Blind hole laser processing system and method

Abstract

The invention belongs to the field of laser drilling, and discloses a blind hole laser machining system and method.The blind hole laser machining system comprises a laser, a zoom beam expander, a dynamic zoom module and a scanning galvanometer; a zoom beam expander is arranged at an outlet of the laser, and the zoom beam expander is sequentially provided with a dynamic zoom module and a scanning galvanometer in the laser emission direction; wherein the dynamic zooming module is used for changing the divergence angle of a laser beam so as to adjust the focal length in real time, and a first laser beam and a second laser beam are emitted through the exit aperture of the scanning galvanometer. Through focusing and microsecond-level compensation of the dynamic focusing module on the laser focus, accurate focusing in a three-dimensional space is achieved, light spots are adjusted in real time, the problem that the light path of double lasers is unstable is solved, and the machining precision in the whole machining process is ensured.

Description

Technical Field

[0001] The invention relates to frequency doubling laser technology, and in particular to a blind hole laser processing system and method. Background Art

[0002] In the manufacturing of modern electronic devices, PCB (Printed Circuit Board) plays a vital role. As electronic devices develop towards miniaturization and integration, the requirements for the precision and complexity of PCB are getting higher and higher. In the manufacturing process of PCB, the processing of guide holes is a key link.

[0003] At present, the mainstream processing technology of guide holes is single laser processing, that is, processing the surface copper first, and then changing the z-axis height and laser energy to process the dielectric layer; the other is dual laser processing, that is, the first laser processes the surface copper, and the second laser processes the dielectric layer. At this time, the second laser has been adjusted to a defocused state, so there is no need to change the z-axis height. Dual laser processing of guide holes can save the mechanical z-axis lifting time, form holes in one go, and greatly improve the processing efficiency of guide holes.

[0004] However, there are some obvious shortcomings in the existing dual-laser processing of guide holes. First, the spatial combination of dual laser beams is difficult and requires precise debugging and control to ensure that the two laser beams can be accurately focused on the target position. This not only increases the complexity and cost of the equipment, but also places high technical requirements on the operator. Secondly, the dual-laser processing of guide holes is greatly affected by the mechanical vibration and mechanical stress of the equipment. During the processing, the mechanical vibration and stress of the equipment may cause the laser beam to deviate and become unstable, thereby affecting the processing accuracy and stability. Especially in PCB manufacturing with high precision and high stability requirements, these problems may lead to a decline in product quality or even fail to meet the use requirements. In addition, the cost of the dual-laser system is relatively high. Since two lasers and a complex optical system are required to achieve beam combination, the procurement and maintenance costs of the equipment are high.

[0005] Therefore, the existing dual-laser guide blind hole processing method is greatly affected by mechanical vibration and stress, and the high difficulty of spatial beam combining leads to laser beam deviation and instability. Technical problems affecting processing accuracy and stability need to be solved urgently. Summary of the invention

[0006] The main purpose of the present invention is to provide a blind hole laser processing system and method, aiming to solve the technical problems in the prior art that the dual laser guide blind hole processing method is greatly affected by mechanical vibration and stress, and the difficulty of spatial beam combining is high, resulting in laser beam deviation and instability, affecting the processing accuracy and stability.

[0007] In order to achieve the above-mentioned purpose of the invention, the first aspect of the present invention proposes a blind hole laser processing system, comprising: a laser, a variable power beam expander, a dynamic zoom module and a scanning galvanometer; a variable power beam expander is arranged at the outlet of the laser, and the variable power beam expander is sequentially arranged with a dynamic zoom module and a scanning galvanometer along the laser emission direction; wherein the dynamic zoom module is used to change the divergence angle of the laser beam, thereby adjusting the focal length in real time, and emitting the first laser beam and the second laser beam through the exit aperture of the scanning galvanometer.

[0008] Furthermore, the dynamic zoom module includes a concave lens and a mobile control vehicle group, and the mobile control vehicle is used to carry the concave lens to move along the laser emission direction.

[0009] Furthermore, the mobile control vehicle includes a motor, an optical bench and a Z-axis dynamic axis; the motor is drivingly connected to the Z-axis dynamic axis, the optical bench is movably connected to the Z-axis dynamic axis, the motor drives the Z-axis dynamic axis to move parallel to the laser emission direction, the concave lens is installed on the optical bench, and the movement of the Z-axis dynamic axis drives the optical bench and the concave lens installed thereon to move synchronously.

[0010] Furthermore, it includes a control system, which is communicatively connected with the motor and sends a driving instruction to the motor according to a calculation result of the control system; wherein the driving instruction includes a moving speed and a moving distance.

