SMT mounting pressure detection method and system

Abstract

The invention relates to an SMT mounting pressure detection method and system. The SMT mounting pressure detection method comprises the following steps: acquiring force data and position data of a mounting head in a first direction movement process; based on the force data and the position data, relation change characteristics between the force and the position are determined; according to the relation change characteristics, identifying a physical state transition point of the component and the flexible circuit board from flexible deformation to rigid contact; determining a force component for overcoming local deformation of the flexible circuit board at the physical state transition point; adjusting the target total acting force of the mounting head according to the expected effective mounting force and the force component of the preset component; and driving the mounting head to apply the target total acting force. The technical problems that in an existing flexible printed circuit (FPC) application, an ineffective component for overcoming local deformation of an FPC and an effective mounting force actually acting on a component cannot be effectively distinguished, so that mounting pressure control is inaccurate, and the mounting quality and the product reliability are further influenced can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of SMT mounting technology, in particular, to an SMT mounting pressure detection method and system. BACKGROUND

[0002] In modern electronic product manufacturing, surface mounting technology (SMT) is a core production link, and accurate mounting of components is crucial, as mounting pressure directly affects soldering quality and product reliability. Existing SMT production lines are usually equipped with pressure detection schemes, which integrate force sensors in the Z-axis of the mounting head to measure the total force when the mounting head contacts the printed circuit board (PCB) in real time, and convert it into a mounting pressure value. For traditional rigid PCBs, due to their high rigidity and negligible deformation, the total force measured by the sensor is almost equal to the effective mounting force actually acting on the component pads, ensuring that the components are mounted in place with the preset pressure.

[0003] However, with the development of consumer electronics towards lightness, thinness, and flexibility, flexible circuit boards (FPCs) are increasingly widely used. To meet specific electrical performance and mechanical reliability, the stiffness distribution of FPCs is often uneven, with some areas increasing copper layer thickness, stacking multiple layers of structure, or adhering reinforcing sheets to improve local rigidity, while other areas remain extremely thin and flexible. When such FPCs with significant local stiffness differences are placed on a standard support pin array designed for rigid PCBs for SMT mounting, the existing pressure detection method faces challenges.

[0004] Specifically, when the mounting head acts on the soft area of the FPC, due to its flexibility, the mounting head first needs to apply an additional force to flatten or deform the local FPC, making it fully contact with the underlying support pin, or making the bottom of the component fully contact with the pad. At this time, the total force measured by the Z-axis sensor includes an "invalid force component" to overcome the local deformation of the FPC and an "effective mounting force" actually acting on the component. When the mounting head acts on the hard area of the FPC, the FPC deforms very little, and the total force measured by the sensor is almost entirely the effective mounting force. This means that for the same FPC, the size of the "board deformation force" in the total force varies significantly when mounted at different positions.

[0005] The core assumption of the existing pressure detection method is to equate the total force measured on the Z-axis to the effective mounting pressure, so it cannot distinguish or analyze the invalid force component used to overcome the deformation of the substrate. This leads to frequent pressure alarms in the production site, and the alarm position corresponds to the soft area of the FPC. Engineers try to adjust the global pressure setting value, but this "one-size-fits-all" approach has proven ineffective: if the overall pressure is increased to ensure adequate mounting in the soft area, it may cause damage to components in the hard area or pad peeling; if the overall pressure is reduced to protect components in the hard area, components in the soft area may not be properly mounted or welded due to insufficient effective mounting force. This inherent contradiction makes the existing pressure detection and control logic ineffective, unable to ensure the integrity of components while ensuring the mounting quality of all components.

[0006] The prior art needs to be improved in view of the above problems. SUMMARY

[0007] The present application discloses an SMT mounting pressure detection method and system, aiming to solve the technical problem that the existing SMT mounting pressure detection method cannot effectively distinguish between the invalid force component used to overcome the local deformation of the FPC and the effective mounting force actually acting on the component in the application of the flexible circuit board (FPC), resulting in inaccurate mounting pressure control and affecting the mounting quality and product reliability.

[0008] In a first aspect, the present application discloses an SMT mounting pressure detection method, specifically comprising the following steps: Obtaining force data and position data of the mounting head during movement in the first direction; Based on the force data and position data, determining the relationship change characteristics between the force and the position; According to the relationship change characteristics, identifying the physical state transition point of the component and the flexible circuit board from flexible deformation to rigid contact; At the physical state transition point, determining the force component used to overcome the local deformation of the flexible circuit board; According to the expected effective mounting force of the component and the force component, adjusting the target total force of the mounting head; Driving the mounting head to apply the target total force.

[0009] Optionally, the step of identifying the physical state transition point of the component and the flexible circuit board from flexible deformation to rigid contact comprises: According to the relationship change characteristics determined by the force data and position data, identifying a plurality of mechanical response feature points; According to the plurality of mechanical response feature points, determining the physical state transition points of a plurality of contact areas; The step of determining the force component used to overcome the local deformation of the flexible circuit board at the physical state transition point comprises: According to the physical state transition points of the plurality of contact areas, a force component for overcoming local deformation of the flexible circuit board is determined.

[0010] Optionally, the step of identifying the plurality of mechanical response feature points according to the relationship variation feature determined from the force data and the position data comprises: collecting force data and position data during the descending process of the mounting head; identifying an initial contact point on the force-displacement curve according to the force data and the position data; starting from the initial contact point, performing segmented analysis on the force-displacement curve, identifying a plurality of regions with a force value change rate greater than a preset change rate threshold, and marking as feature regions; in each feature region, determining a mechanical response feature point of the feature region, the mechanical response feature point being a point in the feature region where the force value change rate reaches a local maximum or exceeds a preset threshold.

[0011] Through the technical solution, the mechanical response features of the flexible circuit board in different deformation stages can be effectively captured through fine segmented analysis of the force-displacement curve, and reliable basis is provided for subsequent identification of the physical state transition points.

[0012] Optionally, the step of determining the mechanical response feature point of the feature region in each feature region, the mechanical response feature point being a point in the feature region where the force value change rate reaches a local maximum or exceeds a preset threshold comprises: performing local smoothing processing on the force data and the position data; calculating the first derivative of the force-displacement curve according to the locally smoothed force data and position data to obtain the force value change rate; identifying a local peak point in the force value change rate that exceeds a preset dynamic threshold to obtain a preliminary mechanical response feature point; in the vicinity of each preliminary mechanical response feature point, determining a point where the force value change rate reaches a local maximum or exceeds a preset threshold as a final mechanical response feature point according to the trend and change amplitude of the force value change rate.

[0013] Optionally, the step of determining the point where the force value change rate reaches a local maximum or exceeds a preset threshold in the vicinity of each preliminary mechanical response feature point comprises: calculating the second derivative of the force value change rate; identifying a local extreme point of the second derivative; evaluating the absolute amplitude of the local peak; comparing the absolute amplitude of the local peak with a preset relative amplitude threshold to obtain a force value change rate local peak point; determining the mechanical response feature point according to the degree of coincidence between the local extreme point of the second derivative and the force value change rate local peak point.

[0014] Optionally, the step of determining the physical state transition point of each contact area according to the plurality of mechanical response feature points comprises: identifying the force value and position information corresponding to each mechanical response feature point; performing interlayer attribution judgment on each mechanical response feature point according to the force value and position information, in combination with the interlayer structure parameters and material stiffness parameters of each layer of the flexible circuit board; determining the physical state transition point of the flexible circuit board layer corresponding to each mechanical response feature point according to the interlayer attribution judgment result.

