single measurement, thereby achieving predictive management of process status.

[0052] In practice, this update can be achieved through Statistical Process Control (SPC) analysis. The system statistically analyzes the center deviation data of N consecutive boards, calculating statistical indicators such as the process capability index Cpk, moving average, and standard deviation. When it is found that Cpk is continuously decreasing or the moving average is continuously deviating from the center, the system can automatically update the criteria according to preset rules. For example, it can tighten the threshold of the compensable range or trigger printing-side correction suggestions more frequently. The technical advantage of this SPC-based dynamic update is that it automates and makes professional quality management methods real-time, enabling the system to act like an experienced engineer, not only handling current deviations but also proactively adjusting control strategies based on the changing trends of process capability, thereby maintaining the entire production process at a higher level of stability.

[0053] The following is a detailed explanation of the process of the SMT solder paste printing stability and component misalignment co-correction method provided in this application, using an application example. In one application example, a circuit board carrying fine-pitch QFN devices enters the control range of this system. First, the data acquisition module obtains the actual solder paste center coordinates S of all pads of the QFN device from the SPI device, and obtains the terminal projection center coordinates T of the QFN device from the pick-and-place machine vision system, while retrieving the pre-stored pad design center coordinates P.

[0054] The deviation calculation and decision-making module initiates a multi-level judgment process. First, the module not only calculates the center deviation vectors of solder paste offset and component offset, but more importantly, it uses this deviation data, combined with the contour data of each part, to accurately calculate two key overlap areas: the overlap area Apt between the terminal and the pad, and the overlap area Ast between the terminal and the solder paste. Simultaneously, it calculates the safe solder paste clearance between adjacent pads. Assume the calculation results are: Apt meets the threshold, but Ast is slightly below its safe threshold, and the safe clearance is also in a critical state.

[0055] Since Ast and safety clearance do not simultaneously meet the thresholds, the system determines that there is an unacceptable soldering risk. At this time, the system will not make any hasty compensation, but will immediately determine the collaborative correction action as "intercept the current circuit board" and send an alarm message to the MES system and production line operation interface, which reads "QFN device has risk of cold solder joint and bridging, Ast or safety clearance is insufficient".

[0056] Meanwhile, the system did not stop analyzing. It continued to perform type diagnosis on the solder paste offset data that had just been detected. By calculating the average offset vector and dispersion of all pad offsets, the system determined that this offset was not a random local problem, but a "board-wide offset" with a high degree of directional consistency.

[0057] Since the system has determined it to be a full-plate misalignment, it will generate a correction suggestion for the "printing side" along with the intercept command: "Full-plate printing misalignment detected. It is recommended to correct the X / Y alignment of the printing press." This information provides engineers with a clear direction for troubleshooting.

[0058] Finally, all data related to this event, including the original deviation, calculated overlap area, decision results, and offset type, are recorded in the system's database. The closed-loop update module periodically performs SPC analysis on the data from the most recent 100 boards. If the analysis reveals that similar Ast insufficiency events caused by board-wide offsets have occurred multiple times, and the Cpk index shows a downward trend, the closed-loop update module may automatically execute a preset update action: temporarily raising the Ast alarm threshold by 5%, making the system more sensitive to this type of risk and thus issuing an earlier warning, until engineers complete fundamental equipment maintenance and the Cpk index recovers.

[0059] Through the collaborative work of the entire process described above, this embodiment achieves a synergistic effect of multiple technologies. First, by introducing the judgment of overlap area and safety clearance, it can more accurately predict and intercept high-probability welding defects compared to embodiments that only use center deviation, thus improving the accuracy of single-board interception. Second, by distinguishing offset types, it provides engineers with precise fault diagnosis information, pointing the root cause of the problem to the printer rather than the pick-and-place machine, avoiding ineffective troubleshooting and improving production line maintenance efficiency. Finally, through the SPC closed-loop update mechanism, it can monitor and adapt to long-term changes in process capabilities, realizing a shift from passive alarm to proactive, predictive process management. The synergistic effect of these technical features significantly improves the overall performance of this invention in complex industrial scenarios, achieving efficient and accurate quality control goals and helping to reduce quality costs.

[0060] The technical solution of this invention demonstrates its unique value in multiple practical application scenarios. In a scenario targeting the risk of bridging in fine-pitch ICs, when SPI detection detects that the solder paste centers of multiple pads on one side of the IC are offset to the right, and the pick-and-place machine's vision also shows a rightward placement offset of the device itself, this system can identify that these two offsets are superimposed in the same direction. The system calculates the superimposed virtual position and determines that the solder paste gap between adjacent pads will be below the safety threshold. Therefore, the system will not perform any compensation action, but instead outputs an "intercept" command and alerts the printer that there may be a problem with alignment, thereby helping to avoid a high-probability bridging accident.

[0061] In another scenario addressing the tombstoning risk of small-sized surface mount components like the 0201, the system focuses not only on positional misalignment but also on the uniformity of solder paste volume. When the system detects a significant difference in solder paste volume between the pads at both ends of a resistor (e.g., one end has normal volume, while the other is only 60% of the target value), even if the positional misalignment of the solder paste at both ends is within acceptable limits, the system will determine, based on its built-in physical model, that this uneven solder volume will generate unbalanced surface tension during reflow soldering, leading to a higher risk of tombstoning. Therefore, the system will output an "intercept" command and suggest checking for blocked vias in the stencil, rather than simply allowing the component to be placed.

