An adaptive precise mounting method for special-shaped devices

Abstract

The method relates to the field of surface mounting of electronic components, and particularly relates to a special-shaped device self-adaptive precise mounting method, which comprises the following steps: S1, characteristic library and reference model construction; S2, pose deviation identification; S3, six-degree-of-freedom self-adaptive deviation compensation; S4, closed-loop force control flexible mounting; and S5, mounting quality feedback and parameter self-optimization. The method has the beneficial effects that: by adopting a positioning mode of three-dimensional characteristic library + multi-scale template matching, the method does not need to depend on standard reference points of devices, can be suitable for special-shaped devices of various irregular shapes and asymmetric pins, and the positioning precision is improved by one order of magnitude compared with a traditional single-vision scheme.

Description

Technical Field

[0001] This method relates to the field of surface mount technology for electronic components, and in particular to an adaptive and precise mounting method for irregularly shaped devices. Background Technology

[0002] As the electronics industry develops towards customization and high density, the application of various irregularly shaped devices, such as irregularly shaped connectors, irregularly shaped sensors, and non-standard power devices, has increased significantly in fields such as automotive electronics, industrial control equipment, consumer electronics, and medical electronics. Compared with standard packaged devices (such as QFP, BGA, 0402 chip components, etc.), irregularly shaped devices have characteristics such as irregular shape, asymmetrical pin distribution, offset center of gravity, fewer positioning reference features, and large geometric tolerances. Traditional standard SMT mounting methods are difficult to achieve high-precision and high-yield mounting.

[0003] A Chinese invention patent application with publication number CN117373929A (publication date January 9, 2024, invention title: A mounting process for irregularly shaped components) discloses a basic mounting process specification for irregularly shaped components: it requires that the center of the bottom of the component coincide with the center of the solder paste stencil surface during mounting, and that the verticality and horizontality of the component be controlled within 5°. Mounting stability is ensured by matching the nozzle type and adjusting the vacuum suction pressure to 20%~40%. This solution can achieve basic mounting of common irregularly shaped components, but it still has the following obvious technical defects:

[0004] Firstly, relying solely on coarse positioning with center alignment lacks refined visual positioning and deviation compensation mechanisms. It can only achieve basic planar position control and cannot correct Z-axis height differences and tilt angle deviations caused by device pin shape and position deviations, substrate warping and deformation. For multi-pin, high coplanarity requirements of irregularly shaped connectors and sensor devices, problems such as pin soldering defects, open connections, and uneven stress deformation are likely to occur.

[0005] Secondly, the placement process only uses a fixed height position control mode without a closed-loop pressure adjustment mechanism. For irregularly shaped components made of brittle materials such as ceramics and glass, crushing and breakage are likely to occur. For asymmetrical irregularly shaped components with a shifted center of gravity, uneven placement pressure distribution can easily lead to excessive solder paste extrusion on one side and insufficient contact of solder paste on the other side, reducing the soldering yield.

[0006] Third, without a self-learning and iterative mechanism for mounting parameters, when changing the type of small batches of various irregularly shaped components, it is necessary to manually and repeatedly adjust parameters such as mounting height and vacuum pressure, resulting in a long production debugging cycle and poor mounting consistency.

[0007] Method content

[0008] The purpose of this invention is to address the shortcomings of existing technologies by providing an adaptive and precise mounting method for irregularly shaped devices. This method solves the problems of insufficient positioning references, inadequate compensation dimensions, uncontrollable mounting pressure, and low changeover efficiency for irregularly shaped devices, thereby achieving high-precision, high-yield, and high-consistency mounting of irregularly shaped devices.

[0009] An adaptive precision mounting method for irregularly shaped devices includes the following steps:

[0010] S1. Feature Library and Benchmark Model Construction: Perform 3D feature acquisition on the target irregular device and construct a feature library of irregular devices that includes device contour features, pin parameters, center of gravity parameters, and pressure bearing parameters; simultaneously acquire the pad layout and flatness parameters of the mounting substrate and establish a substrate mounting benchmark model.

[0011] S2, Position Deviation Recognition: Collect the position deviation data of irregularly shaped devices in the adsorption state, as well as the pad position deviation data of the substrate to be mounted area, and identify the initial alignment deviation between the device and the pad, the device shape deviation and the substrate deformation deviation.

