Laser micro-drilling machining device and method for metal foil lead frame

Abstract

The invention belongs to the technical field of precise laser machining, and particularly discloses a laser micro-drilling machining device and method for a metal foil lead frame, and the device comprises a machining platform, a clamp, a three-axis movement system, a scanning galvanometer and an ultraviolet nanosecond pulse laser; the clamp applies pretension force to the metal foil through a lead screw mechanism, and a laser displacement sensor is integrated to monitor thermal deformation in real time; the three-axis movement system and the scanning galvanometer cooperate to achieve three-dimensional accurate positioning, and in combination with the reflection system dynamically regulated and controlled by multiple reflectors, vertical incidence of laser is ensured. The method comprises the steps of clamping and focusing, image processing and path planning, multidirectional scanning processing and post-processing. Through optical-mechanical coupling multi-axis linkage control, the problems of thermal deformation suppression and micron-sized feature precision maintenance in large-format processing are solved, and the method has the advantages of high precision, environmental protection and high efficiency and is suitable for preparation of the ultrathin metal foil lead frame.

Description

Technical Field

[0001] The present invention relates to the technical field of precision laser processing, and particularly to a laser micro-drilling processing device and method for a metal foil lead frame. Background Art

[0002] The lead frame undertakes key functions of supporting chips, connecting circuits and dissipating heat inside integrated circuits, and is an important basic material indispensable in the electronic information industry. As a carrier of integrated circuit chips, the metal foil lead frame is usually processed with a large number of through-type micro-pattern arrays with micron-level feature sizes on a copper alloy foil with a thickness of only hundreds of microns or even dozens of microns. The size and accuracy of these micro-patterns play a decisive role in the quality and performance of semiconductor packaging.

[0003] At present, stamping and wet etching methods are commonly used to prepare metal foil lead frames. The stamping die has high cost and serious wear, and it is difficult to achieve high-precision processing of complex patterns; the pre-treatment of wet etching is complex, and it is difficult to precisely control the fluid flow during the processing, resulting in problems such as lateral erosion and uneven distribution of etching solution, which easily cause deformation of the metal foil substrate, and it is difficult to prepare an extremely thin metal foil lead frame. Moreover, the etching solution is corrosive and toxic, causing environmental pollution. With the increasing demand for miniaturized and multi-functional products, the requirements for the micro-pattern preparation technology of ultra-low thickness, high density, high precision, and complex integrated circuit metal foil lead frames are higher.

[0004] Laser micro-drilling, as a non-contact, high-precision, acid-free and cutting-fluid-free clean dry processing method, provides new ideas for the green processing and preparation of high-precision lead frame micro-patterns. However, there are still the following technical problems: First, there is a lack of a laser micro-drilling processing device for large-format metal foil lead frames. The processing area of the commonly used laser scanning galvanometer is limited, and the edges are prone to distortion or uneven energy; second, there is a lack of a method for suppressing the thermal deformation of metal foil laser micro-drilling processing. Thermal deformation will cause fluctuations in the focal position of the laser beam, making it difficult to maintain the consistency of the ablation depth; third, there is a lack of a method for maintaining the accuracy of local microscopic features of the lead frame. The stamping and wet etching methods limit the processing accuracy of micron-level key features. Summary of the Invention

[0005] The present invention aims to solve the above problems and proposes a device and method for laser micro-drilling a metal foil lead frame based on opto-mechanical coupling and multi-axis linkage to achieve efficient, environmentally friendly and high-precision processing of lead frames.

[0006] To achieve the above object, in one aspect, the present invention proposes a laser micro-drilling processing device for a metal foil lead frame, including:

[0007] A processing platform;

[0008] A fixture, which is arranged on the processing platform and is used for clamping both ends of the metal foil and applying a pre-tension force;

[0009] A three-axis motion system, including a Y-axis moving platform provided on the processing platform, an X-axis moving platform sliding on the Y-axis moving platform, a Z-axis moving platform sliding on the X-axis moving platform, and a multi-axis motion controller; the multi-axis motion controller synchronously controls a laser switch, laser parameters, and three-axis mechanical motion;

[0010] A scanning galvanometer, fixedly connected to the Z-axis moving platform, and realizing three-dimensional motion through the three-axis operation system;

[0011] An ultraviolet nanosecond pulse laser, fixedly connected to the processing platform, and vertically transmitting the laser to the light inlet of the scanning galvanometer through a reflection system.

