Large-size wafer level packaging handling robot and wafer handling method

Abstract

This invention discloses a loading and unloading robot and method for large-size wafer-level packaging, relating to the field of wafer-level packaging equipment technology. The robot includes a six-axis robotic arm, a six-dimensional force sensor, an actuator connector, a cam angle adjustment mechanism, and a gripper control mechanism. The cam angle adjustment mechanism achieves precise control of the cam disk rotation angle through a crank-slider-rocker mechanism driven by a servo motor. The gripper control mechanism, driven by the cam disk, causes the wafer gripper to move linearly along the wafer radial direction, and works in conjunction with a flexible limiting structure to complete the wafer gripping, centering, and release operations. The six-dimensional force sensor is used to acquire multi-dimensional force information in real time during the wafer loading and unloading process to achieve wafer gripping status judgment and contact detection. Through the coordinated control of the robotic arm movement, gripper stroke, and force information, safe and stable loading and unloading of wafers in the packaging process is achieved.

Description

Technical Field

[0001] This invention relates to the field of wafer-level packaging equipment technology, and more particularly to a loading and unloading robot and wafer loading and unloading method for large-size wafer-level packaging. Background Technology

[0002] Chip packaging technology is a crucial link between wafer manufacturing and end-user applications, and its packaging quality directly affects the chip's electrical performance, reliability, and system integration level. With the rapid development of 5G communication, artificial intelligence, and high-performance computing, the requirements for high-density integration, miniaturized structures, and highly reliable operation of chips are constantly increasing. Traditional packaging methods are gradually becoming insufficient to meet the demands of advanced applications in terms of size control, interconnect density, and production efficiency. In contrast, wafer-level packaging technology can complete interconnect construction and overall packaging at the wafer level, offering advantages such as small package size, high material utilization, and high production efficiency, and has become an important development direction for advanced packaging.

[0003] In wafer-level packaging (WPS) manufacturing, wafer loading, unloading, and transfer are typically automated by robots. These robots' actuators must perform a series of high-precision actions within a limited space, including wafer gripping, alignment, transfer, and release. This is especially true in 12-inch and larger wafer packaging processes, where the larger wafer diameter, increased weight, and enhanced edge brittleness place higher demands on the equipment's structural compactness, motion accuracy, posture stability, and force control capabilities. Improper mechanical control during loading and unloading can easily lead to wafer slippage, edge chipping, microcrack propagation, or positioning deviations, thus affecting packaging yield and product consistency. Existing loading and unloading robots often employ complex or bulky actuators, making them difficult to adapt to the compact spatial layout of highly integrated wafer-level packaging production lines. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a loading and unloading robot and a wafer loading and unloading method for large-size wafer-level packaging, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0006] A loading and unloading robot for large-size wafer-level packaging, the structure of which includes:

[0007] The system comprises a six-axis robotic arm, a six-dimensional force sensor, an actuator connector, a cam angle adjustment mechanism, and a gripper control mechanism. The six-dimensional force sensor is located and fixedly connected between the end effector of the six-axis robotic arm and the actuator connector, and is used to acquire multi-dimensional force information of the end effector in real time during loading and unloading. The actuator connector is coaxially and fixedly connected to the servo motor of the cam angle adjustment mechanism and the main frame of the gripper control mechanism. The output shaft of the servo motor is parallel to the central axis of the main frame and is not coincident.

[0008] In addition to the problems mentioned in the background section, the present invention also needs to solve one or more of the following problems:

[0009] During loading and unloading, the current methods rely heavily on position or speed control strategies, lacking real-time perception of the multi-dimensional force state of the end effector. This makes it difficult to obtain timely mechanical information during wafer gripping or contact with the packaging mold. This can easily lead to wafer slippage, breakage, or positioning deviation, affecting packaging quality and making it difficult to meet the high precision and high reliability requirements of large-size wafer-level packaging processes.

[0010] Furthermore, in terms of clamping mechanisms, existing wafer grippers mostly employ rigid transmission or simple linear drive structures. They lack the ability to finely adjust the gripper opening and closing stroke and the centering process. The drive motor rotation angle and clamping stroke typically exhibit a simple linear relationship, making it difficult to achieve precise, phased control of the gripping, centering, and release processes according to different operating conditions. During the loading and unloading of large-size wafers, the lack of flexible limiting or buffering structures at the moment of clamping and release can easily generate impact loads at the wafer edges, increasing the risk of wafer breakage. Simultaneously, existing mechanisms often do not strictly constrain the vertical axial attitude of the actuators in terms of attitude control; even minor attitude deviations during wafer transfer can affect alignment accuracy.

[0011] Therefore, there is an urgent need for a wafer-level packaging process loading and unloading robot and its loading and unloading method that can achieve controllable wafer clamping stroke and stable posture under the premise of compact structure, and has the ability to sense multi-dimensional force and judge contact status, so as to solve the shortcomings of existing technologies and meet the application requirements of high reliability and high consistency of large-size wafer-level packaging processes.