[0012] S3, Six-DOF Adaptive Deviation Compensation: Based on the initial alignment deviation, device shape and position deviation, substrate deformation deviation, adsorption offset, and device center of gravity parameters, the six-DOF compensation amount of the mounting actuator is calculated and generated. The six degrees of freedom include X-axis translation, Y-axis translation, Z-axis lifting, X-axis tilt angle Rx, Y-axis tilt angle Ry, and rotation angle θ. The compensation amount is iteratively corrected in combination with the alignment overlap between the pins and pads until the alignment deviation meets the preset accuracy requirements.

[0013] S4. Closed-loop force-controlled flexible mounting: The mounting actuator moves to the mounting position according to the compensated posture, and the mounting pressure data is collected in real time during the Z-axis descent. Combined with the device pressure parameters, segmented closed-loop constant force control is executed to ensure that the mounting pressure is applied evenly to the device.

[0014] S5. Mounting quality feedback and parameter self-optimization: Perform quality inspection on the mounted components to obtain mounting quality data; feed back deviation data, pressure parameters and quality results to the irregular component feature library, automatically update the mounting parameters of the corresponding components, and achieve iterative optimization of mounting effect.

[0015] A further solution: Before step S1, a reference calibration step is also included: complete the coordinate mapping calibration between the vision acquisition unit and the placement execution mechanism, establish a globally unified placement reference coordinate system, and realize the coordinate alignment of multiple systems.

[0016] A further solution: The vision acquisition unit includes an upper vision unit and a lower vision unit; the upper vision unit is a 2D vision camera that moves synchronously with the mounting actuator to acquire pose data of the substrate pad area; the lower vision unit is a fixedly installed high-resolution 2D vision unit with a height measurement module to acquire contour and height distribution data of irregularly shaped devices in the adsorption state.

[0017] Further solutions: In step S1, the three-dimensional feature acquisition adopts any one of line laser scanning, structured light scanning, and three-dimensional vision reconstruction, with an acquisition accuracy ≥0.005mm; the contour features include the outer contour polygon of the device, positioning notch, and feature boss; the pin parameters include the number of pins, pin shape, pin coordinates, and pin coplanarity parameters; the pressure parameters include the maximum pressure threshold of the device and the recommended mounting pressure range.

[0018] Further solution: The pose deviation recognition in step S2 adopts a multi-scale template matching method: first, extract the outer contour features of the device for coarse matching to determine the approximate position and rotation angle of the device; then, extract the sub-pixel detail features of the pins and feature protrusions for fine matching, and output the initial planar deviation and tilt angle deviation of the device.

[0019] A further solution: The calculation of the six-degree-of-freedom compensation in step S3 specifically includes:

[0020] S31. Establish a local coordinate system for mounting, taking the geometric center of the corresponding pad group on the substrate as the mounting reference origin;

[0021] S32. The initial planar deviation and adsorption eccentricity deviation of the superimposed device are used to calculate the translation compensation amount of the X-axis and Y-axis.

[0022] S33. Combining the coplanarity deviation of device pins and the local warping of the substrate, calculate the Z-axis lifting compensation, X-axis tilt angle Rx and Y-axis tilt angle Ry compensation;

[0023] S34. Based on the offset between the device rotation center and the origin of the mounting coordinate system, calculate the compensation amount of the rotation θ axis to offset the planar displacement deviation caused by the rotation eccentricity.

[0024] S35. Using the alignment and overlap of all pins and their corresponding pads as the objective function, optimize the six-degree-of-freedom compensation amount through an iterative algorithm until the overlap meets the preset requirements. The alignment and overlap is the ratio of the projection area of ​​the pin on the substrate plane to the area of ​​the corresponding pad. The iterative algorithm includes any one of the Gauss-Newton iteration method, the Levenberg-Marquardt method, and the gradient descent method. The iteration termination condition is that the overlap of the area of ​​the pin and the pad is ≥98% or the alignment deviation is ≤ the preset accuracy threshold.

[0025] A further solution: The segmented closed-loop constant force control in step S4 is specifically divided into four stages:

[0026] S41, Rapid Descent Phase: The placement actuator descends at a speed of 30-60 mm / s to a safe height of 0.5-2 mm from the substrate surface, using a position control mode;

[0027] S42, Slow-descent contact stage: The placement actuator descends slowly at a speed of 1-5mm / s, and the contact force is detected in real time. When the contact force reaches the contact threshold of 0.3-1N, it switches to force closed-loop control.