[0062] Furthermore, this system can efficiently handle compensable offsets. For example, when a slight, stable, full-board solder paste offset occurs on the production line, and the solder paste volume and morphology are normal, the system will perform a compensation feasibility calculation. It will simulate a reverse placement compensation amount and verify whether the compensated device terminals can simultaneously meet the two conditions of "sufficient overlap with the pads" and "sufficient overlap with the solder paste," without affecting the safety clearance. After confirming that the compensation is safe and effective, the system will automatically fine-tune the placement coordinates of the current board and record the offset trend for subsequent process drift analysis. This approach, without sacrificing quality, largely ensures production continuity and improves overall output efficiency.

[0063] In one exemplary embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0064] In one exemplary embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0065] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0066] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0067] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0068] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchain. The processors involved in the embodiments provided in this application may be, but are not limited to, general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc.

[0069] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0070] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for co-correcting SMT solder paste printing stability and component misalignment, characterized in that, include: The system acquires the design outline data and design center coordinates of multiple target pads on the current circuit board, the actual outline data and actual center coordinates of multiple solder pastes obtained through solder paste detection, and the projected outline data and projected center coordinates of multiple device terminals obtained through chip mounting. In a unified coordinate system, a set of center deviations is calculated based on the design center coordinates, the actual center coordinates of the solder paste, and the projected center coordinates of the device terminals. The set of center deviations includes: the solder paste offset of the actual center coordinates of the solder paste relative to the design center coordinates, and the device offset of the projected center coordinates of the device terminals relative to the design center coordinates. Based on the center deviation and the preset criteria, a collaborative correction action is determined and output.

2. The method for coordinated correction of SMT solder paste printing stability and component misalignment according to claim 1, characterized in that, The coordinated correction action is at least one of the following: a correction action for the printed side, a compensation action for the surface mount side, or an action to intercept the current circuit board.

3. The method for coordinated correction of SMT solder paste printing stability and component misalignment according to claim 2, characterized in that, The correction action for the printing side is the action of adjusting the printing position of the subsequent circuit board; The compensation action for the surface mount side is the action of adjusting the surface mount coordinates of the components on the current circuit board.

4. The method for coordinated correction of SMT solder paste printing stability and component misalignment according to any one of claims 1 to 3, characterized in that, Also includes: Calculate the overlap area between the device terminal and the target pad, the overlap area between the device terminal and the solder paste, and the spacing between two adjacent target pads; Based on the center deviation and the preset criteria, a coordinated correction action is determined and output, specifically including: Based on the center deviation, the overlap area between the device terminal and the target pad, the overlap area between the device terminal and the solder paste, the distance between two adjacent target pads, and a preset criterion, a coordinated correction action is determined and output.

5. The method for coordinated correction of SMT solder paste printing stability and component misalignment according to claim 4, characterized in that, The criteria include: When the overlap area between the device terminal and the target pad, the overlap area between the device terminal and the solder paste, and the distance between two adjacent target pads are all greater than their respective thresholds, a correction action for the printing side or a compensation action for the mounting side is output based on the center deviation. Otherwise, output the action that intercepts the current circuit board.

6. The method for coordinated correction of SMT solder paste printing stability and component misalignment according to claim 2 or 3, characterized in that, The correction action for the printed side is determined based on the distinction between whether the solder paste offset is a full-board offset or a local offset.

7. The method for coordinated correction of SMT solder paste printing stability and component misalignment according to claim 6, characterized in that, The steps for distinguishing include: Calculate the average offset vector of the plurality of solder paste offsets; If the magnitude of the average offset vector is greater than a first preset threshold, and the dispersion of the offset of each solder paste from the average offset vector is less than a second preset threshold, then it is determined to be a board-wide offset; otherwise, it is determined to be a local offset.

8. The method for coordinated correction of SMT solder paste printing stability and component misalignment according to any one of claims 1 to 3, characterized in that, Also includes: The criteria for determining the coordinated correction action are updated based on the center deviation of multiple consecutive circuit boards.

9. The method for coordinated correction of SMT solder paste printing stability and component misalignment according to claim 6, characterized in that, The step of updating the criterion for determining the cooperative correction action includes: Statistical process control analysis is performed on the center deviation of the multiple consecutive circuit boards. The statistical process control analysis includes calculating at least one of the moving average, standard deviation, or process capability index Cpk of the center deviation.

10. A system for coordinated correction of SMT solder paste printing stability and component misalignment, characterized in that, include: The data acquisition module is used to acquire the design outline data and design center coordinates of multiple target pads on the circuit board, the actual outline data and actual center coordinates of multiple solder pastes obtained through solder paste detection, and the projection outline data and projection center coordinates of multiple device terminals obtained through chip positioning. The deviation calculation module is used to calculate a set of center deviations in a unified coordinate system based on the design center coordinates, the actual center coordinates of the solder paste, and the projected center coordinates of the device terminals. The center deviations include: the solder paste offset of the actual center coordinates of the solder paste relative to the design center coordinates, and the device offset of the projected center coordinates of the device terminals relative to the design center coordinates. The action output module is used to determine and output a coordinated correction action based on the center deviation and a preset criterion.

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