[0012] Preferably, the cam angle adjustment mechanism further includes a servo motor connector, the servo motor output shaft is connected to the servo motor connector via gear transmission, the servo motor connector is fixedly connected to one end of the crank, and a deep groove ball bearing is embedded in the other end of the crank;

[0013] The inner ring of the deep groove ball bearing is sequentially and fixedly connected to the bearing connector, the slider connector, and the slider; the slider and the guide rail groove cooperate to form a sliding pair, and the guide rail is fixed on the cam plate of the gripper adjustment mechanism;

[0014] A fixed plate is fixedly installed on the main frame, and a second deep groove ball bearing is embedded in the center of the fixed plate. The cam plate is fixedly connected to the inner ring of the second deep groove ball bearing.

[0015] Preferably, the gripper control mechanism further includes a positioning disk and a wafer gripper. The positioning disk is fixedly connected to the lower end of the main frame and is provided with a flange for positioning and an alignment contact surface. The wafer gripper is slidably connected to the gripper connector through a dovetail groove. The inner curvature of the gripper matches the size of the wafer being gripped. The gripper connector provides a dovetail groove to form a slidable connection with the fixed disk, so that the wafer gripper can move linearly along the radial direction of the fixed disk.

[0016] Preferably, a follower connector is fixedly connected to the upper side of the gripper connector, and a cam follower is fixedly connected to the center of the follower connector. The cam follower and the cam groove provided on the cam disk form a sliding fit, which is used to drive the gripper connector to move when the cam disk rotates.

[0017] This invention employs a stroke control method that combines a cam disk and a cam follower. The gripper displacement is limited by the geometric contour of the cam groove. The gripping stroke position, centering stroke position, and maximum unfolding stroke position can be set according to the working conditions to achieve phased fine control and improve the adjustability of the wafer loading and unloading process.

[0018] The lower side of the gripper connector is fixedly connected to a gripper limiting member and a spring seat. The gripper limiting member and the spring seat are provided with limiting bosses for spring positioning and installation. The spring is set between the two to provide flexible limiting effect on the wafer gripper during wafer clamping and alignment.

[0019] The present invention incorporates a spring and a flexible limiting mechanism in the gripper structure to provide buffering and flexible constraints during wafer clamping and alignment, effectively reducing the impact load on the edge of large-size wafers during clamping and release, and improving loading and unloading safety.

[0020] The loading and unloading method for a large-size wafer-level packaging loading and unloading robot, using the aforementioned loading and unloading robot, includes the following steps:

[0021] Step S1: The robot drive actuator moves from the standby position to the wafer placement station where the front-end process is completed along the trajectory planned according to the working conditions. The end of the trajectory makes the bearing surface of the wafer gripper lower than the plane where the wafer is located. During the movement, the position of the actuator is adjusted to be parallel to the wafer plane, and the wafer gripper is placed at the maximum extension stroke position.

[0022] Step S2: Control the servo motor to drive the wafer gripper to retract to the preset wafer gripping stroke position, then vertically lift the actuator, and detect the force feedback information through the six-dimensional force sensor to determine whether the wafer has been successfully gripped. If the gripping is successful, drive the wafer gripper to continue to retract to the wafer centering stroke position.

[0023] Step S3: Transfer the wafer along the planned path to the top of the packaging mold, keeping the vertical axis pose of the actuator constant during the transfer process;

[0024] Step S4: Vertically lower the actuator height, monitor the contact force information in real time, and stop the movement immediately when contact with the packaging mold is detected; drive the wafer gripper to the maximum unfolding stroke position to release the wafer, and then control the actuator to return to the standby position to complete the wafer loading;

[0025] Step S5: After packaging is completed, the actuator is moved above the mold, so that the wafer gripper is at the maximum unfolding stroke position. The actuator is lowered until it detects contact with the mold, and the wafer gripper is controlled to retract to the gripping stroke position to grip the wafer.

[0026] Step S6: Move the wafer back to the wafer placement station along the planned path, control the wafer gripper to the maximum unfolding stroke position to release the wafer, drive the actuator back to the standby position, and complete the wafer unloading.

[0027] Preferably, in the loading and unloading method, the clamping, releasing, and alignment operations of the wafer grippers are all achieved by controlling the servo motor to drive the cam disk to rotate. The formula for calculating the required rotation angle θ2 of the servo motor is as follows:

[0028]

[0029] Where θ1 is the rotation angle of the cam disk according to the working conditions, l is the distance from the servo output shaft to the center of the cam disk, and a is the distance between the positioning holes at both ends of the crank.

