A device for measuring the alignment accuracy of inner layers of an LDI and a method for aligning inner layers thereof

Abstract

The application discloses a device for measuring the alignment accuracy of an inner layer of an LDI and an inner layer alignment method thereof, comprising a base, wherein an XYZ moving table is arranged on the base, a suction plate table capable of moving is controlled to move by the XYZ moving table, a lower alignment assembly is arranged on the base, one end of the suction plate table is provided with a movable calibration target point, a support is further arranged on the base, a first camera and a second camera capable of moving horizontally are arranged on a crossbeam of the support, and a plurality of target point light sources are arranged at intervals on the edge of the suction plate table; the visual alignment method of two-way camera grabbing points is adopted to grab the graphic points on the upper and lower surfaces of the inner layer plate; the graphic points are obtained by LDI exposure on the AB surface of the inner layer plate and then developing and etching, and the graphic points on the A surface and the B surface are theoretically concentric; the rotation matrix of the second camera and the lower alignment assembly relative to the coordinate system of the LDI exposure system is confirmed, then the second camera and the lower alignment assembly read the same target point, and the coaxial position of the upper and lower cameras is obtained.

Description

Technical Field

[0001] This invention relates to alignment technology for direct imaging devices, and particularly to a device for measuring the alignment accuracy of inner layers in an LDI (Liquid Crystal Imaging Device). Background Technology

[0002] With the rise of electronic products, printed circuit boards (PCBs) are becoming increasingly sophisticated, leading to a growing demand for multilayer circuit boards. The yield rate of multilayer circuit boards largely depends on the manufacturing precision of the inner layers. One of the most important processes in inner layer manufacturing is film exposure. However, this process suffers from numerous drawbacks, including film expansion and contraction, difficulty in further improving alignment accuracy, and cumbersome prototyping procedures. As a result, it has been gradually replaced by laser direct-write (LDI) exposure technology.

[0003] LDI (Liquid Crystal Discharge) has limitations in terms of mechanism, software, and cost, and currently cannot achieve direct double-sided exposure, requiring the inner layer board to be flipped for exposure. The lack of holes and target points on both sides of the inner layer board presents a challenge for double-sided alignment. During inner layer exposure, one side (side A) is exposed first, and target points are applied to the edge material of the other side (side B). When flipping the board to expose side B, an alignment system can be used to identify the target points, achieving double-sided alignment. However, the mechanism, target points, and flipping all introduce errors, most of which are systematic errors and can be reduced through compensation. This invention provides a method and apparatus for measuring the alignment accuracy of LDI inner layers, allowing for convenient and quick acquisition of error compensation values ​​and reducing the influence of the mechanism and target points on inner layer alignment. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned deficiencies in the prior art by providing an apparatus for measuring the alignment accuracy of the inner layers of an LDI.

[0005] To address the aforementioned deficiencies in the prior art, the present invention provides the following technical solution: a device for measuring the alignment accuracy of an LDI inner layer, comprising a base, an XYZ moving stage, a suction cup stage controlled by the XYZ moving stage, and a lower alignment assembly, wherein one end of the suction cup stage is provided with a movable calibration target point, a support is also provided on the base, and a first camera and a horizontally movable second camera are provided on the crossbeam of the support, and multiple target point light sources are spaced apart along the edge of the suction cup stage;

[0006] The inner layer plate is placed on the suction cup stage with the first side of the inner layer plate facing upwards. At the same time, the laser directly exposes the pattern on the first side of the inner layer plate, while the target light source on the suction cup stage targets the second side of the inner layer plate.

[0007] When the second side pattern of the inner layer plate is exposed, the second side of the inner layer plate is placed on the suction cup stage with the second side facing up. After the first camera, the second camera and the lower alignment component align the inner layer plate, the laser directly exposes the second side pattern of the inner layer plate.

[0008] As an improvement to the device for measuring the alignment accuracy of the inner layer of LDI according to the present invention, the lower alignment assembly includes a lower CCD camera, a transmission-reflection prism, a telecentric lens, and a reflecting prism. The transmission-reflection prism is disposed between the lower CCD camera and the telecentric lens, and the reflecting prism is disposed on the telecentric lens.

[0009] As an improvement to the device for measuring the alignment accuracy of the inner layer of LDI according to the present invention, the transflective prism includes a reflective surface and a transmissive surface. The transflective prism is placed at an angle of 45 degrees on a cubic inclined mirror base. The surface of the transflective prism is coated with a transflective film. The transflective film transmits light waves with λ < 450nm and reflects light waves with λ > 450nm, where λ is the light wave.

