Coaxial auto focus system and method for chip inspection machine

Abstract

The application provides a coaxial automatic focusing system and method of a chip inspection machine, which comprises a chip transmission device, a visual device and a fixing mechanism; the chip transmission device comprises a transmission track, a tape, a detection site and the fixing mechanism; the tape is arranged in the transmission track, and the fixing mechanism is arranged at the detection site; the tape moves to the detection site and stops, and the fixing mechanism fixes the position of the tape; the visual device comprises an infrared visual mechanism, a height measuring laser sensor and a height adjusting mechanism arranged on the same side; the height measuring laser sensor collects chip height information at the detection site; the height adjusting mechanism controls the infrared visual mechanism to move and focus in the height direction according to the collected chip height information; and the infrared visual mechanism collects chip image information. The position of the tape is fixed by the fixing mechanism, the height of the infrared visual mechanism is adjusted by the height adjusting mechanism according to the height information collected by the height measuring laser sensor, automatic focusing is realized, the definition of the collected image is improved, there is no defocus, and the accuracy of subsequent detection is improved.

Description

Technical Field

[0001] This invention belongs to the technical field of chip inspection equipment, specifically, it relates to a coaxial automatic focusing system and method for a chip inspection machine. Background Technology

[0002] In semiconductor back-end packaging and chip mass production testing scenarios, tape and reel packaging is the mainstream carrier form for the automated storage, transfer, and feeding of small-sized surface-mount chips, widely used in chip mass production processes in consumer electronics, automotive electronics, and industrial control. Chip appearance inspection, as the core process for final quality verification after packaging, directly determines the detection rate of appearance defects in the finished chips. Its core relies on high-precision industrial vision imaging systems to complete micron-level feature recognition of areas such as chip pins, the surface of the molding compound, and printed markings. The stability of the imaging quality directly determines the final inspection yield and production efficiency.

[0003] Chinese patent application CN101936918A discloses a visual inspection system and method for BGA chips. The system includes a control unit with a calculation and analysis module; a camera that transmits image information to the control unit, the camera being coaxially aligned with an optical lens; and a coaxial light source assembly comprising a coaxial light generator and a semi-transparent mirror at a 45° angle to the optical lens. The method involves the coaxial light generator emitting coaxial light, the camera acquiring image information and transmitting it to the control unit; the calculation and analysis module determining whether the image information includes chip image information; if so, threshold segmentation is performed on the image to distinguish the foreground and background of solder ball images; BLOB analysis is performed on the solder ball images to calculate the position, area, and perimeter parameters of each solder ball image; and a circle fitting operation is performed on the solder ball images to identify defective solder balls. This invention can detect inherent defects in chip solder balls, improving inspection quality.

[0004] Currently, chip taping and inspection equipment in the industry generally adopts a fixed station static shooting architecture: the chip carrier base at the inspection station is completely fixed, and the taping and inspection equipment is carried by a servo drive mechanism to move step by step along the feeding direction. Each movement has a fixed preset step distance, which accurately stops the chip to be inspected in the slot of the taping and inspection equipment directly below the vision system to complete the shooting and inspection.

[0005] Because of the inherent trade-off between the depth-of-field parameters and imaging resolution of conventional industrial telecentric lenses, two completely opposing technical approaches have emerged in the industry: 1. High-resolution imaging approach with shallow depth of field: In many scenarios requiring high precision in defect detection, high-resolution vision systems with a depth of field of only 10μm are chosen. However, this approach is only suitable if the object being photographed is precisely located on the lens's optimal focal plane. In actual mass production scenarios, flexible tape itself has injection molding tolerances and warping errors in the carrier groove. At the same time, during the tape's stepping motion, it is affected by conveyor belt friction, servo start-stop vibration, and track gaps, resulting in unavoidable Z-axis vertical jumps. Ultimately, the Z-axis fluctuation range of the chip's actual stopping position often exceeds 10μm, completely exceeding the depth of field coverage range of this type of vision system.