[0030] Preferably, the wafer loading and unloading method involves wafer gripping and contact detection, both of which are achieved by judging changes in the mechanical information of the actuator, including the following steps:

[0031] Step S41: Acquire the measurement data of the six-dimensional force sensor in real time, including the triaxial force component F. x F y F z and triaxial torque components M x M y M z The measurement data were then normalized and fused using a weighted L2 method to obtain a single characteristic parameter F that characterizes the overall contact state between the wafer gripper, the wafer, and the environment. c (t), its calculation formula is:

[0032]

[0033] Among them, F max and M max These represent the maximum range of the six-dimensional force sensor, α is the weighting coefficient used to adjust the contribution of the torque component, and t is the time variable;

[0034] Step S42: Based on the discrete time series, adjust the feature parameter F c(t) The rate of change is calculated using the three-point difference method, and the formula is:

[0035]

[0036] Simultaneously, the feature parameter F is updated using a recursive formula within the sliding time window. c The mean μ(t) and variance σ of (t) 2 (t):

[0037]

[0038]

[0039] Where N is the length of the sliding window;

[0040] Step S43: Based on feature parameter F c The statistical characteristics and trends of (t) are used to determine the wafer gripping status and contact detection. The determination conditions are as follows:

[0041] a. Conditions for successful wafer grabbing:

[0042] If the wafer is stably clamped, the load on the actuator will be superimposed on the weight of the wafer itself, causing a force component and characteristic parameter F along the direction of gravity. c The steady-state shift of (t) is determined by the following criteria:

[0043]

[0044] And within the sliding time window, the following conditions are met:

[0045]

[0046] Where μ0 is the baseline mean of the feature parameters before clamping, and ΔF min With ΔF max To determine the load variation range pre-calibrated based on wafer mass and gravitational acceleration, σ g To capture the stability variance threshold, T g The threshold for the rate of change after the data capture is completed;

[0047] b. Criteria for determining contact detection:

[0048] Due to abrupt changes in contact force or contact torque, the characteristic parameter F c (t) shows a significant change in a short period of time, and the criterion for this is:

[0049] .

[0050] And within the sliding time window, the following conditions are met:

[0051]

[0052] Among them, T c is the contact detection change rate threshold, and k1 is the statistical determination coefficient.

[0053] This invention integrates force and torque information collected by a six-dimensional force sensor and combines statistical characteristics and rate of change analysis to achieve wafer gripping success determination and contact detection. It can accurately identify key loading and unloading states without additional visual or mechanical switches, thereby improving the reliability of system operation.

[0054] Preferably, the constant vertical axis pose of the actuator in step S3 is achieved by a constrained attitude planning method. Specifically, the normal axis vector corresponding to the plane that the actuator needs to maintain horizontality during loading and unloading is constrained to be parallel to the vertical axis direction of the world coordinate system throughout the entire motion process.

[0055] The constrained attitude planning method employs attitude decomposition and partial interpolation, specifically including: converting the current attitude of the end effector from attitude quaternion form to Euler angle form arranged in ZYX order. ,in, θ is the yaw angle, and θ is the pitch angle. The pitch angle θ and roll angle are fixed during motion planning. Only for the yaw angle Time interpolation is performed to plan the attitude changes of the actuator, and the interpolation relationship satisfies ,in, The initial yaw angle, The target yaw angle difference is the normalized value, and f(t) is a continuously smooth interpolation function; the Euler angle sequence obtained based on the interpolation is... The reconstructed interpolated attitude quaternion sequence satisfies the attitude constraints.

[0056] This invention employs an attitude constraint planning method during wafer transfer to ensure that the actuator maintains a stable attitude during critical processes, avoiding wafer tilting and edge interference issues, and improving wafer loading, unloading, and alignment accuracy.

[0057] The present invention has a compact overall structure and clear control logic, which can improve loading and unloading efficiency while enhancing the stability and consistency of the large-size wafer loading and unloading process, which is conducive to improving the production yield and equipment reliability of wafer-level packaging process.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] This invention integrates a six-dimensional force sensor, a cam angle adjustment mechanism, and a gripper control mechanism at the end of a six-axis robotic arm. While ensuring functional integrity, it achieves a compact structural design, making it suitable for the high integration space requirements of large-size wafer-level packaging production lines. By using a servo motor to drive a crank-slider-rocker mechanism to rotate the cam disk, a definite functional relationship is formed between the gripper opening and closing stroke and the servo motor rotation angle, thereby improving the control accuracy and repeatability of the gripping, centering, and release processes. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the overall structure of the loading and unloading robot in this invention.

[0061] Figure 2 This is a schematic diagram of the cam angle adjustment mechanism in this invention.

[0062] Figure 3 This is a schematic diagram of the cam angle adjustment mechanism in this invention.

[0063] Figure 4 This is a schematic diagram of the overall structure of the actuator in this invention.

[0064] Figure 5 This is a schematic diagram of the wafer clamps and their connectors in this invention.

[0065] Figure 6 This is a schematic diagram of the gripper limiting mechanism in this invention.

[0066] Figure 7 This is a schematic flowchart of the wafer loading and unloading method in this invention.