[0012] The above structure aims to propose a device for laser micro-drilling of metal foil lead frames based on optical-mechanical coupling and multi-axis linkage. Through the coordinated cooperation of the three-axis operation system and the scanning galvanometer, three-dimensional precise positioning of the laser focusing spot is realized to meet the processing requirements of micron-level lead frames. The multi-axis motion controller synchronously regulates laser parameters (power, frequency) and mechanical motion, reduces processing errors, ensures the dimensional consistency of complex micro-patterns, and realizes non-contact processing through the ultraviolet nanosecond pulse laser to replace wet etching, avoid chemical pollution, and improve the environmental protection of processing.

[0013] Optionally, the device further includes a laser displacement sensor provided in the fixture for real-time monitoring of the thermal deformation of the metal foil. By real-time monitoring the deformation amount of the metal foil, the pre-tension of the fixture or laser parameters are dynamically adjusted to effectively suppress the focus drift caused by thermal accumulation and ensure the flatness of the processing surface.

[0014] Optionally, the fixture includes:

[0015] A clamp base, which is a U-shaped structure with an upward opening, including a bottom plate and two vertical plates;

[0016] Two guide posts, horizontally installed between the two vertical plates;

[0017] A lead screw, with both ends rotatably connected to the vertical plates, and one end connected with a lead screw knob;

[0018] A slider, slidably sleeved on the two guide posts, and threadedly engaged with the lead screw;

[0019] A first pressing block and a second pressing block, respectively movably connected to the slider and one side vertical plate through adjusting knobs, for forming a pressing clamp from both ends of the metal foil.

[0020] Through the cooperation of the lead screw, slider, and pressing block, fine adjustment of the pressing gap is realized to ensure uniform stress on the metal foil and avoid clamping deformation; and the pre-tension is manually or automatically adjusted through the lead screw knob to adapt to metal foils of different thicknesses.

[0021] Optionally, the reflection system includes multiple mirrors, and the laser is vertically incident through dynamic optical path regulation. The multiple mirrors adjust the optical path angle in real time, reduce the angle deviation error, ensure that the laser is always vertically incident on the galvanometer, eliminate the beam skew caused by mechanical movement, and the multi-mirror beam splitting design reduces the single-mirror load and extends the service life of the optical elements.

[0022] Optionally, the reflection system includes a first mirror, a second mirror, a third mirror, a fourth mirror, and a fifth mirror, and the positions and angles of the mirrors are adjustable. Each mirror is independently adjustable (angle / position) to adapt to the optical path requirements of different processing areas and improve the flexibility of the optical path; the fifth mirror serves as a backup optical path node to enhance the fault tolerance of the system.

[0023] Optionally, the first mirror and the second mirror are respectively fixed on the same fixed column through adjustable clamps. The fixed column is fixed on the processing platform, and the first mirror and the second mirror are equipped with self-rotation mechanisms. The fixed column provides a stable installation reference and reduces the influence of vibration on the optical path. The self-rotation mechanism cooperates with the clamp to achieve rapid calibration of the mirror and simplify the optical path debugging process.

[0024] Optionally, the third mirror is fixed at the top of a vertically arranged telescopic rod one, and the bottom of the telescopic rod one is fixed on a connecting plate one. The connecting plate one is fixedly connected to the X-axis moving platform, and the position in the height direction is finely adjusted through the telescopic rod one. The telescopic rod one finely adjusts the height of the third mirror to compensate for the focus offset during Z-axis movement and keep the laser vertically incident.

[0025] Optionally, the fourth mirror is connected to a connecting plate two through a horizontally arranged telescopic rod two. The connecting plate two is fixedly connected to the Z-axis moving platform, and the position in the Y-axis direction is finely adjusted through the telescopic rod two. The horizontal telescopic rod two finely adjusts the position of the fourth mirror to eliminate the optical path deviation caused by Y-axis movement; it is linked with the Z-axis platform to achieve multi-axis optical path collaborative compensation and improve the accuracy of the processing edge area.

[0026] On the other hand, the present invention also proposes a laser micro-drilling processing method for a metal foil lead frame, using the laser micro-drilling processing device for a metal foil lead frame according to any one of the above embodiments. The method includes the following steps:

[0027] S1. Clamping and focusing: Clamp the metal foil through a fixture and apply a pre-tension force, and adjust the three-axis motion system to focus the laser on the surface of the metal foil;

[0028] S2. Image Processing and Path Planning: Convert the design drawing of the lead frame into a binary pixel grayscale image, where the pixel value "1" represents the non-processing area and the pixel value "0" represents the micro-pattern area to be processed; traverse the grayscale image horizontally and vertically at a scanning interval of 4 μm, extract the coordinates where the pixel value changes from "1" to "0" as the laser turn-on signal, and the coordinates where the pixel value changes from "0" to "1" as the laser turn-off signal, and generate a laser switch instruction sequence.