[0028] S43, Constant pressure holding stage: Control the placement actuator to maintain the target placement pressure of 1-5N for 0.2-1s, and synchronously adjust the tilt angle to ensure that the pressure deviation of each pin does not exceed 10%;

[0029] S44, Release and Reset Stage: After the holding time is reached, the device is released, and after a delay of 0.1-0.3s, the mounting actuator rises and resets.

[0030] Further solutions: The target mounting pressure is pre-called from the feature library based on the device material, number of pins, device weight, and solder paste characteristics; for irregularly shaped devices with a center of gravity offset exceeding 5% of the outer radius of the device outline, the torque difference caused by the center of gravity offset is offset by adjusting the mounting tilt angle during the holding pressure stage, so as to achieve uniform pressure distribution on each pin.

[0031] Further solution: In step S5, the mounting quality inspection adopts any one of orthogonal side vision, 3D laser scanning, and planar vision inspection; the mounting quality acceptance criteria are: XY direction offset ≤ ±0.02mm, θ angle rotation deviation ≤ ±0.1°, component floating height ≤ 0.01mm, and overall tilt angle ≤ 0.05°.

[0032] Further solutions: The parameter self-optimization rules in step S5 are as follows: For devices of the same model that have been successfully mounted multiple times, the alignment accuracy threshold is automatically narrowed and the mounting speed is optimized; for devices that have deviated in the same direction multiple times, the compensation correction coefficient of the corresponding degree of freedom is automatically adjusted; the target mounting pressure is dynamically adjusted according to the mounting float and pin deformation data; all parameter adjustments are set with safety boundaries and updated to the configuration file of the corresponding device in the feature library.

[0033] Compared with existing technologies, the beneficial effects of this method are:

[0034] 1. By adopting a positioning method that combines a 3D feature library with multi-scale template matching, it does not rely on the standard reference points of the device and can adapt to various irregular shapes and asymmetrical pins of irregular devices. The positioning accuracy is an order of magnitude higher than that of traditional single vision solutions.

[0035] 2. By adopting a six-degree-of-freedom deviation compensation mechanism, it simultaneously corrects plane offset, rotational deviation, height difference and bidirectional tilt angle, which can offset the mounting defects caused by device pin coplanarity error and substrate warping deformation, and significantly reduce the failure rate of cold solder joints and open connections.

[0036] 3. By adopting a segmented closed-loop force control scheme, the mounting pressure can be adaptively adjusted according to the device material and pin characteristics. Combined with tilt angle fine adjustment, the problem of uneven pressure on devices with offset center of gravity can be solved, and the device breakage rate can be reduced by more than 90%.

[0037] 4. Through feature library storage and self-learning iterative optimization, the new device import only needs to complete one 3D scan to generate the mounting program, without the need for repeated manual debugging, adapting to flexible production scenarios with multiple varieties and small batches, and reducing the changeover debugging time by more than 80%.

[0038] Additional aspects and advantages of this method will be set forth in part in the description which follows, and in part will become apparent from the description or may be learned through practice of this method. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in this embodiment or the prior art, the drawings used in the description of the embodiment or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a flowchart of the process of this method.

[0041] Figure 2 This is a flowchart of the process for solving the six-degree-of-freedom compensation.

[0042] Figure 3 This is a flowchart of the segmented closed-loop constant force control process. Detailed Implementation

[0043] The technical solutions in the embodiments of this method will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this method, and not all embodiments. Based on the embodiments of this method, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this method.

[0044] In the description of this method, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" 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 method 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 limitations on this method.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this method, "multiple" means two or more, unless otherwise explicitly specified.

[0046] In this method embodiment, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this method according to the specific circumstances.

[0047] Please see Figure 1-3 ,

[0048] The mounting system used in this method includes a six-degree-of-freedom mounting head (i.e., mounting actuator), a vacuum nozzle module, an upper vision unit, a lower vision unit, a side vision module, a high-precision force sensor, a line laser height gauge, a mounting platform, a main control unit, and a feature library for irregularly shaped components.