[0067] In the diagram: 1. Six-axis robotic arm; 2. Six-dimensional force sensor; 3. Actuator connector; 4. Cam angle adjustment mechanism; 41. Servo motor; 42. Servo motor connector; 43. Crank; 44. Guide rail; 45. Slider; 46. Bearing connector; 47. Slider connector; 48. Deep groove ball bearing I; 5. Gripper adjustment mechanism; 51. Main frame; 52. Fixed plate; 53. Cam plate; 54. Positioning plate; 55. Cam follower; 56. Follower connector; 57. Gripper connector; 58. Wafer gripper; 59. Deep groove ball bearing II; 510. Gripper limiter; 511. Spring seat; 512. Spring. Detailed Implementation

[0068] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0069] This invention discloses a loading and unloading robot and method for large-size wafer-level packaging, relating to the field of wafer-level packaging equipment technology. The robot includes a six-axis robotic arm, a six-dimensional force sensor, an actuator connector, a cam angle adjustment mechanism, and a gripper control mechanism. The cam angle adjustment mechanism achieves precise control of the cam disk rotation angle through a crank-slider-rocker mechanism driven by a servo motor. The gripper control mechanism, driven by the cam disk, causes the wafer gripper to move linearly along the wafer radial direction, and works in conjunction with a flexible limiting structure to complete the wafer gripping, centering, and release operations. The six-dimensional force sensor is used to acquire multi-dimensional force information in real time during the wafer loading and unloading process to achieve wafer gripping status judgment and contact detection. Through the coordinated control of the robotic arm movement, gripper stroke, and force information, safe and stable loading and unloading of wafers in the packaging process is achieved.

[0070] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and design details applicable to 12-inch wafer loading and unloading will be provided to further understand the technical solutions of the present invention.

[0071] like Figure 1 and Figure 2 As shown, a large-size wafer-level packaging loading and unloading robot includes: a six-axis robotic arm 1, a six-dimensional force sensor 2, an actuator connector 3, a cam angle adjustment mechanism 4, and a gripper control mechanism 5. The cam angle adjustment mechanism 4 and the gripper control mechanism 5 constitute the actuator. The six-dimensional force sensor 2 is located and fixedly connected between the end of the six-axis robotic arm 1 and the actuator connector 3, used to acquire multi-dimensional force information of the end effector in real time during loading and unloading, thereby achieving force feedback monitoring of the loading and unloading process. The actuator connector 3 is coaxially and fixedly connected to the servo motor 41 of the cam angle adjustment mechanism 4 and the main frame 51 of the gripper control mechanism 5. The output shaft of the servo motor 41 is parallel to and non-coincident with the central axis of the main frame 51, forming an offset transmission structure during the servo motor 41's drive. This allows the rotational motion output by the servo motor 41 to be converted into angle adjustment motion of the cam disk 53 through a subsequent crank-slider-rocker mechanism, avoiding mechanism interference caused by coaxial arrangement and providing necessary transmission space for the cam angle adjustment mechanism 4, thus improving the overall structural compactness.

[0072] like Figure 2 As shown, the cam angle adjustment mechanism 4 also includes a servo motor connector 42. The output shaft of the servo motor 41 is connected to the servo motor connector 42 through gear transmission. The servo motor connector 42 is fixedly connected to one end of the crank 43. The other end of the crank 43 is embedded with a deep groove ball bearing 48.

[0073] The inner ring of the deep groove ball bearing 48 is fixedly connected to the bearing connector 46 in the form of an transition fit. The bearing connector 46 is fixedly connected to the slider connector 47, and the slider connector 47 is fixedly connected to the slider 45.

[0074] The slider 45 and the guide rail 44 form a sliding pair through groove engagement. The guide rail 44 is fixedly mounted on the cam disk 53 of the gripper control mechanism 5, so that the slider 45 can make restricted linear motion along the direction of the guide rail 44 under the drive of the servo motor.

[0075] A fixed plate 52 is fixedly installed on the main frame 51. A deep groove ball bearing 59 is embedded in the center of the fixed plate 52. The cam plate 53 is fixedly connected to the inner ring of the deep groove ball bearing 59 in the form of transition fit.

[0076] The above structure forms a crank-slider-rocker mechanism, as shown in the schematic diagram below. Figure 3 As shown, the output shaft of the servo motor 41 and the central axis of the fixed disk 52 together form the frame of the crank-slider-rocker mechanism. The central axis of the combination of the guide rail 44 and the cam disk 53 is an invisible rocker, which establishes a stable and predictable motion relationship between the rotation angle of the servo motor 41 and the rotation angle of the cam disk 53, making it easy to achieve fine adjustment of the gripper stroke.

[0077] As seen Figure 4 and Figure 5 As shown, the gripper control mechanism 5 also includes a positioning disk 54 and a wafer gripper 58. The positioning disk 54 is fixedly connected to the lower end of the main frame 51, and the positioning disk 54 is provided with a flange for positioning and an alignment contact surface to assist in the precise positioning of the wafer in the packaging mold.

