A method, device and machine for mounting a circuit board

Abstract

This application discloses a method, apparatus, and pick-and-place machine for mounting circuit boards. The method includes: sending a first drive command to a pick-and-place drive motor based on a circuit board arrival signal, causing the pick-and-place drive motor to drive a suction nozzle to perform a material suction action according to the first drive command; acquiring the real-time current of the pick-and-place drive motor during material suction, and generating a current-time curve based on the real-time current; determining the peak current and current change rate of the pick-and-place drive motor based on the current-time curve; if the peak current is less than a first preset threshold and the current change rate is less than a second preset threshold, then sending a second drive command to the pick-and-place drive motor, causing the pick-and-place drive motor to perform a pick-and-place action according to the second drive command; otherwise, re-executing the step of sending the suction command to the pick-and-place drive motor based on the circuit board arrival signal. This method can effectively improve the pick-and-place yield.

Description

Technical Field

[0001] This application relates to the field of circuit board manufacturing technology, and in particular to a method, apparatus and machine for mounting circuit boards. Background Technology

[0002] When placing components onto a circuit board, the pick-and-place machine uses a nozzle to pick up components from the feeder and mount them onto the circuit board. In existing technology, vacuum level detection is used to determine whether the nozzle has successfully picked up the component. When the vacuum level inside the nozzle reaches a preset threshold, the component is considered to have been successfully picked up.

[0003] However, vacuum level testing only reflects the airtightness between the nozzle and the component; it cannot directly prove that the component has actually detached from the tape and been reliably carried. Using vacuum level testing to determine whether the nozzle has successfully picked up a component significantly limits the improvement of surface mount yield. For example, for small components such as 0201 resistors, due to their light weight, static electricity, air eddies, or tape stickiness can cause the vacuum level to reach the target instantaneously, but the component may not actually be picked up, leading to it falling during transport. Furthermore, nozzle wear or minor blockages in the air passage can cause the vacuum baseline to drift, preventing the preset threshold from being reached even if the component is successfully picked up. Summary of the Invention

[0004] This application provides a method, apparatus, and pick-and-place machine for placing circuit boards, in order to solve the technical problem that relying on vacuum level detection to determine whether the nozzle has successfully picked up the component greatly restricts the improvement of the placement yield.

[0005] To address the aforementioned technical problems, in a first aspect, this application provides a method for surface mount technology (SMT) of a circuit board, comprising: sending a first drive command to a surface mount drive motor based on a circuit board arrival signal, causing the surface mount drive motor to drive a suction nozzle to perform a material suction action according to the first drive command; acquiring the real-time current of the surface mount drive motor during the material suction process, and generating a current-time curve based on the real-time current; determining the peak current and current change rate of the surface mount drive motor based on the current-time curve; if the peak current is less than a first preset threshold and the current change rate is less than a second preset threshold, then sending a second drive command to the surface mount drive motor, causing the surface mount drive motor to perform a surface mount action according to the second drive command; otherwise, re-executing the step of sending a suction command to the surface mount drive motor based on the circuit board arrival signal.

[0006] In this surface mount method for the circuit board, the nozzle needs to overcome the release resistance between the component and the tape during the suction action. By monitoring the real-time current of the mount drive motor, a current-time curve can be generated, which reflects the torque consumed by the nozzle to overcome the release resistance during the suction process. When the component is stuck to the tape, the mount drive motor needs to output a larger instantaneous torque, resulting in a significant increase in the peak current; at the same time, the more rapid the torque increase, the greater the rate of change of current. Based on the peak current and the rate of change of current, the release resistance can be quantified from two dimensions: resistance strength and resistance impact velocity, thereby determining whether the component has been successfully picked up. Experiments show that for 0201 resistors, when the tape stickiness causes the component to not detach, the peak current is usually 30% to 50% higher than when it detaches normally, and the rate of change of current is 2 to 5 times higher than when it detaches normally, with obvious distinguishability. By comparing the peak current with a first preset threshold and the rate of change of current with a second preset threshold, it is possible to reliably identify whether the component has been successfully picked up, and the false judgment rate can be reduced to below 0.1% under typical production conditions. The chip placement method for this circuit board does not require the addition of extra sensors, has low modification costs, and is easy to deploy on existing chip placement machines. At the same time, this method can avoid baseline drift problems caused by nozzle wear or micro-blockage of the air path, significantly improving the long-term stability of the equipment and the chip placement yield.

[0007] In one embodiment, determining the peak current and rate of change of the surface mount drive motor based on the current-time curve includes: performing median filtering on the current-time curve to obtain a smoothed current curve; calculating the first derivative of the smoothed current curve to obtain an instantaneous current derivative curve; determining the zero-crossing point of the instantaneous current derivative curve from a negative value to a positive value and the zero-crossing time corresponding to the zero-crossing point; and determining the peak current and rate of change of the surface mount drive motor based on the zero-crossing time and the smoothed current curve, wherein the peak current is the maximum current value on the smoothed current curve after the zero-crossing time, the rate of change of current is the average slope of the smoothed current curve between the zero-crossing time and the peak time, and the peak time is the time corresponding to the peak current.

[0008] In this embodiment, noise can be removed through median filtering, and the instantaneous current derivative curve is obtained by taking the first derivative. The starting point of the current rise is located using the zero-crossing point from negative to positive. Then, the maximum current value after the starting point is calculated as the peak value, and the average slope between the starting point and the peak value is used as the rate of change. This embodiment has strong anti-interference ability and can accurately distinguish the current characteristics under normal material suction and material sticking conditions, avoiding misjudgment caused by current fluctuations or sampling noise, and improving the robustness of the judgment.

[0009] In one embodiment, before sending the first drive command to the surface mount drive motor based on the circuit board arrival signal, the method further includes: acquiring multiple first sample data and multiple second sample data, wherein the first sample data includes the peak current and current change rate of the surface mount drive motor when the nozzle successfully picks up material, and the second sample data includes the peak current and current change rate of the surface mount drive motor when the nozzle fails to pick up material; performing Gaussian distribution fitting on the first sample data to obtain a first mean vector and a first covariance matrix, and performing Gaussian distribution fitting on the second sample data to obtain a second mean vector and a second covariance matrix; constructing a Bayesian decision discriminant function based on the first mean vector, the first covariance matrix, the second mean vector, and the second covariance matrix; determining a decision boundary curve in a two-dimensional plane with the peak current as the horizontal axis and the current change rate as the vertical axis based on the Bayesian decision discriminant function; and determining a first preset threshold and a second preset threshold based on the decision boundary curve, wherein the first preset threshold is the abscissa value of the intersection point of the decision boundary curve and the horizontal axis, and the second preset threshold is the ordinate value of the intersection point of the decision boundary curve and the vertical axis.