[0015] Optionally, the step of determining the physical state transition point of the flexible circuit board layer corresponding to each mechanical response feature point according to the interlayer attribution judgment result comprises: analyzing the force value and position information corresponding to each mechanical response feature point according to the interlayer attribution judgment result; establishing a corresponding relationship between the deformation of each layer and the force-displacement curve feature in combination with the geometric structure and material mechanical properties of the flexible circuit board; determining the layer level of the physical state transition according to the corresponding relationship; dynamically adjusting the deformation threshold in the corresponding relationship between the deformation of each layer and the force-displacement curve feature; performing weighted correction on the mechanical response feature point according to the deviation between the force value and position information corresponding to the mechanical response feature point and the deformation threshold, in combination with historical mounting data and environmental parameters; identifying the main deformation layer level and quantifying the secondary deformation layer level according to the distribution density and force value change gradient of the mechanical response feature points; judging the local defects, voids or prestress inside the flexible circuit board according to the local anomaly of the force-displacement curve; dynamically adjusting or correcting the layer level determination of the physical state transition according to the judgment result.

[0016] Optionally, the step of dynamically adjusting the deformation threshold in the corresponding relationship between the deformation of each layer and the force-displacement curve feature comprises: obtaining temperature data and humidity data of different local areas of the flexible circuit board; calculating the real-time stiffness correction coefficient of each local area according to the temperature data and humidity data of each local area and the pre-calibrated material temperature-humidity-stiffness response curve; applying the real-time stiffness correction coefficient of each local area to the corresponding deformation threshold to obtain the locally dynamically adjusted deformation threshold.

[0017] Optionally, the step of correcting the mechanical response feature points by weighting according to the deviation between the force value and position information corresponding to the mechanical response feature points and the deformation threshold, in combination with historical mounting data and environmental parameters, comprises: quality assessment and screening of the historical mounting data; establishing a correction factor library according to the screened historical mounting data; real-time acquisition of environmental parameters and evaluation of the impact of environmental parameter measurement lag or uncertainty on the mechanical response; dynamic adjustment of the correction factors in the correction factor library according to the impact of the environmental parameters; calculating the correction weight of each mechanical response feature point according to the deviation between the force value and position information corresponding to the mechanical response feature points and the deformation threshold, and the correction factors in the correction factor library; correcting the mechanical response feature points by applying the correction weight.

[0018] In a second aspect, the application also discloses an SMT mounting pressure detection system, which comprises: a force-position data acquisition module configured to acquire force data and position data of the mounting head during movement in the first direction; a relationship feature determination module configured to determine a relationship change feature between the force and the position based on the force data and the position data; a state transition point identification module configured to identify a physical state transition point from flexible deformation to rigid contact of the component and the flexible circuit board according to the relationship change feature; a deformation force component determination module configured to determine a force component for overcoming local deformation of the flexible circuit board at the physical state transition point; a target total acting force adjustment module configured to adjust a target total acting force of the mounting head according to the expected effective mounting force of the component and the force component; a mounting head driving module configured to drive the mounting head to apply the target total acting force.

[0019] Advantages The application discloses an SMT mounting pressure detection method. By acquiring force data and position data of a mounting head during movement in a first direction, and determining the relationship change characteristics between the force and the position based on the data, the physical state conversion point from flexible deformation to rigid contact of a component and a flexible circuit board can be identified. On this basis, the application can accurately determine the force component for overcoming the local deformation of the flexible circuit board at the physical state conversion point. By combining the force component with a preset expected effective mounting force of the component, the application can dynamically adjust the target total acting force of the mounting head, and drive the mounting head to apply the target total acting force. The application can effectively solve the problem of inaccurate mounting pressure control caused by the inability to distinguish invalid force components in the prior art, and avoid the drawbacks caused by the "one-size-fits-all" pressure setting method. By accurately adjusting the target total acting force of the mounting head, the application ensures that the component can be mounted in place with the expected effective mounting force in different areas of the flexible circuit board, significantly improves the mounting quality and product reliability, and avoids the risk of component damage and pad peeling, and has significant practical value and technical progress. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a flowchart of an SMT mounting pressure detection method provided by an embodiment of the application; Figure 2 is a flowchart of step S3 shown in Figure 1 ; Figure 3 is a flowchart of step S31 shown in Figure 2 ; Figure 4 is a flowchart of step S314 shown in Figure 3 ; Figure 5 is a flowchart of step S3144 shown in Figure 4 ; Figure 6 is a flowchart of step S32 shown in Figure 2 ; Figure 7 is a flowchart of step S323 shown in Figure 6 ; Figure 8 is a flowchart of step S3234 shown in Figure 7 ; Figure 9 is a flowchart of step S3235 shown in Figure 7 ; Figure 10 is a structural diagram of an SMT mounting pressure detection system provided by an embodiment of the application. DETAILED DESCRIPTION

[0021] The technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. The components of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0022] It should be noted that: similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. Meanwhile, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0023] In modern electronic product manufacturing, surface mount technology (SMT) is a core production link, in which the accurate mounting of components is crucial, and the mounting pressure directly affects the welding quality and product reliability. The traditional existing SMT production line is usually equipped with a pressure detection scheme, which integrates a force sensor in the Z-axis of the mounting head, measures the total force when the mounting head contacts the printed circuit board (PCB) in real time, and converts it into a mounting pressure value. However, for flexible circuit boards (FPC), due to the uneven stiffness distribution, the existing pressure detection method cannot distinguish or analyze the invalid force component used to overcome the deformation of the substrate, resulting in frequent pressure alarms in the production site, and unable to ensure the mounting quality of all components while ensuring the integrity of the components. In view of this, the present application proposes an SMT mounting pressure detection method.

[0024] Please refer to Figure 1 , comprising the following steps: Step S1: acquiring force data and position data of the mounting head during movement in a first direction; Step S2: determining the relationship change feature between force and position based on the force data and the position data; Step S3: identifying the physical state transition point of the component and the flexible circuit board from flexible deformation to rigid contact according to the relationship change feature; Step S4: determining the force component for overcoming the local deformation of the flexible circuit board at the physical state transition point; Step S5: adjusting the target total force of the mounting head according to the expected effective mounting force of the component and the force component. Step S6: driving the placement head to apply the target total force.

[0025] The present application obtains force data and position data of the placement head during movement in the first direction, and determines the variation characteristics of the relationship between force and position based on the data, and then identifies the physical state transition point of the component and the flexible circuit board from flexible deformation to rigid contact. Thus, the force component for overcoming the local deformation of the flexible circuit board can be accurately determined at the physical state transition point. Finally, the target total force of the placement head is adjusted according to the desired effective placement force of the component and the force component, and the placement head is driven to apply the target total force, thereby effectively solving the problem of inaccurate pressure detection caused by the deformation of the flexible circuit board during the placement process, and ensuring the accurate placement and welding quality of the component.

[0026] The "placement head" refers to the execution component of the SMT equipment for picking up and placing components, which usually moves vertically in the Z-axis direction to achieve the placement of components. The "first direction" usually refers to the direction perpendicular to the surface of the flexible circuit board during the placement process, i.e. the Z-axis direction. The "force data" refers to the force values collected by the Z-axis force sensor of the placement head in real time during movement. The "position data" refers to the position values collected by the Z-axis encoder or displacement sensor of the placement head in real time during movement. The "variation characteristics of the relationship between force and position" refers to the specific pattern or trend that the force exhibits with the change of position during the placement process, such as the slope of the force-displacement curve, the inflection point, etc. The "physical state transition point" refers to the critical point at which the flexible circuit board changes from a flexible state to a rigid state of complete contact with the underlying support structure or component during the contact process. The "flexible deformation" refers to the elastic or plastic deformation of the local area of the flexible circuit board when subjected to the action of the placement head. The "rigid contact" refers to the state in which the local area of the flexible circuit board is completely bonded with the underlying support pin or the bottom of the component after deformation, and no significant deformation occurs. The "force component" refers to the part of the total force that is used to overcome the local deformation of the flexible circuit board, i.e. the "ineffective force". The "desired effective placement force" refers to the force that actually acts on the component pads during the placement process to ensure good welding and electrical connection. The "target total force" refers to the total force that the placement head needs to finally apply, which is the sum of the desired effective placement force and the force component for overcoming the local deformation of the flexible circuit board.

