A femtosecond laser processing method and apparatus for copper-zinc alloy circuit boards

Abstract

This invention proposes a femtosecond laser processing method and apparatus for copper-zinc alloy circuit boards, belonging to the field of circuit board laser processing technology, and solves the technical problem of structural integrity after laser processing of copper-zinc alloy circuit boards. The method includes: setting femtosecond laser parameters; setting the energy density received per unit area and the overlap rate of galvanometer scanning pulses; using the femtosecond laser to perform combined processing on the copper-zinc alloy circuit board to obtain the processed copper-zinc alloy circuit board; the combined processing includes contour preprocessing, cutting, and cleaning; contour preprocessing is performed using an energy-based edge-cleaning scanning method to expose the pure alloy substrate of the copper-zinc alloy circuit board; cutting is performed using an equal-shape, equal-position repeated cutting method to ensure geometric consistency of the cut edges; cleaning is performed using a low-energy edge-cleaning scanning method for shallow surface erasure and refinement to obtain the combined processed copper-zinc alloy circuit board. This invention is applicable to femtosecond laser processing of copper-zinc circuit boards.

Description

Technical Field

[0001] This invention belongs to the field of circuit board laser processing technology, specifically relating to the technical field of femtosecond laser processing of copper-zinc circuit boards. Background Technology

[0002] Copper-zinc alloys are widely used in the manufacture of electronic circuit boards due to their excellent electrical conductivity, corrosion resistance, and good machinability, especially in applications requiring high-frequency response and strong thermal stability. As microelectronic devices evolve towards higher density and miniaturization, traditional methods for processing resistive elements, such as etching, electroforming, or mechanical cutting, are no longer sufficient to meet the higher demands for dimensional accuracy, edge quality, and heat-affected zone control. Against this backdrop, ultrafast laser processing technology, particularly femtosecond lasers, has become a cutting-edge approach in precision micromachining due to its extremely short pulse width and extremely low heat-affected zone. Femtosecond lasers achieve a "cold working" effect when applied to material surfaces, significantly reducing edge melting and microcracks caused by thermal diffusion, making them particularly suitable for high-precision cutting and shaping of intricate circuit structures.

[0003] Currently, laser processing methods are used in some aspects of the manufacturing of microstructures for metal or alloy circuit boards. For example, nanosecond or picosecond lasers are used to cut the resistive region, and the conductive layer is locally removed to form resistance by controlling the laser energy. However, these methods still have a certain heat-affected zone, which can easily cause problems such as edge deformation of alloy materials, delamination, or unstable resistance values. In addition, existing technologies often fail to maintain the integrity of the overall circuit board structure after cutting, especially in flexible circuits or heterogeneous structures, where the structure may deform or detach after cutting.

[0004] Current processing methods for copper-zinc alloy circuit boards primarily rely on mechanical cutting and thermal laser cutting. While mechanical methods offer low processing costs and are suitable for large-size circuit segmentation, they suffer from significant drawbacks. For example, burrs and microcracks easily form at the cutting edges, negatively impacting the structural strength and electrical performance of the circuit board. Furthermore, they struggle to meet the demands of modern electronic manufacturing, which requires miniaturization and high-density wiring. Thermal laser processing, while highly automated and flexible, is based on thermal ablation, which readily creates a heat-affected zone (HAZ) in the copper-zinc alloy and its underlying substrate. This leads to surface melting and resolidification, altered microstructure, and even delamination and reduced dielectric strength. Moreover, due to the high reflectivity of copper-zinc alloys to infrared lasers, conventional laser sources suffer from low energy coupling efficiency, excessive edge ablation, or instability during processing. Summary of the Invention

[0005] In view of this, the present invention aims to provide a femtosecond laser processing method and apparatus for copper-zinc alloy circuit boards, so as to solve the technical problem of structural integrity after laser processing of copper-zinc alloy circuit boards.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention proposes a femtosecond laser processing method for copper-zinc alloy circuit boards, the method comprising:

[0008] S1. Set the femtosecond laser parameters;

[0009] S2. Based on the femtosecond laser parameters, set the energy density received per unit area and the overlap rate of the galvanometer scanning pulses;

[0010] S3. A femtosecond laser is used to assemble and process a copper-zinc alloy circuit board to obtain the processed copper-zinc alloy circuit board; the assembly and processing includes contour preprocessing, cutting and cleaning;

[0011] Contour preprocessing is performed using an energy-based edge-cleaning scanning method to expose the pure alloy substrate on the copper-zinc alloy circuit board.