[0006] 2. Large Depth-of-Field Anti-Defocus Imaging Approach: To avoid the high defocusing defects of small depth-of-field solutions, some equipment manufacturers have turned to large depth-of-field vision systems at the 20μm level. Relying on a larger depth-of-field coverage area, these systems directly accommodate Z-axis positional fluctuations caused by tape movement and their own geometric tolerances, theoretically reducing the defocusing rate to near zero. However, this approach also has significant inherent drawbacks: at the same optical magnification, increasing the depth of field inevitably requires compressing the lens aperture and changing the optical assembly configuration. This results in a significant decrease in edge sharpness and detail contrast in the final image, affecting the accuracy of subsequent inspection. In high-end chip scenarios with stringent requirements for inspection accuracy, such compromises in image quality are completely unacceptable.

[0007] There is an urgent need for a visual inspection system that can fully adapt to the Z-axis positional fluctuations caused by tape movement and its own shape and position errors without reducing the image clarity, so as to achieve stable imaging with zero defocus and retain the ultra-high imaging sharpness of a 10μm small depth-of-field vision system. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a coaxial autofocus system and method for a chip inspection machine.

[0009] The coaxial autofocus system for a chip inspection machine provided by the present invention includes a frame, a chip transfer device and a vision device disposed on the frame, wherein the vision device is located above the detection point of the chip transfer device. The chip transmission device includes: a transmission track, a tape, a detection point, and a fixing mechanism. The tape is set in the transmission track and moves along the direction of the transmission track. The fixing mechanism is set at the detection point. The tape stops when it moves to the detection point, and the fixing mechanism fixes the position of the tape. The vision device includes an infrared vision mechanism, a height-measuring laser sensor, and a height adjustment mechanism, all located on the same side. The height-measuring laser sensor collects chip height information at the detection point. The height adjustment mechanism controls the infrared vision mechanism to move and focus in the height direction based on the collected chip height information. The infrared vision mechanism collects chip image information.

[0010] In a preferred embodiment, the fixing mechanism includes a pressure plate, a boss, a first adjusting block, a fixing block, and a linear reciprocating drive assembly; The boss is fixedly mounted on the transmission track, and the boss is located below the tape. The pressure plate is positioned above the tape tray, the first adjusting block is movably positioned on the side of the transmission track, the pressure plate is fixedly connected to the first adjusting block, the fixed block is fixedly connected to the frame, the linear reciprocating drive assembly is mounted on the fixed block, and the output end of the linear reciprocating drive assembly is connected to the first adjusting block, driving the first adjusting block to move along the height direction.

[0011] In a preferred embodiment, the fixing mechanism further includes a spring and a second adjusting block, the second adjusting block being detachably mounted on the fixing block, one end of the spring being connected to the second adjusting block, and the other end of the spring being connected to the first adjusting block via a connecting rod, the extension and retraction direction of the spring being the height direction, and neither the spring nor the connecting rod interfering with the fixing block.

[0012] In a preferred embodiment, the linear reciprocating drive assembly includes a mounting block, a cylinder, and a linear guide rail. The mounting block is fixedly mounted on a fixed block, the guide rail portion of the linear guide rail is fixedly mounted on the fixed block, the slider portion of the linear guide rail is fixedly connected to a first adjusting block, the fixed portion of the cylinder is mounted on the mounting block, and the movable portion of the cylinder is connected to the slider portion of the linear guide rail. Furthermore, the extension and retraction direction of the cylinder and the length direction of the guide rail of the linear guide are both in the same direction as the height direction.

[0013] In a preferred embodiment, the pressure plate is provided with a detection port that can expose the chip.

[0014] In a preferred embodiment, the height adjustment mechanism is mounted on the frame via a mounting plate. The height adjustment mechanism includes a servo motor and a linear module. The fixed part of the servo motor is fixedly connected to the mounting plate, and the guide rail part of the linear module is fixedly connected to the mounting plate. The output part of the servo motor is drivenly connected to the lead screw part of the linear module. The slider part of the linear module is provided with a connecting plate for mounting an infrared vision mechanism and a height measuring laser sensor.

