Laser confined cleaning system and method for curved substrates

Abstract

The application belongs to the technical field of laser processing, and particularly relates to a curved surface substrate laser limited cleaning system and method. The system comprises a control system, a three-dimensional motion platform, a laser and a laser focusing unit, and a curved surface substrate with a metal pattern to be cleaned is fixed on the three-dimensional motion platform; further comprising a visual auxiliary positioning system for recognizing the spatial posture of the cleaning area and being electrically connected with the control system. The control system generates a CAD model and a cleaning path based on the recognition result, cooperatively controls the three-dimensional motion platform and the laser, and makes the laser incidence direction keep within the range of the normal line of the target point ±5°, so as to realize limited cleaning of the curved surface metal pattern. The application further establishes an intelligent reverse decision model of "performance deviation-adjustment amount-laser parameter", takes the deviation between the measured electromagnetic performance and the design target as the input, automatically solves the material removal amount and the laser parameter, and forms a closed-loop control of performance diagnosis and adjustment processing. The method has the advantages of high-precision positioning, normal line incidence control, curvature adaptive compensation and performance-oriented intelligent adjustment, and is suitable for high-precision, low-damage local metal removal of LTCC substrates and array microstrip lines.

Description

Technical Field

[0001] This invention belongs to the field of laser beam processing technology, and specifically relates to a laser confined cleaning system and method for curved substrates. Background Technology

[0002] With the continuous development of technologies such as high-frequency communication, radar systems, aerospace, and 5G millimeter-wave, low-temperature co-fired ceramic (LTCC) substrates and microstrip arrays have been widely used in RF / microwave devices, antenna arrays, and high-density modules due to their excellent dielectric properties, thermal stability, and 3D packaging integration capabilities. In these devices, the substrate surface is typically designed with metallic patterns such as gold, copper, or silver to achieve conductive interconnects, electromagnetic matching, and signal transmission functions. However, during device manufacturing, debugging, rework, or structural adjustment, it is often necessary to restrict and remove the metallic patterns in specific areas to meet the requirements of functional reconstruction, defect removal, or local circuit modification.

[0003] Currently, common methods for removing localized metal patterns include manual scribing, wet etching, and laser cleaning. However, these techniques have significant shortcomings in curved substrate scenarios. First, manual scribing heavily relies on the operator's experience, making it difficult to ensure consistency in removal positions and boundaries, resulting in low positioning accuracy and potential damage to the substrate. Second, wet etching relies on mask fabrication and chemical etching, making it difficult to adapt to changes in spatial curvature, leading to complex processes, over-etching, or incomplete cleaning. Third, traditional laser cleaning often uses nanosecond lasers for large-area planar scanning, making it difficult to achieve dynamic focusing and confined control on complex curved surfaces, easily causing edge melting, thermal diffusion, and substrate damage.

[0004] In summary, while existing metal pattern removal technologies are relatively mature for planar structures, they still struggle to meet the demands for high positioning accuracy, edge sharpness, and confined cleaning without thermal damage to the substrate, particularly for complex curved surfaces such as LTCC substrates and microstrip arrays with three-dimensional spatial curvature. Furthermore, existing technologies generally lack intelligent adjustment methods based on electrical performance feedback. The cleaning process is often disconnected from the target electrical properties, leading to discrepancies between the processing results and design specifications, making it difficult to achieve performance-driven precise adjustment and closed-loop optimization. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, the present invention aims to provide a laser confined cleaning system and method for curved substrates, which possesses high-precision spatial positioning capability, laser normal incident control and adaptive curvature compensation capability, and further realizes closed-loop intelligent adjustment based on electrical performance feedback.