[0012] Cutting is a process of repeated cutting with equal shape and position to cut a pure alloy matrix, so that the cut edges have geometric consistency.

[0013] Cleaning is performed using a low-energy edge-cleaning scanning method to perform shallow surface erasure and fine finishing, resulting in a copper-zinc alloy circuit board after assembly processing.

[0014] Furthermore, the femtosecond laser parameters include single-pulse energy. Pulse repetition frequency f, focused spot diameter Scanning speed And pulse width τ.

[0015] Furthermore, the energy density received per unit area as described in S2 is obtained using the single-pulse energy density expression, and this energy density is higher than the ablation threshold of the copper-zinc alloy.

[0016] The expression for the single-pulse energy density is: .

[0017] Furthermore, the galvanometer scanning pulse overlap rate mentioned in S2 is obtained using a pulse overlap rate expression, and the overlap rate ranges from 80% to 100%.

[0018] The expression for the pulse overlap rate is: .

[0019] Furthermore, the energy edge-cleaning scanning method described in S3 is as follows:

[0020] Based on the femtosecond laser parameters, the parameters set include single pulse energy, scanning speed, and pulse repetition frequency;

[0021] The surface of the copper-zinc alloy circuit board is scanned in a single loop along a preset scanning path to remove surface oxide, plating, and contaminants.

[0022] Furthermore, the isomorphic and iso-positional repeated cutting method described in S3 is as follows:

[0023] Based on the femtosecond laser parameters, the parameters set include the focused spot diameter, pulse repetition frequency, and scanning speed;

[0024] The linear energy density is calculated as follows: ;

[0025] It was determined that the single-pulse incident energy density corresponding to the single-pulse incident energy was higher than the ablation threshold of the copper-zinc alloy;

[0026] Pre-calibrated equivalent ablation coefficient The thickness of a single cut is calculated using an equivalent removal depth model;

[0027] The number of repeated cuts, the time interval between two adjacent cuts, and the laser power are set according to the thickness of the conductive layer of the pure alloy substrate.

[0028] Furthermore, the equivalent removal depth model is as follows: .

[0029] Furthermore, the low-energy edge-cleaning scanning method described in S3 is as follows:

[0030] Based on the femtosecond laser parameters, the parameters include single pulse energy, scanning speed, and pulse repetition frequency;

[0031] Adjust the linear energy density and scan along the preset scan path.

[0032] This invention also proposes a femtosecond laser processing device for copper-zinc alloy circuit boards, the device comprising:

[0033] Femtosecond laser 1 outputs a high peak power pulsed beam to beam expansion and collimation module 2;

[0034] The beam expanding and collimating module 2 adjusts the beam diameter and the incident angle into the dual-axis galvanometer scanning system 3;

[0035] The dual-axis galvanometer scanning system 3 controls the planar deflection path of the beam through a high-speed mirror and performs combined processing along a preset scanning path;

[0036] The focusing field lens 5 receives the beam deflected by the dual-axis galvanometer scanning system 3 and focuses the beam onto the copper-zinc alloy circuit board.

[0037] The industrial camera and recognition module 4 presets the scanning path and transmits the preset information to the three-axis motion platform 6 and the dual-axis galvanometer scanning system 3;

[0038] The three-axis motion platform 6 supports a copper-zinc alloy circuit board.

[0039] The industrial control system 7 is electrically connected to the femtosecond laser 1, the dual-axis galvanometer scanning system 3, the three-axis motion platform 6, and the industrial camera and recognition module 4, and transmits control information thereto.