[0011] Furthermore, the scanning galvanometer includes an x-axis galvanometer 19 and a y-axis galvanometer 20, which are used to deflect the laser beam in a two-dimensional plane.

[0012] Furthermore, a pinhole aperture is provided between the dynamic zoom module and the scanning galvanometer for filtering stray light and concentrating the laser beam into the scanning galvanometer.

[0013] Furthermore, the incident aperture of the scanning galvanometer is perpendicular to the incident light beam 12, and the exit aperture is perpendicular to the exit light beam.

[0014] Furthermore, a telecentric field mirror is threadedly connected to the exit aperture of the scanning galvanometer to focus and flatten the laser beam after being deflected by the scanning galvanometer, so that the laser beam acts on the product to be processed with a preset shape and energy distribution.

[0015] In a second aspect of the present application, a blind hole laser processing method is proposed, comprising:

[0016] The first laser beam and the second laser beam are transmitted to the surface to be processed of the composite laminated material.

[0017] Using a first laser beam to perform window processing on the surface copper layer of the side to be processed of the composite laminated material to expose the material dielectric layer;

[0018] The second laser beam generated after adjustment by the dynamic zoom module is aimed at the position where the surface copper layer has been processed, and the dielectric layer in the window is punched or peeled and scanned until the bottom conductive material layer is exposed to form a blind hole.

[0019] Furthermore, the spot of the second laser beam is larger than the spot of the first laser beam, and the laser peak power density of the second laser beam is smaller than the laser peak power density of the first laser beam.

[0020] Beneficial effects:

[0021] This application changes the divergence angle of the laser beam through a dynamic zoom module, adjusts the focal length in real time, and thus accurately controls the action position and energy distribution of the laser beam on the material to be processed, significantly improving the accuracy of blind hole processing, generating the first laser beam and the second laser beam through rapid adjustment (microsecond level), and accurately transmitting them to the surface to be processed through a scanning galvanometer. Compared with traditional dual-laser processing, it reduces the time of mechanical movement and adjustment, simplifies the processing process, improves the reliability of the system, greatly reduces the processing time, and improves production efficiency. It can effectively remove the surface copper layer and process the dielectric layer to form high-quality blind holes, avoid unnecessary damage to the underlying conductive material, and ensure the stability of the processing quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of an embodiment of a blind hole laser processing system of the present invention;

[0023] Figure 2 It is a partial structural schematic diagram of an embodiment of a blind hole laser processing system of the present invention;

[0024] Among them: 1. Laser; 2. Variable magnification beam expander; 3. Dynamic zoom module; 4. Pinhole aperture 5. Scanning galvanometer; 6. Telecentric field mirror; 7. Focus beam; 8. Defocus beam; 9. Focus plane; 10. Defocus plane; 11. Concentric optical axis; 12. Incident beam 12; 13. Concave lens; 14. Motor; 15. Optical bench; 16. Z-axis dynamic axis; 17. Light beam after changing divergence angle; 19. X-axis galvanometer; 20. Y-axis galvanometer;

[0025] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0026] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0030] Reference Figure 1-Figure 2 The present invention proposes a blind hole laser processing system, comprising: a blind hole laser processing system is proposed, comprising: a laser 1, a variable power beam expander 2, a dynamic zoom module 3 and a scanning galvanometer 5; a variable power beam expander 2 is arranged at the exit of the laser 1, and the variable power beam expander 2 is sequentially arranged with a dynamic zoom module 3 and a scanning galvanometer 5 along the laser emission direction; wherein the dynamic zoom module 3 is used to change the divergence angle of the laser beam, thereby adjusting the focal length in real time, and emitting a first laser beam and a second laser beam through the exit aperture of the scanning galvanometer 5.

[0031] In this embodiment, the blind hole laser processing system is mainly used for blind hole processing of materials such as PCB. The laser beam generated by the laser 1 first passes through the variable magnification beam expander 2 to adjust the diameter and divergence angle of the laser beam. The variable magnification beam expander 2 can change the magnification of the laser beam as needed to meet different processing requirements. Then, the laser beam enters the dynamic zoom module 3, and the three-dimensional dynamic focus adjustment axis of the dynamic zoom module 3 is concentric with the optical axis direction, that is, the concentric axis 11. Based on the concentric axis 11, the Z-axis dynamic axis divergence lens can be adjusted relative to the focusing lens. The motor is driven to achieve dynamic and precise positioning on the optical axis, and the focus position of the laser beam under the field mirror can be adjusted. The module adjusts the focal length in real time by changing the divergence angle of the laser beam, thereby generating two laser beams one in front and one behind, namely the first laser beam and the second laser beam. The two laser beams are emitted through the exit aperture of the scanning galvanometer 5 and act on the material to be processed. At the same time, the optical axis of the entire system is the concentric optical axis 11, which ensures the transmission stability and accuracy of the laser beam.

