High-precision SMT patch positioning device and system

Abstract

The invention belongs to the technical field of surface mounting, and particularly relates to a high-precision SMT patch positioning device and system, and the system comprises a PCB bearing and transmission unit, a fixing mechanism, a visual detection unit, a dynamic compensation platform, a lifting mechanism and an intelligent control unit. The visual detection unit continuously monitors the position of the optical reference mark on the PCB through a high-speed image acquisition device; and the intelligent control unit processes the image data in real time, calculates the offset between the current position of the PCB and the theoretical reference, and controls the dynamic compensation platform to carry out rapid and precise compensation motion according to the offset, so as to offset dynamic disturbance in the surface mounting process. According to the invention, through closed-loop control combining real-time visual feedback and active motion compensation, the positioning of the PCB is improved from static fixation to dynamic stability, the problem of PCB micro-displacement caused by equipment vibration and impact is effectively solved, the mounting precision and yield are remarkably improved, and the method is especially suitable for precise mounting of high-difficulty PCBs such as ultra-thin plates and flexible plates.

Description

TECHNICAL FIELD

[0001] The present application relates to the surface mount technology field, especially to a high-precision SMT patch positioning device and system. BACKGROUND

[0002] In the SMT patch production line, after the PCB enters the patch machine working position through the conveying system, the traditional fixing method mainly relies on the mechanical edge clamping device. This method belongs to static fixing, and its defect is that it cannot effectively offset the dynamic, high-frequency micro-disturbance caused by the high-speed running of the patch head, the vibration of the equipment itself and the environmental air flow disturbance.

[0003] These micro-disturbances will cause the fixed PCB to produce micron-level displacement or slight deformation, especially for ultra-thin boards, large-size boards or flexible circuit boards (FPC), the influence is more significant. This uncontrollable micro-displacement directly reduces the mounting precision of components, and is one of the key bottlenecks restricting the yield improvement of ultra-high density and ultra-fine pitch mounting process. The existing technology lacks real-time perception and dynamic compensation ability of the real position of the PCB in the patch process, and it is difficult to meet the increasing demand for electronic manufacturing precision. SUMMARY

[0004] In order to overcome the defects of the existing static fixing technology, the present application provides a high-precision SMT patch positioning device and system. The core of the device and system is to introduce a closed-loop control mechanism combining real-time visual perception and active motion compensation, which upgrades the positioning mode of the PCB from passive fixing to active stabilization, thereby maintaining the ultra-stability of the PCB position in the dynamic patch environment.

[0005] In order to achieve the above purpose, the technical scheme provided by the present application is as follows: A high-precision SMT patch positioning system, comprising: A PCB bearing and transmission unit for conveying the PCB to the patch station and transporting it away from the patch station after the patch is completed to enter the next process; A fixing mechanism arranged at the patch station for preliminarily clamping the arriving PCB; A lifting mechanism, the lifting mechanism comprising a lifting base plate, a driving device for driving the lifting base plate to move vertically, and a positioning assembly for guiding; A visual detection unit comprising at least one high-speed image acquisition device and at least two optical reference marks prearranged on the PCB, the high-speed image acquisition device being configured to continuously acquire image information of the optical reference marks during the mounting process; A dynamic compensation platform is arranged below the fixing mechanism or integrated at the patching station of the PCB carrying and transferring unit, the fixing mechanism and the PCB clamped thereby are carried on the dynamic compensation platform, the dynamic compensation platform can perform precise micro-motion in at least one plane in response to a control instruction and synchronously ascend and descend with the lifting mechanism; An intelligent control unit is connected with the visual detection unit, the dynamic compensation platform and a patching machine main control system; the intelligent control unit is configured to receive and process image information sent by the visual detection unit, to calculate a transient position of the PCB in real time, to compare the transient position with a pre-stored theoretical reference position, to calculate a position offset, to generate a driving signal based on the offset, and to control the dynamic compensation platform to generate a corresponding compensation motion so as to make the actual position of the PCB return to or approach the theoretical reference position.

[0006] In a preferred embodiment, the high-speed image acquisition device is a high-frame-rate industrial camera, which is installed at a fixing point on the side of a patching head, an upper beam or a patching machine rack, to ensure that its field of view can continuously cover the optical reference mark on the PCB.

[0007] In a preferred embodiment, the dynamic compensation platform is a two-dimensional micro-motion platform based on a piezoelectric ceramic actuator or a high-response linear motor, which has a motion stroke of not less than ±1 mm in X and Y directions, a repeat positioning accuracy of better than 1 micrometer and a full-stroke response time of less than 10 milliseconds.