[0040] Furthermore, the industrial control system 7 is equipped with a laser synchronization unit. The laser synchronization unit generates control information according to the preset scanning path to synchronously control the femtosecond laser 1, the dual-axis galvanometer scanning system 3, and the three-axis motion platform 6, so as to realize the combined processing of copper-zinc alloy circuit boards.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] Compared with existing nanosecond or picosecond laser processing technologies, the femtosecond laser processing method for copper-zinc alloy circuit boards described in this invention has significant advantages in terms of heat-affected zone control, processing accuracy, and edge quality. Because the duration of the femtosecond pulse is much shorter than the material's thermal diffusion time, the laser energy deposition process generates almost no thermal diffusion, enabling a "cold processing" mechanism that effectively avoids material melting, resolidification, and microstructure changes caused by traditional heat sources. The measured width of the heat-affected zone can be controlled within 2 μm, and the edge roughness can be reduced to Ra≤0.8 μm through low-energy edge clearing, significantly superior to existing processes.

[0043] Secondly, this invention employs a fixed-trajectory, repeated scanning strategy. By precisely controlling a single variable—energy density—it achieves stable layer-by-layer removal of the conductive layer and optimization of edge quality. Compared to the problems of dimensional fluctuations, contour shifts, and corner overburning that easily occur in traditional laser processing, this method, while maintaining constant trajectory, speed, and frequency, can achieve consistent thickness, stable kerf width (24±2μm), and clean edge morphology through energy control, significantly improving processing consistency and repeatability.

[0044] Furthermore, this invention, in conjunction with a bottom ceramic support structure, enables high-precision cutting of micron-level patterns without causing deformation or delamination, making it particularly suitable for the stable separation and processing of resistive regions in flexible circuits and heterogeneous multilayer structures. Simultaneously, the laser system possesses trajectory recognition, energy compensation, and multi-region path scheduling capabilities, supporting automatic switching of complex patterns and adaptive control of local parameters, offering higher structural adaptability and process controllability compared to traditional systems.

[0045] The device described in this invention introduces a layer of ceramic support material at the bottom of a copper-zinc alloy circuit board and combines it with femtosecond laser to achieve high-precision cutting, thereby accurately forming a single small-sized resistor unit without damaging the overall structure of the alloy. This solves the problems of large heat-affected zone and easy separation of structure in traditional processes, and is a novel, efficient and highly controllable method for manufacturing microstructure resistors.

[0046] The combined processing described in this invention employs a femtosecond laser, utilizing its pulse duration, which is significantly shorter than the material's thermal diffusion time. This avoids thermal diffusion during energy deposition, thereby reducing melting, resolidification, and microstructural changes in the material. The width of the heat-affected zone can be controlled within 2 μm. Before cutting, an energy-based edge-cleaning scan is performed on the surface of the copper-zinc alloy circuit board to remove oxide layers, plating, and contaminants, exposing the pure alloy substrate and stabilizing the laser-substrate interaction during subsequent cutting. During cutting, a repetitive, equilateral cutting method is used, performing multiple repetitive cuts along a predetermined trajectory. By setting the focused spot diameter, pulse repetition frequency, and scanning speed, the pulse overlap rate is maintained within the range of 80% to 100%, gradually penetrating the conductive layer and ensuring geometric consistency of the cut edge. The cut width is stabilized at 24 ± 2 μm. By pre-calibrating the equivalent ablation coefficient and using an equivalent removal depth model to determine the thickness of a single cut, the number of repetitions is set according to the conductive layer thickness, achieving controllable removal in the thickness direction. After cutting, a low-energy edge-cleaning scan is used for shallow surface erasing and finishing to further reduce edge roughness to Ra≤0.8 μm, achieving a clean cutting effect. To avoid energy accumulation at the beginning and end of the path, 50 μm introduction / exit segments are set on the outer side of the trajectory, and a 0.3 ms linear ramp is used to control the laser power, ensuring a smooth energy distribution during entry and exit from the cut and reducing overburning marks. The time interval between two adjacent repeated cuts on the same path is set to 8 ms, which is much longer than the plasma lifetime and thermal diffusion characteristic time, ensuring cold processing conditions in the time domain. A ceramic support structure is installed at the bottom of the circuit board to prevent deformation or delamination during cutting, ensuring the complete separation of the conductive layer. Through trajectory recognition, energy compensation, and multi-region path scheduling functions, automatic path switching and adaptive control of local parameters can be achieved under complex graphic conditions, improving processing consistency and process controllability.