[0049] The six-DOF placement head enables motion control with six degrees of freedom: X / Y / Z three-axis translation, Rx / Ry bidirectional tilt adjustment, and θ-axis rotation. A vacuum nozzle module is mounted at the bottom of the placement head to pick up irregularly shaped components. A high-precision force sensor, with a range of 0-20N and a sampling frequency of 1kHz, is integrated with the nozzle module to collect placement pressure in real time. An upper vision unit is coaxially mounted on the side of the placement head and moves synchronously with it to capture images of the substrate pads and Mark reference points. A lower vision unit is fixedly mounted on the frame of the placement platform and, in conjunction with a line laser height gauge, captures the outline and height distribution of the components picked up by the nozzle. The side vision module includes two orthogonally mounted line scan cameras to capture the side profile of the components after placement and detect their floating height and tilt angle. The main control unit is connected to each hardware module to perform image recognition, motion calculation, force control logic, and data storage functions. A feature library for irregularly shaped components stores the three-dimensional features and placement parameters of various irregularly shaped components.

[0050] Detailed implementation of the core steps of the method:

[0051] Step S0, System Coordinate System One Calibration:

[0052] The system coordinate mapping was completed using the nine-point calibration method:

[0053] 1. Prepare a calibration plate with 9 standard calibration dots and fix it on the mounting platform;

[0054] 2. The upper vision unit sequentially captures 9 calibration points to establish a mapping matrix between the upper vision pixel coordinate system and the mounting platform coordinate system;

[0055] 3. The mounting head, carrying the standard calibration pins, moves sequentially to 9 preset positions within the field of view of the lower vision unit, establishing a mapping matrix between the lower vision pixel coordinate system and the mounting head motion coordinate system;

[0056] 4. Using the mounting platform coordinate system as the global reference, complete the alignment and unification of all coordinate systems, with a calibration accuracy of ≤0.005mm, to ensure that all deviation data are calculated under the same coordinate system.

[0057] Step S1: Construction of the feature library for irregularly shaped devices and mounting substrates:

[0058] A structured light 3D scanner was used to perform a full-area scan of the target irregularly shaped device, obtaining a 3D point cloud model with a resolution of 0.005 mm. The following feature parameters were extracted through point cloud processing and stored in the irregularly shaped device feature library:

[0059] 1. Contour features: coordinates of the outer contour polygon of the device, positioning notch, and position and size of the feature boss;

[0060] 2. Pin distribution characteristics: number of pins, pin cross-sectional shape, three-dimensional coordinates of each pin, and pin coplanarity tolerance;

[0061] 3. Mechanical and center of gravity parameters: device center of gravity coordinates (offset relative to the geometric center), device maximum pressure threshold, recommended mounting pressure range;

[0062] 4. Nozzle compatibility parameters: The position, area, and flatness of the adsorption area on the top of the device must be matched with the corresponding nozzle model.

[0063] The Gerber design file of the substrate is imported synchronously, the pad layout and Mark reference point coordinates are extracted, the substrate warpage distribution data is obtained through whole board flatness scanning, and a substrate mounting reference model is established.

[0064] Step S2, Initial localization and deviation recognition through multi-vision fusion:

[0065] The placement head picks up irregularly shaped components based on the nozzle model matched in the feature library, moves it directly above the lower vision unit, and performs component deviation identification.

[0066] 1. A 2D camera captures a top-view image of the device, while a line laser height gauge scans the height distribution of the pins at the bottom of the device.

[0067] 2. Perform multi-scale template matching:

[0068] (1) Coarse matching stage: Project the three-dimensional point cloud model in the feature library along the Z-axis to generate a standard two-dimensional contour template, extract the outer contour of the device from the acquired image, calculate the Hu invariant moment of the contour and match it with the standard template, output the approximate position and rotation angle of the device, and the matching accuracy is ±0.1mm;

[0069] (2) Fine matching stage: Based on the coarse positioning results, sub-pixel edge extraction is performed on the pin area, and the actual coordinates of the pin are fitted with the detail feature template by least squares to output the accurate X / Y / θ initial deviation of the device, with a matching accuracy of ±0.01mm;

[0070] (3) Height calculation: Based on the height data collected by line laser, calculate the pin coplanarity deviation and the initial tilt angles Rx0 and Ry0 of the device.

[0071] Simultaneously, the upper vision unit moves with the placement head to the substrate area to be placed, captures images of the pads and Mark reference points, identifies the actual coordinates of the pads, and calculates the local warpage of the area to be placed by combining the substrate warpage model.