[0008] In a preferred embodiment, the intelligent control unit comprises: An image processing module is configured to perform feature extraction and sub-pixel level analysis on the collected optical reference mark image, and to output the plane coordinates and rotation angle of the PCB in real time; An error calculation and decision module is configured to store the theoretical reference position of the PCB and to calculate the deviation between the transient position and the reference position; the module has a pre-stored offset allowance threshold, and decides whether to trigger compensation according to whether the deviation value exceeds the threshold; A motion control module is configured to generate a corresponding driving signal according to the deviation value and to accurately control the motion amount and speed of each axis of the dynamic compensation platform when triggering compensation; A data management module is configured to record the position deviation data, compensation action log and equipment vibration characteristic data in all mounting periods, and to support data export and analysis.

[0009] In a preferred embodiment, the system further comprises an integrated vibration suppression unit, which comprises an array of vibration sensors distributed on the key structures of the equipment and an active force generator mounted on the base or frame of the dynamic compensation platform; the intelligent control unit controls the active force generator to output a counteracting force according to the signals of the vibration sensors, so as to actively attenuate the mechanical vibration in a specific frequency band.

[0010] The application also provides a key device constituting the system, i.e., a high-precision SMT patch positioning device, which mainly comprises the visual detection unit, the dynamic compensation platform, the intelligent control unit, and a special structure frame for mounting the integrated high-speed image acquisition device, the dynamic compensation platform, and the interface with the fixing mechanism, and can be integrated into an existing or new patch machine as a modular unit.

[0011] Compared with the prior art, the application provides a high-precision SMT patch positioning device and system, which has the following beneficial effects: 1. The device and system dynamically correct the PCB position drift in the patching process through a closed loop of real-time visual feedback and fast motion compensation, and convert the dynamic interference problem that cannot be solved by traditional static fixation into a measurable and compensable system error, thereby fundamentally improving the stability of the mounting process.

[0012] 2. The system has low dependence on the physical properties (such as thickness and rigidity) of the PCB, greatly expands the processing capacity of the patching equipment for high-difficulty boards (such as ultra-thin rigid boards, flexible boards, and mixed material boards), and improves the process adaptability and versatility of the equipment.

[0013] 3. The final positioning accuracy of the system is determined by the optical vision system and can reach microns or even sub-microns, and this accuracy does not degrade with the wear of mechanical parts, realizing long-term and stable ultra-high-precision mounting and providing a reliable hardware foundation for micro components such as 01005 and 008004, as well as advanced technologies such as chip-scale packaging (CSP) and board-level fan-out (Fan-Out).

[0014] 4. The intelligent control unit has perfect data acquisition and analysis functions, not only serving real-time control, but also providing data support for process optimization, equipment health state monitoring and predictive maintenance, and is an important technical component for promoting the intelligent and digital development of SMT production lines. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 FIG. 1 is a schematic diagram of the integration of the high-precision SMT patch positioning system of the application in a patch machine; Figure 2 FIG. 2 is a structural schematic diagram of the position relationship between the lifting mechanism, the dynamic compensation platform, the fixing mechanism, and the PCB bearing and transmission unit in the application. Figure 3 This is a schematic diagram showing the positional relationship between the lifting mechanism, the dynamic compensation platform, and the fixing mechanism in this invention. Figure 4 This is a block diagram of the hardware and functional modules of the intelligent control unit of the present invention; Figure 5 This is a schematic diagram of the real-time position compensation control logic of the system of the present invention during the patch placement process.

[0016] In the diagram: 1. Main body of the pick-and-place machine; 2. Placement head; 3. Component feeder; 4. PCB carrier and transmission unit; 5. Conveyor rail; 6. Support table; 7. Fixing mechanism; 8. Gripper; 9. Vision inspection unit; 10. Dynamic compensation platform; 11. Platform moving part; 12. Platform fixed base; 13. Intelligent control unit; 14. Integrated vibration damping unit; 15. Lifting mechanism; 16. Lifting substrate; 17. Positioning sleeve; 18. Positioning column; 19. Hydraulic cylinder. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] In the description of this invention, it should be understood that the terms upper, lower, front, back, left, right, top, bottom, inside, outside, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0019] Example 1, such as Figures 1 to 4 As shown in the figure, this embodiment demonstrates a high-precision SMT placement positioning system integrated into a general-purpose arch-type pick and place machine. The basic components of the system include a pick and place machine body 1, which is equipped with a multi-axis movable placement head 2 and a component feeder 3. The PCB carrying and transmission unit 4 consists of a conveying guide rail 5 and a support table 6, which is used to transport the PCB and temporarily support it in an accurate position. The fixing mechanism 7 uses a precision linear module with synchronous drive on both sides to drive the gripper 8 to achieve reliable clamping of the PCB edge.