[0047] This invention belongs to the field of circuit board laser processing technology and is applied to femtosecond laser processing of copper-zinc circuit boards. Attached Figure Description

[0048] Figure 1 This is a flowchart of a femtosecond laser processing method for a copper-zinc alloy circuit board according to Specific Implementation Method 1.

[0049] Figure 2This is a schematic diagram of a femtosecond laser processing device for a copper-zinc alloy circuit board in Specific Implementation Method 2. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0051] Specific implementation method one, such as Figure 1 As shown in this embodiment, a femtosecond laser processing method for copper-zinc alloy materials is described. The method includes:

[0052] S1. Set the femtosecond laser parameters;

[0053] S2. Based on the femtosecond laser parameters, set the energy density received per unit area and the overlap rate of the galvanometer scanning pulses;

[0054] S3. A femtosecond laser is used to assemble and process a copper-zinc alloy circuit board to obtain the processed copper-zinc alloy circuit board; the assembly and processing includes contour preprocessing, cutting and cleaning;

[0055] Contour preprocessing is performed using an energy-based edge-cleaning scanning method to expose the pure alloy substrate on the copper-zinc alloy circuit board.

[0056] Cutting is a process of repeated cutting with equal shape and position to cut a pure alloy matrix, so that the cut edges have geometric consistency.

[0057] Cleaning is performed using a low-energy edge-cleaning scanning method to perform shallow surface erasure and fine finishing, resulting in a copper-zinc alloy circuit board after assembly processing.

[0058] In this embodiment, the method begins with step one, in which the femtosecond laser parameters are set; the femtosecond laser parameters include single-pulse energy. Pulse repetition frequency f, focused spot diameter Scanning speed And pulse width τ.

[0059] To achieve high-precision non-thermal cutting of the conductive layer of copper-zinc alloy circuit boards, the processing relies on the precise setting of various parameters of the femtosecond laser. The configuration of laser parameters mainly involves the single-pulse energy. Pulse repetition frequency f, focused spot diameter Scanning speed And pulse width τ, etc. The basic principle is that by adjusting these parameters, the energy density received per unit area when the laser acts on the material surface can be increased. Capable of exceeding the ablation threshold of copper-zinc alloys This threshold has a certain range of values ​​in femtosecond laser processing, thus achieving material vaporization and ablation in an extremely short time. The expression for single-pulse energy density is:

[0060]

[0061] In actual settings, when E p When the energy density is 6 μJ and the d=22 μm, the obtained single-pulse energy density is approximately 0.789 J / cm². 2 This is far higher than the typical ablation threshold of 0.3 J / cm for copper-zinc alloys. 2 This ensures effective material ablation.

[0062] During galvanometer scanning, a high pulse overlap rate needs to be maintained to control the continuity and uniformity of the pattern edges. This is defined as:

[0063]

[0064] when , , At that time, the calculated overlap rate was approximately 83.6%, which meets the requirements for high-quality graphic contour forming.

[0065] The scanning strategy of this invention adopts a combined processing mode of "low-energy pretreatment loop + multi-loop progressive cutting + edge cleaning scanning". In this process, the femtosecond laser integrates sample pretreatment, cutting and cleaning into one device, which simplifies the production line and ensures the shape accuracy of the processed edge and the uniformity of internal material removal.

[0066] Contour pretreatment: Copper-zinc alloy surfaces typically contain copper oxide, zinc oxide, and residual organic matter. These impurity layers have low absorption rates for 1030 nm femtosecond lasers, and their uneven thickness leads to uneven energy deposition during subsequent cutting, resulting in irregular edge ablation or fluctuating cutting depth. Low-energy pretreatment scanning can achieve uniform ablation removal within the shallow surface layer, exposing a pure alloy matrix with a uniform grain structure.