[0006] The technical solution adopted in this invention is as follows:

[0007] A laser-confined cleaning system for curved substrates includes a control system and a three-dimensional motion platform electrically connected to the control system. A curved substrate with a metal pattern to be cleaned is fixed on the three-dimensional motion platform. The control system is electrically connected to a laser, and the laser output end is equipped with a laser focusing unit, which is positioned corresponding to the curved substrate. The system also includes a vision-assisted positioning system for recognizing the spatial posture of the metal pattern to be cleaned, which is electrically connected to the control system. The control system is further electrically connected to an intelligent reverse decision-making module, which receives the deviation between the measured electromagnetic properties of the curved substrate and the design target, automatically generates the corresponding material removal location, removal amount, and laser cleaning parameters, achieving closed-loop control from performance diagnosis to adjustment processing.

[0008] The control system first acquires the spatial posture (3D point cloud data of the surface) of the metal pattern to be cleaned through a vision recognition module, converts the spatial posture into a CAD model, and then generates a cleaning path using the CAD model. The control system dynamically adjusts the laser position on the curved substrate by controlling a 3D motion platform, thereby achieving precise removal of localized metal patterns on the surface of the curved substrate. It can perform confined processing on any specified area with high positioning accuracy and controllable cleaning range. This invention can dynamically adjust the laser incident angle and the angle of the 3D motion platform to ensure that the laser remains nearly perpendicular to the normal direction of the scanning position of the metal pattern to be cleaned, ensuring focusing accuracy and energy uniformity.

[0009] This invention introduces an intelligent reverse decision-making model based on performance deviation, adjustment amount, and laser parameters, which directly couples the cleaning process with the target electrical performance, achieving closed-loop optimization of performance feedback and process parameters, thereby significantly improving the consistency and efficiency of electrical performance adjustment.

[0010] As a preferred embodiment of the present invention, the laser focusing unit includes a reflector group and a scanning galvanometer system, and the laser emitted from the laser passes through the reflector group and the scanning galvanometer system in sequence before reaching the surface of the curved substrate.

[0011] In a preferred embodiment of the present invention, the laser is a femtosecond laser or a picosecond laser, and the pulse width of the laser is less than 10 ps. The present invention uses femtosecond / picosecond lasers, which can effectively suppress thermal diffusion, significantly outperforming nanosecond laser cleaning, resulting in a minimal laser heat-affected zone and excellent substrate protection.

[0012] In a preferred embodiment of the present invention, the laser emits a wavelength of 780nm or 1040nm, a laser pulse energy of 10–30μJ, a laser repetition frequency of 100kHz–1MHz, and an average laser power of 8–10W. The laser spot control is precise and the energy density is uniform, making it suitable for high-consistency batch processes.

[0013] In a preferred embodiment of the present invention, the metal pattern to be cleaned on the curved substrate is a gold-plated layer with a thickness of 0.5–5 μm, or a copper layer, silver layer, or copper-silver alloy layer with a thickness of 5–20 μm. The present invention is applicable to metal patterns such as gold, copper, and silver, and is compatible with different substrates such as LTCC, ceramics, and glass, meeting the needs of various high-end electronic packaging scenarios.

[0014] A laser-confined cleaning method for curved substrates includes the following steps:

[0015] S1: Fix the curved substrate with the metal pattern to be cleaned onto a three-dimensional motion platform;

[0016] S2: Identify the spatial pose of the target area through a vision-assisted positioning system, convert the spatial pose into a CAD model, and then generate a cleaning path through the CAD model;

[0017] S3: The control system controls the laser to start and controls the posture of the three-dimensional motion platform according to the cleaning path, so that the laser cleans the metal pattern to be cleaned along the cleaning path; dynamically adjusts the laser incident angle and the angle of the three-dimensional motion platform so that the laser incident direction is controlled within ±5° of the normal direction of the target point of the metal pattern.

[0018] S4: After laser cleaning is completed, the cleaning area is cleaned by gas blowing device and / or vacuum dust collection device to remove residue and perform surface treatment.