[0020] The core device of this invention is integrated herein, comprising: Visual detection unit 9: a high frame rate, high resolution miniature industrial camera is used as a high-speed image acquisition device in this embodiment. The camera is mounted on the side of the patch head 2 through a rigid support, and can move synchronously with the patch head 2, but it has independent Z direction adjustment and locking mechanism to ensure its focal length is fixed. Two standard circular optical reference marks have been printed on the PCB, and the optical axis of the camera is calibrated to be perpendicular to the PCB plane. The field of view size is designed to ensure that when the patch head 2 moves to any picking or mounting position, as long as the PCB is near the theoretical position, at least one optical reference mark is always in its field of view, preferably both marks are in the field of view for redundant calculation.

[0021] Dynamic compensation platform 10: the platform is a two-dimensional precision motion platform in series. The upper surface of the platform moving part 11 (mover) is rigidly connected to the bottom of the fixed mechanism 7 through a connecting plate. Therefore, when the PCB is clamped, the PCB, the fixed mechanism 7 and the platform moving part 11 form a rigid whole. The dynamic compensation platform 10 is driven by a non-contact voice coil motor, and cooperates with a high-precision grating ruler feedback to realize a stroke of ±1.5mm in X and Y directions, a resolution of 0.1 microns and a step response time of less than 5 milliseconds.

[0022] Lifting mechanism 15: the mechanism uses a hydraulic telescopic device to realize lifting action. The mechanism is arranged below the dynamic compensation platform 10. The lifting base plate 16 is rigidly connected to the bottom of the platform fixed base 12 of the dynamic compensation platform 10. When the PCB is transported to the mounting station, the mechanism drives the dynamic compensation platform 10 and the fixed mechanism 7 to move upwards through the output shaft of the hydraulic cylinder 19 until the two clamping jaws 8 are located on both sides of the PCB, and then the PCB is clamped by the two clamping jaws 8. When the PCB is mounted, the fixed mechanism 7 releases the clamping, and the lifting mechanism 15 resets the dynamic compensation platform 10 and the fixed mechanism 7 to the initial position. The hydraulic cylinder 19 is directly installed on the solid base of the patch machine main body 1 through a damping pad. The positioning assembly includes a positioning column 18 and a positioning sleeve 17. Four positioning columns 18 are fixedly installed at the corner positions on the bottom of the lifting base plate 16. A matching positioning sleeve 17 is respectively sleeved on each positioning column 18. The positioning sleeve 17 is installed on the base of the patch machine main body 1 through bolts.

[0023] Intelligent control unit 13: this is a special controller based on a real-time industrial computer. It is connected with the visual detection unit 9 through a high-speed camera interface, connected with the driver of the dynamic compensation platform 10 through a motion control card, and synchronized and exchanged data with the patch machine main control system through an industrial Ethernet. The software running in the controller constitutes Figure 4 the various functional modules shown.

[0024] The operation principle of the system is as shown in Figure 5 . Initialization and Reference Calibration: When a new PCB is delivered to the position and clamped by the fixture 7, the intelligent control unit 13 is instructed by the SMT main control system to start working. The intelligent control unit 13 instructs the placement head 2 to move to a pre-set photographing position, and the high-speed camera is driven to take pictures of the two optical reference marks on the PCB. The image processing module processes the images and accurately calculates the actual position P_actual of the PCB in the coordinate system of the dynamic compensation platform 10 at this time. This position is stored in the error calculation and decision module and is set as the theoretical reference position P_reference of the PCB in the current placement cycle. Generally, under the condition that the equipment is well calibrated, P_actual and P_reference should be very close, but the system still takes the measured value as the standard to eliminate the repetitive errors of mechanical transmission and clamping.

[0025] Dynamic Placement and Real-time Compensation: After entering the placement cycle, the placement head 2 starts to move. During the flight time of the placement head 2 moving to the feeder 3 to take materials or moving between different placement points, the high-speed camera continuously captures the optical reference marks at a set high frequency. The image processing module solves the instantaneous position P_instant of the PCB corresponding to each image in real time. The error calculation and decision module receives P_instant in real time and calculates the deviation between P_instant and P_reference: the translation deviation Δd and the rotation deviation Δθ. Two threshold values are pre-set in the module: the translation allowable threshold ε_d and the rotation allowable threshold ε_θ.