[0010] In this embodiment, before sending the first driving command, successful and failed samples are collected, and a Bayesian decision discriminant function is obtained by fitting a Gaussian distribution. This determines the decision boundary curve, and the first and second preset thresholds are obtained from the intersection of this curve and the coordinate axes. This method enables the thresholds to automatically adapt to the component type and material batch in actual production, avoiding deviations caused by manually setting thresholds based on experience. It achieves dynamic self-learning of the thresholds, improving versatility for different materials and different feeder states.

[0011] In one embodiment, determining the decision boundary curve in a two-dimensional plane with the peak current as the horizontal axis and the rate of change of current as the vertical axis according to the Bayesian decision discriminant function includes: determining a first sample coordinate and a second sample coordinate in the two-dimensional plane, wherein the horizontal coordinate of the first sample coordinate is equal to the mean value of the peak current in the first sample data, the vertical coordinate of the first sample coordinate is equal to the mean value of the rate of change of current in the first sample data, the horizontal coordinate of the second sample coordinate is equal to the mean value of the peak current in the second sample data, and the vertical coordinate of the second sample coordinate is equal to the mean value of the rate of change of current in the second sample data; and determining the decision boundary curve based on the first sample coordinate and the second sample coordinate, wherein the decision boundary curve is the perpendicular bisector of the line connecting the first sample coordinate and the second sample coordinate.

[0012] In this embodiment, the decision boundary curve is concretized as the perpendicular bisector of the line connecting the center points of the two types of samples. This eliminates the need for complex covariance matrix inversion or iterative optimization, resulting in low computational complexity and easy real-time implementation in the embedded controller of the chip mounter. Furthermore, the perpendicular bisector approaches the Bayesian optimal boundary when the covariances of the two types of samples are similar, balancing accuracy and efficiency, making it particularly suitable for quickly establishing thresholds during production changeover and debugging.

[0013] In one embodiment, after determining the first preset threshold and the second preset threshold based on the decision boundary curve, the method further includes: sending a third drive command to the patch drive motor, causing the patch drive motor to drive the nozzle to perform a calibration action according to the third drive command, the calibration action being used to make the nozzle pick up the calibration piece; determining a reference peak value and a reference rate of change based on the real-time current of the patch drive motor during the nozzle calibration action, the reference peak value and the reference rate of change being the maximum current value and the average current rate of change of the patch drive motor during the nozzle calibration action, respectively; obtaining a peak compensation value based on the reference peak value and the preset rated peak value, and obtaining a rate of change compensation value based on the reference rate of change and the preset rated rate of change, wherein the peak compensation value is equal to the difference between the reference peak value and the preset rated peak value, and the rate of change compensation value is equal to the difference between the reference rate of change and the preset rated rate of change; and updating the first preset threshold and the second preset threshold based on the peak compensation value and the rate of change compensation value, respectively.

[0014] In this embodiment, by periodically picking up standard calibration parts, measuring the current reference peak value and rate of change of the nozzle, comparing it with the factory calibration value to obtain a compensation value, and dynamically updating the first preset threshold and the second preset threshold, the influence of additional resistance caused by nozzle wear, contamination or air path aging on the judgment result can be effectively eliminated, the effective service life of the nozzle can be extended, false alarm shutdowns caused by changes in nozzle status can be reduced, and production continuity can be improved.

[0015] In one embodiment, after sending a first drive command to the surface mount drive motor based on the circuit board arrival signal, the method further includes: acquiring the real-time acceleration of the nozzle during the material suction process, generating an acceleration-time curve based on the real-time acceleration; determining the peak acceleration and rate of change of the nozzle based on the acceleration-time curve; if the peak current is less than a first preset threshold, the rate of change of the current is less than a second preset threshold, the peak acceleration is less than a third preset threshold, and the rate of change of the acceleration is less than a fourth preset threshold, then sending a second drive command to the surface mount drive motor, causing the surface mount drive motor to perform a surface mount operation according to the second drive command; otherwise, re-executing the step of sending a material suction command to the surface mount drive motor based on the circuit board arrival signal.

[0016] In this embodiment, the bonding process is only considered successful and executed when the peak current, rate of change of current, peak acceleration, and rate of change of acceleration are all less than their respective thresholds. The acceleration is determined by the actual movement of the nozzle and is independent of the current, forming a dual-mode mutual detection mechanism. This avoids misjudgments caused by a single sensor malfunction, making it particularly suitable for bonding scenarios with high reliability requirements, such as automotive electronics.

[0017] In one embodiment, determining the peak acceleration and rate of change of the nozzle based on the acceleration-time curve includes: determining an initial descent point and a negative maximum point on the acceleration-time curve, wherein the initial descent point corresponds to the point where acceleration begins to decrease, and the negative maximum point corresponds to the point where the algebraic value of acceleration is minimum; determining the peak acceleration of the nozzle based on the negative maximum point, wherein the peak acceleration is equal to the absolute value of acceleration at the negative maximum point; determining the acceleration descent time and acceleration descent amount based on the initial descent point and the negative maximum point, wherein the acceleration descent time is the time difference between the initial descent point and the negative maximum point, and the acceleration descent amount is the acceleration change between the initial descent point and the negative maximum point; and determining the rate of change of acceleration based on the acceleration descent time and acceleration descent amount, wherein the rate of change of acceleration is equal to the ratio of the acceleration descent amount to the acceleration descent time.

[0018] In this embodiment, the average rate of change is calculated using the acceleration descent time and descent amount by determining the initial descent point and the negative maximum point. This definition maintains physical symmetry with the calculation of current characteristics, facilitating modular software implementation; at the same time, the deceleration metric is converted into a positive peak value using absolute values, intuitively reflecting the release impact intensity, and the algorithm is simple and efficient.

[0019] In one embodiment, the sampling frequency of the real-time current of the patch drive motor is greater than 5kHz.