[0029] S3. Multi-directional Scanning Machining: Set the laser power, frequency, scanning speed, and number of repeated scans. First, perform a 0° direction scan, and then perform an orthogonal scan in the 90° direction to eliminate the shape error caused by one-way scanning; during the scanning process, by controlling the laser switch, the deflection of the scanning galvanometer, and the three-axis motion system, high-precision micro-pattern machining is achieved.

[0030] S4. Post-processing: Immerse the processed metal foil in a 15% hydrochloric acid solution for ultrasonic cleaning to remove the surface slag and oxide layer. After pickling, rinse with pure water and dry, and finally perform electroplating.

[0031] Further, the ultrasonic cleaning parameters are a frequency of 20 kHz and a duration of 500 s. After pickling, the metal foil is dried by an air pump.

[0032] Compared with the prior art, the present invention discloses at least the following beneficial effects:

[0033] The present invention innovatively mounts a two-dimensional laser scanning galvanometer on a three-axis mechanical platform skillfully. With the help of a multi-axis motion controller, strong coupling between the mechanical system and the laser system is achieved. This coupling method enables the two to work together and give full play to their respective advantages. At the same time, through a carefully designed reflection system, dynamic following and precise regulation of the light path are realized, ensuring that the laser can always accurately act on the processing area, providing a strong guarantee for high-precision machining.

[0034] Further, during the processing, the deformation of the metal foil is an issue that cannot be ignored. To solve this problem, the present invention introduces a laser displacement sensor and cooperates with a special fixture. The laser displacement sensor can monitor the deformation of the metal foil during the processing in real time, and the special fixture can be adjusted in a timely manner according to the monitoring data, thereby effectively suppressing the deformation of the metal foil and ensuring the stability of the processing quality.

[0035] In summary, the device of the present invention has a compact structure, is convenient for installation and maintenance; operates stably and can work continuously for a long time without failure; has high processing accuracy and can meet the strict requirements for accuracy in lead frame manufacturing. At the same time, the device and method of the present invention also have significant cost-effectiveness, reducing production costs; are easy to operate, easy to master and use; have excellent processing efficiency and can greatly improve production efficiency; have excellent control performance and can achieve precise control of the processing process. Brief Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0037] Figure 1 It is a schematic structural diagram of the processing device of the present invention;

[0038] Figure 2 It is a schematic structure diagram of the part above the processing platform in the processing device of the present invention Figure 1 ;

[0039] Figure 3 It is a schematic structure diagram of the part above the processing platform in the processing device of the present invention Figure 2 ;

[0040] Figure 4 It is a schematic structural diagram of the fixture in the processing device of the present invention;

[0041] Figure 5 It is a laser light path transmission path diagram of the processing device of the present invention;

[0042] Figure 6 It is a schematic diagram of the method for ensuring the accuracy of local features in the processing method of the present invention;

[0043] Figure 7 It is a flowchart of the processing method of the present invention;

[0044] In the figure: 1, vibration isolation base; 2, processing platform; 3, Y-axis moving platform; 4, X-axis moving platform; 5, Z-axis moving platform; 6, cylinder; 7, ultraviolet nanosecond pulsed laser; 8, reflection system; 801, first reflector; 802, second reflector; 803, third reflector; 804, fourth reflector; 805, fifth reflector; 9, scanning galvanometer; 10, fixture; 101, clamp seat; 102, guide post; 103, lead screw; 104, lead screw knob; 105, slider; 106, pressing block one; 107, adjusting knob one; 108, pressing block two; 109, adjusting knob two; 11, laser displacement sensor; 12, fixed column; 13, connecting plate one; 14, telescopic rod one; 15, connecting plate two; 16, telescopic rod two. Detailed Embodiments

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0046] With the rapid development of electronic information products towards miniaturization and multi-functionality, the market has put forward higher requirements for the preparation technology of integrated circuit metal foil lead frames. Specifically, it is necessary to prepare metal foil lead frame micro-patterns with ultra-low thickness, high density, high precision, and complex shapes to meet the growing demand for high-performance integrated circuit packaging.

[0047] Laser micro-drilling, as a non-contact, high-precision, acid-free, and cutting-fluid-free clean dry processing method, has significant advantages. Among them, nanosecond laser micro-drilling realizes the evaporation and removal of materials through the interaction between high-energy laser beams and materials, utilizing the photothermal effect, and has been widely used in the processing of metal foil micro-patterns, providing new ideas for the green processing and preparation of high-precision lead frame micro-patterns. However, at present, the research on laser micro-drilling of copper alloy foil lead frames is relatively less, and there are still many technical challenges in practical applications. However, the existing technologies lack large-format processing capabilities and processing equipment and methods for effectively suppressing thermal deformation.