[0067] Single pulse energy used during scanning =3.0μJ, corresponding to an energy density of 0.396J / cm2, and a scanning speed of v=1.5m / s, performing one single-circle scan along the designed contour. This step mainly removes the surface oxide layer, coating, and contaminants to stabilize the laser absorption rate for subsequent cutting.

[0068] Then proceed to step two, in which the energy density received per unit area and the overlap rate of the galvanometer scanning pulses are set based on the femtosecond laser parameters.

[0069] The energy density received per unit area in S2 is obtained using the single-pulse energy density expression, and this energy density is higher than the ablation threshold of the copper-zinc alloy.

[0070] The expression for the single-pulse energy density is: .

[0071] The overlap rate of the galvanometer scanning pulses in S2 is obtained using the pulse overlap rate expression, and the overlap rate ranges from 80% to 100%.

[0072] The expression for the pulse overlap rate is: ;

[0073] High-power repeated cutting along a predetermined path; without altering the established trajectory, multiple equal-shape and equal-position repeated cuts are performed along the same vector path (imported from DXF / G code) to gradually penetrate the copper-zinc alloy conductive layer and ensure the geometric consistency of the cut edges. During processing, the aforementioned spot diameter d = 22 μm, repetition frequency f = 300 kHz, and scanning speed v = 0.8 m / s are still used, with a linear energy density (energy deposited per unit length) of [missing value].

[0074] ;

[0075] When single pulse energy At 62μJ, J / m. The corresponding single-pulse incident energy density is higher than the ablation threshold range of copper-zinc alloys, enabling stable removal. To maintain the pulse overlap rate consistent with the previous description, the layout along the path direction is s=2.67μm. To quantify the penetration power of "fixed path, repeated cutting," an equivalent removal depth model corresponding to word repetition is given using the "logarithmic ablation law":

[0076] ;

[0077] in, This is the equivalent ablation coefficient obtained after calibration. Under the above parameters in this embodiment of the invention, it has been pre-calibrated. When the thickness of the conductive layer is 100 micrometers, the required number of repetitions is 10.

[0078] To avoid energy accumulation at the fixed start and end points of the path, "introduction / exit" idle runs and shutter gating are set at the beginning and end of the path: a 50-micron introduction / exit segment is reserved on the outer side of the geometric path, the shutter only opens after entering the design contour and closes before leaving, and the laser power uses a 0.3 ms linear ramp to suppress overburn marks at the beginning and end. For fixed paths with sharp angles or small radius corners, the trajectory geometry remains unchanged. To decouple from the heat accumulation caused by repeated cutting, the time interval between two adjacent repetitions on the same path is set to Δt = 8 ms, which is significantly greater than the plasma lifetime (in the μs order of magnitude) and thermal diffusion characteristic time (in the sub-millisecond order of magnitude) in metal fs processing, ensuring "cold processing" conditions in the time domain.

[0079] In terms of quality and efficiency metrics, the single-lap time for repeated cutting along a fixed path is... For a typical diagram with a 100*100mm outer contour and several inner contours, the total path length is 13.68m, and the single-loop repetition time is approximately 17.12s. When repeated 10 times, considering the time consumed by laser introduction and extraction, the total processing time is approximately 268s, meeting the batch processing cycle requirements. After the above window processing, the kerf width is maintained at 30±2μm, the edge roughness Ra<0.8μm, and the heat-affected zone width<2μm.

[0080] Then, step three is performed, in which a femtosecond laser is used to perform combined processing on the surface of the copper-zinc alloy; the combined processing includes contour preprocessing, cutting and cleaning;

[0081] Contour preprocessing is performed using an energy-based edge-cleaning scanning method to expose the pure alloy matrix of the copper-zinc alloy.

[0082] Cutting is a process of repeated cutting with equal shape and position to cut a pure alloy matrix, so that the cut edges have geometric consistency.

[0083] Cleaning is performed using a low-energy edge-cleaning scanning method to perform shallow surface erasing and fine finishing, resulting in copper-zinc alloy materials after combined processing.