[0072] Step S3, Six-DOF Adaptive Deviation Compensation:

[0073] A local coordinate system for mounting is established with the geometric center of the corresponding pad group on the substrate as the origin, and six-degree-of-freedom compensation is calculated:

[0074] 1. Planar translation compensation: The X-axis translation compensation amount is calculated by superimposing the initial XY deviation of the device, the radial runout deviation of the nozzle, and the device adsorption eccentricity deviation. Y-axis translation compensation amount ;

[0075] 2. Height and Tilt Compensation: Based on the coplanarity deviation of device pins, local warpage of the substrate, and the initial tilt angle of the device, calculate the Z-axis height compensation. X-axis tilt compensation amount Y-axis tilt compensation amount ;

[0076] 3. Rotation Compensation: Based on the offset between the device rotation center and the origin of the local coordinate system for mounting, calculate the rotation θ-axis compensation amount. This counteracts the additional planar displacement caused by rotational eccentricity;

[0077] 4. Iterative Optimization: Using pin-pad overlap as the objective function, the Gauss-Newton iterative algorithm is employed to optimize the six-degree-of-freedom compensation. Overlap is defined as the ratio of the sum of the intersections of the projected areas of all pins on the substrate plane and the corresponding pad areas to the sum of the projected areas of all pins. The calculation formula is as follows:

[0078]

[0079] in, For the degree of overlap, This represents the total number of pins. For the first The projected area of ​​the root pin, For the first The area of ​​the pad corresponding to the root pin.

[0080] When the degree of coincidence If the alignment deviation is less than the preset accuracy threshold, the iteration stops and the final six-degree-of-freedom compensation parameters are output.

[0081] Step S4, Closed-loop force control flexible placement execution:

[0082] The placement head adjusts its posture according to the compensated six-degree-of-freedom parameters, moves to directly above the position to be placed, and performs four-segment segmented force-controlled placement.

[0083] 1. Rapid Descent Phase: The placement head descends rapidly at a speed of 40mm / s to a safe height of 1mm from the bottom of the device to the substrate surface. Pure position control is used in this phase to ensure placement efficiency.

[0084] 2. Slow descent contact phase: Switch to a slow descent speed of 2mm / s. The force sensor collects pressure data in real time at a frequency of 1kHz. When the contact force reaches the contact threshold of 0.5N, the position feed stops and the force closed-loop control is switched.

[0085] 3. Constant pressure holding stage: The placement head is controlled to maintain the target placement pressure preset by the feature library for 0.5 seconds. For irregularly shaped devices with a center of gravity offset exceeding 5% of the outer radius of the device outline, the Rx and Ry angles of the placement head are finely adjusted based on the pre-calibrated center of gravity offset-tilt angle compensation mapping relationship to offset the torque difference caused by the center of gravity offset and ensure that the pressure deviation of each pin is ≤10%.

[0086] 4. Nozzle release stage: After the pressure holding period ends, the nozzle releases the device by breaking the vacuum. After a 0.2s delay to ensure the device is fully bonded, the mounting head rises and resets at a speed of 30mm / s.

[0087] Step S5: Post-mount verification and parameter self-optimization:

[0088] After mounting, two sets of orthogonal side-view vision modules acquire side profile images of the device. Combined with the top-view image, they detect the device's XY offset, θ rotation deviation, float height, and overall tilt angle. The mounting quality is judged according to preset standards: XY offset ≤ ±0.02mm, θ deviation ≤ ±0.1°, float height ≤ 0.01mm, and tilt angle ≤ 0.05° are considered qualified. If the values ​​exceed the threshold, the device is judged as unqualified and an alarm is triggered.

[0089] The initial deviation, compensation parameters, pressure data, and quality results of this mounting are fed back to the feature library to perform parameter self-optimization. The specific rules are as follows:

[0090] 1. Accuracy threshold optimization: If the same model of device passes the placement test 5 times in a row, the alignment accuracy threshold will be automatically narrowed by 10%, down to a minimum of 0.01mm, while the speed of the rapid descent phase will be appropriately increased.

[0091] 2. Compensation Parameter Correction: When the same type of component exhibits the same direction and magnitude of mounting deviation twice consecutively, the compensation correction coefficient for the corresponding degree of freedom is automatically adjusted. The adjustment range is 30% of the deviation, and the maximum adjustment range in a single instance shall not exceed 20% of the original coefficient.