[0048] Therefore, there is an urgent need to develop a device and method that can not only retain the high precision of laser scanning galvanometer processing but also break through the processing area limitation, realizing the high-precision laser micro-drilling preparation of large-format metal foil lead frames and meeting the processing requirements of ultra-low thickness, high density, high precision, and complex micro-patterns.

[0049] For this reason, the embodiments of the present invention propose a laser micro-drilling processing device and method for metal foil lead frames. By converting the lead frame design drawing into a pixel point grayscale image and performing binary processing, traversing the entire pixel point image according to the set scanning spacing, and extracting the coordinates of the points with numerical changes as the basis for laser on / off, the high-quality processing of local microscopic features is ensured, and the overall service performance of the lead frame is improved.

[0050] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Refer to Figures 1 to 5 As shown, the present invention provides a laser micro-drilling processing device for a metal foil lead frame, including a vibration isolation base 1, a processing platform 2, a three-axis motion system, an ultraviolet nanosecond pulsed laser 7, a reflection system 8, a scanning galvanometer 9, a fixture 10, and a control system.

[0052] Specifically, the vibration isolation base 1 is supported at the bottom of the processing platform 2. The vibration isolation base 1 is made of high-damping alloy material, and the processing platform 2 is made of granite with a flatness ≤ 0.005 mm / m. 2 , and is fixed on the vibration isolation base 1 through anchor bolts to form a rigid support. A polyurethane buffer gasket is arranged between the two to further attenuate high-frequency vibration. This combination can ensure that the vibration amplitude of the platform during the laser processing is < 0.1 μm, providing a stable reference for high-precision processing.

[0053] In a specific embodiment, an air-bearing vibration isolation module is integrated inside the vibration isolation base 1, which can eliminate external vibrations with a frequency ≥ 5 Hz.

[0054] Specifically, as Figures 1 to 3 shown, the three-axis motion system includes a Y-axis moving platform 3 arranged on the processing platform 2, an X-axis moving platform 4 sliding on the Y-axis moving platform 3, a Z-axis moving platform 5 sliding on the X-axis moving platform 4, and a multi-axis motion controller for controlling the motion of each moving platform.

[0055] In a specific embodiment, the Y-axis moving platform 3 is fixed on the processing platform 2 and can stably drive the scanning galvanometer 9 to move in the Y direction. The Y-axis moving platform 3 is driven by dual linear motors and is equipped with a high-precision grating scale (resolution 0.1 μm), with a maximum moving speed of 500 mm / s and a repeat positioning accuracy of ±0.5 μm. It is fixed on the processing platform 2 through a rigid connection and bears the X-axis moving platform 4 and subsequent components.

[0056] In a specific embodiment, the X-axis moving platform 4 is linearly movably connected to the Y-axis moving platform 3 and can stably drive the scanning galvanometer 9 to move in the X direction. The X-axis moving platform 4 has a crossed roller guide structure and is linked with the Y-axis platform through a servo motor to achieve a processing area of 600 × 600 mm. 2 It is equipped with a gravity balance mechanism to eliminate the track wear caused by uneven load.

[0057] In a specific embodiment, the Z-axis moving platform 5 is installed on the X-axis moving platform 4 and can stably drive the scanning galvanometer 9 to move in the Z direction. The cylinder 6 is installed on the Z-axis moving platform 5 and can balance the load gravity on the Z axis, improving the motion accuracy of the Z axis. The Z-axis moving platform 5 uses a ball screw with closed-loop control to achieve a focusing position adjustment accuracy of ±1 μm. The scanning galvanometer 9 is installed on the Z-axis moving platform 5 and is driven by the Z-axis moving platform 5 to achieve the laser beam focusing function, ensuring that the laser focusing spot always remains on the processing surface.

[0058] Specifically, the ultraviolet nanosecond pulse laser 7 is installed on the processing platform 2, and the laser is always vertically incident into the light inlet of the scanning galvanometer 9 through the reflection system 8. In a specific embodiment, the ultraviolet nanosecond pulse laser 7 can adopt a laser emission device with the following parameters: output wavelength 355 nm, pulse energy 2 mJ, and the repetition frequency is adjustable from 1 to 100 kHz. The ultraviolet nanosecond pulse laser 7 is coupled to the reflection system 8 through an optical fiber, and the ultraviolet nanosecond pulse laser 7 and the reflection system 8 cooperate to form a laser optical path system.