[0015] In a preferred embodiment, the infrared vision mechanism includes an infrared camera, an infrared lens tube, and an infrared microscope connected sequentially from top to bottom along the height direction.

[0016] In a preferred embodiment, the height-measuring laser sensor and the infrared vision mechanism both acquire height information and image information from the same chip.

[0017] In a preferred embodiment, the accuracy of the height-measuring laser sensor is at least 0.01 μm.

[0018] A coaxial autofocusing method for a chip inspection machine includes the following steps: The chip transfer device delivers the chip under test to the detection site; The height-measuring laser sensor collects the height information from the chip and transmits the height information to the host system. The host system generates control commands and sends them to the height adjustment mechanism; The height adjustment mechanism executes control commands; The infrared vision mechanism takes pictures and uploads the picture data to the host system; The host system determines the clarity of the captured image data; If the focus is successful, the focusing is considered complete. If the focus fails, the height-measuring laser sensor collects the chip's height information again, and the above steps are repeated until the focus is complete.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses a fixing mechanism to fix the position of the tape after the chip is transmitted to the detection site, which facilitates the acquisition of chip information by the vision device, thereby improving the accuracy of the vision device's automatic focusing; the height adjustment mechanism adjusts the height of the infrared vision mechanism according to the height information acquired by the height-measuring laser sensor to achieve automatic focusing, which helps to improve the clarity of the acquired image and achieve zero defocus, thereby helping to improve the accuracy of subsequent detection.

[0020] 2. The present invention utilizes a spring and a second adjusting block. During the upward movement of the first adjusting block and the pressure plate, the spring is stretched, and during the downward movement of the first adjusting block and the pressure plate, the spring is compressed. Due to the buffering effect of the spring, the tape is protected from being damaged by the pressure plate and the boss, thus improving the service life of the system. Attached Figure Description

[0021] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram illustrating the overall system structure of the present invention; Figure 2 This is a schematic diagram illustrating the main structure of the transmission track in this invention; Figure 3 This is a schematic diagram illustrating the overall structure of the fixing mechanism, which is the main feature of this invention. Figure 4 This is a schematic diagram illustrating the main cylinder mounting structure of the present invention; Figure 5 This is a schematic diagram illustrating the overall structure of the visual device of the present invention.

[0022] Reference numerals: 1. Vision device; 2. Chip transmission device; 10. Altitude laser sensor; 20. Infrared microscope; 30. Infrared tube; 40. Infrared camera; 50. Servo motor; 60. Linear module; 70. Connecting plate; 80. Mounting plate; 101. Transmission track; 102. Fixing mechanism; 1021. Tape; 1022. Pressure plate; 1023. Boss; 1024. First adjusting block; 1025. Linear guide rail; 1026. Fixing block; 1027. Spring; 1028. Second adjusting block; 1029. Cylinder; 1030. Mounting block. Detailed Implementation

[0023] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0024] like Figures 1 to 5 As shown, the coaxial autofocus system of the chip inspection machine provided by the present invention includes a frame, a chip transfer device 2 and a vision device 1 disposed on the frame, the vision device 1 being located above the detection point of the chip transfer device 2.

[0025] The chip transmission device 2 includes a transmission track 101, a tape 1021, a detection point, and a fixing mechanism 102. The tape 1021 is positioned within the transmission track 101 and moves along its direction. The fixing mechanism 102 is positioned at the detection point. The tape 1021 stops at the detection point, and the fixing mechanism 102 secures its position. Due to the vibrations generated during the movement of the tape 1021 and inherent equipment errors, when the tape 1021 delivers the chip to the detection point, the chip may exhibit a height deviation exceeding the tolerance range, causing the vision device 1 to lose focus. Therefore, the chip transmission device 2 of this application, after transmitting the chip to the detection point, uses the fixing mechanism 102 to fix the position of the tape 1021, facilitating the vision device 1's acquisition of chip information and thus improving the accuracy of the vision device 1's automatic focusing.