[0092] 3. Pressure parameter optimization: If the float exceeds the limit for 3 consecutive placements, the target placement pressure will be automatically increased by 10%; if the pin deformation or device damage occurs for 3 consecutive placements, the target placement pressure will be automatically reduced by 10%; the pressure adjustment range shall not exceed 60%-90% of the device's pressure threshold.

[0093] All optimized parameters are automatically updated to the configuration file of the corresponding device, realizing iterative self-optimization of mounting parameters.

[0094] Example 1:

[0095] This embodiment uses a certain L-shaped connector (12 pins on one side, center of gravity offset of 0.8mm, made of high-temperature resistant plastic with copper pins) as the mounting object, and the specific implementation process is as follows:

[0096] 1. Feature library construction: Scan to obtain the 3D model of the device, extract the coordinates of 12 pins, the center of gravity offset X+0.8mm / Y+0.2mm, the maximum bearing pressure of 5N, and the recommended mounting pressure of 2.5N, and store them in the feature library; import the substrate Gerber file to establish a baseline model.

[0097] 2. System calibration: Nine-point hand-eye calibration is completed in advance, with a global coordinate system accuracy of 0.004mm.

[0098] 3. Initial positioning: The lower vision acquires the device image, and multi-scale matching is used to obtain the initial deviations X=+0.115mm, Y=-0.078mm, θ=+3.18°, the pin coplanarity deviation is 0.012mm, and the initial tilt angle Ry=+0.03°; the upper vision detects the local warpage of the substrate as 0.015mm.

[0099] 4. Six-degree-of-freedom compensation: After kinematic calculation and two iterations of optimization, the compensation amount is output. =+0.120mm、 =-0.083mm, =+0.015mm, =0°、 =+0.03°、 = -3.18°, pin overlap reaches 99.2%.

[0100] 5. Force-controlled placement: Perform four-stage placement with a target pressure of 2.5N. During the pressure holding stage, fine-tune the Ry axis by 0.02° to offset the center of gravity shift, and control the pressure deviation of each pin within 8%.

[0101] 6. Verification and optimization: After mounting, if the XY offset is 0.012mm, the θ deviation is 0.07°, and the floating height is 0.008mm, it is considered qualified and the parameters are stored in the feature library for iterative optimization.

[0102] Example 2:

[0103] This embodiment uses an irregularly shaped ceramic MEMS sensor (irregular shape, brittle material, 4 asymmetric pins) as the mounting object. The implementation process is basically the same as in Embodiment 1, except that:

[0104] 1. The feature library presets a maximum pressure resistance of 1.5N for the device and a target mounting pressure of 1N to prevent brittle ceramics from breaking.

[0105] 2. During the deviation compensation stage, the focus is on optimizing the Z-axis and tilt angle compensation to ensure that all four asymmetrical pins contact the pads simultaneously.

[0106] 3. The pressure holding phase is extended to 0.8s, and the descent speed is adjusted to 1mm / s to ensure that brittle components are subjected to stable stress.

[0107] Example 3:

[0108] This embodiment uses a single 3D line laser vision unit to replace the upper and lower dual vision modules. The placement head carries a 3D line laser scanning head, which sequentially scans the bottom of the adsorbed device and the substrate pad area, simultaneously acquiring the 3D contour of the device and the 3D pose data of the pads. The initial deviation and substrate warpage are directly calculated. The subsequent six-degree-of-freedom compensation, closed-loop force control, and parameter self-optimization steps are completely consistent with those in Embodiment 1. This embodiment can achieve the same placement accuracy and effect, with only a different hardware configuration, and still falls within the protection scope of this invention.

[0109] Example 4:

[0110] This embodiment uses the Levonburg-Marquardt algorithm instead of the Gauss-Newton algorithm for iterative optimization of six-degree-of-freedom compensation. For irregularly shaped devices with more pins and more complex contours, the iterative convergence speed is improved by 30%, while the final overlap ratio still reaches over 98.5%, and the mounting effect is consistent with the original solution. This embodiment verifies that the iterative algorithm of the present invention can adopt a variety of nonlinear optimization schemes and is not limited to the single algorithm disclosed in the embodiment.

[0111] Example 5:

[0112] For large-sized, irregularly shaped shielding devices, the rapid descent speed was adjusted to 30 mm / s, the target mounting pressure to 5 N, and the holding time to 1 s. For miniature, irregularly shaped MEMS sensors, the rapid descent speed was adjusted to 60 mm / s, the target mounting pressure to 1 N, and the holding time to 0.2 s. Both types of devices achieved successful mounting, verifying that the parameter range of this invention can be flexibly adjusted according to the device type, covering the entire parameter range disclosed in the claims.