[0026] Decision and Execution: If Δd≤ε_d and Δθ≤ε_θ, it is determined that the position of the PCB is stable, and the motion control module does not output any compensation instruction. The placement head 2 completes the material taking and placement actions according to the original planned path and coordinates. If Δd>ε_d or Δθ>ε_θ, it is determined that the PCB has a non-negligible deviation. The motion control module immediately calculates the required compensation amount, and then sends a high-priority instruction to the driver of the dynamic compensation platform 10. The driving platform 11 accurately completes the compensation movement in a very short time, thereby pushing the clamped PCB back to the vicinity of the theoretical reference position P_reference. After the compensation is completed, the motion control module sends a ready signal to the SMT main control system, and the placement head 2 executes accurate placement in the corrected position environment.

[0027] Data Recording: During the entire process, the data management module continuously records the time stamp, P_instant, deviation value, compensation trigger event, and compensation amount. These data form the placement stability file of the PCB and can be used for subsequent statistical process control (SPC) analysis.

[0028] Example 2, on the basis of example 1, this embodiment further enhances the anti-interference ability of the system, as Figure 4 As shown in the figure, the integrated vibration suppression unit 14 is integrated in the system.

[0029] The integrated vibration suppression unit 14 includes a plurality of high-sensitivity vibration sensors distributed on the crossbeam of the chip mounter, the base and the platform fixed base 12 of the dynamic compensation platform 10, and an electromagnetic active force generator installed at the four corners of the platform fixed base 12. The vibration sensor collects the vibration frequency spectrum signal of the device in the mounting process in real time and sends it to the intelligent control unit 13.

[0030] The motion control module of the intelligent control unit 13 is embedded with an adaptive filtering algorithm, which can identify the characteristic frequency vibration generated by the high-speed movement of the chip head 2, the switching of the component feeder 3, etc. The motion control module not only compensates the position according to the visual feedback, but also calculates and drives the active force generator to generate a force equal in amplitude and opposite in phase to the detected disturbance vibration, so as to actively cancel the vibration energy transmitted to the platform fixed base 12 and even the entire PCB fixed module. This feedforward active vibration suppression, in conjunction with the position compensation based on visual feedback, can attenuate at the source or transmission path of the disturbance, further improving the overall stability of the system under high-speed operation.

[0031] Example 3, this embodiment details the determination and control logic of the system through a specific application scenario, which is to mount a batch of ultra-thin flexible printed circuit boards (FPC) for wearable devices, which contain 0201 size micro inductors.

[0032] System configuration and parameter setting: Dynamic compensation platform 10: voice coil motor drive, resolution 0.05µm.

[0033] High-speed camera: frame rate 800fps, with ring-shaped LED coaxial lighting.

[0034] The preset determination threshold in the intelligent control unit 13: considering the slight tremor of the FPC, set ε_d=5.0µm, ε_θ=0.05°.

[0035] The theoretical reference position P_reference is calibrated at the initialization of each board.

[0036] The state determination and action logic of the system is as follows: At time t, the image processing module calculates the instantaneous position P_instant of the PCB, and the error calculation and decision module calculates the translation deviation Δd_t and the rotation deviation Δθ_t.

[0037] The system defines a two-dimensional state point S_t=(L_t, H_t), where L_t=ε_d / Δd_t (when Δd_t is 0, L_t is defined as infinite); H_t=ε_θ / Δθ_t (when Δθ_t is 0, H_t is defined as infinite).

[0038] The system decides to perform what action according to the position of the state point S_t in the preset judgment area: 1. Normal compensation state: when Δd_t>ε_d or Δθ_t>ε_θ, that is, L_t<1.0 or H_t<1.0, which indicates that the PCB position has exceeded the allowed range.

[0039] System action: the motion control module immediately triggers the compensation process, and the compensation displacement vector is calculated as the difference between the theoretical position and the instantaneous position. After receiving the instruction, the dynamic compensation platform 10 performs fast and precise motion, and after compensation, the system updates the internal state and prepares for mounting.

[0040] 2. Early warning monitoring state: when the deviation is close to but does not exceed the threshold value (for example, 0.8≤L_t<1.0 and 0.8≤H_t<1.0), which indicates that the system is on the edge of instability.

[0041] System action: the motion control module does not trigger active compensation, but the data management module marks this event as a warning and records relevant data, and the system remains highly monitored.

[0042] 3. Stable working state: when the deviation is significantly lower than the threshold value (L_t≥1.0 and H_t≥1.0, and not in the early warning state), which indicates that the PCB position is stable within the allowed range, System action: the system does not perform any compensation, and the mounting head 2 performs mounting according to the original planned coordinates, and all sensor data is recorded regularly.