[0026] Specifically, the fixing mechanism 102 includes a pressure plate 1022, a boss 1023, a first adjusting block 1024, a fixing block 1026, and a linear reciprocating drive assembly. The boss 1023 is fixedly mounted on the transmission track 101 and is located below the tape 1021. The pressure plate 1022 is positioned above the tape 1021 and has a detection port that exposes the chip. When the tape 1021 delivers the chip to be tested to the detection point, the tape 1021 stops, and the pressure plate 1022 presses down to cooperate with the boss 1023 to fix the position of the tape 1021. At this time, the chip to be tested is exposed directly below the vision device 1 through the detection port.

[0027] The first adjusting block 1024 is movably disposed on the side of the transmission track 101. The pressure plate 1022 is fixedly connected to the first adjusting block 1024. The fixing block 1026 is fixedly connected to the frame. A linear reciprocating drive assembly is mounted on the fixing block 1026, and its output end is connected to the first adjusting block 1024, driving the first adjusting block 1024 to move along the height direction. In one feasible embodiment, both the first adjusting block 1024 and the linear reciprocating drive assembly are mounted on the side wall of the fixing block 1026 near the tape tray 1021. The pressure plate 1022 can be fixedly mounted on the top of the first adjusting block 1024 with screws.

[0028] Furthermore, the linear reciprocating drive assembly includes a mounting block 1030, a cylinder 1029, and a linear guide rail 1025. The mounting block 1030 is fixedly mounted on the side wall of the fixing block 1026 near the tape 1021. The guide rail portion of the linear guide rail 1025 is fixedly mounted on the side wall of the fixing block 1026 near the tape 1021. The slider portion of the linear guide rail 1025 is fixedly connected to the first adjusting block 1024 by screws. The fixed portion of the cylinder 1029 is mounted on the mounting block 1030, and the movable portion of the cylinder 1029 is connected to the slider portion of the linear guide rail 1025. Furthermore, the extension / retraction direction of the cylinder 1029 and the length direction of the guide rail portion of the linear guide rail 1025 are both in the same direction as the height direction. It should be noted that the linear guide rail 1025 in this application adopts a linear reciprocating mechanism composed of a guide rail and a slider embedded in the guide rail, as used in the prior art.

[0029] When the tape 1021 moves, the movable part of the cylinder 1029 extends, lifting the slider part of the linear guide 1025 and the first adjusting block 1024, and then lifting the pressure plate 1022 to disengage from the tape 1021. At this time, the tape 1021 can move within the transmission track 101. When the tape 1021 delivers the chip to be tested to the detection point, the tape 1021 stops moving, the movable part of the cylinder 1029 retracts, driving the slider part of the linear guide 1025 to move downward, and then driving the first adjusting block 1024 and the pressure plate 1022 to move downward, until the pressure plate 1022, in conjunction with the boss 1023, clamps and fixes the tape 1021.

[0030] In a preferred embodiment, the fixing mechanism 102 further includes a spring 1027 and a second adjusting block 1028. The second adjusting block 1028 is detachably mounted on the fixing block 1026. One end of the spring 1027 is connected to the second adjusting block 1028, and the other end of the spring 1027 is connected to the first adjusting block 1024 via a connecting rod. The extension and retraction direction of the spring 1027 is the height direction, and neither the spring 1027 nor the connecting rod interferes with the fixing block 1026.

[0031] In a preferred embodiment, both the spring 1027 and the second adjusting block 1028 are disposed on the side wall of the fixed block 1026 away from the tape 1021. The second adjusting block 1028 is detachably mounted on the fixed block 1026 by screws and screw holes pre-drilled in the fixed block 1026. The fixed block 1026 has multiple sets of screw holes along its height direction to facilitate height adjustment of the second adjusting block 1028 on the fixed block 1026. To avoid interference between the connecting rod and the fixed block 1026, a clearance opening is provided on the fixed block 1026. The size of the clearance opening is such that the connecting rod does not contact the side wall of the clearance opening during movement.