[0078] The wafer gripper 58 is slidably connected to the gripper connector 57 via a dovetail groove with clearance fit, and the inner curvature of the gripper is the same as the size of the wafer being gripped. The gripper connector 57 is slidably connected to the fixed disk 52 via a dovetail groove with clearance fit, so that the wafer gripper 58 can move linearly along the radial direction of the fixed disk 52.

[0079] A follower connector 56 is fixedly connected to the upper side of the gripper connector 57. A cam follower 55 is fixedly connected to the center of the follower connector 56. The cam follower 55 and the cam groove provided on the cam disk 53 are connected by clearance to form a sliding connection. When the cam disk 53 is driven to rotate by the cam angle adjustment mechanism, the cam follower 55 moves along the cam groove in a restricted manner, thereby driving the gripper connector 57 and the wafer gripper 58 to move synchronously in the radial direction, realizing the opening and closing action of the gripper.

[0080] The cam angle adjustment mechanism and the gripper control mechanism are linked by the cam disk 53. The cam angle adjustment mechanism outputs controllable rotational motion, and the gripper control mechanism converts the rotational motion into linear displacement of the wafer gripper in the radial direction. The two are structurally independent but functionally complementary, enabling precise control of the gripper's opening and closing action and clamping stroke while maintaining a compact mechanism.

[0081] In this embodiment, the polar coordinate expression of the geometric dimensions of the cam groove provided on the cam disk 53 is as follows:

[0082]

[0083] The cam groove of this design is shown in [reference]. Figure 5 In the geometrically shown position, the wafer gripper 58 is at the wafer centering travel position. Rotating 10 degrees moves its travel radially outward by 3.5 mm, which is the wafer gripping travel position. Rotating 30 degrees moves its travel radially outward by 16 mm, which is the maximum unfolding travel position. The inner radius of the wafer gripper 58 is 150 mm, and the gripper flange width is 5 mm. This design ensures gripping stability while minimizing contact with the wafer to prevent damage.

[0084] like Figure 6 As shown, a gripper limiting member 510 and a spring seat 511 are fixedly connected to the lower side of the gripper connector 57. The gripper limiting member 510 and the spring seat 511 are provided with limiting bosses for positioning and installing the spring 512, and the spring 513 is disposed between the two. The limiting bosses axially position the spring 512, so that the spring 512 maintains a stable force direction during compression and release, forming an integrated flexible limiting structure.

[0085] During wafer alignment and clamping, when the wafer gripper 58 contacts the wafer edge, the spring 512 can generate controllable elastic deformation under the stroke limitation of the gripper limiting member 510, providing radial flexible compliance and buffering effect to the wafer gripper 58, absorbing the impact load generated at the moment of clamping. Simultaneously, the spring seat 511 limits the compression stroke of the spring 512, ensuring that the gripper mechanism maintains clamping stability while avoiding excessive clamping force, reducing stress concentration at the wafer edge caused by rigid clamping. This structure creates a flexible adjustment mechanism with buffering, limiting, and resetting functions during wafer gripping, alignment, and release, improving contact safety and clamping stability during wafer loading and unloading, and reducing the risk of wafer edge breakage. This structure enables the gripper mechanism to maintain clamping accuracy while possessing micro-adaptability, adapting to minor errors in wafer alignment during high-precision packaging, and improving alignment stability during the loading and unloading of large-size wafers.

[0086] In this embodiment, when the wafer gripper 58 is in the maximum unfolding position, the radial distance between the four circumferentially distributed gripper flanges is greater than the 12-inch wafer size, indicating a wafer release state; when the wafer gripper 58 is in the gripping position, the radial distance between the gripper flanges is less than the wafer size, while the radial distance on the inner side of the gripper is slightly greater than the wafer size; when the wafer gripper 58 is in the centering position, the radial distance on the inner side of the gripper is less than the wafer size by 2 mm, and the circumferentially distributed spring 512 is slightly compressed to center the wafer.

[0087] During wafer loading and unloading, a six-axis robotic arm 1 provides spatial orientation adjustment and path movement, while a cam angle adjustment mechanism drives the grippers to perform unfolding, gripping, and centering actions under different working conditions. The gripper control mechanism, in conjunction with a flexible limiting structure, achieves stable wafer clamping. A six-dimensional force sensor collects end-effector force information in real time, providing a data basis for wafer gripping status judgment and contact detection. Through the coordinated work of these components, stable, efficient, and safe operation of the wafer loading and unloading process is achieved.