[0059] Specifically, the reflection system 8 includes a first reflecting mirror 801, a second reflecting mirror 802, a third reflecting mirror 803, a fourth reflecting mirror 804 and a fifth reflecting mirror 805. Each reflecting mirror is equipped with a multi-angle adjustment mechanism to achieve adjustable position and angle. The optical path design adopts the dynamic compensation principle: the first reflecting mirror 801 is fixed on the processing platform 2, and the second to fifth reflecting mirrors 805 move with the three-axis motion system and adjust the angle in real time to ensure that the laser is always vertically incident into the light inlet of the scanning galvanometer 9, and the optical path angle offset error < 5 μrad.

[0060] In a specific embodiment, the first reflecting mirror 801 and the second reflecting mirror 802 are fixedly installed on a fixed column 12, and the fixed column 12 is fixedly installed on the processing platform 2 through bolts, providing a stable installation foundation for the first reflecting mirror 801 and the second reflecting mirror 802. The height and position of the fixed column 12 are precisely adjusted according to the design requirements of the laser optical path to ensure that the reflecting mirror can accurately guide the laser beam to the light inlet of the scanning galvanometer 9. To realize the adjustment of the angles of the first reflecting mirror 801 and the second reflecting mirror 802, the first reflecting mirror 801 and the second reflecting mirror 802 are equipped with self-rotation mechanisms, and at the same time, they are fixed on the fixed column 12 through adjustable clamps, and can be adjusted by 360 degrees around the fixed column 12 when needed, and can be adjusted arbitrarily in the up and down positions.

[0061] In a specific embodiment, the third reflecting mirror 803 is fixed at the top of the first telescopic rod 14. The first telescopic rod 14 is vertically arranged, and its bottom end is fixedly installed on the first connecting plate 13. The first connecting plate 13 is fixedly connected to the X-axis moving platform 4 and can linearly move in the Y-axis direction along with the X-axis moving platform 4. The first telescopic rod 14 can be adjusted arbitrarily in the height direction. The design of the first connecting plate 13 and the first telescopic rod 14 takes into account the layout of the laser optical path and the adjustment requirements of the reflecting mirror, and can provide sufficient space and flexibility for precise angle and position adjustment of the reflecting mirror.

[0062] In a specific embodiment, the fourth mirror 804 is fixed in a similar manner to the third mirror 803. It is connected to the second connecting plate 15 through a horizontal second telescopic rod 16. The second connecting plate 15 is fixedly connected to the Z-axis moving platform 5 and can linearly move in the X-axis direction along with the Z-axis moving platform 5. The second telescopic rod 16 can be telescopically adjusted in the horizontal direction (Y-axis direction).

[0063] In the above structure, the first telescopic rod 14 and the second telescopic rod 16 are used to finely adjust the position of the mirror, and the front and back positions of the mirror are adjusted through telescopic actions. This design allows for dynamic adjustment of the laser optical path during the processing to compensate for the optical path offset caused by mechanical movement or environmental changes. The telescopic range and accuracy of the telescopic rod are designed according to the requirements of laser processing to ensure that the laser beam can always accurately focus on the processing area. Through the above structural design and adjustment method, the reflection system 8 can achieve dynamic following and precise control of the laser optical path, ensuring that the laser always vertically enters the light inlet of the scanning galvanometer 9, thus providing a strong guarantee for high-precision processing.

[0064] Specifically, the scanning galvanometer 9 is installed on the Z-axis moving platform 5 and is driven by the Z-axis moving platform 5 to achieve the function of laser beam focusing, ensuring that the laser focused spot always remains on the processing surface.

[0065] In a specific embodiment, the scanning galvanometer 9 uses a high-speed galvanometer motor (deflection speed ≥ 2 m / s) combined with an f-θ lens, and the focused spot diameter is 5 - 10 μm (adjustable). It is rigidly connected to the Z-axis moving platform 5 through an aviation plug, and heat dissipation fins are provided on the galvanometer base, with a temperature control accuracy of ±0.5 °C. Its working principle is: receiving the instructions of the multi-axis motion controller, and cooperating with the movement of the X-axis moving platform 4 and the Y-axis moving platform 3 to achieve a composite processing mode of "galvanometer local processing + mechanical platform large-area splicing", reducing processing errors.