[0020] In this embodiment, the real-time current sampling frequency is limited to greater than 5kHz to ensure that the transient details of the current peak can be fully captured, avoiding peak loss or distortion of the rate of change calculation due to insufficient sampling rate, and providing sufficient time resolution for subsequent feature extraction.

[0021] Secondly, this application provides a board placement device, comprising: a sending module, configured to send a first driving command to a placement drive motor according to a board arrival signal, causing the placement drive motor to drive a suction nozzle to perform a material suction action according to the first driving command; a generating module, configured to acquire the real-time current of the placement drive motor during the material suction process and generate a current-time curve based on the real-time current; a determining module, configured to determine the peak current and current change rate of the placement drive motor based on the current-time curve; a judging module, configured to judge whether the peak current is less than a first preset threshold and whether the current change rate is less than a second preset threshold; a control module, configured to send a second driving command to the placement drive motor if the judging module judges that the peak current is less than the first preset threshold and the current change rate is less than the second preset threshold, causing the placement drive motor to perform a placement action according to the second driving command; the sending module is further configured to, if the judging module judges that the peak current is not less than the first preset threshold or the current change rate is not less than the second preset threshold, re-execute the step of sending a suction command to the placement drive motor according to the board arrival signal.

[0022] Thirdly, this application provides a chip mounter, including a processor and a memory, wherein the memory is used to store a computer program, and the computer program, when executed by the processor, implements the above-described chip mounter method for circuit boards. Attached Figure Description

[0023] Figure 1 This is a schematic flowchart illustrating a method for mounting a circuit board according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a circuit board mounting device shown in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a chip mounter as shown in an embodiment of this application. Detailed Implementation

[0024] 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 of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0025] Please refer to Figure 1 , Figure 1 This is a schematic flowchart illustrating a method for mounting a circuit board according to an embodiment of this application. Figure 1 As shown, the circuit board mounting method of this embodiment includes steps S11 to S15, which are described in detail below: Step S11: Send a first drive command to the surface mount drive motor according to the circuit board position signal, so that the surface mount drive motor drives the nozzle to perform the suction action according to the first drive command.

[0026] In this step, the circuit board arrival signal indicates that the circuit board has been delivered to the placement station and positioned. This signal can be obtained through a position sensor. The first drive command includes parameters such as target position, speed curve, and acceleration. During the material suction process, the nozzle first rapidly descends from its standby height to the feeder's pick-up position until the nozzle tip gently contacts the component surface. Then, simultaneously with the nozzle contacting the component, the nozzle's vacuum solenoid valve opens, and the air system begins to generate negative pressure. The vacuum level inside the nozzle gradually increases, adsorbing the component onto the nozzle tip. The nozzle maintains contact with the component for a short, preset time, waiting for the vacuum level to stabilize and reach the expected value. Finally, the placement drive motor drives the nozzle upward at a set speed, attempting to peel the component off the tape. It should be noted that for some small components, stabilizing the vacuum level and reaching the expected value does not guarantee that the component has been detached from the tape.

[0027] Step S12: Obtain the real-time current of the patch drive motor during the material suction process of the nozzle, and generate a current-time curve based on the real-time current.

[0028] In this step, throughout the entire material suction process, the real-time current of the motor is continuously acquired using a precision sampling resistor connected in series in the motor power supply circuit, in conjunction with an analog-to-digital converter. After low-pass filtering, the current signal is plotted on the horizontal axis (time) and the current value on the vertical axis to generate a current-time curve. For example, let the sampling time be... (i=1,2,...N), corresponding current values ​​are Then the current-time curve is based on the discrete point set { The results were obtained through fitting.

[0029] Step S13: Determine the peak current and current change rate of the patch drive motor based on the current-time curve.

[0030] In this step, by processing and analyzing the current-time curve, the peak current and current change rate of the surface mount drive motor can be obtained.

[0031] In some embodiments, when performing step S13, because the original current-time curve is mixed with high-frequency noise, such as motor commutation ripple, electromagnetic interference, and sampling quantization errors, it is necessary to first perform median filtering on the current-time curve to obtain a smooth current curve. This effectively suppresses impulse noise while preserving the edge characteristics of the current waveform, avoiding peak clipping and rising edge passivation. Next, the first derivative of the smooth current curve is calculated to obtain the instantaneous current derivative curve, which reflects the rate of change of current over time, thereby dynamically and explicitly expressing the change of current. Then, the zero-crossing point where the instantaneous current derivative curve crosses from a negative value to a positive value and the corresponding zero-crossing time are determined. The zero-crossing point represents the critical point where the current changes from a stable or decreasing trend to an increasing trend, corresponding to the initial moment when the nozzle begins to experience release resistance and the motor torque begins to increase. Then, based on the zero-crossing moment and the smoothed current curve, the peak current and current change rate of the surface mount drive motor are determined. The peak current is the maximum current value on the smoothed current curve after the zero-crossing moment, and the current change rate is the average slope of the smoothed current curve between the zero-crossing moment and the peak moment. The peak moment is the moment corresponding to the peak current. It should be noted that the peak current reflects the maximum release resistance that needs to be overcome during the nozzle's upward movement, and the current change rate reflects the average rate of increase of the release resistance from its initial appearance to reaching its peak.

[0032] Step S14: Determine whether the peak current is less than a first preset threshold and whether the rate of change of current is less than a second preset threshold.

[0033] In this step, if the peak current is less than the first preset threshold and the rate of change of current is less than the second preset threshold, then step S15 is executed; otherwise, step S11 is executed. In specific implementation, a maximum number of retries can be set (e.g., 3 times). If this number is exceeded, the current material level is skipped and an anomaly is recorded.

[0034] Step S15: Send a second drive command to the surface mount driver motor, so that the surface mount driver motor performs the surface mount action according to the second drive command.

[0035] In this step, if the peak current is less than the first preset threshold and the rate of change of current is less than the second preset threshold, then the nozzle is considered to have successfully picked up the component. For example, for a 0201 component, experiments have shown that when the component is successfully picked up, the peak current ranges from 0.5A to 0.8A, and the rate of change of current is approximately 0.2A / ms; when the component is not picked up, the peak current can reach more than 1.2A, and the rate of change of current exceeds 0.8A / ms. In this case, the first preset threshold can be set to 1.0A, and the second preset threshold can be set to 0.5A / ms.