[0010] As an improvement to the device for measuring the alignment accuracy of the inner layer of LDI according to the present invention, one end of the suction cup stage is provided with two symmetrically arranged calibration target mounting plates. The calibration target mounting plates are connected to the calibration target points through a linear slide rail and a slider. The end of the calibration target mounting plate is provided with a moving cylinder. The moving cylinder can push the calibration target points to move along the linear slide rail. The calibration target points move to find a coaxial position with the lower alignment component.

[0011] As an improvement to the device for measuring the alignment accuracy of the inner layer of LDI in this invention, when the inner layer plate is exposed on the first and second sides, the alignment of the calibration target point is required. The alignment of the calibration target point means that the calibration target point is aligned with the position of the second camera and the lower alignment component. First, the rotation matrix of the second camera and the lower alignment component relative to the LDI exposure system coordinate system is confirmed. Then, the second camera and the lower alignment component read the same target point to obtain the coaxial position of the upper and lower cameras. When the second camera, the calibration target point and the lower alignment component are in a coaxial state, the laser will expose the inner layer plate on the first and second sides.

[0012] The second camera is driven by a servo motor that drives a synchronous pulley and belt, enabling the second camera to move along a linear slide rail to find calibration target points at different positions.

[0013] As an improvement to the device for measuring the alignment accuracy of the inner layer of LDI according to the present invention, the exposed inner layer plate is placed back on the suction cup stage, and the target point pattern position in the field of view is obtained by the second camera and the lower alignment component. The inner layer alignment error is obtained by comparing it with the preset positions of the first and second surfaces of the inner layer plate.

[0014] As an improvement to the device for measuring the alignment accuracy of the inner layer of LDI according to the present invention, the laser wavelength is all in the ultraviolet band, and the illumination source used for the target light source is red light, green light or infrared light.

[0015] As an improvement to the device for measuring the alignment accuracy of the inner layer of LDI according to the present invention, the XYZ moving stage includes an X-axis moving module, a Y-axis moving module and a Z-axis moving module. The Y-axis moving module is controlled by the X-axis moving module to move in the X direction, the Z-axis moving module is controlled by the Y-axis moving module to move in the Y direction, and the Z-axis moving module controls the lifting and lowering of the entire suction cup stage.

[0016] The X-axis moving module, Y-axis moving module, and Z-axis moving module each include a servo motor, a transmission lead screw, and a slide rail assembly. The X-axis moving module is connected to the Y-axis moving module through the slide rail assembly, and the Y-axis moving module is connected to the Z-axis moving module through the slide rail assembly.

[0017] Another object of the present invention is to provide a method for measuring the alignment accuracy of the inner layer of an LDI, comprising the following steps:

[0018] 1) Confirm the rotation matrix R of the second camera and the lower alignment component relative to the coordinate system of the laser direct writing exposure system;

[0019] The specific method is as follows: the second camera reads the position of the calibration target point, moves the calibration target point a distance within the field of view in the X direction, and then reads the position of the target point after the movement. The rotation matrix R is calculated based on the two target point positions; the angle between the line connecting the two target point positions and the x-axis of the second camera coordinate system is the rotation matrix angle.

[0020] 2) The laser projects a circular spot with a diameter of 1-2 mm, which is reflected by a prism and imaged by a CCD camera. The circular spot is moved a distance within the field of view in the X direction, and the position of the circular spot after the movement is read. The rotation matrix P is calculated based on the positions of the two circular spots.

[0021] 3) The second camera and the lower alignment component read the same target point on the calibration target point to obtain the coaxial position of the second camera and the lower CCD camera;

[0022] 4) Expose the designed graphic on both sides of the inner layer board, and the graphic points on the first and second sides are theoretically concentric;

[0023] 5) Place the etched inner layer board back onto the suction cup stage, and for each placement, use the second camera to confirm the rotation matrix S of the array pattern points on the inner layer board relative to the LDI exposure system coordinate system.

[0024] 6) Finally, the second camera and the lower alignment component read multiple graphic points at the same position on the inner layer board. The distance deviation obtained is used to calculate the deviation in the X and Y directions through the rotation matrix S. Then, the average of multiple points is calculated to obtain the position deviation (Δx, Δy) that can be used for inner layer alignment compensation.