[0088] like Figure 7 As shown, the loading and unloading method of the loading and unloading robot for large-size wafer-level packaging, using the above-mentioned loading and unloading robot, includes the following steps:

[0089] Step S1: The robot drives the actuator to move from the standby position to the wafer placement station where the front-end process is completed along the trajectory planned according to the working conditions. The end of the trajectory makes the bearing surface of the wafer gripper 58 lower than the plane where the wafer is located. During the movement, the position of the actuator is adjusted to be parallel to the wafer plane, and the wafer gripper 58 is placed at the maximum extension stroke position to avoid interference during the approach to the wafer.

[0090] Specifically, the clamping, releasing, and alignment operations of the wafer grippers 58 are all achieved by controlling the servo motor 41 to drive the cam disk 53 to rotate. The mechanism for the rotation angle is described in [reference needed]. Figure 3 As shown, the formula for calculating the required rotation angle θ2 of the servo motor 41 is as follows:

[0091]

[0092] Where θ1 is the rotation angle of the cam disk 53 according to the working conditions, l is the frame length of the crank-slider-rocker mechanism, and a is the crank length of the crank-slider-rocker mechanism;

[0093] When the servo motor 41 drives the cam disk 53 to rotate, the cam follower 56, which is mounted on the gripper connector 57, slides in a restricted manner along the cam groove provided on the cam disk 53, thereby converting the rotational motion of the cam disk 53 into the linear displacement of the wafer gripper 58 along the radial direction of the fixed disk 52. The displacement stroke is limited by the geometric contour of the cam groove.

[0094] In this embodiment, the frame length of the crank-slider-rocker mechanism is 210 mm, which is the distance from the output shaft of the servo motor 41 to the center of the cam disk 53; the crank length of the crank-slider-rocker mechanism is 115 mm, which is the distance between the positioning holes at both ends of the crank 43; based on the design parameters of the cam groove stroke position and combined with the calculation formula of the required rotation angle θ2 of the servo motor 41, the corresponding rotation angle used to control the gripper stroke can be obtained.

[0095] Step S2: Control the servo motor to drive the wafer gripper 58 to retract to the preset wafer gripping stroke position, then vertically lift the actuator, and detect the force feedback information through the six-dimensional force sensor 2 to determine whether the wafer has been successfully gripped. If the gripping is successful, drive the wafer gripper 58 to continue to retract to the wafer centering stroke position, so that the wafer is radially centered.

[0096] Step S3: Transfer the wafer along the planned path to the top of the packaging mold. During the transfer, keep the vertical axis position of the actuator constant to avoid the wafer tilting during the movement and causing the packaging material to spill.

[0097] Specifically, the constant vertical axis pose of the actuator is achieved through a constrained attitude planning method. This method involves constraining the normal axis vector corresponding to the plane that the actuator needs to maintain horizontality during loading and unloading to always be parallel to the vertical axis direction of the world coordinate system throughout the entire motion process.

[0098] The constrained attitude planning method employs attitude decomposition and partial interpolation, specifically including: converting the current attitude of the end effector from attitude quaternion form to Euler angle form arranged in ZYX order. ,in, θ is the yaw angle, and θ is the pitch angle. The pitch angle θ and roll angle are fixed during motion planning. Only for the yaw angle Time interpolation is performed to plan the attitude changes of the actuator, and the interpolation relationship satisfies ,in, The initial yaw angle, The target yaw angle difference is the normalized value, and f(t) is a continuously smooth interpolation function; the Euler angle sequence obtained based on the above interpolation is... The reconstructed interpolated attitude quaternion sequence satisfies the attitude constraints.

[0099] Step S4: Vertically lower the height of the actuator, monitor the contact force information in real time, and stop the movement immediately when contact with the packaging mold is detected; drive the wafer gripper 58 to the maximum unfolding stroke position to release the wafer, and then control the actuator to return to the standby position to complete the wafer loading process;

[0100] Specifically, the wafer gripping and contact detection methods in the loading and unloading process are all implemented by judging changes in the actuator's mechanical information, including the following steps:

[0101] Step S41: Acquire measurement data from the six-dimensional force sensor 2 in real time, including the triaxial force component F. x F y F z and triaxial torque components M x M yM z The measurement data were then normalized and fused using a weighted L2 method to obtain a single characteristic parameter F that characterizes the overall contact state between the wafer gripper, the wafer, and the environment. c (t), its calculation formula is:

[0102]

[0103] Among them, F max and M max These represent the maximum range of the six-dimensional force sensor, α is the weighting coefficient used to adjust the contribution of the torque component, and t is the time variable;

[0104] Step S42: Based on the discrete time series, adjust the feature parameter F c (t) The rate of change is calculated using the three-point difference method, and the formula is:

[0105]

[0106] Simultaneously, the feature parameter F is updated using a recursive formula within the sliding time window. c The mean μ(t) and variance σ of (t) 2 (t):

[0107]

[0108]

[0109] Where N is the length of the sliding window;

[0110] Step S43: Based on feature parameter F c The statistical characteristics and trends of (t) are used to determine the wafer gripping status and contact detection. The determination conditions are as follows:

[0111] a. Conditions for successful wafer grabbing:

[0112] If the wafer is stably clamped, the load on the actuator will be superimposed on the wafer's own weight, causing a force component along the direction of gravity and the characteristic parameter F. c The steady-state shift of (t) is determined by the following criteria:

[0113]

[0114] And within the sliding time window, the following conditions are met:

[0115]

[0116] Where μ0 is the baseline mean of the feature parameters before clamping, and ΔF min With ΔF maxTo determine the load variation range pre-calibrated based on wafer mass and gravitational acceleration, σ g To capture the stability variance threshold, T g The threshold for the rate of change after the data capture is completed;

[0117] b. Criteria for determining contact detection:

[0118] Due to abrupt changes in contact force or contact torque, the characteristic parameter F c (t) shows a significant change in a short period of time, and the criterion for this is:

[0119] .

[0120] And within the sliding time window, the following conditions are met:

[0121]

[0122] Among them, T c is the contact detection change rate threshold, and k1 is the statistical determination coefficient.

[0123] Step S5: During the wafer unloading process, the loading and unloading robot performs operations in the reverse order of the loading process; after packaging is completed, the drive actuator moves above the mold, so that the wafer gripper 58 is at the maximum unfolded stroke position, the actuator is lowered until it detects contact with the mold, and the wafer gripper 58 is controlled to retract to the gripping stroke position to grip the wafer.

[0124] Step S6: Move the wafer back to the wafer placement station along the planned path, control the wafer gripper 58 to the maximum unfolding stroke position to release the wafer, control the actuator to return to the standby position, and complete the wafer unloading.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A loading and unloading robot for large-size wafer-level packaging, characterized in that, The robot includes: a six-axis robotic arm (1), a six-dimensional force sensor (2), an actuator connector (3), a cam angle adjustment mechanism (4), and a gripper control mechanism (5); Among them, the six-dimensional force sensor (2) is set between the end of the six-axis robotic arm (1) and the actuator connector (3) and fixedly connected, and is used to obtain multi-dimensional force information of the end actuator in real time during the loading and unloading process; The actuator connector (3) is coaxially fixed to the main frame (51) of the servo motor (41) with the cam angle adjustment mechanism (4) and the gripper control mechanism (5); and the output shaft of the servo motor (41) is parallel to the central axis of the main frame (51) and is not coincident.

2. The loading and unloading robot according to claim 1, characterized in that: The cam angle adjustment mechanism (4) also includes a servo motor connector (42). The output shaft of the servo motor (41) is connected to the servo motor connector (42) through gear transmission. The servo motor connector (42) is fixedly connected to one end of the crank (43). The other end of the crank (43) is embedded with a deep groove ball bearing (48). The inner ring of the deep groove ball bearing (48) is fixedly connected to the bearing connector (46), the slider connector (47), and the slider (45) in sequence; the slider (45) and the guide rail (44) are grooved to form a sliding pair, and the guide rail (44) is fixed on the cam disk (53) of the gripper control mechanism (5); A fixed plate (52) is fixedly installed on the main frame (51), and a deep groove ball bearing (59) is embedded in the center of the fixed plate (52). The cam plate (53) is fixedly connected to the inner ring of the deep groove ball bearing (59).

3. The loading and unloading robot according to claim 1, characterized in that: The gripper control mechanism (5) further includes a positioning disk (54) and a wafer gripper (58). The positioning disk (54) is fixedly connected to the lower end of the main frame (51) and is provided with a flange for positioning and an alignment contact surface. The wafer gripper (58) is slidably connected to the gripper connector (57) through a dovetail groove. The inner curvature of the gripper matches the size of the gripped wafer. The gripper connector (57) is slidably connected to the fixed disk (52) through a dovetail groove, so that the wafer gripper (58) can move linearly along the radial direction of the fixed disk (52).

4. The loading and unloading robot according to claim 3, characterized in that: The upper side of the gripper connector (57) is fixedly connected to the follower connector (56), and the center position of the follower connector (56) is fixedly connected to the cam follower (55). The cam follower (55) and the cam groove provided on the cam disk (53) form a sliding fit, which is used to drive the gripper connector (57) to move when the cam disk (53) rotates. The gripper connector (57) is fixedly connected to a gripper limiting member (510) and a spring seat (511) on its lower side. The gripper limiting member (510) and the spring seat (511) are provided with limiting bosses for positioning and installing the spring (512). The spring (512) is located between the two to provide flexible limiting effect on the wafer gripper (58) during wafer clamping and alignment.