[0043] In summary, the high-precision SMT mounting positioning device and system provided by the application realizes dynamic locking of the PCB position during mounting through innovative hardware architecture and intelligent control logic. It not only significantly improves mounting precision and yield, but also enhances the adaptability of the device to complex boards, and the built-in data intelligence provides insight for process optimization and device maintenance.

[0044] The above is only the preferred specific implementation of the application, but the protection scope of the application is not limited to this. Any skilled person in the art can make equivalent substitutions or changes to the technical solution and the inventive concept of the application within the technical scope disclosed by the application, which should be covered within the protection scope of the application.

Claims

1. A high-precision SMT patch positioning system, characterized in that, Comprising: a PCB carrying and conveying unit (4) for conveying a PCB to a mounting station; a fixing mechanism (7) arranged at the mounting station for clamping and fixing the PCB; a vision detection unit (9) comprising at least one high-speed image acquisition device and at least two optical reference marks prearranged on the PCB, the high-speed image acquisition device being configured to continuously acquire images of the optical reference marks during the mounting process; a lifting mechanism (15) comprising a lifting base plate (16), a driving device for driving the lifting base plate (16) to move vertically, and a positioning assembly for guiding; a dynamic compensation platform (10), the fixing mechanism (7) and the clamped PCB being carried on the dynamic compensation platform (10) as a whole, the dynamic compensation platform (10) being capable of precise micro-motion in a plane, the dynamic compensation platform (10) being rigidly connected to the lifting base plate (16) and synchronously lifting with the lifting base plate (16); an intelligent control unit (13) being signal-connected with the vision detection unit (9) and the dynamic compensation platform (10), the intelligent control unit (13) being configured to process the images to obtain an instantaneous position of the PCB, calculate an offset between the instantaneous position and a theoretical reference position, and control the dynamic compensation platform (10) to generate a compensation motion based on the offset.

2. The high precision SMT paster positioning system according to claim 1, characterized in that: The high-speed image acquisition device is a high-frame-rate industrial camera, and the high-frame-rate industrial camera is installed at a position such that the field of view of the high-frame-rate industrial camera can continuously cover the optical reference marks on the PCB during the mounting process.

3. The high precision SMT paster positioning system according to claim 1, wherein: The dynamic compensation platform (10) is a two-dimensional micro-motion platform based on a piezoelectric ceramic actuator or a linear motor, the motion stroke of the dynamic compensation platform (10) is not less than ±1 mm, and the positioning resolution is better than 1 µm.

4. The high precision SMT paster positioning system according to claim 1, wherein: The intelligent control unit (13) comprises: an image processing module for calculating the plane coordinates and the rotation angle of the PCB in real time from the images; an error calculation and decision module for storing the theoretical reference position, calculating the deviation between the instantaneous position and the reference position, and deciding whether to trigger compensation according to a preset threshold value; a motion control module for generating a driving signal to control the motion of the dynamic compensation platform (10) when compensation is triggered.

5. The high precision SMT paster positioning system according to claim 4, characterized in that: The intelligent control unit (13) further comprises a data management module for recording the position deviation data, the compensation action log and the equipment state data during the mounting process.

6. The high precision SMT paster positioning system according to any one of claims 1-5, characterized in that: Further comprising an integrated vibration suppression unit (14) comprising a vibration sensor and an active force generator, the intelligent control unit (13) controlling the active force generator to actively suppress mechanical vibration according to the signal of the vibration sensor.

7. The high precision SMT paster positioning system according to claim 4 or 5, characterized in that: The error calculation and decision module is configured to comprehensively judge the system state and decide the compensation action by calculating the ratio L of the translational deviation Δd to a preset translational threshold value ε_d and the ratio H of the rotational deviation Δθ to a preset rotational threshold value ε_θ.

8. A high precision SMT paster positioning device for the system of any one of claims 1-7, characterized in that, Comprising: a structural frame; the vision detection unit (9) mounted on the structural frame; The dynamic compensation platform (10) installed on the structure frame, the dynamic compensation platform (10) has an interface for connecting an external fixing mechanism (7); And the intelligent control unit (13); Wherein, the visual detection unit (9), dynamic compensation platform (10) are integrated into a modular device which can be independently installed and debugged through the structure frame.

9. The high precision SMT paster positioning device according to claim 8, characterized in that: The structure frame is also integrated with the active force generator of the integrated vibration suppression unit (14) and its installation site.

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