[0036] In some embodiments, before executing step S11, multiple first sample data and multiple second sample data can be acquired. The first sample data includes the peak current and current change rate of the patch drive motor when the nozzle successfully picks up material, and the second sample data includes the peak current and current change rate of the patch drive motor when the nozzle fails to pick up material. Then, Gaussian distribution fitting is performed on the first sample data to obtain a first mean vector and a first covariance matrix, and Gaussian distribution fitting is performed on the second sample data to obtain a second mean vector and a second covariance matrix. Next, a Bayesian decision discriminant function is constructed based on the first mean vector, the first covariance matrix, the second mean vector, and the second covariance matrix. Based on the Bayesian decision discriminant function, a decision boundary curve is determined in a two-dimensional plane with the peak current as the horizontal axis and the current change rate as the vertical axis. A first preset threshold and a second preset threshold are determined based on the decision boundary curve, where the first preset threshold is the abscissa value of the intersection of the decision boundary curve and the horizontal axis, and the second preset threshold is the ordinate value of the intersection of the decision boundary curve and the vertical axis.

[0037] For example, by controlling the nozzle to perform M pre-feeding operations on the same type of feeder and component, the peak current and current change rate of the surface mount drive motor are recorded during each feeding process. The success of each feeding operation is then manually confirmed, thus obtaining first sample data and second sample data. The first sample data forms a first set of points in a two-dimensional plane with the peak current as the horizontal axis and the current change rate as the vertical axis. A first mean vector is used to characterize the center position of the first set of points in the two-dimensional plane, and a first covariance matrix is ​​used to characterize the divergence shape of the first set of points. The second sample data forms a second set of points in a two-dimensional plane with the peak current as the horizontal axis and the current change rate as the vertical axis. A second mean vector is used to characterize the center position of the second set of points in the two-dimensional plane, and a second covariance matrix is ​​used to characterize the divergence shape of the second set of points. For any newly measured current characteristic point, such as the peak current and rate of change of current measured during a certain suction action, the probability that this point belongs to the first point set region can be determined based on the first mean vector and the first covariance matrix. The probability that this point belongs to the second point set region can be determined based on the second mean vector and the second covariance matrix. The Bayesian decision discriminant function is used to determine the ratio of the probability that this point belongs to the first point set region to the probability that it belongs to the second point set region. Furthermore, the decision boundary curve is the curve formed by connecting the points in a two-dimensional plane with the peak current as the horizontal axis and the rate of change of current as the vertical axis, where the function value of the Bayesian decision discriminant function equals 1. The x-coordinate of the intersection point of the decision boundary curve and the horizontal axis is the maximum allowable peak current when the rate of change of current approaches 0. Even if the rate of change of current is very low, if the peak current exceeds this value, it is still considered a suction failure, corresponding to an adhesive on the material strip that is extremely viscous but tough and will not suddenly break. The second preset threshold is the vertical coordinate value of the intersection of the decision boundary curve and the vertical axis. When the current peak value approaches 0, that is, the motor outputs almost no additional torque, the maximum allowable current change rate is determined. Even if the current peak value is not high, if the current change rate is large, it is also judged as a failure to feed material. This corresponds to adhesives with a very brittle adhesive layer on the material strip that break quickly but have a large impact at the moment of breakage.

[0038] In some embodiments, when determining the decision boundary curve in a two-dimensional plane with the peak current as the horizontal axis and the rate of change of current as the vertical axis according to the Bayesian decision discriminant function, firstly, the first sample coordinates and the second sample coordinates are determined in the two-dimensional plane. The horizontal axis of the first sample coordinates is equal to the mean value of the peak current in the first sample data, and the vertical axis of the first sample coordinates is equal to the mean value of the rate of change of current in the first sample data. The horizontal axis of the second sample coordinates is equal to the mean value of the peak current in the second sample data, and the vertical axis of the second sample coordinates is equal to the mean value of the rate of change of current in the second sample data. Then, the decision boundary curve is determined based on the first sample coordinates and the second sample coordinates. The decision boundary curve is the perpendicular bisector of the line connecting the first sample coordinates and the second sample coordinates.

[0039] The first sample coordinate represents the typical current characteristics when the nozzle successfully picks up material. Located in the lower left of the two-dimensional plane, it has a small current peak and a small rate of change. The second sample coordinate represents the typical current characteristics when the nozzle fails to pick up material. Located in the upper right of the first sample coordinate, it has a larger current peak and a larger rate of change. The direction of the line connecting the first and second sample coordinates reflects the separation direction of successful and failed material picking in the feature space. In Bayesian decision-making, when the covariance matrices of the two classes of samples are equal or approximately equal, the optimal classification boundary is the perpendicular bisector of the line connecting the two center points. At this time, the distance from the perpendicular bisector to the two centers is equal, and it is perpendicular to the line connecting the two centers, which minimizes the classification error rate. Although the covariances of the successful and failed classes in actual production may not be completely equal, for the specific scenario of nozzle picking up material, the scattering shape of the two classes of samples is not significantly different, and the perpendicular bisector is approximately accurate enough. Furthermore, the perpendicular bisector divides the plane into two half-planes: the side closer to the first sample coordinate is the successful picking area, and the side closer to the second sample coordinate is the failed picking area. Any point falling to the lower left of the perpendicular bisector is closer to the success center and is considered successful, while points falling to the upper right are considered failures. This classification method aligns with intuitive human experience: smaller peak current and rate of change increase the likelihood of successful material picking, while larger peak current and rate of change increase the likelihood of failure. Compared to the full Bayesian boundary, the perpendicular bisector does not require calculating the inverse of the covariance matrix and the determinant, resulting in extremely low computational cost, making it suitable for real-time execution in embedded controllers of pick-and-place machines. Simultaneously, it maintains good classification performance. For example, in actual test data of 0201 components, the accuracy of the perpendicular bisector classifier is less than 1% different from that of the full Bayesian classifier, but the computation time is reduced by more than 90%. Furthermore, using the intersections of the perpendicular bisector with the horizontal and vertical axes as the first and second preset thresholds, respectively, essentially projects the perpendicular bisector classification rules onto two coordinate axes, forming a rectangular decision region. That is, when one feature value is extremely low, the upper limit of another feature value is determined by the intersection of the perpendicular bisector with the corresponding coordinate axis. This approach retains the classification capability of the vertical axis while implementing a simplified threshold comparison logic. If the decision boundary curve does not intersect the horizontal axis, the minimum horizontal coordinate value on the boundary curve is taken as the first preset threshold; if it does not intersect the vertical axis, the minimum vertical coordinate value on the boundary curve is taken as the second preset threshold.