[0027] The SMT placement pressure detection method of the present application is characterized by accurately identifying the physical state transition point of the flexible circuit board, and separating the force component for overcoming the local deformation of the flexible circuit board based on this.

[0028] In the step of "obtaining force data and position data of the mounting head during movement in the first direction", it can be achieved in various ways. For example, a high-precision force sensor and a displacement sensor can be integrated on the Z-axis of the mounting head. The force sensor can be a piezoelectric, resistance strain or capacitive sensor, which is used to measure the force of the mounting head in contact with the flexible circuit board during the descent process. The displacement sensor can be an optical encoder, laser displacement sensor or eddy current sensor, which is used to accurately measure the vertical position of the mounting head relative to the surface of the flexible circuit board. The data of these sensors can be collected synchronously through a high-speed data acquisition card and transmitted to the data processing unit.

[0029] In the step of "determining the relationship change feature between force and position based on the force data and the position data", the collected raw force data and position data can be pre-processed, such as noise filtering, data smoothing, etc., to eliminate measurement errors and environmental interference. Then, the processed force data and position data are plotted into a force-displacement curve. This curve can intuitively reflect the trend of the force changing with displacement during the descent of the mounting head. The determination of the relationship change feature can include analyzing the slope, curvature, inflection point, etc. of the curve, which can reflect the mechanical response characteristics of the flexible circuit board in different deformation stages. For example, in the flexible deformation stage, the slope of the force-displacement curve may be small, while in the rigid contact stage, the slope will increase significantly.

[0030] In the step of "identifying the physical state transition point of the component and the flexible circuit board from flexible deformation to rigid contact according to the relationship change feature", the physical state transition point can be identified using the relationship change feature determined above. For example, the slope change rate of the force-displacement curve can be analyzed, and when the slope suddenly increases from a small value to a large value, this point can be identified as the physical state transition point. In addition, a threshold value of force or displacement can also be set, and when the force or displacement reaches a certain threshold value, it is considered that the physical state transition has occurred. For example, when the force value change rate exceeds a pre-set threshold value, it can be considered that the flexible circuit board has changed from flexible deformation to rigid contact.

[0031] In the step of "determining the force component for overcoming local deformation of the flexible circuit board at the physical state transition point", once the physical state transition point is identified, the corresponding force value at this point can be read. This force value is the force component required to overcome the local deformation of the flexible circuit board before the component and the flexible circuit board are in rigid contact. For example, the force component can be obtained by integrating the force values between the initial contact point and the physical state transition point on the force-displacement curve, or directly reading the force value at the physical state transition point as the force component.

[0032] In the step of "adjusting the target total force of the mounting head according to the preset expected effective mounting force of the component and the force component", the preset expected effective mounting force of the component is determined according to the type, size, pad characteristics of the component and the welding process requirement. The force component is a key parameter for ensuring good welding between the component and the pad. The expected effective mounting force is added to the force component determined for overcoming the local deformation of the flexible circuit board, so as to obtain the target total force required to be applied by the mounting head. For example, if the expected effective mounting force is F_effective and the determined force component is F_deformation, the target total force F_total = F_effective + F_deformation.

[0033] In the step of "driving the mounting head to apply the target total force", the calculated target total force is sent to the driving system of the mounting head as a control instruction. The driving system of the mounting head, such as a servo motor or a pneumatic cylinder, accurately controls the descending speed and the final force of the mounting head according to the instruction, so as to ensure that the mounting head mounts the component on the flexible circuit board with the calculated target total force.

[0034] The SMT mounting pressure detection method of the present application forms a complete closed-loop control system through the synergistic effect of the above steps. The method first provides a reliable basis for subsequent analysis through accurate force data and position data collection. Then, through in-depth analysis of the change characteristics of the force-displacement relationship, the physical state transition point of the component and the flexible circuit board from flexible deformation to rigid contact can be accurately identified. This identification process is the key innovation point of the present application, which makes it possible to distinguish between "invalid force component" and "effective mounting force". Once the force component for overcoming the local deformation of the flexible circuit board is determined, it can be combined with the preset expected effective mounting force to dynamically adjust the target total force of the mounting head. Finally, the mounting head is driven to apply the adjusted target total force, ensuring that the components in different areas of the flexible circuit board can obtain accurate effective mounting force, thereby solving the problem of inaccurate pressure detection caused by the deformation of the flexible circuit board in the traditional method.

[0035] Please refer to Figure 2 , the previous step S3: the scheme of identifying the physical state transition point of the component and the flexible circuit board from flexible deformation to rigid contact further comprises: Step S31: identifying a plurality of mechanical response feature points according to the relationship change characteristics determined by the force data and the position data; Step S32: determining a plurality of physical state transition points of the contact areas according to the plurality of mechanical response feature points; The step S4 in the foregoing can specifically include the following steps.

[0036] In the process, specific points showing significant changes in the relationship between force and position are identified. These points usually correspond to key moments such as initial contact, compaction or structural deformation of different levels or regions of the flexible circuit board. For example, when the component contacts the surface layer, adhesive layer or substrate layer of the flexible circuit board, the slope or rate of change of the force-displacement curve will change significantly, and these change points are identified as mechanical response feature points.

[0037] Further, the physical state transition points of the multiple contact regions are determined according to the multiple mechanical response feature points. This means that after identifying these discrete mechanical response feature points, the points need to be classified into different contact regions in combination with the structural characteristics of the flexible circuit board, and the precise transition points of the component and the flexible circuit board from flexible deformation to rigid contact in each region are determined.

[0038] Therefore, the force component for overcoming the local deformation of the flexible circuit board at the physical state transition point is determined. Specifically, once the physical state transition points of the multiple contact regions are determined, the force component required to overcome the deformation of the corresponding local region of the flexible circuit board at the point can be calculated or estimated for each transition point. For example, when the component and a specific layer of the flexible circuit board reach rigid contact, the change in force value before the point is mainly due to the flexible deformation of the layer. By analyzing the force value at the transition point and the previous force-displacement curve, the force component for overcoming the local deformation of the layer can be accurately separated.

[0039] The scheme of the present application can more accurately capture the multi-stage mechanical response of the component and the flexible circuit board during the mounting process by refining the process of identifying the physical state transition point and determining the force component into identifying multiple mechanical response feature points and determining the physical state transition points of multiple contact regions.

[0040] Specifically, please refer to Figure 3 The step S31 of identifying multiple mechanical response feature points according to the relationship change characteristics determined by the force data and the position data can include the following operations: Step S311: Collecting force data and position data during the descent of the mounting head; Step S312: Identifying the initial contact point on the force-displacement curve according to the force data and the position data; Step S313: From the initial contact point, segmental analysis is performed on the force-displacement curve to identify multiple regions with a force value change rate greater than a preset change rate threshold, marked as feature regions. Step S314: In each feature region, a mechanical response feature point of the feature region is determined, which is a point where the force value change rate reaches a local maximum or exceeds a preset threshold in the feature region.

[0041] Wherein, collecting force data and position data during the descent of the mounting head refers to, in the SMT mounting process, through the force sensor and displacement sensor installed on the mounting head, the force and corresponding position information of the mounting head when moving downward in the vertical direction (first direction) are obtained in real time. These data constitute the basis of the force-displacement curve, which is used for subsequent analysis.