5. A wafer loading and unloading method using a loading and unloading robot for large-size wafer-level packaging as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step S1: The robot drive actuator moves from the standby position to the wafer placement station where the front-end process is completed along the trajectory planned according to the working conditions. The end of the trajectory makes the bearing surface of the wafer gripper (58) lower than the plane where the wafer is located. When moving, the actuator position is adjusted to be parallel to the wafer plane, and the wafer gripper (58) is in the maximum unfolding stroke position. Step S2: Control the servo motor to drive the wafer gripper (58) to retract to the preset wafer gripping stroke position, then vertically lift the actuator, and detect the force feedback information through the six-dimensional force sensor (2) to determine whether the wafer is successfully gripped. If the gripping is successful, drive the wafer gripper (58) to continue to retract to the wafer centering stroke position. Step S3: Transfer the wafer along the planned path to the top of the packaging mold, keeping the vertical axis pose of the actuator constant during the transfer process; Step S4: Vertically lower the actuator height, monitor the contact force information in real time, and stop the movement immediately when contact with the packaging mold is detected; drive the wafer gripper (58) to the maximum unfolding stroke position to release the wafer, and then control the actuator to return to the standby position to complete the wafer loading; Step S5: After packaging is completed, the actuator is moved above the mold, so that the wafer gripper (58) is at the maximum unfolding stroke position. The actuator is lowered until it detects contact with the mold, and the wafer gripper (58) is controlled to retract to the gripping stroke position to grip the wafer. Step S6: Move the wafer back to the wafer placement station along the planned path, control the wafer gripper (58) to the maximum unfolding stroke position to release the wafer, drive the actuator back to the standby position, and complete the wafer unloading.

6. The wafer loading and unloading method according to claim 5, characterized in that: The clamping, releasing, and alignment operations of the wafer gripper (58) are all achieved by controlling the servo motor (41) to drive the cam disk (53) to rotate. The formula for calculating the required rotation angle θ2 of the servo motor (41) is as follows: Wherein, θ1 is the rotation angle of the cam disk (53) according to the working conditions, l is the distance from the output shaft of the servo motor (41) to the center of the cam disk (53), and a is the distance between the positioning holes at both ends of the crank (43).

7. The wafer loading and unloading method according to claim 5, characterized in that, The methods involving wafer gripping and contact detection are all implemented by judging changes in the mechanical information of the actuator, including the following steps: Step S41: Real-time acquisition of the measurement data of the six-dimensional force sensor (2), including three-axis force components F x , y , z and three-axis moment components M x , y , z , and then normalization processing is performed on the measurement data and a single characteristic parameter F c (t) representing the comprehensive contact state between the wafer chucking jaw and the wafer and the environment is obtained by fusion in a weighted two-norm manner, and the calculation formula is: Among them, F max and M max These are the maximum ranges of the six-dimensional force sensor (2), α is the weighting coefficient used to adjust the contribution of the torque component, and t is the time variable; Step S42: Based on the discrete time series, adjust the feature parameter F c (t) The rate of change is calculated using the three-point difference method, and the formula is: Simultaneously, within the sliding time window, the mean μ(t) and variance σ of the characteristic parameters are updated using a recursive formula. 2 (t): Where N is the length of the sliding window; Step S43: Based on feature parameter F c The statistical characteristics and trends of (t) are used to determine the wafer gripping status and contact detection. The determination conditions are as follows: a. Conditions for successful wafer grabbing: If the wafer is stably clamped, the load on the actuator will be superimposed on the weight of the wafer itself, causing a force component and characteristic parameter F along the direction of gravity. c The steady-state shift of (t) is determined by the following criteria: And within the sliding time window, the following conditions are met: Where μ0 is the baseline mean of the feature parameters before clamping, and ΔF min With ΔF max To determine the load variation range pre-calibrated based on wafer mass and gravitational acceleration, σ g To capture the stability variance threshold, T g The threshold for the rate of change after the data capture is completed; b. Criteria for determining contact detection: Due to abrupt changes in contact force or contact torque, the characteristic parameter F c (t) shows a significant change in a short period of time, and the criterion for this is: ； And within the sliding time window, the following conditions are met: Among them, T c is the contact detection change rate threshold, and k1 is the statistical determination coefficient.

8. The wafer loading and unloading method according to claim 5, characterized in that: In step S3, the vertical axis pose of the actuator is kept constant by a constrained attitude planning method. Specifically, the normal axis vector corresponding to the plane that the actuator needs to keep horizontal during loading and unloading is constrained to be parallel to the vertical axis direction of the world coordinate system throughout the entire motion process. The constrained attitude planning method employs attitude decomposition and partial interpolation, specifically including: converting the current attitude of the end effector from attitude quaternion form to Euler angle form arranged in ZYX order. ; in, θ is the yaw angle, and θ is the pitch angle. The pitch angle θ and roll angle are fixed during motion planning. Only for the yaw angle Time interpolation is performed to plan the attitude changes of the actuator, and the interpolation relationship satisfies ; in, The initial yaw angle, The target yaw angle difference is the normalized value, and f(t) is a continuously smooth interpolation function; the Euler angle sequence obtained based on the interpolation is... The reconstructed interpolated attitude quaternion sequence satisfies the attitude constraints.

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