[0084] The energy edge-clearing scan method in S3 is as follows:

[0085] Based on the femtosecond laser, the parameters include single pulse energy, scanning speed, and pulse repetition frequency;

[0086] The copper-zinc alloy surface is scanned in a single loop along a preset scanning path to remove surface oxides, plating, and contaminants.

[0087] The S3 equal-shape, equipotential, and repetitive cutting method is as follows:

[0088] Based on the femtosecond laser, the parameters set include the focused spot diameter, pulse repetition frequency, and scanning speed;

[0089] The calculated linear energy density is: ;

[0090] It was determined that the single-pulse incident energy density corresponding to the single-pulse incident energy was higher than the ablation threshold of the copper-zinc alloy;

[0091] Pre-calibrated equivalent ablation coefficient The thickness of a single cut is calculated using an equivalent removal depth model;

[0092] The number of repeated cuts, the time interval between two adjacent cuts, and the laser power are set according to the thickness of the conductive layer of the pure alloy substrate.

[0093] The equivalent removal depth model is as follows: .

[0094] The low-energy edge-cleaning scan method in S3 is as follows:

[0095] Based on the femtosecond laser parameters, the parameters include single pulse energy, scanning speed, and pulse repetition frequency;

[0096] Adjust the linear energy density and scan along the preset scan path.

[0097] Edge cleaning and spatter removal: To improve the quality of the cut contour edges and remove metal particles, spatter, and edge burrs formed during femtosecond laser processing, a low-energy edge cleaning scan is performed along a predetermined scanning path. This operation does not change the graphic contour trajectory; it only adjusts the laser energy density for shallow surface erasing and finishing. Specific parameters are as follows: =3.0μJ, scan speed 2m / s, pulse frequency 300kHz, repeated twice. The corresponding single-pulse energy density is 0.396J / cm2. This is slightly higher than the ablation threshold of sputtering particles such as copper oxide and zinc oxide, but lower than the ablation range of copper-zinc alloy substrate problems, thus achieving effective removal of surface sputtering particles without damaging the formed structure.

[0098] This method utilizes the ultrafast energy deposition characteristics of femtosecond lasers with extremely short pulse widths to achieve instantaneous vaporization and removal of materials before significant thermal diffusion occurs, realizing a "cold processing" mechanism. This significantly reduces the formation of heat-affected zones and ensures that the insulating layer is not thermally broken down. Simultaneously, femtosecond lasers possess excellent focusing capabilities and beam quality, enabling sub-micron precision pattern cutting, effectively meeting the forming requirements of complex circuit structures and miniature resistor structures. By optimizing process parameters such as pulse energy, repetition frequency, and scanning trajectory, as well as auxiliary substrate design, this invention achieves precise separation of circuit patterns and stable structural forming, improving overall processing quality and electrical performance consistency. It is suitable for mass production of precision electronic manufacturing, high-reliability communication devices, and small integrated modules.

[0099] This embodiment is suitable for achieving high-precision cutting and structural separation of conductive layer patterns, especially for processing complex pattern structures and micro-resistive regions without thermal damage. This embodiment uses a femtosecond laser as the processing light source, combined with a high-speed galvanometer scanning system to achieve two-dimensional trajectory control of the laser beam, thus achieving high-resolution and high-efficiency metal pattern cutting; a high-precision three-axis motion platform is used to complete initial alignment and automatic multi-region repositioning, ensuring overall processing accuracy and positioning consistency.

[0100] Specific Embodiment Two: The femtosecond laser processing device for copper-zinc alloy circuit boards described in this embodiment is prepared based on the method described in any one of the present invention, such as... Figure 2 As shown, the device includes:

[0101] Femtosecond laser 1 outputs a high peak power pulsed beam to beam expansion and collimation module 2;

[0102] The beam expanding and collimating module 2 adjusts the beam diameter and the incident angle into the dual-axis galvanometer scanning system 3;

[0103] The dual-axis galvanometer scanning system 3 controls the planar deflection path of the beam through a high-speed mirror and performs combined processing along a preset scanning path;

[0104] The focusing field lens 5 receives the beam deflected by the dual-axis galvanometer scanning system 3 and focuses the beam onto the copper-zinc alloy circuit board.