[0040] In some embodiments, after determining the first preset threshold and the second preset threshold based on the decision boundary curve, a third drive command can be sent to the patch drive motor, causing the patch drive motor to drive the nozzle to perform a calibration action. The calibration action is used to make the nozzle pick up the calibration piece. Then, based on the real-time current of the patch drive motor during the nozzle calibration action, a reference peak value and a reference rate of change are determined. The reference peak value and the reference rate of change are the maximum current and the average current rate of change of the patch drive motor during the nozzle calibration action, respectively. Based on the reference peak value and the preset rated peak value, a peak compensation value is obtained, and based on the reference rate of change and the preset rated rate of change, a rate of change compensation value is obtained. The peak compensation value is equal to the difference between the reference peak value and the preset rated peak value, and the rate of change compensation value is equal to the difference between the reference rate of change and the preset rated rate of change. Finally, based on the peak compensation value and the rate of change compensation value, the first preset threshold and the second preset threshold are updated, respectively.

[0041] In this embodiment, by updating the first and second preset thresholds respectively, the interference of additional resistance caused by wear, contamination, or aging of the air path on the threshold judgment can be eliminated, thus ensuring that the first and second preset thresholds truly reflect the tape stickiness rather than the nozzle state. The pick-and-place machine actively sends a third drive command to drive the nozzle to pick up the standard calibration element. This calibration element is a specially made part with a smooth surface, no stickiness, and uniform size, such as a ceramic sheet or a polished metal block. Since the calibration element itself does not generate release resistance, the additional load on the drive motor when the nozzle picks it up comes entirely from the friction, damping, and other resistance of the nozzle and transmission mechanism itself. The reference peak value is the maximum current value recorded on the current-time curve of the calibration action, which reflects the maximum torque required to overcome its own mechanical friction and air path resistance under the current nozzle state. The reference rate of change is the average slope on the current-time curve of the calibration action from the start of the current rise to the current peak value, which reflects the impact characteristics when the nozzle's own resistance suddenly increases. The preset rated peak value and preset rated rate of change are baseline values ​​measured using standard calibration elements of the same specification under ideal clean conditions when the pick-and-place machine leaves the factory. The preset rated peak value and preset rated rate of change represent the standard resistance characteristics of the nozzle when it is brand new and uncontaminated, and are stored in the pick-and-place machine's non-volatile memory.

[0042] Furthermore, the peak compensation value = reference peak value - preset rated peak value. When the nozzle's resistance increases due to wear or contamination, the reference peak value will be higher than the factory value, and the compensation value will be positive; if the nozzle becomes smoother after maintenance, the compensation value may be negative. The rate of change compensation value = reference rate of change - preset rated rate of change. Similarly, a positive compensation value indicates that the nozzle's resistance is increasing faster. Increasing the peak compensation value by the first preset threshold and increasing the rate of change compensation value by the second preset threshold makes the nozzle's resistance greater, and the allowable peak current and rate of change are correspondingly relaxed when judging sticky materials. Suppose that the nozzle's no-load current peak value increases by 0.2A due to wear. Without compensation, components that were normally detached may be misjudged as sticky materials because the peak value exceeds the original threshold, leading to frequent retries or rejections. After compensation, the threshold is increased by 0.2A simultaneously. Normal detachment still falls within the success zone, while the peak value when truly sticky materials (usually more than 30% higher than normal) will still exceed the compensated threshold, thus ensuring the accuracy of the judgment. This compensation mechanism only corrects for the effects caused by changes in the nozzle's own state and does not affect the sensitivity to the stickiness of the material. Experiments show that, with compensation, the false alarm rate for material sticking detection decreases from 15% without compensation to below 2% throughout the nozzle's entire lifespan, while the false negative rate hardly increases.

[0043] By performing calibration regularly, the current resistance characteristics of the nozzle are dynamically measured and compared with the factory calibration value to obtain a compensation value. The first and second preset thresholds are then updated in real time, ensuring that the first and second preset thresholds always match the physical state of the nozzle. This eliminates baseline drift caused by nozzle wear, contamination, or air path aging, significantly improving the long-term stability of material sticking detection and the overall efficiency of the equipment.

[0044] In some embodiments, after sending the first drive command to the surface mount drive motor according to the circuit board positioning signal, the real-time acceleration of the nozzle during the suction process can be obtained, and an acceleration-time curve can be generated based on the real-time acceleration. The peak acceleration and rate of change of the nozzle are determined based on the acceleration-time curve. If the peak current is less than a first preset threshold, and the rate of change of the current is less than a second preset threshold, and the peak acceleration is less than a third preset threshold, and the rate of change of the acceleration is less than a fourth preset threshold, then a second drive command is sent to the surface mount drive motor, so that the surface mount drive motor performs the surface mount action according to the second drive command; otherwise, step S11 is re-executed.