[0019] S5: Perform electromagnetic performance testing on the cleaned curved substrate, input the test results into the intelligent reverse decision module, automatically generate adjustment parameters based on performance deviation, and repeat steps S3 and S4 until the electrical performance meets the preset target.

[0020] As a preferred embodiment of the present invention, the following steps are also included:

[0021] S6: Clean the cleaning area for 5-10 minutes using an ultrasonic device.

[0022] As a preferred embodiment of the present invention, the following steps are also included:

[0023] S7: The processed area is evaluated using optical microscopy and laser confocal surface substrate morphology.

[0024] As a preferred embodiment of the present invention, in step S2, the cleaning path consists of contour-guided scanning and internal filling scanning, with an overlap rate of 70% to 90% between adjacent scan lines.

[0025] As a preferred embodiment of the present invention, in step S3, the laser scanning speed is 50-200 mm / s and the laser spot diameter is 10-30 μm.

[0026] The beneficial effects of this invention are as follows:

[0027] The control system of this invention first acquires the spatial posture of the metal pattern to be cleaned through a visual recognition module, converts the spatial posture into a CAD model, and then generates a cleaning path using the CAD model. The control system dynamically adjusts the laser position on the curved substrate by controlling a three-dimensional motion platform, thereby achieving precise removal of localized metal patterns on the surface of the curved substrate. It can perform confined processing on any specified area with high positioning accuracy and controllable cleaning range. This invention can dynamically adjust the laser incident angle and the angle of the three-dimensional motion platform to ensure that the laser remains nearly perpendicular to the normal direction of the scanning position of the metal pattern to be cleaned, ensuring focusing accuracy and energy uniformity. This invention introduces an intelligent reverse decision-making model of performance deviation, adjustment amount, and laser parameters, directly coupling the cleaning process with the target electrical performance, achieving closed-loop optimization of performance feedback and process parameters, thereby significantly improving the consistency and efficiency of electrical performance adjustment. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the present invention;

[0029] Figure 2 This is a schematic diagram of the curved substrate structure.

[0030] In the diagram: 1-Control system; 2-Laser; 3-Laser; 4-Reflector group; 5-Scanning galvanometer system; 6-Curved substrate; 7-Three-dimensional motion platform. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the invention can be combined with each other.

[0033] This invention is specifically designed for non-contact, non-thermally damaging removal of localized conductive metallic patterns in curved substrates, meeting the needs of fine-grained structural adjustments or fault repair in high-frequency microwave circuits, radio frequency devices, and antenna array modules. This invention is specifically designed for the localized removal of metallic patterns in low-temperature co-fired ceramics (LTCC) and microstrip array structures, and combines this with an intelligent reverse decision-making module to achieve closed-loop tuning driven by electrical performance.

[0034] like Figure 1 and Figure 2 As shown, the curved substrate laser confined cleaning system of this embodiment includes a control system 1 and a three-dimensional motion platform 7 electrically connected to the control system 1. The curved substrate 6 with the metal pattern to be cleaned is fixed on the three-dimensional motion platform 7. The control system 1 is electrically connected to a laser 2. The output end of the laser 2 is provided with a laser focusing unit, which is set corresponding to the curved substrate 6. It also includes a visual auxiliary positioning system for recognizing the spatial posture of the metal pattern to be cleaned. The visual auxiliary positioning system is electrically connected to the control system 1. And an intelligent reverse decision module is electrically connected to the control system 1. The intelligent reverse decision module is used to dynamically output adjustment parameters according to the electrical performance deviation.