[0105] The industrial camera and recognition module 4 presets the scanning path and transmits the preset information to the three-axis motion platform 6 and the dual-axis galvanometer scanning system 3;

[0106] The three-axis motion platform 6 supports a copper-zinc alloy circuit board.

[0107] The industrial control system 7 is electrically connected to the femtosecond laser 1, the dual-axis galvanometer scanning system 3, the three-axis motion platform 6, and the industrial camera and recognition module 4, and transmits control information thereto.

[0108] Furthermore, the industrial control system 7 is equipped with a laser synchronization unit. The laser synchronization unit generates control information according to the preset scanning path to synchronously control the femtosecond laser 1, the dual-axis galvanometer scanning system 3, and the three-axis motion platform 6, so as to realize the combined processing of copper-zinc alloy circuit boards.

[0109] In this embodiment, the high peak power pulsed beam output from the femtosecond laser first passes through a beam expander and collimator system to improve the spatial energy density uniformity and optimize the incident angle entering the galvanometer. Subsequently, the laser beam is guided into a dual-axis galvanometer head, where its deflection path in the plane is controlled by high-speed mirrors in the X and Y directions. After being deflected by the galvanometer, the laser beam is focused onto the workpiece surface by an f-θ field mirror, forming a stable and constant spot diameter processing focal point, ensuring consistent focal plane planarity throughout the scanning area.

[0110] Before processing, the circuit board is moved to a set position by a three-axis motion platform, and precise positioning is achieved through image recognition or origin reset. After the platform is locked, the galvanometer system scans the processing trajectory according to the preset G-code path or vector graphic data such as DXF. The femtosecond laser injects picosecond-level energy onto the surface of the copper-zinc alloy layer, causing it to vaporize and peel off in an extremely short time. At the same time, because the processing cycle is much shorter than the heat diffusion time, the side effects such as melting, oxidation, and flash caused by traditional heat source processing are avoided. The system has programmable path scheduling, automatic recognition of multi-layer graphics, area recognition scanning, and continuous cutting of multiple graphics, and is suitable for the separation of various types of resistor structures, contact pads, and high-density metal graphics. Its control core realizes precise synchronous control of laser pulses and scanning trajectory through an industrial control computer or FPGA, ensuring clear processing boundaries, sharp contours, and good repeatability.

[0111] The copper-zinc alloy circuit board to be processed is fixed on the processing platform. After positioning is completed through image recognition or a preset program, the galvanometer scanning control system uses a femtosecond laser beam to scan the target area at high speed according to the set path. The laser pulse energy and frequency are precisely adjusted to cause the copper-zinc alloy layer to undergo non-thermal vaporization peeling within a femtosecond timescale without causing thermal breakdown or deformation to the underlying ceramic or resin insulating substrate. The galvanometer system has high-speed repeatable positioning and dynamic trajectory adjustment capabilities, adapting to continuous processing of multi-region and multi-pattern structures.

[0112] Furthermore, to ensure the integrity of the cut area during processing, a temporary support structure can be set on the bottom layer of the circuit board, or a cutting strategy that does not completely penetrate the surface can be used, allowing the target area to remain connected to the parent material after the femtosecond laser scan is completed, until final separation is achieved in the subsequent peeling process. By optimizing the scanning strategy (such as multiple contour scans, layered processing, etc.) and pulse energy modulation, this method can achieve micron-level pattern edge control and highly repeatable processing results, making it particularly suitable for applications such as high-density assembly of electronic components, chip resistor molding, and precision microstructure separation.

[0113] Specific implementation method three: This implementation method verifies the method of the present invention through experiments. The experiments adopt... , Femtosecond lasers, without altering the galvanometer scanning trajectory, frequency, or speed, achieve polarization by adjusting the energy density of a single pulse. High-quality cutting of thick copper-zinc alloy conductive layers. Actual measurements show that at a single pulse energy of... Under the condition that the scanning path is repeated 10 times, complete penetration can be achieved, and the kerf width is... Edge roughness Width of heat-affected zone The cross-section showed no weld edges, flash, or microcracks. Repeatability tests revealed contour errors. The cuts showed good consistency, and the finished structure was verified by reflow soldering and damp heat testing, proving that the method is stable and structurally complete, and is suitable for laser processing applications of high-precision electronic graphics.