[0045] The peak acceleration is the absolute value of the negative maximum on the acceleration-time curve during the nozzle's upward lifting phase, representing the moment of maximum deceleration. This value directly reflects the instantaneous impact intensity experienced by the nozzle when overcoming release resistance. When components are stuck to the tape, the release resistance is suddenly released or continuously increases, causing the nozzle to experience severe deceleration and vibration, resulting in a significant increase in the peak acceleration. The rate of change of acceleration is the absolute value of the average slope from the start of the continuous decrease in acceleration to the point of negative maximum, reflecting the steepness of the deceleration impact. For brittle adhesives, once the component begins to detach, the impact is rapid and intense, resulting in a very high rate of change of acceleration; for tough adhesives, the rate of change of acceleration is relatively gentle. By comparing the four characteristics—peak current, rate of change of current, peak acceleration, and rate of change of acceleration—with their respective preset thresholds, success is determined and mounting is performed only when all four characteristics are less than their corresponding thresholds; otherwise, failure is determined, and material is re-picked, achieving redundant verification. Since current and acceleration are generated by different physical mechanisms, their sensor paths are also independent. Therefore, an anomaly in a single sensor will not lead to false judgments. Current is sensitive to static resistance and tough adhesives, while acceleration is sensitive to dynamic impact and brittle adhesives. Combining both covers all possible adhesive failure modes, avoiding missed detections due to inconspicuous characteristics. In certain special conditions, such as current spikes caused by fluctuations in motor power supply voltage, current alone might mistakenly identify normal detachment as adhesive failure. Adding acceleration verification prevents failures due to the smooth actual movement of the nozzle and normal acceleration characteristics, avoiding unnecessary retries. Experiments show that introducing acceleration further reduces the false positive rate from 0.1% to below 0.02%. The pick-and-place machine's operating environment is subject to interference such as electromagnetic noise and mechanical vibration. Dual-mode verification makes the system insensitive to occasional anomalies in a single physical quantity, improving overall robustness. For fields requiring zero defects, such as automotive electronics and medical equipment, current detection alone may still carry a very low risk of missed detections. Acceleration, as an independent redundant channel, provides additional safety assurance, meeting the diverse redundancy requirements of functional safety standards such as ISO 26262. The third and fourth preset thresholds can be obtained in a similar manner to the first and second preset thresholds: during the production changeover and debugging phase, the acceleration characteristics of successful and failed samples are collected, Gaussian distribution fitting is performed, and then the corresponding thresholds are determined according to Bayesian decision or the perpendicular bisector method. Alternatively, they can be set to fixed values ​​based on experience, such as peak acceleration < 0.5g and acceleration change rate < 0.2g / ms, and calibrated periodically. By adding acceleration characteristics, dual-mode redundancy verification of current and acceleration is achieved, covering different viscous failure modes from a physical perspective, significantly reducing misjudgments caused by single sensor anomalies, and providing solid technical support for high-reliability surface mount technology (SMT) scenarios.

[0046] In some embodiments, determining the peak acceleration and rate of change of the nozzle based on the acceleration-time curve includes: determining the initial descent point and the negative maximum point on the acceleration-time curve, wherein the initial descent point corresponds to the point where acceleration begins to decrease, and the negative maximum point corresponds to the point where the algebraic value of acceleration is the smallest; determining the peak acceleration of the nozzle based on the negative maximum point, wherein the peak acceleration is equal to the absolute value of acceleration at the negative maximum point; determining the acceleration descent time and acceleration descent amount based on the initial descent point and the negative maximum point, wherein the acceleration descent time is the time difference between the initial descent point and the negative maximum point, and the acceleration descent amount is the amount of acceleration change between the initial descent point and the negative maximum point; and determining the rate of change of acceleration based on the acceleration descent time and acceleration descent amount, wherein the rate of change of acceleration is equal to the ratio of the acceleration descent amount to the acceleration descent time.

[0047] In this embodiment, the initial descent point is the critical point where the acceleration-time curve changes from a stable or slowly fluctuating state to a continuous decline during the nozzle's upward lifting phase. This point corresponds to the moment when the nozzle begins to experience release resistance in the physical process. Before this point, the nozzle mainly overcomes its own gravity and conventional friction; after this point, the adhesiveness of the material strip begins to generate additional resistance, causing the nozzle's deceleration to gradually increase. The negative maximum point is the point where the algebraic value of acceleration is the smallest, i.e., the moment of maximum deceleration. This point corresponds to the moment when the release resistance reaches its peak or the component detaches from the material strip—when the resistance is at its maximum, the nozzle's deceleration is also at its maximum; once the component detaches, the deceleration will rapidly decrease.

[0048] The peak acceleration is obtained by taking the absolute value of the acceleration at the negative maximum point. This process converts the deceleration metric into a positive value, intuitively reflecting the intensity of the release impact. For example, if the negative maximum is -0.8g, the peak acceleration is 0.8g. The larger this value, the stronger the instantaneous impact the nozzle experiences when overcoming release resistance. The acceleration descent time is the time difference between the initial descent point and the negative maximum point; it represents the length of time it takes for the release resistance to reach its peak after it begins to act. Tough adhesives typically have a longer descent time, while brittle adhesives have an extremely short descent time. The acceleration descent amount is the difference between the acceleration value at the initial descent point and the acceleration value at the negative maximum point; it reflects the total reduction in acceleration during the entire impact process, i.e., the cumulative change in deceleration. Dividing the acceleration descent amount by the acceleration descent time yields the average descent slope, which is the rate of change of acceleration. This value characterizes the average steepness of the deceleration impact. Given the same amount of decrease, the shorter the decrease time, the greater the rate of change; given the same decrease time, the greater the amount of decrease, the greater the rate of change.

[0049] The rate of change of current reflects the rate at which the motor torque increases, while the rate of change of acceleration reflects the rate at which the actual deceleration of the nozzle increases. They are physically related but independent, forming a complementary relationship. For example, when the motor current surges sharply, the nozzle's acceleration may not change abruptly due to the elasticity and clearance of the transmission mechanism; conversely, the impact on the nozzle may be caused by mechanical vibration, while the current may not change abruptly. Monitoring both simultaneously allows for a more comprehensive assessment of the dynamic characteristics of release resistance.

[0050] By using the initial descent point and the negative maximum point, the calculation window is limited to the effective time period of the drag effect, avoiding meaningless averaging in the stable or noisy segments and improving the signal-to-noise ratio of feature extraction. Compared with directly differentiating the original acceleration signal, this method only relies on two feature points to calculate the average slope, is insensitive to sampling noise and instantaneous jitter, and is suitable for the vibration environment of pick-and-place machines. Furthermore, the calculation is simple, requiring only one extreme value search and one difference operation, without the need for filtering and derivative calculations, making it ideal for embedded real-time systems.

[0051] In some embodiments, the sampling frequency of the real-time current of the surface mount drive motor is greater than 5 kHz. To ensure accurate capture of current peak details, especially for 0201 components where the entire feed process may only take tens of milliseconds, a current sampling frequency greater than 5 kHz is required. Preferably, it is 10 kHz or higher. A sampling frequency that is too low can lead to missed peak points or distorted rate-of-change calculations due to insufficient time resolution. In this embodiment, the ADC sampling rate is preferably set to 10 kHz, and linear interpolation is performed in the software to increase the effective sampling rate to 20 kHz, further ensuring feature extraction accuracy.