[0032] During the upward movement of the first adjusting block 1024 and the pressure plate 1022, the spring 1027 is stretched; during the downward movement of the first adjusting block 1024 and the pressure plate 1022, the spring 1027 is compressed. Due to the buffering effect of the spring 1027, the tape 1021 is protected from being pinched and damaged by the pressure plate 1022 and the boss 1023, thus improving the service life of the system.

[0033] The vision device 1 includes an infrared vision mechanism, a height-measuring laser sensor 10, and a height adjustment mechanism, all located on the same side. The height-measuring laser sensor 10 collects chip height information at the detection point. The height adjustment mechanism controls the infrared vision mechanism to move and focus in the height direction based on the collected chip height information. The infrared vision mechanism collects chip image information.

[0034] Specifically, the height adjustment mechanism is mounted on the frame via a mounting plate 80. The height adjustment mechanism includes a servo motor 50 and a linear module 60. The fixed part of the servo motor 50 is fixedly connected to the mounting plate 80, and the guide rail part of the linear module 60 is fixedly connected to the mounting plate 80. The output part of the servo motor 50 is connected to the lead screw part of the linear module 60. A connecting plate 70 for mounting the infrared vision mechanism and the height-measuring laser sensor 10 is provided on the slider part of the linear module 60. The height-measuring laser sensor 10 and the infrared vision mechanism both acquire height information and image information from the same chip.

[0035] It should be noted that the linear module 60 of the technical solution of this application can adopt the existing threaded screw pair structure to convert the rotation of the servo motor 50 into the linear reciprocating motion of the slider.

[0036] In a preferred embodiment, the infrared vision mechanism includes an infrared camera 40, an infrared lens tube 30, and an infrared microscope 20 connected sequentially from top to bottom along the height direction.

[0037] In a preferred embodiment, the accuracy of the height-measuring laser sensor 10 is at least 0.01 μm. It employs the principle of triangulation laser ranging.

[0038] A coaxial autofocus method for a chip inspection machine, employing the aforementioned coaxial autofocus system for the chip inspection machine, includes the following steps: Chip transmission device 2 delivers the chip to be tested to the detection site; The height-measuring laser sensor 10 collects the height information from the chip and transmits the height information to the host system; The host system generates control commands and sends them to the height adjustment mechanism; The height adjustment mechanism executes control commands; The infrared vision mechanism takes pictures and uploads the picture data to the host system; The host system determines the clarity of the captured image data; If the focus is successful, the focusing is considered complete. If the focus fails, the height-measuring laser sensor 10 collects the height information of the chip again, and the above steps are repeated until the focus is complete.

[0039] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application 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 application.

[0040] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A coaxial automatic focusing system for a chip inspection machine, characterized in that, Includes a rack, a chip transfer device (2) and a vision device (1) mounted on the rack, the vision device (1) being located above the detection point of the chip transfer device (2); The chip transmission device (2) includes: a transmission track (101), a tape (1021), a detection point, and a fixing mechanism (102). The tape (1021) is arranged in the transmission track (101) and moves along the direction of the transmission track (101). The fixing mechanism (102) is arranged at the detection point. The tape (1021) stops when it moves to the detection point. The fixing mechanism (102) fixes the position of the tape (1021). The vision device (1) includes an infrared vision mechanism, a height-measuring laser sensor (10), and a height adjustment mechanism, all located on the same side. The height-measuring laser sensor (10) collects chip height information at the detection point. The height adjustment mechanism controls the infrared vision mechanism to move and focus in the height direction based on the collected chip height information. The infrared vision mechanism collects chip image information.