[0114] Specific implementation method four: This implementation method is a computer, including a processor and a memory. The memory stores a computer program, and the processor executes the computer program to implement the method described in any one of the present invention when it runs.

[0115] Specific implementation method five: This implementation method is a storage medium that stores a computer program, which implements the method described in any one of the present invention when it is run.

[0116] Specific implementation method six: This implementation method is a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of any one of the methods described in this invention.

Claims

1. A femtosecond laser processing method for copper-zinc alloy circuit boards, characterized in that, The method includes: S1. Set the femtosecond laser parameters; S2. Based on the femtosecond laser parameters, set the energy density received per unit area and the overlap rate of the galvanometer scanning pulses; S3. A femtosecond laser is used to assemble and process a copper-zinc alloy circuit board to obtain the processed copper-zinc alloy circuit board; the assembly and processing includes contour preprocessing, cutting and cleaning; Contour preprocessing is performed using an energy-based edge-cleaning scanning method to expose the pure alloy substrate on the copper-zinc alloy circuit board. Cutting is a process of repeated cutting with equal shape and position to cut a pure alloy matrix, so that the cut edges have geometric consistency. Cleaning is performed using a low-energy edge-cleaning scanning method to perform shallow surface erasure and fine finishing, resulting in a copper-zinc alloy circuit board after assembly processing.

2. The femtosecond laser processing method for copper-zinc alloy circuit boards according to claim 1, characterized in that, The femtosecond laser parameters include single-pulse energy. Pulse repetition frequency f, focused spot diameter Scanning speed And pulse width τ.

3. The femtosecond laser processing method for copper-zinc alloy circuit boards according to claim 1, characterized in that, The energy density received per unit area as described in S2 is obtained using the single-pulse energy density expression, and this energy density is higher than the ablation threshold of copper-zinc alloy. The expression for the single-pulse energy density is: .

4. The femtosecond laser processing method for copper-zinc alloy circuit boards according to claim 1, characterized in that, The galvanometer scanning pulse overlap rate mentioned in S2 is obtained using the pulse overlap rate expression, and the overlap rate ranges from 80% to 100%. The expression for the pulse overlap rate is: .

5. The femtosecond laser processing method for copper-zinc alloy circuit boards according to claim 1, characterized in that, The energy edge-cleaning scanning method described in S3 is as follows: Based on the femtosecond laser parameters, the parameters set include single pulse energy, scanning speed, and pulse repetition frequency; The surface of the copper-zinc alloy circuit board is scanned in a single loop along a preset scanning path to remove surface oxide, plating, and contaminants.

6. The femtosecond laser processing method for copper-zinc alloy circuit boards according to claim 1, characterized in that, The isomorphic and iso-positional repeated cutting method described in S3 is as follows: Based on the femtosecond laser parameters, the parameters set include the focused spot diameter, pulse repetition frequency, and scanning speed; The linear energy density is calculated as follows: ; It was determined that the single-pulse incident energy density corresponding to the single-pulse incident energy was higher than the ablation threshold of the copper-zinc alloy; Pre-calibrated equivalent ablation coefficient The thickness of a single cut is calculated using an equivalent removal depth model; The number of repeated cuts, the time interval between two adjacent cuts, and the laser power are set according to the thickness of the conductive layer of the pure alloy substrate.

7. The femtosecond laser processing method for a copper-zinc alloy circuit board according to claim 6, characterized in that, The equivalent removal depth model is as follows: .

8. The femtosecond laser processing method for copper-zinc alloy circuit boards according to claim 1, characterized in that, The low-energy edge-cleaning scanning method described in S3 is as follows: Based on the femtosecond laser parameters, the parameters include single pulse energy, scanning speed, and pulse repetition frequency; Adjust the linear energy density and scan along the preset scan path.

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