[0035] The control system 1 of this invention first acquires the spatial posture of the metal pattern to be cleaned through a visual recognition module, converts the spatial posture into a CAD model, and then generates a cleaning path using the CAD model. The control system 1 dynamically adjusts the position of the laser 3 on the curved substrate 6 by controlling the three-dimensional motion platform 7, thereby achieving precise removal of localized metal patterns on the surface of the curved substrate 6. It can perform confined processing on any specified area with high positioning accuracy and controllable cleaning range. After cleaning, the system tests the electromagnetic properties of the curved substrate, and the test results are input into the intelligent reverse decision module. The module calculates the required removal amount and laser parameters, and drives the cleaning process again, achieving closed-loop control of performance feedback and process adjustment. This invention can dynamically adjust the incident angle of the laser 3 and the angle of the three-dimensional motion platform 7 to ensure that the laser 3 remains nearly perpendicular to the normal direction of the scanning position of the metal pattern to be cleaned, ensuring focusing accuracy and energy uniformity.

[0036] This invention is applicable to the thermal damage-free peeling of conductive patterns with a thickness of less than 5 μm, and has the ability to adaptively focus and fit synchronous paths for structures with different radii of curvature. It is one of the key processes for realizing the fine manufacturing and maintenance of millimeter-wave and high-frequency microwave modules.

[0037] Specifically, the laser focusing unit includes a mirror group 4 and a scanning galvanometer system 5. The mirror group 4 includes two mirrors. The laser beam 3 is reflected sequentially by the two mirrors to adjust the optical path direction, and then enters the scanning galvanometer system. The scanning galvanometer system 5 is used to dynamically deflect and precisely focus the laser beam 3, so that it accurately acts on the metal pattern area to be cleaned on the curved substrate 6.

[0038] The laser 2 is a femtosecond laser 2 or a picosecond laser 2, and the pulse width of the laser 2 is less than 10 ps. This invention uses a femtosecond / picosecond laser 3, which can effectively suppress heat diffusion and is significantly superior to nanosecond laser 3 cleaning. The heat-affected zone of the laser 3 is extremely small, resulting in good substrate protection.

[0039] The laser 2 emits laser light 3 with a wavelength of 780nm or 1040nm, the pulse energy of laser light 3 is set to 10-30μJ, the repetition frequency of laser light 3 is 100kHz-1MHz, and the average power of laser light 3 is 8-10W. The laser light spot is precisely controlled and the energy density is uniform, making it suitable for high-consistency batch processes.

[0040] The metal pattern to be cleaned on the curved substrate 6 is a gold-plated layer with a thickness of 0.5–5 μm, or a copper, silver, or copper-silver alloy layer with a thickness of 5–20 μm. This invention is applicable to metal patterns such as gold, copper, and silver, and is compatible with different substrates such as LTCC, ceramics, and glass, meeting the needs of various high-end electronic packaging scenarios.

[0041] The laser confined cleaning method for curved substrates in this embodiment includes the following steps:

[0042] S1: Fix the curved substrate 6 with the metal pattern to be cleaned onto the three-dimensional motion platform 7;

[0043] S2: Identify the spatial pose of the target area through a vision-assisted positioning system, convert the spatial pose into a CAD model, and then generate a cleaning path through the CAD model;

[0044] The cleaning path consists of contour-guided scanning and internal filling scanning, with an overlap rate of 70%–90% between adjacent scan lines.

[0045] S3: Control system 1 controls laser 2 to start, and control system 1 controls the posture of three-dimensional motion platform 7 according to the cleaning path, so that laser 3 cleans the metal pattern to be cleaned along the cleaning path; dynamically adjust the incident angle of laser 3 and the angle of three-dimensional motion platform 7 so that the incident direction of laser 3 is controlled within ±5° of the normal direction of the target point of the metal pattern.

[0046] The laser scanning speed is 50–200 mm / s, and the laser spot diameter is 10–30 μm.

[0047] S4: After completing laser cleaning, the cleaning area is cleaned by removing residue and surface treatment using a gas purging device and / or a vacuum dust collection device.

[0048] S5: Perform electromagnetic performance testing on the cleaned curved substrate 6, input the test results into the intelligent reverse decision module, generate adjustment parameters based on performance deviation, and repeat steps S3 and S4 until the electrical performance meets the preset target.