[0025] Compared with existing technologies, the advantages of this invention are: This invention employs a bidirectional visual alignment method to capture graphic points on both the upper and lower surfaces of the inner layer plate. These graphic points are obtained by LDI exposure on the AB surfaces of the inner layer plate followed by development and etching; theoretically, the graphic points on surfaces A and B are concentric. First, the rotation matrix of the second camera and the lower alignment assembly relative to the LDI exposure system coordinate system is determined. Then, the second camera and the lower alignment assembly read the same target point to obtain the coaxial position of the upper and lower cameras. The inner layer plate is then reset on the suction cup stage for measurement. The rotation matrix of the array graphic points on the inner layer plate relative to the system is first confirmed by the second camera. This allows the distance deviation calculated by the second camera and the lower alignment assembly to be converted into compensation values ​​for inner layer alignment in the X and Y axes, solving the problem of inner layer alignment accuracy measurement and improving the double-sided alignment of the inner layer exposure. Attached Figure Description

[0026] The present invention and its beneficial technical effects will now be described in further detail with reference to the accompanying drawings and specific embodiments, wherein:

[0027] Figure 1 This is a schematic diagram of the structure of the present invention.

[0028] Figure 2 This is a schematic diagram of the suction cup platform structure of the present invention.

[0029] Figure 3 This is a schematic diagram of the second camera and the lower alignment component of the present invention being in a coaxial position.

[0030] Figure 4 This is a schematic diagram of the rotation matrix coordinates of the present invention.

[0031] Figure 5 This is a schematic diagram of the structure of the inner layer plate after both sides are concentric.

[0032] Reference numerals in the attached figures: 1. Base; 2. XYZ moving stage; 3. Suction cup stage; 4. Lower alignment assembly; 5. Calibration target point; 6. Support; 7. Crossbeam; 8. First camera; 9. Second camera; 10. Target light source; 41. Lower CCD camera; 42. Transmitting prism; 43. Telecentric lens; 44. Reflecting prism; 31. Calibration target point mounting plate; 32. Moving cylinder. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the components in a specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0035] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0036] like Figures 1-5 As shown, a device for measuring the alignment accuracy of the inner layer of an LDI includes a base 1, an XYZ moving stage 2, a suction cup stage 3 controlled by the XYZ moving stage 2, and a lower alignment assembly 4. One end of the suction cup stage 3 is provided with a movable calibration target point 5. The base 1 is also provided with a support 6. A first camera 8 and a second camera 9 capable of horizontal movement are provided on the crossbeam 7 of the support 6. Multiple target light sources 10 are spaced apart along the edge of the suction cup stage 3.

[0037] The inner layer plate is placed on the suction cup stage 3 with the first side of the inner layer plate facing upward. At the same time, the laser directly exposes the pattern on the first side of the inner layer plate, and the target light source 10 on the suction cup stage 3 targets the second side of the inner layer plate.

[0038] When the second side pattern of the inner layer plate is exposed, the second side of the inner layer plate is placed on the suction cup stage 3 with the second side facing up. After the first camera 8, the second camera 9 and the lower alignment component 4 align the inner layer plate, the second side pattern of the inner layer plate is directly exposed by the laser.

[0039] Preferably, the lower alignment assembly 4 includes a lower CCD camera 41, a transmission-reflection prism 42, a telecentric lens 43, and a reflection prism 44. The transmission-reflection prism 42 is disposed between the lower CCD camera 41 and the telecentric lens 43, and the reflection prism 44 is disposed on the telecentric lens 43. The lower alignment assembly 4 can realize the function of calibrating the suction cup camera, and can also be used for inner layer error measurement.

[0040] Preferably, the transflective prism 42 includes a reflective surface and a transmissive surface. The transflective prism 42 is placed at an angle of 45 degrees on a cubic inclined mirror base 45. The surface of the transflective prism 42 is coated with a transflective film. The transflective film transmits light waves with wavelengths λ < 450 nm and reflects light waves with wavelengths λ > 450 nm, where λ is the light wave.

[0041] Preferably, one end of the suction cup platform 3 is provided with two symmetrically arranged calibration target mounting plates 31. The calibration target mounting plates 31 are connected to the calibration target 5 via a linear slide rail and a slider. The end of the calibration target mounting plate 31 is provided with a moving cylinder 32. The moving cylinder 32 can push the calibration target 5 to move along the linear slide rail. The calibration target 5 moves to find a coaxial position with the lower alignment component 4. The moving cylinder 32 can be set to move in the direction of movement as needed. It can be set to move forward and backward or left and right. The working principle is the same.

[0042] Preferably, when the inner layer plate is exposed on the first and second sides, the calibration target point 5 needs to be aligned. The alignment of the calibration target point 5 means that the calibration target point is aligned with the position of the second camera 9 and the lower alignment component 4. First, the rotation matrix of the second camera 9 and the lower alignment component 4 relative to the LDI exposure system coordinate system is confirmed. Then, the second camera 9 and the lower alignment component 4 read the same target point to obtain the coaxial position of the second camera 9 and the lower CCD camera 41. When the second camera 9, the calibration target point 5 and the lower alignment component 4 are in a coaxial state, the laser will expose the inner layer plate on the first and second sides.