[0042] According to the force data and position data, the initial contact point on the force-displacement curve is identified, which refers to the point when the component first contacts the surface of the flexible circuit board during the descent of the mounting head, at which point the force value begins to change significantly. This point is usually characterized by a first significant change in the slope of the force-displacement curve, marking the beginning of physical contact between the component and the flexible circuit board.

[0043] From the initial contact point, segmental analysis is performed on the force-displacement curve to identify multiple regions with a force value change rate greater than a preset change rate threshold, and mark them as feature regions. The purpose is to capture the stage changes in mechanical response when the flexible circuit board deforms at different depths or different levels. The flexible circuit board is usually composed of multiple layers of materials, and each layer may exhibit different deformation characteristics when subjected to pressure, resulting in different characteristics of the slope (i.e. force value change rate) of the force-displacement curve at different stages. By setting a preset change rate threshold, regions with significant changes in mechanical response can be effectively screened out, which usually correspond to the deformation or contact of different levels inside the flexible circuit board.

[0044] In each feature region, a mechanical response feature point of the feature region is determined. The mechanical response feature point is a point where the force value change rate reaches a local maximum or exceeds a preset threshold in the feature region. These points represent the most intense or representative moments of mechanical response in a specific deformation stage. For example, when the component contacts a certain specific layer of the flexible circuit board, a local peak of the force value change rate may occur, and this peak point is identified as a mechanical response feature point, which reflects the stiffness characteristics or deformation behavior of the layer of material.

[0045] By the technical scheme, deeper understanding and more accurate characterization of a complex mechanical interaction process between a component and a flexible circuit board in an SMT mounting process can be achieved. Compared with only identifying a single physical state transition point, the scheme can more finely depict the delamination deformation characteristics of the multi-layer structure of the flexible circuit board under pressure by identifying multiple mechanical response feature points, thereby improving the accuracy and robustness of the physical state transition point identification. Thus, a more reliable basis is provided for subsequent accurate calculation of a force component overcoming local deformation of the flexible circuit board, thereby helping to achieve more accurate mounting pressure control, effectively avoiding component damage or false soldering and the like, and improving mounting quality and yield.

[0046] Referring to Figure 4 , the foregoing step S314 of determining the mechanical response feature point of the feature region, the mechanical response feature point being a point at which a force value change rate reaches a local maximum value or exceeds a preset threshold, further includes the following steps. Step S3141: locally smoothing the force data and the position data; Step S3142: calculating a first derivative of the force-displacement curve according to the locally smoothed force data and the position data to obtain the force value change rate; Step S3143: identifying a local peak point of the force value change rate that exceeds a preset dynamic threshold to obtain a preliminary mechanical response feature point; Step S3144: determining, near each preliminary mechanical response feature point, a point at which the force value change rate reaches a local maximum value or exceeds a preset threshold as a final mechanical response feature point according to a trend and a change amplitude of the force value change rate.

[0047] Specifically, the local smoothing of the force data and the position data aims to eliminate random noise and burrs in the data, so that subsequent derivative calculation is more stable and accurate. For example, the original data can be processed by using a moving average filter, a Savitzky-Golay filter or wavelet denoising and the like. The window size or filter parameters of the local smoothing can be dynamically adjusted according to the actual noise level and data sampling frequency.

[0048] Further, the first derivative of the force-displacement curve is calculated according to the locally smoothed force data and the position data to obtain the force value change rate. The first derivative of the force-displacement curve reflects the rate of change of force with displacement, and the local peak value thereof usually corresponds to the time at which the physical contact state changes significantly. The first derivative can be obtained by a numerical differentiation method, such as a central difference method or a finite difference method.

[0049] Thus, local peak points exceeding a preset dynamic threshold in the force value change rate are identified to obtain preliminary mechanical response feature points. The preset dynamic threshold can be adaptively adjusted according to historical data, material characteristics or real-time data fluctuation. The local peak point refers to a point at which the force value change rate reaches a maximum value in a certain neighborhood.

[0050] Finally, at each of the preliminary mechanical response feature points, points at which the force value change rate reaches a local maximum value or exceeds a preset threshold are determined according to the trend and change amplitude of the force value change rate, as final mechanical response feature points. This step aims to finely screen and confirm the preliminary identified feature points, to ensure that the identified points truly represent important physical state transitions. For example, the width, symmetry and slope of the change rate before and after the peak point can be analyzed to exclude false peaks caused by noise.

[0051] Through the above technical solution, the application can effectively overcome the interference of original data noise on the identification of mechanical response feature points, and significantly improve the accuracy and stability of feature point identification. Specifically, local smoothing effectively suppresses noise, making the calculation of the force value change rate more accurate; and the multi-stage peak identification and fine confirmation mechanism ensures that the identified feature points can truly reflect the key mechanical responses in the physical contact process, avoiding misjudgment and omission. Thus, a reliable foundation is provided for the accurate determination of the physical state transition point, thereby improving the precision and reliability of SMT mounting pressure control, and helping to achieve better component mounting quality and yield.

[0052] Referring to Figure 5 , the application further proposes the above step S3144: determining points at which the force value change rate reaches a local maximum value or exceeds a preset threshold according to the trend and change amplitude of the force value change rate in the vicinity of each preliminary mechanical response feature point, which further includes the following steps: S3145: calculating the second derivative of the force value change rate; S3146: identifying local extreme points of the second derivative; S3147: evaluating the absolute amplitude of the local peak of the force value change rate; S3148: comparing the absolute amplitude of the local peak with a preset relative amplitude threshold to obtain a force value change rate local peak point; S3149: determining the mechanical response feature point according to the degree of coincidence between the local extreme point of the second derivative and the force value change rate local peak point.

[0053] Specifically, calculating the second derivative of the force rate aims to obtain the instantaneous change trend of the force rate, i.e., the "acceleration" of the force rate. By analyzing the second derivative, the inflection points or points with the most drastic change in slope on the force rate curve can be more accurately located, which often correspond to the local maximum or minimum values of the first derivative (force rate). Identifying the local extreme points of the second derivative, i.e., finding the peaks or valleys on the second derivative curve, these extreme points indicate the moments when the force rate changes the fastest, thus helping to accurately lock the mechanical response feature points.

[0054] At the same time, evaluating the absolute amplitude of the local peak of the force rate and comparing it with the preset relative amplitude threshold is to ensure that the identified peak is significant enough to avoid misjudging minor fluctuations or noise as feature points. For example, a threshold can be set that requires the local peak to be higher than the average force rate in its surroundings by a certain percentage to be considered as a valid local peak of the force rate.

[0055] Finally, by comprehensively considering the degree of coincidence between the local extreme points of the second derivative and the local peak points of the force rate, the mechanical response feature points can be finally determined. The degree of coincidence can be based on the proximity in position, for example, if the local extreme points of the second derivative and the local peak points of the force rate are very close in position, then this point can be considered as a reliable mechanical response feature point. This multi-dimensional verification mechanism significantly improves the accuracy and robustness of feature point identification.

[0056] Through the above technical solutions, the present application can more accurately and robustly identify the mechanical response feature points on the force-displacement curve. By introducing second derivative analysis and multi-verification mechanism, the influence of noise on feature point identification can be effectively reduced, avoiding misjudgment or omission, thus ensuring that the determination of subsequent physical state transition points is more accurate. Thus, it can provide more detailed perception of the contact state between the components and the flexible circuit board during SMT mounting process, and then realize more accurate mounting pressure control, which helps to improve the mounting yield and product reliability.