[0032] In one embodiment, the dynamic zoom module 3 includes a concave lens 13 and a mobile control vehicle group, and the mobile control vehicle is used to carry the concave lens 13 to move along the laser emission direction.

[0033] In this embodiment, the concave lens 13 in the dynamic zoom module 3 is used to change the divergence angle of the laser beam, and the mobile control vehicle group carries the concave lens 13 and enables it to move along the laser emission direction. Specifically, the mobile control vehicle includes a motor 14, an optical bench 15 and a Z-axis dynamic axis 16. The motor 14 is drivingly connected to the Z-axis dynamic axis 16, and the optical bench 15 is movably connected to the Z-axis dynamic axis 16. An open connecting rod transmission is adopted, which helps to dissipate heat and reduce the possibility of jamming. The motor 14 drives the Z-axis dynamic axis 16 to move parallel to the laser emission direction. The concave lens 13 is installed on the optical bench 15. The movement of the Z-axis dynamic axis 16 drives the optical bench 15 and the concave lens 13 installed thereon to move synchronously. Among them, a high-precision position sensor calibration platform test is used to ensure that the linearity, temperature drift and resolution of the Z-axis dynamic axis 16 meet the preset standards, and the concave lens can be replaced with a beam expander lens, a focusing lens or other lenses according to different requirements for laser beam processing. Figure 2As shown, when the motor 14 drives the Z-axis dynamic axis 16 to move, the optical bench 15 moves accordingly, thereby driving the concave lens 13 to move along the laser emission direction, changing the divergence angle of the incident light beam 12, and then adjusting the focus of the laser beam. The concave lens 13 in the dynamic zoom module 3 moves along the laser emission direction under the coordinated action of the motor 14, the optical bench 15 and the Z-axis dynamic axis 16. When the concave lens 13 moves, the divergence angle of the incident light beam 12 will be changed, thereby affecting the focal position of the laser beam, thereby generating two laser beams one in front and one behind, namely, the first laser beam (positive focus beam 7) falling on the positive focal plane 9 and the second laser beam (defocused beam 8) falling on the defocused plane. These two laser beams are emitted through the exit aperture of the scanning galvanometer 5 and act on the material to be processed. Specifically, when the concave lens 13 moves along the laser emission direction, the divergence angle of the incident light beam 12 will be changed, thereby affecting the focal position of the laser beam. For example, when the concave lens 13 moves away from the laser 1, the divergence angle of the laser beam increases and the focal position moves backward; when the concave lens 13 moves toward the laser 1, the divergence angle of the laser beam decreases and the focal position moves forward. In this way, the focus of the laser beam can be adjusted in real time to meet the requirements for opening blind holes at different stages. The three-axis coordinated control between the xY axis of the scanning galvanometer 5 and the dynamic zoom module 3 is realized to achieve precise focusing in three-dimensional space, replace the mechanical defocusing of the galvanometer, reduce mechanical movement during processing, and improve processing efficiency.

[0034] In one embodiment, a control system is included, and the control system is in communication with the motor 14, and a driving instruction is sent to the motor 14 according to the calculation result of the control system; wherein the driving instruction includes a moving speed and a moving distance.

[0035] In this embodiment, the control system performs calculations based on the processing requirements and real-time feedback data, and then sends a driving instruction to the motor 14, including information such as the moving speed and moving distance, to accurately control the position of the concave lens 13, thereby achieving precise adjustment of the focus of the laser beam. For example, when it is necessary to process blind holes of different depths, the control system will calculate the distance and speed that the concave lens 13 needs to move, and send the corresponding driving instruction to the motor 14, so that the motor 14 drives the Z-axis dynamic axis 16 to drive the concave lens 13 to move to a suitable position, and receives the movement status of the concave lens in real time through the cooperative sensor, thereby changing the divergence angle of the laser beam and achieving focus adjustment; by dynamically collimating and expanding the laser output beam and modulating the focusing focal length, the precise focusing of the three-dimensional spatial coordinate point under the coordinated control of the xY galvanometer is achieved.

[0036] In one embodiment, the scanning galvanometer 5 includes an x-axis galvanometer 19 and a y-axis galvanometer 20, which are used to deflect the laser beam in a two-dimensional plane.