[0052] In this surface mount method for the circuit board, the nozzle needs to overcome the release resistance between the component and the tape during the suction action. By monitoring the real-time current of the mount drive motor, a current-time curve can be generated, which reflects the torque consumed by the nozzle to overcome the release resistance during the suction process. When the component is stuck to the tape, the mount drive motor needs to output a larger instantaneous torque, resulting in a significant increase in the peak current; at the same time, the more rapid the torque increase, the greater the rate of change of current. Based on the peak current and the rate of change of current, the release resistance can be quantified from two dimensions: resistance strength and resistance impact velocity, thereby determining whether the component has been successfully picked up. Experiments show that for 0201 resistors, when the tape stickiness causes the component to not detach, the peak current is usually 30% to 50% higher than when it detaches normally, and the rate of change of current is 2 to 5 times higher than when it detaches normally, with obvious distinguishability. By comparing the peak current with a first preset threshold and the rate of change of current with a second preset threshold, it is possible to reliably identify whether the component has been successfully picked up, and the false judgment rate can be reduced to below 0.1% under typical production conditions. The chip placement method for this circuit board does not require the addition of extra sensors, has low modification costs, and is easy to deploy on existing chip placement machines. At the same time, this method can avoid baseline drift problems caused by nozzle wear or micro-blockage of the air path, significantly improving the long-term stability of the equipment and the chip placement yield.

[0053] To implement the surface mount method for the circuit board corresponding to the above method embodiments, in order to achieve the corresponding functions and technical effects, see [link to documentation]. Figure 2 , Figure 2 This diagram illustrates a structural block diagram of a circuit board mounting device according to an embodiment of this application. For ease of explanation, only the parts relevant to this embodiment are shown. The circuit board mounting device 20 provided in this embodiment includes a sending module 21, a generating module 22, a determining module 23, a judging module 24, and a control module 25, which are described in detail below: The sending module 21 is used to send a first drive command to the surface mount drive motor according to the circuit board arrival signal, so that the surface mount drive motor drives the nozzle to perform a material suction action according to the first drive command; the generating module 22 is used to acquire the real-time current of the surface mount drive motor during the material suction process of the nozzle, and generate a current-time curve according to the real-time current; the determining module 23 is used to determine the peak current and current change rate of the surface mount drive motor according to the current-time curve; the judging module 24 is used to judge whether the peak current is less than a first preset threshold and whether the current change rate is less than a second preset threshold; the control module 25 is used to send a second drive command to the surface mount drive motor if the judging module 24 judges that the peak current is less than the first preset threshold and the current change rate is less than the second preset threshold, so that the surface mount drive motor performs a surface mount action according to the second drive command; the sending module 21 is also used to re-execute the step of sending a material suction command to the surface mount drive motor according to the circuit board arrival signal if the judging module 24 judges that the peak current is not less than the first preset threshold or the current change rate is not less than the second preset threshold.

[0054] The aforementioned circuit board mounting apparatus can implement the circuit board mounting method of the above method embodiments. The options in the above method embodiments are also applicable to this embodiment, and will not be detailed here. The remaining content of this application embodiment can be referred to the content of the above method embodiments, and will not be repeated in this embodiment.

[0055] Figure 3 This is a schematic diagram of the structure of a chip mounter provided in one embodiment of this application. Figure 3 As shown, the pick-and-place machine 30 of this embodiment includes: at least one processor 31 ( Figure 3 (Only one is shown in the diagram), memory 32, and computer program 33 stored in the memory 32 and executable on the at least one processor 31, wherein the processor 31 executes the computer program 33 to implement the steps in any of the above method embodiments.

[0056] The pick-and-place machine 30 may include, but is not limited to, a processor 31 and a memory 32. Those skilled in the art will understand that... Figure 3 This is merely an example of a pick-and-place machine 30 and does not constitute a limitation on the pick-and-place machine 30. It may include more or fewer components than shown, or combine certain components, or different components, such as input / output devices, network access devices, etc.

[0057] The processor 31 may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0058] In some embodiments, the memory 32 may be an internal storage unit of the pick-and-place machine 30, such as a hard disk or memory of the pick-and-place machine 30. In other embodiments, the memory 32 may be an external storage device of the pick-and-place machine 30, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the pick-and-place machine 30. Furthermore, the memory 32 may include both internal storage units and external storage devices of the pick-and-place machine 30. The memory 32 is used to store operating systems, applications, bootloaders, data, and other programs, such as the program code of the computer program 33. The memory 32 can also be used to temporarily store data that has been output or will be output.

[0059] In addition, embodiments of this application also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps in any of the above method embodiments.

[0060] This application provides a computer program product that, when run on a computer device, enables the computer device to execute the steps described in the various method embodiments above.

[0061] In the several embodiments provided in this application, it will be understood that each block in the flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those shown in the figures. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved.

[0062] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0063] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit the scope of protection of this application. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application for those skilled in the art.

Claims

1. A method for mounting a circuit board, characterized in that, include: The first drive command is sent to the surface mount drive motor according to the circuit board position signal, so that the surface mount drive motor drives the nozzle to perform the suction action according to the first drive command; The real-time current of the patch drive motor during the material feeding process of the nozzle is obtained, and a current-time curve is generated based on the real-time current; The peak current and rate of change of the surface mount drive motor are determined based on the current-time curve. If the peak current is less than a first preset threshold and the rate of change of current is less than a second preset threshold, a second drive command is sent to the surface mount drive motor, causing the surface mount drive motor to perform a surface mount operation according to the second drive command; otherwise, the step of sending a material suction command to the surface mount drive motor according to the circuit board position signal is re-executed.

2. The method for surface mounting a circuit board as described in claim 1, characterized in that, The step of determining the peak current and rate of change of the patch drive motor based on the current-time curve includes: The current-time curve is subjected to median filtering to obtain a smooth current curve; The instantaneous current derivative curve is obtained by calculating the first derivative of the smoothed current curve. Determine the zero-crossing point where the instantaneous current derivative curve crosses from a negative value to a positive value, and the zero-crossing time corresponding to the zero-crossing point; The peak current and current change rate of the patch drive motor are determined based on the zero-crossing time and the smooth current curve, wherein the peak current is the maximum current value on the smooth current curve after the zero-crossing time, the current change rate is the average slope of the smooth current curve between the zero-crossing time and the peak time, and the peak time is the time corresponding to the peak current.