[0113] Comparative Example 1:

[0114] Using the existing mounting process disclosed in CN117373929A, 100 batch mounting tests were conducted on the same L-shaped connector as in Example 1. The test results were as follows: average offset in the XY direction was 0.042mm, average deviation of the θ angle was 0.21°, the poor soldering rate was 3.2%, the component breakage rate was 1.1%, and the time for new component replacement and debugging was approximately 4 hours.

[0115] Performance Verification: Using the method of Embodiment 1 of this invention, 100 batch placement tests were conducted on the same type of L-shaped connector. The test results were as follows: average offset in the XY direction was 0.013mm, average deviation of the θ angle was 0.06°, the rate of poor soldering was 0.1%, the component breakage rate was 0.1%, and the time for introducing and debugging new components was approximately 0.5 hours. Compared with existing technologies, the placement accuracy was improved by approximately 69%, the rate of poor soldering was reduced by 96.9%, the component breakage rate was reduced by 90.9%, and the efficiency of changeover debugging was improved by 87.5%, demonstrating significant technical effectiveness.

[0116] The circuits, electronic components, and control modules involved are all existing technologies, which can be fully implemented by those skilled in the art, and need not be elaborated upon. The content protected by this method does not involve any improvement to the software or method.

[0117] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0118] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for adaptive and precise mounting of irregularly shaped devices, characterized in that, Includes the following steps: S1. Feature Library and Benchmark Model Construction: Perform 3D feature acquisition on the target irregular device and construct a feature library of irregular devices that includes device contour features, pin parameters, center of gravity parameters, and pressure bearing parameters; simultaneously acquire the pad layout and flatness parameters of the mounting substrate and establish a substrate mounting benchmark model. S2, Position Deviation Recognition: Collect the position deviation data of irregularly shaped devices in the adsorption state, as well as the pad position deviation data of the substrate to be mounted area, and identify the initial alignment deviation between the device and the pad, the device shape deviation and the substrate deformation deviation. S3, Six-DOF Adaptive Deviation Compensation: Based on the initial alignment deviation, device shape and position deviation, substrate deformation deviation, adsorption offset, and device center of gravity parameters, the six-DOF compensation amount of the mounting actuator is calculated and generated. The six degrees of freedom include X-axis translation, Y-axis translation, Z-axis lifting, X-axis tilt angle Rx, Y-axis tilt angle Ry, and rotation angle θ. The compensation amount is iteratively corrected in combination with the alignment overlap between the pins and pads until the alignment deviation meets the preset accuracy requirements. S4. Closed-loop force-controlled flexible mounting: The mounting actuator moves to the mounting position according to the compensated posture, and the mounting pressure data is collected in real time during the Z-axis descent. Combined with the device pressure parameters, segmented closed-loop constant force control is executed to ensure that the mounting pressure is applied evenly to the device. S5. Mounting quality feedback and parameter self-optimization: Perform quality inspection on the mounted components to obtain mounting quality data; feed back deviation data, pressure parameters and quality results to the irregular component feature library, automatically update the mounting parameters of the corresponding components, and achieve iterative optimization of mounting effect.

2. The adaptive precision mounting method for irregularly shaped devices according to claim 1, characterized in that: Before step S1, there is also a reference calibration step: complete the coordinate mapping calibration between the vision acquisition unit and the placement execution mechanism, establish a globally unified placement reference coordinate system, and realize the coordinate alignment of multiple systems.

3. The adaptive precision mounting method for irregularly shaped devices according to claim 2, characterized in that: The vision acquisition unit includes an upper vision unit and a lower vision unit; the upper vision unit is a 2D vision camera that moves synchronously with the mounting actuator to acquire pose data of the substrate pad area; the lower vision unit is a fixedly installed high-resolution 2D vision unit with a height measurement module to acquire contour and height distribution data of irregularly shaped devices in the adsorption state.

4. The adaptive precision mounting method for irregularly shaped devices according to claim 1, characterized in that: In step S1, the three-dimensional feature acquisition adopts any one of line laser scanning, structured light scanning, and three-dimensional vision reconstruction, with an acquisition accuracy ≥0.005mm; the contour features include the outer contour polygon of the device, positioning notch, and feature boss; the pin parameters include the number of pins, pin shape, pin coordinates, and pin coplanarity parameters; the pressure parameters include the maximum pressure threshold of the device and the recommended mounting pressure range.