[0037] In this embodiment, the x-axis galvanometer 19 and the y-axis galvanometer 20 of the scanning galvanometer 5 work together to accurately deflect the laser beam in a two-dimensional plane so that the laser beam acts on the material to be processed according to a predetermined trajectory. Figure 1 As shown, the x-axis galvanometer 19 and the y-axis galvanometer 20 can achieve precise control of the laser beam in a two-dimensional plane by changing the deflection angle of the laser beam, thereby meeting the requirements for blind hole processing of different shapes and positions.

[0038] In one embodiment, a pinhole aperture 4 is provided between the dynamic zoom module 3 and the scanning galvanometer 5 for filtering stray light and concentrating the laser beam into the scanning galvanometer 5 .

[0039] In this embodiment, the pinhole aperture 4 is arranged between the dynamic zoom module 3 and the scanning galvanometer 5, which can effectively filter out stray light, ensure that the laser beam enters the scanning galvanometer 5 in a concentrated and stable manner, and improve the processing accuracy and stability. Figure 1 As shown, the pinhole aperture 4 can block the surrounding stray light, so that the laser beam adjusted by the dynamic zoom module 3 can pass through the aperture 4 and enter the scanning galvanometer 5 more concentratedly, thereby reducing the interference of stray light on the processing process.

[0040] In one embodiment, the incident aperture of the scanning galvanometer 5 is perpendicular to the incident light beam 12 , and the exit aperture is perpendicular to the exit light beam.

[0041] In this embodiment, this design ensures the normal transmission and deflection of the laser beam in the scanning galvanometer 5, reduces energy loss, and improves the utilization efficiency of the laser beam. Figure 1 As shown, when the laser beam enters the scanning galvanometer 5 from the incident hole, the laser beam can smoothly enter the interior of the galvanometer because the incident aperture is perpendicular to the incident light beam 12; when the laser beam is emitted from the exit aperture, the exit aperture is perpendicular to the exit light beam, ensuring that the laser beam can be emitted in a predetermined direction and accurately act on the material to be processed.

[0042] In one embodiment, the exit aperture of the scanning galvanometer 5 is threadedly connected to a telecentric field mirror 6 for focusing and smoothing the laser beam deflected by the scanning galvanometer 5 so that the laser beam acts on the product to be processed with a preset shape and energy distribution.

[0043] In this embodiment, the telecentric field mirror 6 is connected to the exit aperture of the scanning galvanometer 5 by means of a thread, and it can focus and flatten the laser beam after being deflected by the scanning galvanometer 5, so that the laser beam acts on the product to be processed with a more uniform and accurate energy distribution, thereby improving the processing quality. Figure 1As shown, the laser beam deflected by the scanning galvanometer 5 enters the telecentric field mirror 6, which focuses and flattens the laser beam so that the laser beam can act on the product to be processed with a preset shape and energy distribution, ensuring the processing accuracy and quality. Different telecentric field mirrors 6 have different focusing and flattening effects, and need to be selected according to specific processing requirements. At the same time, the threaded connection between the telecentric field mirror 6 and the exit aperture of the scanning galvanometer 5 needs to ensure a firm connection to avoid loosening during the processing process, which affects the processing accuracy.

[0044] In one embodiment, a blind hole laser processing method is also provided, comprising:

[0045] S1, transmitting the first laser beam and the second laser beam to the surface to be processed of the composite laminated material;

[0046] S2, using a first laser beam to perform window processing on the surface copper layer of the side to be processed of the composite laminated material to expose the material dielectric layer;

[0047] S3, aiming the second laser beam generated after adjustment by the dynamic zoom module 3 at the position where the surface copper layer has been processed, and performing punching or rotary cutting scanning on the dielectric layer in the window until the bottom conductive material layer is exposed to form a blind hole.

[0048] In this embodiment, the laser beam generated by the laser is adjusted by the variable magnification beam expander and the dynamic zoom module, and finally generates the first laser beam and the second laser beam through the scanning galvanometer. These two laser beams will be transmitted to the surface to be processed of the composite laminated material. When the first laser beam (positive focus beam 7) reaches the surface to be processed, its focus is located on the surface of the product, which can effectively remove the surface copper layer of the composite material and expose the dielectric layer in the middle. The energy density of the first laser beam is high, and the spot is relatively small, which is suitable for the processing of removing the surface copper layer. After the divergence angle is changed, the beam 17 is the second laser beam (defocused beam 8) adjusted by the dynamic zoom module 3. After microsecond zoom compensation, the spot size and energy density change, align with the position where the surface copper layer has been processed, and punch or peel the dielectric layer in the window until the conductive material layer on the bottom surface is exposed, thereby forming a blind hole. After the second laser beam (defocused beam 8) is compensated by microsecond zoom, the spot size and energy density change, mainly acting on the dielectric layer, and the dielectric layer can be effectively processed. For different types of composite laminated materials, the processing parameters need to be adjusted according to their characteristics. For example, for surface copper layers and dielectric layers of different thicknesses, the energy density, spot size, and processing time of the first and second laser beams need to be adjusted to ensure that the surface copper layer can be effectively removed and the dielectric layer can be processed to form high-quality blind holes.