[0043] The second camera 9 is driven by a servo motor that drives a synchronous pulley and belt, enabling it to move along a linear slide rail to locate the calibration target 5 at different positions. The ability of the second camera 9 to move and locate the calibration target 5 at different positions facilitates the acquisition of the calibration target position with the lower alignment component 4.

[0044] Preferably, the exposed inner layer plate is placed back on the suction cup stage 3, and the target point pattern position in the field of view is obtained by the second camera 9 and the lower alignment component 4. The inner layer alignment error is obtained by comparing it with the preset positions of the first and second surfaces of the inner layer plate.

[0045] Preferably, the laser wavelength is ultraviolet, and the illumination source used for the target light source 11 is red light, green light, or infrared light.

[0046] Preferably, the XYZ moving stage 2 includes an X-axis moving module, a Y-axis moving module and a Z-axis moving module. The Y-axis moving module is controlled by the X-axis moving module to move in the X direction, the Z-axis moving module is controlled by the Y-axis moving module to move in the Y direction, and the Z-axis moving module controls the lifting and lowering of the entire suction cup table surface.

[0047] The X-axis, Y-axis, and Z-axis moving modules each consist of a servo motor, a lead screw, and a slide rail assembly. The X-axis moving module is connected to the Y-axis moving module via the slide rail assembly, and the Y-axis moving module is connected to the Z-axis moving module via the slide rail assembly. The XYZ moving stage 2 performs high-precision movements in three directions, forming the numerical source of the LDI exposure coordinate system, which is sufficient to meet the accuracy requirements of LDI motion and inner layer error measurement.

[0048] A method for measuring the alignment accuracy of the inner layer of an LDI includes the following steps:

[0049] 1) Confirm the rotation matrix R of the second camera and the lower alignment component relative to the coordinate system of the laser direct writing exposure system;

[0050] The specific method is as follows: the second camera reads the position of the calibration target point 5, moves the calibration target point 5 a distance within the field of view in the X direction, and then reads the position of the target point after the movement. The rotation matrix R is calculated based on the two target point positions; the angle between the line connecting the two target point positions and the x-axis of the second camera coordinate system is the rotation matrix angle.

[0051] 2) The laser projects a circular spot with a diameter of 1-2 mm, which is reflected by a prism and imaged by a CCD camera. The circular spot is moved a distance within the field of view in the X direction, and the position of the circular spot after the movement is read. The rotation matrix P is calculated based on the positions of the two circular spots.

[0052] 3) The second camera and the lower alignment component read the same target point on the calibration target point, obtaining the coaxial position of the second camera and the lower CCD camera 41; (e.g.) Figure 3 (as shown);

[0053] 4) Expose the designed graphic on both sides of the inner layer board, with the graphic points on the first and second sides theoretically concentric; (e.g.) Figure 5 (as shown);

[0054] 5) Place the etched inner layer board back onto the suction cup stage, and for each placement, use the second camera to confirm the rotation matrix S of the array pattern points on the inner layer board relative to the LDI exposure system coordinate system.

[0055] 6) Finally, the second camera and the lower alignment component read multiple graphic points at the same position on the inner layer board. The distance deviation obtained is used to calculate the deviation in the X and Y directions through the rotation matrix S. Then, the average position of multiple graphic points is calculated to obtain the position deviation (Δx, Δy) that can be used for inner layer alignment compensation.

[0056] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and structure of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for measuring the alignment accuracy of the inner layers of an LDI (Liquid Crystal Disc Reinforced Plastic), comprising a base, characterized in that, The base is provided with an XYZ moving stage, a suction cup platform controlled by the XYZ moving stage, and a lower alignment assembly. One end of the suction cup platform is provided with a movable calibration target point. The base is also provided with a bracket. A first camera and a second camera capable of horizontal movement are provided on the crossbeam of the bracket. Multiple target point light sources are spaced apart on the edge of the suction cup platform. The inner layer plate is placed on the suction cup stage with the first side of the inner layer plate facing upwards. At the same time, the laser directly exposes the pattern on the first side of the inner layer plate, while the target light source on the suction cup stage targets the second side of the inner layer plate. When the second side pattern of the inner layer plate is exposed, the second side of the inner layer plate is placed on the suction cup stage with the second side facing up. After the first camera, the second camera and the lower alignment component align the inner layer plate, the laser directly exposes the second side pattern of the inner layer plate. Two symmetrically arranged calibration target mounting plates are provided at one end of the suction cup platform. The calibration target mounting plates are connected to the calibration target points through a linear slide rail and a slider. A moving cylinder is provided at the end of the calibration target mounting plate. The moving cylinder can push the calibration target points to move along the linear slide rail. The calibration target points move to find a coaxial position with the lower alignment component. The transmissive prism includes a reflective surface and a transmissive surface. The transmissive prism is tilted at 45 degrees and placed on a cubic inclined mirror base. The surface of the transmissive prism is coated with a transmissive film. λ <450 nm Light wave transmission, and reflection of light waves with λ>450nm, where λ is the light wave.