[0066] Specifically, the control system is equipped with an image processing module, and the image processing module includes a host computer and a slave computer. The host computer is used to convert the CAD drawing into a binary grayscale image (4 μm / pixel) and generate a laser switch instruction sequence. The slave computer synchronously coordinates the three-axis motion (500 Hz refresh rate), laser parameters (pulse synchronization error < 10 ns), and galvanometer deflection through an FPGA controller to achieve 0° / 90° two-way scanning path filling. The PID-feedforward composite control algorithm is adopted, and the position tracking error < 0.3 μm.

[0067] In a specific embodiment, as Figure 4As shown in the figure, the fixture 10 is mainly composed of a clamping seat 101, guide columns 102, a lead screw 103, a slider 105, a pressing block, an adjusting knob and other components. The clamping seat 101 has a U-shaped structure with an upward opening, including a bottom plate and two vertical plates fixedly connected to the bottom plate, forming a stable support frame. Two guide columns 102 are horizontally installed between the two side plates, and the slider 105 is slidably sleeved on the guide columns 102 to ensure the linearity and stability of its movement trajectory. The two ends of the lead screw 103 are rotatably connected to the side plates through bearings, and one end extends out of the side plate and is connected with a manual knob for driving the rotation of the lead screw 103. The slider 105 is in threaded cooperation with the lead screw 103. When the lead screw 103 rotates, the slider 105 can reciprocate along the guide columns 102 to achieve the clamping or releasing function.

[0068] A pressing block 106 is fixed above the slider 105, and a pressing block 108 is installed above the corresponding side plate. The two together form a clamping surface. The pressing block 106 controls the vertical gap between it and the slider 105 through an adjusting knob 107, and the pressing block 108 adjusts the gap between it and the side plate through an adjusting knob 109 to adapt to workpieces of different thicknesses. In addition, a laser displacement sensor 11 is integrated inside the clamping seat 101 to monitor the displacement change during the clamping process in real time, ensuring the clamping accuracy and stability. The lead screw 103 drives the slider 105 to move along the guide columns 102 through rotation, realizing the clamping or loosening action of the pressing block 106 and the pressing block 108. The laser displacement sensor 11 feeds back its real-time clamping state by monitoring the thermal deformation of the metal foil to support high-precision clamping control.

[0069] In a specific embodiment, the pressing block 106 and the pressing block 108 are made of tungsten carbide. The gap can be finely adjusted by ±0.01 mm through the adjusting knob 107 and the adjusting knob 109. The laser displacement sensor 11 is integrated inside the side plate of the clamping seat 101. Using the principle of confocal white light, it monitors the deformation amount of the metal foil in real time and feeds it back to the control system to dynamically adjust the pre-tension to suppress thermal deformation, so that the deformation amount in the processing area is controlled within ±1 μm.

[0070] The working principle of the fixture 10 is as follows: By rotating the lead screw knob 104 to drive the rotation of the lead screw 103, the slider 105 is driven to move along the guide columns 102, making the pressing block 106 and the pressing block 108 approach or move away from each other to complete the clamping or loosening of the workpiece. The adjusting knob 107 and the adjusting knob 109 can respectively finely adjust the vertical positions of the two pressing blocks to ensure that the clamping surface is parallel and the pressure distribution is uniform. The laser displacement sensor 11 can feedback the clamping state in real time, providing data support for high-precision clamping. This structural design is reasonable and easy to operate, and is suitable for occasions with high requirements for clamping accuracy.

[0071] Refer to Figures 6 to 7As shown in the figure, an embodiment of the present invention also proposes a laser micro-drilling processing method for a metal foil lead frame. Using the laser micro-drilling processing device for a metal foil lead frame described in any one of the above embodiments, this method includes the following steps:

[0072] S1. Clamping and focusing

[0073] S11. Installation of fixture 10 and application of pre-tension: Clamp both ends of the metal foil using the special fixture 10 to ensure that the metal foil is flat and without slack; Apply pre-tension through the screw rod 103 mechanism of the fixture 10 to suppress the possible thermal deformation during the subsequent laser processing; The specific value of the pre-tension can be dynamically adjusted according to the material and thickness of the metal foil, and the deformation amount is monitored in real time through the laser displacement sensor 11 to ensure that the deformation is controlled within ±1μm;

[0074] S12. Laser focusing: Adjust the Z-axis moving platform 5 to accurately align the focused spot of the ultraviolet nanosecond pulsed laser 7 with the upper surface of the metal foil; The scanning galvanometer 9 cooperates with the Z-axis movement to ensure that the laser beam can maintain the best focusing state in different processing areas, and the adjustable range of the spot diameter is 5–10μm;

[0075] S13. Large-format stitching processing: For areas that exceed the single galvanometer scanning format, adjust the moving platforms of each axis through the three-axis motion system, and use the method of "local processing + mechanical stitching" to complete the preparation of the large-format lead frame. The processing format can reach 600×600mm 2 .