3. The method for surface mounting a circuit board as described in claim 1, characterized in that, Before sending the first drive command to the surface mount drive motor based on the circuit board position signal, the method further includes: Acquire multiple first sample data and multiple second sample data. The first sample data includes the peak current and current change rate of the patch drive motor when the nozzle successfully picks up the material, and the second sample data includes the peak current and current change rate of the patch drive motor when the nozzle fails to pick up the material. The first sample data is fitted with a Gaussian distribution to obtain a first mean vector and a first covariance matrix, and the second sample data is fitted with a Gaussian distribution to obtain a second mean vector and a second covariance matrix. Construct a Bayesian decision discriminant function based on the first mean vector, the first covariance matrix, the second mean vector, and the second covariance matrix; Based on the Bayesian decision discriminant function, a decision boundary curve is determined in a two-dimensional plane with the peak current as the horizontal axis and the rate of change of current as the vertical axis; The first preset threshold and the second preset threshold are determined based on the decision boundary curve, wherein the first preset threshold is the abscissa value of the intersection of the decision boundary curve and the horizontal axis, and the second preset threshold is the ordinate value of the intersection of the decision boundary curve and the vertical axis.

4. The method for mounting a circuit board as described in claim 3, characterized in that, The step of determining the decision boundary curve in a two-dimensional plane with the peak current as the horizontal axis and the rate of change of current as the vertical axis based on the Bayesian decision discriminant function includes: In the two-dimensional plane, the first sample coordinates and the second sample coordinates are determined respectively, wherein the abscissa of the first sample coordinate is equal to the mean value of the current peak value in the first sample data, the ordinate of the first sample coordinate is equal to the mean value of the current change rate in the first sample data, the abscissa of the second sample coordinate is equal to the mean value of the current peak value in the second sample data, and the ordinate of the second sample coordinate is equal to the mean value of the current change rate in the second sample data. The decision boundary curve is determined based on the first sample coordinates and the second sample coordinates, wherein the decision boundary curve is the perpendicular bisector of the line connecting the first sample coordinates and the second sample coordinates.

5. The method for mounting a circuit board as described in claim 4, characterized in that, After determining the first preset threshold and the second preset threshold based on the decision boundary curve, the method further includes: A third drive command is sent to the patch drive motor, causing the patch drive motor to drive the nozzle to perform a calibration action according to the third drive command. The calibration action is used to make the nozzle pick up the calibration part. Based on the real-time current of the patch drive motor during the nozzle calibration process, the reference peak value and the reference rate of change are determined. The reference peak value and the reference rate of change are the maximum current value and the average current rate of change of the patch drive motor during the nozzle calibration process, respectively. A peak compensation value is obtained based on the reference peak value and the preset rated peak value, and a change rate compensation value is obtained based on the reference change rate and the preset rated change rate, wherein the peak compensation value is equal to the difference between the reference peak value and the preset rated peak value, and the change rate compensation value is equal to the difference between the reference change rate and the preset rated change rate; The first preset threshold and the second preset threshold are updated based on the peak compensation value and the rate of change compensation value, respectively.

6. The method for surface mounting a circuit board as described in claim 1, characterized in that, After sending the first drive command to the surface mount drive motor based on the circuit board position signal, the method further includes: The real-time acceleration of the suction nozzle during the material feeding process is obtained, and an acceleration-time curve is generated based on the real-time acceleration. The peak acceleration and rate of change of acceleration of the nozzle are determined based on the acceleration-time curve. If the peak current is less than the first preset threshold, the rate of change of current is less than the second preset threshold, the peak acceleration is less than the third preset threshold, and the rate of change of acceleration is less than the fourth preset threshold, then a second drive command is sent to the surface mount drive motor, causing the surface mount drive motor to perform the surface mount action according to the second drive command; otherwise, the step of sending the material suction command to the surface mount drive motor according to the circuit board position signal is re-executed.

7. The method for surface mounting a circuit board as described in claim 6, characterized in that, The determination of the peak acceleration and rate of change of acceleration of the nozzle based on the acceleration-time curve includes: Determine the initial descent point and the negative maximum point on the acceleration-time curve. The initial descent point corresponds to the point where the acceleration begins to decrease, and the negative maximum point corresponds to the point where the algebraic value of the acceleration is the minimum. The peak acceleration of the nozzle is determined based on the negative maximum point, wherein the peak acceleration is equal to the absolute value of the acceleration at the negative maximum point; Based on the initial descent point and the negative maximum point, the acceleration descent time and acceleration descent amount are determined, wherein the acceleration descent time is the time difference between the initial descent point and the negative maximum point, and the acceleration descent amount is the acceleration change between the initial descent point and the negative maximum point; The rate of change of acceleration is determined based on the acceleration descent time and the acceleration descent amount, wherein the rate of change of acceleration is equal to the ratio of the acceleration descent amount to the acceleration descent time.

8. The method for surface mounting a circuit board as described in claim 1, characterized in that, The sampling frequency of the real-time current of the patch drive motor is greater than 5kHz.

9. A circuit board mounting device, characterized in that, include: The sending module is used to send a first driving command to the surface mount drive motor according to the circuit board arrival signal, so that the surface mount drive motor drives the suction nozzle to perform a material suction action according to the first driving command. The generation module is used to acquire the real-time current of the patch drive motor during the suction process of the nozzle, and generate a current-time curve based on the real-time current; The determination module is used to determine the peak current and current change rate of the patch drive motor based on the current-time curve; The judgment module is used to determine whether the peak current is less than a first preset threshold and whether the rate of change of current is less than a second preset threshold. The control module is configured to send a second drive command to the surface mount drive motor if the judgment module determines that the peak current is less than a first preset threshold and the rate of change of current is less than a second preset threshold, so that the surface mount drive motor performs a surface mount action according to the second drive command. The sending module is further configured to, if the judging module determines that the peak current is not less than a first preset threshold, or the rate of change of current is not less than a second preset threshold, then re-execute the step of sending a material feeding command to the surface mount drive motor based on the circuit board positioning signal.

10. A pick-and-place machine, characterized in that, It includes a processor and a memory, the memory being used to store a computer program that, when executed by the processor, implements the board mounting method as described in any one of claims 1 to 8.

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