[0049] In one embodiment, the spot of the second laser beam is larger than the spot of the first laser beam, and the laser peak power density of the second laser beam is smaller than the laser peak power density of the first laser beam.

[0050] In this embodiment, during the processing, the first laser beam (focused beam 7) is mainly used to remove the surface copper layer, which requires a higher energy density, so its spot is relatively small; while the second laser beam (defocused beam 8) mainly acts on the dielectric layer, in order to avoid damage to the underlying conductive material, its spot is larger and the laser peak power density is lower. Figure 1 As shown, the dielectric layer removal laser beam spot (the spot of the defocused beam 8), that is, the punching spot size or the spot rotary cutting scanning profile, is larger than the surface copper layer removal spot size (the spot of the positive focus beam 7); the laser peak power density of the dielectric layer removal laser beam spot is smaller than the laser peak power density of the surface copper layer removal. When the dielectric layer removal laser beam power density is less than the power destruction threshold of the processing layer, it is considered that the dielectric removal laser beam after compensation by the dynamic focusing module only acts on the dielectric layer. Such a design can ensure the accuracy and stability of the processing process and avoid unnecessary damage to the underlying conductive material during the processing.

[0051] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A blind hole laser processing system, characterized in that: include: A laser, a variable-power beam expander, a dynamic zoom module and a scanning galvanometer; a variable-power beam expander is arranged at the exit of the laser, and the variable-power beam expander is sequentially provided with a dynamic zoom module and a scanning galvanometer along the laser emission direction; wherein the dynamic zoom module is used to change the divergence angle of the laser beam, thereby adjusting the focal length in real time, and emitting the first laser beam and the second laser beam through the exit aperture of the scanning galvanometer.

2. The blind hole laser processing system according to claim 1, characterized in that: The dynamic zoom module includes a concave lens and a mobile control vehicle group, and the mobile control vehicle is used to carry the concave lens to move along the laser emission direction.

3. The blind hole laser processing system according to claim 2, characterized in that: The mobile control vehicle includes a motor, an optical bench and a Z-axis dynamic axis; the motor is drivingly connected to the Z-axis dynamic axis, the optical bench is movably connected to the Z-axis dynamic axis, the motor drives the Z-axis dynamic axis to move parallel to the laser emission direction, the concave lens is installed on the optical bench, and the movement of the Z-axis dynamic axis drives the optical bench and the concave lens installed thereon to move synchronously.

4. The blind hole laser processing system according to claim 3, characterized in that: It includes a control system, which is in communication with the motor and sends a driving instruction to the motor based on the calculation result of the control system; wherein the driving instruction includes a moving speed and a moving distance.

5. The blind hole laser processing system according to claim 1, characterized in that: The scanning galvanometer includes an x-axis galvanometer and a y-axis galvanometer, which are used to deflect the laser beam in a two-dimensional plane.

6. The blind hole laser processing system according to claim 2, characterized in that: A small aperture diaphragm is arranged between the dynamic zoom module and the scanning galvanometer to filter stray light and make the laser beam enter the scanning galvanometer in a concentrated manner.

7. The blind hole laser processing system according to claim 1, characterized in that: The incident aperture of the scanning galvanometer is perpendicular to the incident light beam 12 , and the exit aperture is perpendicular to the exit light beam.

8. The blind hole laser processing system according to claim 1, characterized in that: The exit aperture of the scanning galvanometer is threadedly connected to a telecentric field mirror for focusing and flattening the laser beam deflected by the scanning galvanometer, so that the laser beam acts on the product to be processed with a preset shape and energy distribution.

9. A blind hole laser processing method, characterized in that: include: The first laser beam and the second laser beam are transmitted to the surface to be processed of the composite laminated material. Using a first laser beam to perform window processing on the surface copper layer of the side to be processed of the composite laminated material to expose the material dielectric layer; The second laser beam generated after adjustment by the dynamic zoom module is aimed at the position where the surface copper layer has been processed, and the dielectric layer in the window is punched or peeled and scanned until the bottom conductive material layer is exposed to form a blind hole.

10. The blind hole laser processing method according to claim 9, characterized in that: The spot of the second laser beam is larger than the spot of the first laser beam, and the laser peak power density of the second laser beam is smaller than the laser peak power density of the first laser beam.

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