[0076] S2. Image processing and path planning

[0077] S21. Drawing conversion and binarization processing: Convert the CAD design drawing of the lead frame into a high-resolution binarized grayscale image (4μm / pixel), where "1" represents the non-processing area (reserved part), and "0" represents the micro-pattern area to be processed;

[0078] S22. Laser switch coordinate extraction: Traverse the grayscale image at a 4μm interval along the horizontal and vertical directions, and record the coordinate points where the pixel value changes from "1" to "0" or "0" to "1"; These coordinate points serve as the trigger signals for the laser switch;

[0079] The laser is turned on; When the pixel value changes from "1" to "0", it indicates the start of processing the edge of the micro-pattern;

[0080] The laser is turned off; When the pixel value changes from "0" to "1", it indicates the end of the current processing area;

[0081] S23. Path optimization: Combine the instruction sequence of the multi-axis motion controller to generate an efficient scanning path, avoid repeated processing or missed processing, and ensure the dimensional accuracy (±0.5μm) of the micro-pattern.

[0082] S3. Multi-directional scanning machining

[0083] S31. Parameter setting: Set the laser power (such as 2 mJ / pulse), frequency (adjustable from 1 - 100 kHz), scanning speed (up to 500 mm / s), and number of repeated scans (adjusted according to the material removal depth) through the host computer;

[0084] S32. Bi-directional scanning strategy: Use orthogonal parallel contour path filling scans at 0° and 90°;

[0085] First, scan along the 0° direction to complete the machining of the main contour;

[0086] Then, scan along the 90° direction to eliminate the directional errors (such as edge tilt or material accumulation) that may be caused by unidirectional scanning;

[0087] S33. Real-time monitoring and adjustment: The laser displacement sensor 11 feeds back the real-time deformation data of the metal foil, and dynamically adjusts the pre-tension or laser parameters to ensure the consistency of the ablation depth.

[0088] S4. Post-processing (pickling and electroplating)

[0089] S41. Ultrasonic pickling: Immerse the machined metal foil in a 15% hydrochloric acid solution, and use 20 kHz ultrasonic waves to clean for 500 seconds to completely remove the surface slag and oxide layer; After pickling, rinse with pure water and dry with an air pump to avoid corrosion by residual acid solution;

[0090] S42. Electroplating process: Electroplate the lead frame after cleaning and drying (such as gold plating or silver plating) to enhance its electrical conductivity and antioxidant properties to meet the requirements of semiconductor packaging.

[0091] Through a series of innovative technical means, the embodiments of the present invention achieve the high-precision, large-format, and green preparation of metal foil lead frames, providing a reliable process solution for integrated circuit packaging. Specifically, the closed-loop control technology of the pre-tension and the laser displacement sensor 11 effectively solves the problem of focus drift caused by heat accumulation in traditional laser processing, and significantly suppresses thermal deformation. At the same time, combined with binary image processing and bi-directional scanning strategy, the processing accuracy of micron-level features (such as narrow slots, through holes) is significantly improved, ensuring a high-precision processing effect. In addition, compared with wet etching, laser dry processing does not require the use of chemical etching solution, greatly reducing environmental pollution, and the processing efficiency is increased by more than 50%, with the advantages of environmental protection and high efficiency. This method also has good scalability and can be adapted to other ultra-thin metal materials, such as stainless steel foil, titanium foil, etc., and is widely applicable to fields such as MEMS devices and flexible electronics.

[0092] In summary, the device and method for machining metal foil lead frames by opto-mechanical coupling multi-axis linkage laser micro-drilling according to the present invention, with its unique advantages, show broad application prospects in the field of electronic manufacturing. It can not only effectively solve many problems in the preparation of traditional lead frames, but also meet the urgent needs of modern electronic manufacturing for high precision, high efficiency, environmental protection and low cost. It is expected to become the mainstream technology for lead frame processing in the future, promoting the technological progress and industrial upgrading of the electronic manufacturing industry.

[0093] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention, 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 should not be construed as a limitation of the present invention.