[0049] S6: Clean the cleaning area for 5-10 minutes using an ultrasonic device.

[0050] S7: The processing area is evaluated using an optical microscope and the morphology of the confocal curved substrate 6 using a laser 3.

[0051] Example:

[0052] The projected length of the curved substrate 6 is 200 μm; the thickness of the local metal pattern formed on the surface of the curved substrate 6 is approximately 2 μm, with a projected length of 200 μm. First, the complete surface coordinate data (spatial attitude) of the metal pattern to be cleaned is obtained through 3D structured light or laser 3D triangulation using a vision-assisted positioning system. Then, the spatial attitude is converted into a CAD model, and a cleaning path is generated from the CAD model. The cleaning system adopts a five-axis linkage mode, where XYZ is translationally compensated, and the rotation angle is achieved through the coordinated tilting of the 3D motion platform 7 and the laser 3D scanning deflection, ensuring that the laser 3D focusing direction is always controlled within ±5° of the target point's normal direction. After cleaning, the electromagnetic properties of the curved substrate are tested. If the S-parameters or resonant frequency deviate from the target value, the intelligent reverse decision module automatically calculates the material thickness to be removed and the laser parameters, driving the system to perform a second cleaning, achieving performance-driven iterative adjustment. During the cleaning process, the sampling frequency is 1 MHz, the unit energy density is controlled at 0.6 J / cm², and the removal depth is kept stable within the metal layer thickness range by superimposing three scanning paths, while the edge roughness Ra is controlled below 150 nm.

[0053] The laser confinement cleaning method for curved substrate 6 is as follows:

[0054] Step 1: Mount the curved substrate 6 to be cleaned on the three-dimensional motion platform 7. Adjust the three-dimensional plane to make the target cleaning area of ​​the metal pattern basically perpendicular to the incident direction of the laser 3. To adapt to the curvature of the curved substrate 6, an automatic focusing control module is introduced to adjust the Z-axis position of the focal point in real time to ensure effective focusing of the laser 3 on the curved substrate 6.

[0055] Step 2: The selected laser source is a femtosecond laser 2 (Yb-based fiber laser 2) with a pulse width <300 fs, a working wavelength of 1040 nm, a pulse repetition frequency of 500 kHz, a single pulse energy of 20 μJ, and an average output power not exceeding 10 W. The focusing system uses an f-theta field lens, with an output spot diameter of approximately 20 μm and a focal depth that meets the cleaning stability requirements within ±0.5 mm.

[0056] Step 3: Generate the cleaning path for the target graphic by importing the CAD drawing, and program the scanning strategy of contour priority + staggered fill in the system. Set the scanning speed to 100mm / s, the scan line overlap rate to 80%, and use a bidirectional scanning method to complete one complete peeling operation during the cleaning process.

[0057] Step 4: During the cleaning process, turn on the positive pressure nitrogen nozzle to cool the processing area and blow away metal particles. At the same time, start the air extraction port to remove molten debris to prevent it from redepositing in the processing area or causing secondary contamination. Ultrasonic cleaning for 5-10 minutes.

[0058] Step 5: Clean the area using an ultrasonic device for 5-10 minutes.

[0059] Step 6: After cleaning, the processed area was evaluated using an optical microscope and a laser 3-confocal microscopy system to assess the morphology of the metal pattern. The adjustment effect was confirmed by combining the results with electrical performance tests, verifying the effectiveness of the closed-loop optimization. The results showed that the metal pattern was completely removed, with clear, linear edges and no obvious burrs or remelting. No discoloration or thermal cracks occurred on the substrate surface, verifying the effectiveness and controllability of this process in high-precision, low-damage surface processing.

[0060] This invention is not limited to the above-described optional embodiments. Anyone can derive other various forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that falls within the scope of the claims of this invention shall be protected by this invention.