[0057] Please refer to Figure 6 , the scheme of determining the physical state transition points of the plurality of contact regions according to the plurality of mechanical response feature points can include the following contents: Step S321: identifying the force value and position information corresponding to each of the mechanical response feature points; Step S322: according to the force value and the position information, combining the interlayer structure parameters and the material stiffness parameters of each layer of the flexible circuit board, performing interlayer attribution judgment on each of the mechanical response feature points; Step S323: determining the physical state transition point of the flexible circuit board layer corresponding to each of the mechanical response feature points according to the inter-layer attribution judgment result.

[0058] Specifically, when identifying the force value and position information corresponding to each mechanical response feature point, the force value and position coordinates corresponding to the identified mechanical response feature point can be directly extracted from the pre-collected force data and position data. These information are the basis for subsequent inter-layer attribution judgment.

[0059] Further, according to the force value and the position information, the inter-layer attribution of each of the mechanical response feature points is judged in combination with the inter-layer structure parameters of the flexible circuit board and the material stiffness parameters of each layer. The inter-layer structure parameters of the flexible circuit board can include the thickness of each layer, the thickness of the inter-layer adhesive, and the arrangement order of the material of each layer, etc. The material stiffness parameters of each layer refer to the mechanical performance parameters such as elastic modulus and Poisson's ratio of different material layers (e.g. substrate layer, conductive layer, insulating layer, cover film, etc.) in the flexible circuit board. By comparing and analyzing the force value and position information corresponding to the mechanical response feature points with these known flexible circuit board structure and material parameters, it can be determined which layer's deformation or contact causes the mechanical response feature point. For example, when the mounting head descends and contacts the flexible circuit board, the outermost cover film is contacted first, and with the increase of pressure, the conductive layer, the insulating layer, the substrate layer, etc. will be contacted in turn. The contact or deformation of each layer will produce a specific mechanical response feature point on the force-displacement curve. By establishing a corresponding relationship model between the force-displacement curve features and the deformation of each layer of the flexible circuit board, the inter-layer attribution of the mechanical response feature points can be determined.

[0060] Therefore, according to the inter-layer attribution judgment result, the physical state transition point of the flexible circuit board layer corresponding to each of the mechanical response feature points is determined. Once it is determined which layer a certain mechanical response feature point belongs to, the point is regarded as the physical state transition point of the layer from flexible deformation to rigid contact. For example, if a certain mechanical response feature point is judged to correspond to the substrate layer of the flexible circuit board, the point represents the starting point of rigid contact between the component and the substrate layer.

[0061] By the technical solution, the physical state transition points of each layer in the multi-layer structure of the flexible circuit board can be accurately identified. Compared with identifying only the overall physical state transition point, the application can distinguish the contact and deformation transition points of different levels (such as the cover film, conductive layer, substrate layer, etc.) of the components and the flexible circuit board, so as to more accurately quantify the mechanical response of each level in the mounting process. This fine identification helps to more accurately determine the force component for overcoming the local deformation of the flexible circuit board, avoid the mounting force deviation caused by insufficient understanding of the internal structure of the flexible circuit board, and thus improve the accuracy and reliability of SMT mounting, and effectively reduce the risk of component damage or poor mounting.

[0062] Please refer to Figure 7 , the previous step S323: according to the interlayer attribution judgment result, determining the physical state transition point of the flexible circuit board layer corresponding to each mechanical response feature point includes: Step S3231: according to the interlayer attribution judgment result, analyzing the force value and position information corresponding to each mechanical response feature point; Step S3232: combining the geometric structure and material mechanics characteristics of the flexible circuit board, establishing the correspondence between the deformation of each layer and the force-displacement curve characteristics; Step S3233: according to the correspondence, determining the level of physical state transition; Step S3234: dynamically adjusting the deformation threshold in the correspondence between the deformation of each layer and the force-displacement curve characteristics; Step S3235: according to the deviation between the force value and position information corresponding to the mechanical response feature point and the deformation threshold, combining historical mounting data and environmental parameters, weighting and correcting the mechanical response feature point; Step S3236: according to the distribution density and force value change gradient of the mechanical response feature point, identifying the main deformation level and quantifying the secondary deformation level; Step S3237: according to the local anomaly of the force-displacement curve, judging the local defects, voids or prestress in the flexible circuit board; Step S3238: according to the judgment result, dynamically adjusting or correcting the level of physical state transition.

[0063] Specifically, in determining the physical state transition point of each mechanical response feature point corresponding to the flexible circuit board layer, first, according to the interlayer attribution judgment result, the force value and position information corresponding to each mechanical response feature point are analyzed in depth. This analysis aims to understand the contact state of the component and the flexible circuit board and the deformation of each layer inside the flexible circuit board under a certain force value and position. Among them, combined with the geometric structure and material mechanical properties of the flexible circuit board, the correspondence between the deformation of each layer and the force-displacement curve characteristics is established, that is, through theoretical modeling, finite element simulation or experimental calibration, the mapping relationship between the deformation degree of different layers (such as cover film, copper foil, substrate, adhesive layer, etc.) of the flexible circuit board in the compression process and certain feature points (such as slope change, inflection point, etc.) on the force-displacement curve is constructed. This correspondence is the basis for identifying the physical state transition layer. In practical applications, according to the above correspondence, the layer level of the physical state transition can be preliminarily determined. For example, when the slope of the force-displacement curve changes significantly at a certain position, combined with the preset correspondence, it can be preliminarily judged that the component may have contacted a certain specific layer of the flexible circuit board at this time and started to deform the layer.

[0064] Further, in order to improve the accuracy and adaptability of the judgment, the present application proposes to dynamically adjust the deformation threshold in the correspondence between the deformation of each layer and the force-displacement curve characteristics. This means that the correspondence established above is not fixed, but can be adjusted in real time or quasi-real time according to the actual situation. For example, when the environmental temperature or humidity changes, the material stiffness of the flexible circuit board will change accordingly, at which time the deformation threshold for judging the layer transition needs to be adjusted accordingly to ensure the accuracy of the judgment. In addition, in order to further improve the robustness of the mechanical response feature point determination, the present application also proposes to correct the mechanical response feature point according to the deviation between the force value and position information corresponding to the mechanical response feature point and the deformation threshold, combined with historical mounting data and environmental parameters. This means that if the currently detected mechanical response feature point deviates from the preset or dynamically adjusted deformation threshold, the historical successful mounting data and the current environmental parameters (such as temperature, humidity, etc.) can be used as correction factors to weight the feature point, so as to correct its position or force value, so that it more accurately reflects the real physical state transition.

[0065] In the process of determining the physical state transition level, the application also identifies the main deformation level and quantifies the secondary deformation level by analyzing the distribution density of the mechanical response characteristic points and the force value change gradient. For example, in the force-displacement curve, the mechanical response characteristic points in a certain area are densely distributed and the force value change gradient is large, which may indicate that this area is the main level of deformation or contact between the components and the flexible circuit board; while the characteristic points in other areas are sparsely distributed or have smaller gradients, which may correspond to the secondary deformation level. This distinction helps to better understand the mechanical behavior in the mounting process. As a preferred embodiment, the application can also determine the local defects, voids or pre-stresses inside the flexible circuit board according to the local anomalies of the force-displacement curve. For example, if the force-displacement curve shows a sudden drop in force value or abnormal fluctuations at a certain point, it may indicate that there are defects such as voids, delamination or local stress concentration inside the flexible circuit board. Thus, according to the above determination results, the level determination of the physical state transition can be dynamically adjusted or corrected. This means that if local defects are detected in the flexible circuit board, or the environmental parameters cause significant changes in material properties, the system can adjust the previously determined physical state transition level in real time based on this information to ensure the accuracy of subsequent force component determination and total force adjustment.