[0094] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A laser micro-drilling device for a metal foil lead frame, characterized in that: Including: Processing platform (2); Fixture (10), arranged on the processing platform (2), used for clamping both ends of the metal foil and applying a pre-tension force; Three-axis motion system, including a Y-axis moving platform (3) arranged on the processing platform (2), an X-axis moving platform (4) sliding on the Y-axis moving platform (3), a Z-axis moving platform (5) sliding on the X-axis moving platform (4), and a multi-axis motion controller; the multi-axis motion controller synchronously controls the laser switch, laser parameters, and three-axis mechanical motion; Scanning galvanometer (9), fixedly connected to the Z-axis moving platform (5), realizing three-dimensional motion through the three-axis operation system; Ultraviolet nanosecond pulsed laser (7), fixedly connected to the processing platform (2), vertically transmitting the laser to the light inlet of the scanning galvanometer (9) through the reflection system (8).

2. The laser micro-drilling processing device for metal foil lead frame according to claim 1, characterized in that: It further includes a laser displacement sensor (11) arranged inside the fixture (10), used for real-time monitoring of the thermal deformation of the metal foil.

3. The laser micro-drilling processing device for metal foil lead frame according to claim 1, characterized in that: The fixture (10) includes: Clamping seat (101), in a U-shaped structure with an upward opening, including a bottom plate and two vertical plates; Two guide columns (102), horizontally installed between the two vertical plates; Lead screw (103), rotatably connected to the vertical plates at both ends, and one end is connected with a lead screw knob (104); Slider (105), slidably sleeved on the two guide columns (102), and threadedly engaged with the lead screw (103); First pressing block (106) and second pressing block (108), respectively movably connected to the slider (105) and one side vertical plate through adjusting knobs, used for forming a pressing clamp from both ends of the metal foil.

4. The laser micro-drilling processing device for metal foil lead frame according to claim 1, characterized in that: The reflection system (8) includes multiple reflectors, realizing the vertical incidence of the laser through dynamic optical path regulation.

5. The laser micro-drilling processing device for metal foil lead frame according to claim 4, characterized in that: The reflection system (8) includes a first reflector (801), a second reflector (802), a third reflector (803), a fourth reflector (804), and a fifth reflector (805), and the positions and angles of each reflector are adjustable.

6. The laser micro-drilling processing device for metal foil lead frame according to claim 5, characterized in that: The first reflector (801) and the second reflector (802) are respectively fixed on the same fixed column (12) through adjustable clamps, the fixed column (12) is fixed on the processing platform (2), and the first reflector (801) and the second reflector (802) are equipped with self-rotation mechanisms.

7. The laser micro-drilling processing device for metal foil lead frame according to claim 5, characterized in that: The third reflector (803) is fixed at the top of a vertically arranged telescopic rod one (14), the bottom end of the telescopic rod one (14) is fixed on a connecting plate one (13), the connecting plate one (13) is fixedly connected with the X-axis moving platform (4), and the position fine-tuning in the height direction is realized through the telescopic rod one (14).

8. The laser micro-drilling processing device for metal foil lead frame according to claim 5, characterized in that: The fourth reflector (804) is connected to a connecting plate two (15) through a horizontally arranged telescopic rod two (16), the connecting plate two (15) is fixedly connected with the Z-axis moving platform (5), and the position fine-tuning in the Y-axis direction is realized through the telescopic rod two (16).

9. A laser micro-drilling method for a metal foil lead frame, using the laser micro-drilling device for a metal foil lead frame according to any one of claims 1 to 8, characterized in that: Including the following steps: S1. Clamping and focusing: Clamp the metal foil through the fixture (10) and apply a pre-tension force, and adjust the three-axis motion system to make the laser focus on the surface of the metal foil; S2. Image processing and path planning: Convert the design drawing of the lead frame into a binary pixel grayscale image, where the pixel value "1" represents the non-processing area, and the pixel value "0" represents the micro-pattern area to be processed; traverse the grayscale image horizontally and vertically at a scanning interval of 4μm, extract the coordinates of the pixel value changing from "1" to "0" as the laser on signal, and the coordinates changing from "0" to "1" as the laser off signal, and generate a laser switch instruction sequence; S3, multi-directional scanning processing: setting the laser power, frequency, scanning speed and number of repeated scanning, first scanning in the 0° direction, then orthogonal scanning in the 90° direction, to eliminate the shape error caused by unidirectional scanning; during the scanning process, high-precision micro-pattern processing is achieved by controlling the laser switch, the deflection of the scanning galvanometer (9) and the three-axis operation system; S4. Post-treatment: The processed metal foil is immersed in a 15% hydrochloric acid solution for ultrasonic cleaning to remove the surface slag and oxide layer. After pickling, it is rinsed with pure water and dried, and finally electroplated.

10. The laser micro-drilling method for a metal foil lead frame according to claim 9, characterized in that: The ultrasonic cleaning parameters are 20 kHz frequency and 500 s duration, and the metal foil is dried by an air pump after pickling.

Images