2. The coaxial autofocus system of the chip inspection machine according to claim 1, characterized in that, The fixing mechanism (102) includes a pressure plate (1022), a boss (1023), a first adjusting block (1024), a fixing block (1026), and a linear reciprocating drive assembly; The boss (1023) is fixedly mounted on the transmission track (101), and the boss (1023) is located below the tape (1021); The pressure plate (1022) is disposed above the tape (1021), the first adjusting block (1024) is movably disposed on the side of the transmission track (101), the pressure plate (1022) is fixedly connected to the first adjusting block (1024), the fixed block (1026) is fixedly connected to the frame, the linear reciprocating drive assembly is mounted on the fixed block (1026), the output end of the linear reciprocating drive assembly is connected to the first adjusting block (1024), and drives the first adjusting block (1024) to move along the height direction.

3. The coaxial autofocus system of the chip inspection machine according to claim 2, characterized in that, The fixing mechanism (102) further includes a spring (1027) and a second adjusting block (1028). The second adjusting block (1028) is detachably mounted on the fixing block (1026). One end of the spring (1027) is connected to the second adjusting block (1028), and the other end of the spring (1027) is connected to the first adjusting block (1024) through a connecting rod. The extension and retraction direction of the spring (1027) is the height direction, and neither the spring (1027) nor the connecting rod interferes with the fixing block (1026).

4. The coaxial autofocus system of the chip inspection machine according to claim 2, characterized in that, The linear reciprocating drive assembly includes a mounting block (1030), a cylinder (1029), and a linear guide rail (1025). The mounting block (1030) is fixedly mounted on a fixed block (1026). The guide rail portion of the linear guide rail (1025) is fixedly mounted on the fixed block (1026). The slider portion of the linear guide rail (1025) is fixedly connected to a first adjusting block (1024). The fixed portion of the cylinder (1029) is mounted on the mounting block (1030), and the movable portion of the cylinder (1029) is connected to the slider portion of the linear guide rail (1025). Furthermore, the extension and retraction direction of the cylinder (1029) and the length direction of the guide rail portion of the linear guide rail (1025) are both in the same direction as the height direction.

5. The coaxial autofocus system of the chip inspection machine according to claim 2, characterized in that, The pressure plate (1022) is provided with a detection port that can expose the chip.

6. The coaxial autofocus system of the chip inspection machine according to claim 1, characterized in that, The height adjustment mechanism is mounted on the frame via a mounting plate (80). The height adjustment mechanism includes a servo motor (50) and a linear module (60). The fixed part of the servo motor (50) is fixedly connected to the mounting plate (80), and the guide rail part of the linear module (60) is fixedly connected to the mounting plate (80). The output part of the servo motor (50) is connected to the lead screw part of the linear module (60) for transmission. The slider part of the linear module (60) is provided with a connecting plate (70) for mounting the infrared vision mechanism and the height measuring laser sensor (10).

7. The coaxial autofocus system of the chip inspection machine according to claim 1, characterized in that, The infrared vision mechanism includes an infrared camera (40), an infrared lens tube (30), and an infrared microscope (20) connected sequentially from top to bottom along the height direction.

8. The coaxial autofocus system of the chip inspection machine according to claim 1, characterized in that, The height-measuring laser sensor (10) and the infrared vision mechanism both collect height information and image information from the same chip.

9. The coaxial autofocus system of the chip inspection machine according to claim 1, characterized in that, The accuracy of the height-measuring laser sensor (10) is at least 0.01 μm.

10. A coaxial autofocusing method for a chip inspection machine, characterized in that, The coaxial autofocus system of the chip inspection machine according to any one of claims 1 to 9 includes the following steps: The chip transmission device (2) delivers the chip to be tested to the detection site; The height-measuring laser sensor (10) collects the height information of the chip and transmits the height information to the host system; The host system generates control commands and sends them to the height adjustment mechanism; The height adjustment mechanism executes control commands; The infrared vision mechanism takes pictures and uploads the picture data to the host system; The host system determines the clarity of the captured image data; If the focus is successful, the focus is confirmed to be complete. If the focus is unsuccessful, the height-measuring laser sensor (10) will collect the height information of the chip again and repeat the above steps until the focus is completed.

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