[0066] The scheme of the application effectively solves the problem of inaccurate determination of the physical state transition point of the flexible circuit board in complex and variable environments by introducing mechanisms such as dynamic adjustment of deformation threshold, weighted correction of mechanical response characteristic points, identification of main / secondary deformation levels and judgment of internal defects. Specifically, the dynamic adjustment of deformation threshold mechanism enables the system to compensate for the influence of real-time environmental parameters (such as temperature, humidity) on the stiffness of the flexible circuit board material, ensuring the accuracy of the deformation threshold in different working conditions and improving the adaptability of the physical state transition level determination. The weighted correction mechanism uses historical mounting data and environmental parameters to correct the mechanical response characteristic points, which helps to eliminate the influence of measurement noise, system errors and external disturbances that are not fully modeled on the identification of characteristic points, so that the characteristic points can more accurately reflect the true physical contact state. In addition, by analyzing the distribution density of the mechanical response characteristic points and the force value change gradient, the main and secondary deformation regions between the components and the layers of the flexible circuit board can be identified more carefully, which is crucial for understanding and controlling the complex deformation behavior of multi-layer flexible circuit boards. More importantly, by monitoring the local anomalies of the force-displacement curve to determine the local defects, voids or pre-stresses inside the flexible circuit board, the system not only adapts to external environmental changes, but also identifies and compensates for the inherent defects of the flexible circuit board itself, further improving the accuracy and reliability of the physical state transition level determination and providing a solid foundation for the subsequent accurate calculation of the force component to overcome the local deformation of the flexible circuit board.

[0067] By the technical solutions, the accuracy and robustness of the determination of the physical state transition points of the flexible circuit board in the SMT mounting process can be improved. Specifically, the dynamic adjustment of the deformation threshold enables the system to adapt to different environmental conditions and material batch differences, avoiding misjudgment caused by changes in material properties; the weighted correction mechanism effectively reduces the influence of measurement errors and external interference on feature point recognition, ensuring the accuracy of the feature points; the ability to identify major / minor deformation levels enables the system to more finely understand and control the complex deformation process of multi-layer flexible circuit boards; and the judgment and correction of internal defects further improve the system's ability to identify and handle abnormal situations, avoiding mounting force deviations caused by defects in the flexible circuit board. Thus, the application can more accurately determine the force component for overcoming local deformation of the flexible circuit board, thereby achieving more precise mounting pressure control, effectively reducing component damage and mounting failure rate, and improving the yield and reliability of SMT mounting.

[0068] To this end, the application further provides a specific scheme for dynamically adjusting the deformation threshold in the correspondence between the deformation of each layer and the force-displacement curve feature, which is described in detail in step S3234, and is described in detail as follows: Figure 8 Specifically, the specific scheme includes the following steps: S81: Obtain temperature data and humidity data of different local regions of the flexible circuit board; S82: Calculate the real-time stiffness correction coefficient of each local region according to the temperature data and humidity data of each local region and the pre-calibrated material temperature-humidity-stiffness response curve; S83: Apply the real-time stiffness correction coefficient of each local region to the corresponding deformation threshold to obtain a locally dynamically adjusted deformation threshold.

[0069] Specifically, the material properties of the flexible circuit board, such as its stiffness, will change with the variation of ambient temperature and humidity. To ensure the accuracy of the deformation threshold, temperature data and humidity data of different local regions of the flexible circuit board need to be obtained in real time. These data can be obtained by deploying temperature sensors and humidity sensors inside the mounting device or near the flexible circuit board. After obtaining these environmental parameters, a pre-calibrated material temperature-humidity-stiffness response curve can be used. This response curve describes the variation of the stiffness of a specific flexible circuit board material under different temperature and humidity conditions. Based on this response curve, real-time stiffness correction coefficients of each local region under the current temperature and humidity conditions can be calculated. The correction coefficient reflects the degree of change in material stiffness under the current environment relative to the standard condition. Subsequently, these real-time stiffness correction coefficients are applied to the pre-set or initial deformation threshold, thereby obtaining the dynamically adjusted deformation threshold for each local region of the flexible circuit board. This means that when the temperature of a certain local region of the flexible circuit board increases or the humidity increases, causing the stiffness to decrease, the corresponding deformation threshold will be adjusted accordingly to more accurately reflect the actual deformation characteristics of the region.

[0070] The scheme of the present application can accurately calculate the real-time stiffness correction coefficients of each local region by introducing real-time acquisition of temperature data and humidity data of local regions of the flexible circuit board, and combining a pre-calibrated material temperature-humidity-stiffness response curve. Since the material stiffness of the flexible circuit board is a key factor affecting its deformation characteristics, and it is significantly affected by environmental temperature and humidity, by applying these real-time stiffness correction coefficients to the corresponding deformation threshold, it can be ensured that the determined deformation threshold can accurately reflect the actual mechanical response of the flexible circuit board under the current environmental conditions. Thus, even in the case of environmental condition fluctuations, the accuracy of the physical state transition point identification can be ensured, and false positives caused by changes in material properties can be avoided.

[0071] Through the above technical scheme, the present application can achieve fine and dynamic adjustment of the deformation threshold of the flexible circuit board. Compared with schemes that do not consider environmental factors or only perform rough adjustment, the present application can significantly improve the accuracy and robustness of physical state transition point identification. This ensures that even in the face of fluctuations in the material properties of the flexible circuit board caused by changes in environmental temperature and humidity, the force applied by the mounting head can more accurately overcome the local deformation of the flexible circuit board, thereby achieving more accurate component mounting, effectively avoiding damage to components or circuit boards caused by excessive mounting force, or problems such as virtual welding and poor contact caused by insufficient mounting force, thereby improving mounting quality and production efficiency.

[0072] Reference should be made to Figure 9: The step S3235: According to the deviation between the force value and position information corresponding to the mechanical response feature point and the deformation threshold, and in combination with historical mounting data and environmental parameters, a scheme for weighted correction of the mechanical response feature point further includes the following steps: Step S91: Quality assessment and screening of the historical mounting data; Step S92: Establishing a correction factor library according to the screened historical mounting data; Step S93: Real-time acquisition of the environmental parameters and evaluation of the influence of environmental parameter measurement lag or uncertainty on the mechanical response; Step S94: Dynamically adjusting the correction factors in the correction factor library according to the influence of the environmental parameters; Step S95: Calculating the correction weight of each mechanical response feature point according to the deviation between the force value and position information corresponding to the mechanical response feature point and the deformation threshold, and the correction factors in the correction factor library; Step S96: Applying the correction weight to correct the mechanical response feature point.

[0073] Specifically, quality assessment and screening of historical mounting data refers to systematically checking and evaluating information such as force data, position data, component types, flexible circuit board batches, and environmental conditions recorded in past mounting operations. This process aims to identify and eliminate abnormal data, incomplete data, or disturbed data, ensuring that the data set used for correction has high reliability and representativeness. For example, screening can be based on data integrity, data consistency, and outlier detection standards to ensure the effectiveness of subsequent correction.

[0074] Among them, the correction factor library established according to the screened historical mounting data can be understood as extracting the deviation rules of the mechanical response feature points under different conditions (such as different components, different flexible circuit board batches, different environmental temperatures or humidity, etc.) through analysis of a large amount of high-quality historical mounting data. These rules are quantified as correction factors and stored in a database for querying and application. The correction factor library aims to provide an empirical reference benchmark for subsequent real-time correction.

[0075] In practical applications, real-time acquisition of environmental parameters and evaluation of the influence of environmental parameter measurement lag or uncertainty on the mechanical response specifically refers to continuously monitoring environmental factors such as temperature, humidity, and air pressure during the mounting process. At the same time, considering factors such as sensor response time, data transmission delay, or measurement error, the lag or uncertainty of real-time measurement values of these environmental parameters is quantitatively evaluated. The purpose is to ensure that the introduction of environmental parameters is accurate and timely, avoiding the introduction of new errors due to the inaccuracy of environmental data.