5. The adaptive precision mounting method for irregularly shaped devices according to claim 1, characterized in that: The pose deviation recognition in step S2 adopts a multi-scale template matching method: first, extract the outer contour features of the device for coarse matching to determine the approximate position and rotation angle of the device; then, extract the sub-pixel detail features of the pins and feature protrusions for fine matching, and output the initial planar deviation and tilt angle deviation of the device.

6. The adaptive precision mounting method for irregularly shaped devices according to claim 1, characterized in that: The calculation of the six-degree-of-freedom compensation in step S3 specifically includes: S31. Establish a local coordinate system for mounting, taking the geometric center of the corresponding pad group on the substrate as the mounting reference origin; S32. The initial planar deviation and adsorption eccentricity deviation of the superimposed device are used to calculate the translation compensation amount of the X-axis and Y-axis. S33. Combining the coplanarity deviation of device pins and the local warping of the substrate, calculate the Z-axis lifting compensation, X-axis tilt angle Rx and Y-axis tilt angle Ry compensation; S34. Based on the offset between the device rotation center and the origin of the mounting coordinate system, calculate the compensation amount of the rotation θ axis to offset the planar displacement deviation caused by the rotation eccentricity. S35. Using the alignment and overlap of all pins and their corresponding pads as the objective function, optimize the six-degree-of-freedom compensation amount through an iterative algorithm until the overlap meets the preset requirements. The alignment and overlap is the ratio of the projection area of ​​the pin on the substrate plane to the area of ​​the corresponding pad. The iterative algorithm includes any one of the Gauss-Newton iteration method, the Levenberg-Marquardt method, and the gradient descent method. The iteration termination condition is that the overlap of the area of ​​the pin and the pad is ≥98% or the alignment deviation is ≤ the preset accuracy threshold.

7. The adaptive precision mounting method for irregularly shaped devices according to claim 1, characterized in that: Step S4, the segmented closed-loop constant force control, is specifically divided into four stages: S41, Rapid Descent Phase: The placement actuator descends at a speed of 30-60 mm / s to a safe height of 0.5-2 mm from the substrate surface, using a position control mode; S42, Slow-descent contact stage: The placement actuator descends slowly at a speed of 1-5mm / s, and the contact force is detected in real time. When the contact force reaches the contact threshold of 0.3-1N, it switches to force closed-loop control. S43, Constant pressure holding stage: Control the placement actuator to maintain the target placement pressure of 1-5N for 0.2-1s, and synchronously adjust the tilt angle to ensure that the pressure deviation of each pin does not exceed 10%; S44, Release and Reset Stage: After the holding time is reached, the device is released, and after a delay of 0.1-0.3s, the mounting actuator rises and resets.

8. The adaptive precision mounting method for irregularly shaped devices according to claim 7, characterized in that: The target placement pressure is pre-called from the feature library based on the device material, number of pins, device weight, and solder paste characteristics. For irregularly shaped devices with a center of gravity offset exceeding 5% of the radius of the outer circle of the device outline, the torque difference caused by the center of gravity offset is offset by adjusting the placement tilt angle during the holding pressure stage, so as to achieve uniform pressure distribution on each pin.

9. The adaptive precision mounting method for irregularly shaped devices according to claim 1, characterized in that: In step S5, the mounting quality inspection adopts any one of orthogonal side-view vision, 3D laser scanning, and planar vision inspection; the mounting quality acceptance criteria are: XY direction offset ≤ ±0.02mm, θ angle rotation deviation ≤ ±0.1°, component floating height ≤ 0.01mm, and overall tilt angle ≤ 0.05°.

10. The adaptive precision mounting method for irregularly shaped devices according to claim 1, characterized in that: The parameter self-optimization rules in step S5 are as follows: for devices of the same model that have been successfully mounted multiple times, the alignment accuracy threshold is automatically narrowed and the mounting speed is optimized; for devices that have deviated in the same direction multiple times, the compensation correction coefficient of the corresponding degree of freedom is automatically adjusted; the target mounting pressure is dynamically adjusted according to the mounting float and pin deformation data; all parameter adjustments are set with safety boundaries and updated to the configuration file of the corresponding device in the feature library.

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