2. The apparatus for measuring the alignment accuracy of the inner layer of an LDI according to claim 1, characterized in that, The lower alignment assembly includes a lower CCD camera, a transmission-reflecting prism, a telecentric lens, and a reflecting prism. The transmission-reflecting prism is disposed between the lower CCD camera and the telecentric lens, and the reflecting prism is disposed on the telecentric lens.

3. The apparatus for measuring the alignment accuracy of the inner layer of an LDI according to claim 1, characterized in that, When the inner layer plate is exposed on the first and second sides, the alignment of the calibration target point is required. The alignment of the calibration target point means aligning the calibration target point with the position of the second camera and the lower alignment component. First, the rotation matrix of the second camera and the lower alignment component relative to the LDI exposure system coordinate system is determined. Then, the second camera and the lower alignment component read the same target point to obtain the coaxial position of the upper and lower cameras. Only when the second camera, the calibration target point and the lower alignment component are in a coaxial state can the laser expose the first and second sides of the inner layer plate. The second camera is driven by a servo motor that drives a synchronous pulley and belt, enabling the second camera to move along a linear slide rail to find calibration target points at different positions.

4. The apparatus for measuring the alignment accuracy of the inner layer of an LDI according to claim 1, characterized in that, The exposed inner layer plate is placed back on the suction cup stage, and the target point pattern position in the field of view is obtained by the second camera and the lower alignment component. The inner layer alignment error is obtained by comparing it with the preset positions of the first and second surfaces of the inner layer plate.

5. The apparatus for measuring the alignment accuracy of the inner layer of an LDI according to claim 1, characterized in that, The laser wavelengths are all in the ultraviolet band, and the illumination source used for the target light source is red light, green light, or infrared light.

6. The apparatus for measuring the alignment accuracy of the inner layer of an LDI according to claim 1, characterized in that, The XYZ moving stage includes an X-axis moving module, a Y-axis moving module, and a Z-axis moving module. The Y-axis moving module is controlled by the X-axis moving module to move in the X direction, and the Z-axis moving module is controlled by the Y-axis moving module to move in the Y direction. The Z-axis moving module controls the lifting and lowering of the entire suction cup platform. The X-axis moving module, Y-axis moving module, and Z-axis moving module each include a servo motor, a transmission lead screw, and a slide rail assembly. The X-axis moving module is connected to the Y-axis moving module via the slide rail assembly, and the Y-axis moving module is connected to the Z-axis moving module via the slide rail assembly.

7. A method for measuring the alignment accuracy of the inner layer of an LDI, characterized in that, Includes the following steps: 1) Confirm the rotation matrix R of the second camera and the lower alignment component relative to the coordinate system of the laser direct writing exposure system; The specific method is as follows: the second camera reads the position of the calibration target point, moves the calibration target point a distance within the field of view in the X direction, and then reads the position of the target point after the movement. The rotation matrix R is calculated based on the two target point positions; the angle between the line connecting the two target point positions and the x-axis of the second camera coordinate system is the rotation matrix angle. 2) The laser projects a circular spot with a diameter of 1~2mm, which is reflected by the transmission and reflection prism into the lower CCD camera for imaging. The circular spot is moved a distance within the field of view in the X direction, and the position of the circular spot after the movement is read. The rotation matrix P is calculated based on the positions of the two circular spots. 3) The second camera and the lower alignment component read the same target point on the calibration target point to obtain the coaxial position of the second camera and the lower CCD camera; 4) Expose the designed graphic on both sides of the inner layer board, and the graphic points on the first and second sides are theoretically concentric; 5) Place the etched inner layer board back onto the suction cup stage, and for each placement, use the second camera to confirm the rotation matrix S of the array pattern points on the inner layer board relative to the LDI exposure system coordinate system. 6) Finally, the second camera and the lower alignment component read multiple graphic points at the same position on the inner layer board. The distance deviations obtained are used to calculate the deviations in the X and Y directions using the rotation matrix S. Then, the average of multiple points is calculated to obtain the positional deviation (Δ) that can be used for inner layer alignment compensation. x , Δ y ).

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