Claims

1. A laser-confined cleaning method for curved substrates, characterized in that: The curved substrate laser confined cleaning system includes a control system (1) and a three-dimensional motion platform (7) electrically connected to the control system (1). The curved substrate (6) with the metal pattern to be cleaned is fixed on the three-dimensional motion platform (7). The control system (1) is electrically connected to a laser (2). The output end of the laser (2) is provided with a laser focusing unit, which is set corresponding to the curved substrate (6). The system also includes a visual auxiliary positioning system for recognizing the spatial posture of the metal pattern to be cleaned. The visual auxiliary positioning system is electrically connected to the control system (1). The control system (1) is also electrically connected to an intelligent reverse decision module. The intelligent reverse decision module is used to receive the deviation between the measured electromagnetic performance of the curved substrate (6) and the design target, automatically generate the corresponding material removal position, removal amount and laser cleaning parameters, and output them to the control system (1) for closed-loop adjustment. Includes the following steps: S1: Fix the curved substrate (6) with the metal pattern to be cleaned onto the three-dimensional motion platform (7); S2: Identify the spatial pose of the target area through a vision-assisted positioning system, convert the spatial pose into a CAD model, and then generate a cleaning path through the CAD model; S3: The control system (1) controls the laser (2) to start. The control system (1) controls the posture of the three-dimensional motion platform (7) according to the cleaning path, so that the laser (3) cleans the metal pattern to be cleaned along the cleaning path. The incident angle of the laser (3) and the angle of the three-dimensional motion platform (7) are dynamically adjusted so that the incident direction of the laser (3) is controlled within ±5° of the normal direction of the target point of the metal pattern. S4: After completing the laser (3) cleaning, the cleaning area is cleaned by gas purging device and / or vacuum dust collection device to remove residue and perform surface treatment. S5: Perform electromagnetic performance testing on the cleaned curved substrate (6), input the results into the intelligent reverse decision module, automatically generate adjustment parameters based on performance deviation, and repeat steps S3 and S4 until the electrical performance meets the preset target.

2. The laser confined cleaning method for curved substrates according to claim 1, characterized in that: It also includes the following steps: S6: Clean the cleaning area for 5-10 minutes using an ultrasonic device.

3. The laser confined cleaning method for curved substrates according to claim 2, characterized in that: It also includes the following steps: S7: The processing area is evaluated by using an optical microscope and a laser (3) confocal curved substrate (6) morphology.

4. The laser confined cleaning method for curved substrates according to claim 1, characterized in that: In step S2, the cleaning path consists of contour-guided scanning and internal filling scanning, with an overlap rate of 70% to 90% between adjacent scan lines.

5. The laser confined cleaning method for curved substrates according to claim 1, characterized in that: In step S3, the laser (3) scanning speed is 50-200 mm / s, and the laser (3) spot diameter is 10-30 μm.

6. The laser confined cleaning method for curved substrates according to claim 1, characterized in that: The laser focusing unit includes a mirror group (4) and a scanning galvanometer system (5). The laser (3) emitted from the laser (2) passes through the mirror group (4) and the scanning galvanometer system (5) in sequence before reaching the surface of the curved substrate (6).

7. The laser confined cleaning method for curved substrates according to claim 1, characterized in that: The laser (2) is a femtosecond laser (2) or a picosecond laser (2), and the pulse width of the laser (2) is less than 10 ps.

8. The laser confined cleaning method for curved substrates according to claim 1, characterized in that: The laser (2) emits a laser (3) with a wavelength of 780nm or 1040nm, a laser (3) pulse energy of 10 to 30μJ, a laser (3) repetition frequency of 100kHz to 1MHz, and an average laser (3) power of 8 to 10W.

9. The laser confined cleaning method for curved substrates according to claim 1, characterized in that: The metal pattern to be cleaned on the curved substrate (6) is a gold plating layer with a thickness of 0.5 to 5 μm, or a copper layer, silver layer, or copper-silver alloy layer with a thickness of 5 to 20 μm.

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