[0076] Further, dynamically adjusting the correction factors in the correction factor library according to the influence of the environmental parameters means that the pre-set correction factors in the correction factor library are updated or fine-tuned in real time based on the real-time acquisition and evaluation of the environmental parameters and their influence on the mechanical response. For example, when the environmental temperature rises, the stiffness of the flexible circuit board may decrease, and at this time, the correction factors related to deformation in the correction factor library will be adjusted accordingly to more accurately reflect the physical properties under the current environment. This aims to enable the correction factors to adapt to changing environmental conditions and improve the adaptability of the correction.

[0077] Thus, the correction weight of each mechanical response feature point is calculated according to the deviation between the force value and position information corresponding to the mechanical response feature point and the deformation threshold, and the correction factors in the correction factor library. Specifically, the difference between the currently detected mechanical response feature point and the pre-set deformation threshold is combined with the corresponding correction factor obtained from the dynamically adjusted correction factor library, and a correction weight is calculated through a specific algorithm (such as weighted average, regression analysis, etc.). The correction weight reflects the degree and direction of the correction required for the current mechanical response feature point.

[0078] Finally, applying the correction weight to correct the mechanical response feature point means that the correction weight calculated is applied to the corresponding mechanical response feature point to adjust its force value or position information. For example, if the correction weight indicates that a certain mechanical response feature point is too high due to environmental factors, its force value will be appropriately reduced, thereby obtaining a more accurate mechanical response feature point to provide more reliable input for subsequent force component determination.

[0079] The scheme of the present application introduces a quality evaluation and screening mechanism for historical mounting data to ensure that the empirical data used for correction is reliable and representative, thereby avoiding errors introduced by poor data. On this basis, a correction factor library is established to convert historical experience into quantifiable correction basis. Further, by real-time acquisition and evaluation of the measurement lag or uncertainty of the environmental parameters, the present application can more accurately grasp the influence of the current mounting environment on the mechanical response, and dynamically adjust the correction factors in the correction factor library accordingly. This dynamic adjustment mechanism enables the correction factors to adapt to environmental changes in real time, ensuring the accuracy and timeliness of the correction. Finally, the correction weight of each feature point is accurately calculated by combining the deviation of the mechanical response feature point from the deformation threshold and the dynamically adjusted correction factors, and is applied to the correction, thereby effectively eliminating the interference of factors such as historical data quality and environmental parameter uncertainty on the determination of the mechanical response feature point, making the determined mechanical response feature point more accurate and reliable.

[0080] By the technical solution, the accuracy and robustness of the determination of the mechanical response feature point in the SMT mounting process can be improved. Specifically, by strictly screening the historical data and establishing the correction factor library, the past experience is effectively utilized, and the repetitive errors are avoided. Meanwhile, the environmental parameters are monitored and the uncertainty is evaluated in real time, and the correction factor is dynamically adjusted accordingly, so that the system can be self-adapted to the changing environmental conditions, and the stability and reliability of the mounting process are greatly enhanced. Thus, the force component for overcoming the local deformation of the flexible circuit board determined will be more accurate, so as to ensure that the components are applied with the best effective mounting force, and the mounting defects caused by inaccurate calculation of the force component, such as virtual welding, component damage or insecure mounting, etc. are effectively avoided, and finally the yield and production efficiency of the SMT mounting are improved.

[0081] Please refer to Figure 10 The specific embodiments of the present application also disclose an SMT mounting pressure detection system, which comprises: a force-position data acquisition module 11, configured to acquire force data and position data of a mounting head in a first direction movement process; a relationship feature determination module 12, configured to determine a relationship change feature between the force and the position based on the force data and the position data; a state transition point identification module 13, configured to identify a physical state transition point of a component and a flexible circuit board from flexible deformation to rigid contact according to the relationship change feature; a deformation force component determination module 14, configured to determine a force component for overcoming the local deformation of the flexible circuit board at the physical state transition point; a target total acting force adjustment module 15, configured to adjust a target total acting force of the mounting head according to a preset expected effective mounting force of the component and the force component; a mounting head driving module 16, configured to drive the mounting head to apply the target total acting force.

[0082] The SMT mounting pressure detection system aims to solve the problem of inaccurate flexible circuit board mounting pressure detection in the prior art. The force-position data acquisition module 11 accurately collects force data and position data during the mounting process, and the relationship characteristic determination module 12 can deeply analyze the internal relationship between force and position. On this basis, the state transition point identification module 13 can accurately identify the key physical state transition point from flexible deformation to rigid contact of the component and the flexible circuit board. Subsequently, the deformation force component determination module 14 can accurately quantify the force component for overcoming the local deformation of the flexible circuit board at this transition point. Finally, the target total force adjustment module 15 combines the expected effective mounting force with the force component to dynamically adjust the target total force of the mounting head, and the mounting head driving module 16 accurately applies it, thereby ensuring that the components on different areas of the flexible circuit board can obtain accurate effective mounting force, significantly improving the mounting quality and product reliability.

[0083] The specific steps and principles of the SMT mounting pressure detection method have been described in the above embodiments and will not be repeated here. It should be emphasized that the SMT mounting pressure detection system of the present application realizes the above method in a modular manner, and each module works together to achieve the purpose of accurately controlling the mounting pressure.

[0084] Specifically, the force-position data acquisition module 11 can be configured to include one or more force sensors and one or more position sensors. For example, the force sensor can be a piezoelectric force sensor or a resistance strain force sensor mounted on the Z-axis of the mounting head, which is used to collect the acting force during the descent of the mounting head in real time. The position sensor can be an optical encoder, a laser displacement sensor or an eddy current sensor, which is used to accurately measure the vertical position of the mounting head relative to the surface of the flexible circuit board. These sensors can be independently deployed or integrated in a single sensing unit. Data acquisition can be completed through a dedicated data acquisition card or an embedded controller, and transmitted to the subsequent processing module.

[0085] The relationship characteristic determination module 12 can be implemented as a data processing unit, such as a microcontroller, a digital signal processor (DSP) or an industrial PC. This module receives the force data and position data provided by the force-position data acquisition module, and performs data preprocessing, filtering, smoothing and other operations. Subsequently, the module can calculate the slope, curvature and other characteristic parameters of the force-displacement curve to reveal the relationship between the force and the position. For example, these characteristics can be analyzed by differential operation, curve fitting or machine learning algorithm.

[0086] The state transition point identification module 13 can be implemented as an extended function of the relationship feature determination module, or a separate software module. Based on the relationship change features between force and position output by the relationship feature determination module, such as the slope mutation point of the force-displacement curve, the second derivative extreme point, etc., the module identifies the physical state transition point of the component and the flexible circuit board from flexible deformation to rigid contact. The identification algorithm can include threshold judgment, pattern recognition or learning model based on historical data.

[0087] The deformation force component determination module 14 can be implemented as a calculation unit, which calculates the force component for overcoming the local deformation of the flexible circuit board according to the physical state transition point determined by the state transition point identification module. For example, the module can read the force value at the physical state transition point, or integrate the force-displacement curve between the initial contact point and the transition point to quantify the force component. The module can be a separate software program segment running on the main controller.

[0088] The target total force adjustment module 15 can be implemented as a control logic unit, which receives the preset expected effective mounting force of the component and the force component output by the deformation force component determination module. The module calculates the target total force that the mounting head needs to apply according to the preset algorithm (such as simple addition operation). The module can be a programmable logic controller (PLC) or a software module in an embedded system.

[0089] The mounting head driving module 16 can be implemented as a motion control system of the mounting equipment, such as a servo motor driver, a stepper motor driver or a pneumatic actuator. The module receives the control instructions issued by the target total force adjustment module, and accurately controls the descending speed, position and final force of the mounting head to ensure that the component is mounted on the flexible circuit board with the calculated target total force. The module is usually tightly integrated with the mechanical structure and sensor feedback system of the mounting head to form a closed-loop control.

[0090] The coordinated work of the modules of the system of the present application enables the system to dynamically adjust the target total force of the mounting head to compensate for the local deformation of different areas of the flexible circuit board. Thus, regardless of the change in the local stiffness of the flexible circuit board, the effective mounting force acting on the component can always reach the preset value, thereby avoiding the problems caused by the traditional "one-size-fits-all" pressure setting. This systematic solution significantly improves the precision, reliability and yield of SMT mounting of flexible circuit boards, effectively reducing the risk of pressure alarm and component damage in the production process.

[0091] The above merely provides an example of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A SMT mounting pressure detection method, characterized in that: The following steps are involved: Acquiring force data and position data of the placement head during movement in a first direction; determining a characteristic of a change in a relationship between force and position based on the force data and the position data; Identifying a point where the physical state of the component and the flexible circuit board transitions from flexible deformation to rigid contact based on the relationship change characteristics; At the physical state transition point, determining a force component for overcoming a local deformation of the flexible circuit board; Adjusting the target total force of the placement head according to the preset expected effective placement force of the component and the force component; The placement head is driven to apply the target total force.

2. The SMT mounting pressure detection method according to claim 1, characterized in that: The step of identifying the point where the physical state of the component and the flexible circuit board changes from flexible deformation to rigid contact includes: identifying a plurality of mechanical response feature points based on the relationship change characteristics determined between the force data and the position data; determining physical state transition points of a plurality of contact areas according to the plurality of mechanical response characteristic points; The step of determining the force component for overcoming the local deformation of the flexible circuit board at the physical state transition point includes: A force component for overcoming local deformation of the flexible circuit board is determined according to the physical state transition points of the plurality of contact areas.

3. The SMT mounting pressure detection method according to claim 2, characterized in that: The step of identifying a plurality of mechanical response feature points based on the relationship change characteristics determined by the force data and the position data comprises: Collect force and position data during the descent of the placement head; identifying an initial contact point on a force-displacement curve based on the force data and the position data; Starting from the initial contact point, the force-displacement curve is segmented and analyzed to identify multiple regions where the force value change rate is greater than a preset change rate threshold, and mark them as characteristic regions; In each of the characteristic regions, a mechanical response characteristic point of the characteristic region is determined. The mechanical response characteristic point is a point in the characteristic region where the rate of change of the force value reaches a local maximum value or exceeds a preset threshold.

4. The SMT mounting pressure detection method according to claim 3, characterized in that: The step of determining, within each characteristic region, a mechanical response characteristic point of the characteristic region, wherein the mechanical response characteristic point is a point where the force value change rate within the characteristic region reaches a local maximum value or exceeds a preset threshold, comprises: Perform local smoothing on force and position data; According to the force data and position data after local smoothing, the first-order derivative of the force-displacement curve is calculated to obtain the force value change rate; Identifying a local peak point in the force value change rate that exceeds a preset dynamic threshold value to obtain a preliminary mechanical response characteristic point; Near each of the preliminary mechanical response characteristic points, based on the trend and variation range of the force value variation rate, the point where the force value variation rate reaches a local maximum value or exceeds a preset threshold value is determined as the final mechanical response characteristic point.

5. The SMT mounting pressure detection method according to claim 4, characterized in that: The step of determining, near each of the preliminary mechanical response characteristic points, a point where the force value change rate reaches a local maximum or exceeds a preset threshold value based on the trend and change amplitude of the force value change rate comprises: calculating a second derivative of the rate of change of the force value; identifying local extreme points of the second-order derivative; evaluating the absolute amplitude of the local peak of the force change rate; Comparing the absolute amplitude of the local peak with a preset relative increase threshold to obtain a local peak point of the force value change rate; The mechanical response characteristic point is determined according to the degree of coincidence between the local extreme point of the second-order derivative and the local peak point of the force value change rate.

6. The SMT mounting pressure detection method according to claim 2, characterized in that: The step of determining the physical state transition points of the plurality of contact areas according to the plurality of mechanical response characteristic points comprises: Identifying the force value and position information corresponding to each of the mechanical response characteristic points; According to the force value and the position information, combined with the interlayer structure parameters of the flexible circuit board and the stiffness parameters of each layer material, the interlayer attribution of each mechanical response characteristic point is judged; According to the inter-layer attribution judgment result, the physical state transition point of the flexible circuit board layer corresponding to each of the mechanical response characteristic points is determined.

7. The SMT mounting pressure detection method according to claim 6, characterized in that: The step of determining the physical state transition point of the flexible circuit board layer corresponding to each of the mechanical response characteristic points according to the inter-layer attribution judgment result includes: Analyzing the force value and position information corresponding to each of the mechanical response characteristic points according to the inter-layer attribution judgment result; Combining the geometric structure and material mechanical properties of the flexible circuit board, the corresponding relationship between the deformation of each layer and the force-displacement curve characteristics is established; Determining the level of the physical state conversion according to the corresponding relationship; Dynamically adjusting the deformation threshold in the corresponding relationship between the deformation of each layer and the force-displacement curve characteristics; Performing weighted correction on the mechanical response feature point according to the deviation between the force value and position information corresponding to the mechanical response feature point and the deformation threshold value, combined with historical placement data and environmental parameters; Identify the main deformation level and quantify the secondary deformation level according to the distribution density of the mechanical response characteristic points and the force value change gradient; judging local defects, gaps or prestress inside the flexible printed circuit board based on the local anomaly of the force-displacement curve; According to the judgment result, the level judgment of the physical state transition is dynamically adjusted or modified.

8. The SMT mounting pressure detection method according to claim 7, characterized in that: The step of dynamically adjusting the deformation threshold in the corresponding relationship between the deformation of each layer and the force-displacement curve characteristics includes: Obtain temperature and humidity data of different local areas of the flexible circuit board; Calculating a real-time stiffness correction coefficient for each local area based on the temperature data and humidity data of each local area and a pre-calibrated material temperature-humidity-stiffness response curve; The real-time stiffness correction coefficient of each local area is applied to the corresponding deformation threshold to obtain the deformation threshold after local dynamic adjustment.

9. The SMT mounting pressure detection method according to claim 7, characterized in that: The step of weighting correction of the mechanical response characteristic point according to the deviation between the force value and position information corresponding to the mechanical response characteristic point and the deformation threshold value, combined with historical placement data and environmental parameters, includes: Performing quality assessment and screening on the historical placement data; Establishing a correction factor library based on the filtered historical mounting data; Acquiring the environmental parameters in real time and evaluating the impact of the environmental parameter measurement hysteresis or uncertainty on the mechanical response; Dynamically adjusting the correction factors in the correction factor library according to the influence of the environmental parameters; Calculating a correction weight for each mechanical response characteristic point according to a deviation between the force value and position information corresponding to the mechanical response characteristic point and the deformation threshold, and a correction factor in the correction factor library; The correction weight is applied to correct the mechanical response characteristic point.

10. An SMT mounting pressure detection system, characterized in that: The system includes: A force and position data acquisition module, used for acquiring force data and position data of the placement head during movement in the first direction; a relationship feature determination module, configured to determine a relationship change feature between force and position based on the force data and the position data; A state transition point identification module is used to identify the physical state transition point between the component and the flexible circuit board from flexible deformation to rigid contact based on the relationship change characteristics; a deformation force component determination module, configured to determine a force component for overcoming a local deformation of the flexible circuit board at the physical state transition point; a target total force adjustment module, configured to adjust the target total force of the placement head according to a preset expected effective placement force of the component and the force component; The placement head driving module is used to drive the placement head to apply the target total force.

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