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

Abstract

The application belongs to the technical field of precision laser processing, and specifically discloses a laser micro-drilling and cutting device and method for a metal foil lead frame, which comprises a processing platform, a clamp, a three-axis motion system, a scanning galvanometer and an ultraviolet nanosecond pulse laser. The clamp applies a pre-tension to the metal foil through a screw rod mechanism and integrates a laser displacement sensor to monitor thermal deformation in real time. The three-axis motion system and the scanning galvanometer cooperate to realize three-dimensional accurate positioning, and a reflection system dynamically regulated by multiple mirrors is combined to ensure that the laser is vertically incident. The method comprises clamping and focusing, image processing and path planning, multi-directional scanning processing and post-processing. The application solves the problems of thermal deformation suppression and micron-level feature accuracy maintenance in large-format processing through optical-mechanical coupling multi-axis linkage control, has the advantages of high precision, environmental protection and high efficiency, and is suitable for the preparation of ultra-thin metal foil lead frames.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precision laser processing, and in particular to a laser micro-drilling processing device and method for a metal foil lead frame. BACKGROUND

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

[0003] At present, the metal foil lead frame is usually prepared by stamping and wet etching. 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 the fluid flow is difficult to control accurately during the processing, which causes problems such as lateral erosion and uneven distribution of etching liquid, and easily leads to deformation of the metal foil substrate, making it difficult to prepare extremely thin metal foil lead frames, and the etching liquid is corrosive and toxic, polluting the environment. With the increasing demand for miniaturization and multi-functionality, the requirements for the preparation technology of ultra-low thickness, high density, high precision and complex integrated circuit metal foil lead frame micro-patterns are higher.

[0004] Laser micro-drilling, as a non-contact, high-precision, acid-free and cutting fluid-free clean dry processing method, provides a new idea for 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 large-area metal foil lead frame laser micro-drilling processing device, and the commonly used laser scanning galvanometer processing area is limited and the edge is prone to distortion or uneven energy; second, there is a lack of metal foil laser micro-drilling processing thermal deformation suppression method, and thermal deformation will cause fluctuation of the laser beam focal point position, making it difficult to maintain the consistency of the ablation depth; third, there is a lack of precision retention method for local micro-features of the lead frame, and stamping and wet etching methods limit the processing precision of micron-level key features. SUMMARY

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

[0006] To achieve the above-mentioned purpose, in one aspect, the present application provides a laser micro-drilling processing device for a metal foil lead frame, comprising:

[0007] a processing platform;

[0008] a clamp provided on the processing platform for clamping both ends of the metal foil and applying a pre-tension.

[0009] A three-axis motion system, comprising a Y-axis moving platform arranged on the machining 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, which realizes three-dimensional motion through the three-axis motion system;

[0011] An ultraviolet nanosecond pulse laser fixedly connected to the machining platform, which vertically transmits 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 and machining metal foil lead frame based on light-mechanical coupling multi-axis linkage, which realizes three-dimensional accurate positioning of laser focusing spot through the cooperation of the three-axis motion system and the scanning galvanometer, and meets the machining needs of micron-level lead frame. The multi-axis motion controller synchronously regulates and controls laser parameters (power, frequency) and mechanical motion, reduces machining errors, ensures the size consistency of complex micro-patterns, and realizes non-contact processing through the ultraviolet nanosecond pulse laser to replace wet etching, avoids chemical pollution, and improves the environmental friendliness of processing.

[0013] Optionally, the device further comprises a laser displacement sensor arranged in the clamp for real-time monitoring of thermal deformation of the metal foil. By real-time monitoring of the deformation amount of the metal foil, the pre-tension of the clamp or the laser parameters are dynamically adjusted, effectively inhibiting the focus drift caused by heat accumulation, and ensuring the flatness of the processed surface.

[0014] Optionally, the clamp comprises:

[0015] A clamping seat in a open-topped U-shaped structure, comprising a bottom plate and two vertical plates;

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

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

[0018] A sliding block slidingly sleeved on the two guide columns and threadedly matched with the lead screw;

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

[0020] Through the cooperation of the lead screw, the sliding block and the pressing block, the pressing gap is finely adjusted to ensure uniform stress on the metal foil and avoid clamping deformation; and the pre-tension is manually or automatically adjusted by the lead screw knob to adapt to metal foil materials of different thicknesses.

[0021] Optionally, the reflection system comprises a plurality of mirrors, and the vertical incidence of the laser is achieved through dynamic light path regulation. The plurality of mirrors adjusts the light path angle in real time, reduces the angle deviation error, ensures that the laser is always vertically incident on the galvanometer, eliminates the beam deflection caused by mechanical movement, and the multi-mirror light splitting design reduces the load of a single mirror and prolongs the service life of the optical element.

[0022] Optionally, the reflection system comprises 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 light path requirements of different processing areas and improve the flexibility of the light path. The fifth mirror serves as a backup light path node to enhance the fault tolerance of the system.

[0023] Optionally, the first mirror and the second mirror are 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 provided with a self-rotation mechanism. The fixed column provides a stable installation reference to reduce the influence of vibration on the light path, and the self-rotation mechanism cooperates with the clamps to realize rapid calibration of the mirrors and simplify the light path debugging process.

[0024] Optionally, the third mirror is fixed at the top end of a vertically arranged telescopic rod one, the bottom end of the telescopic rod one is fixed on a connecting plate one, the connecting plate one is fixedly connected with the X-axis moving platform, and the position fine adjustment in the height direction is realized through the telescopic rod one. The telescopic rod one fine adjusts the height of the third mirror, compensates for the focal point deviation when the Z-axis moves, and maintains the vertical incidence of the laser.

[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 with the Z-axis moving platform, and the position fine adjustment in the Y-axis direction is realized through the telescopic rod two. The horizontal telescopic rod two fine adjusts the position of the fourth mirror to eliminate the light path deviation caused by the movement of the Y-axis; and cooperates with the Z-axis platform to realize multi-axis light path collaborative compensation and improve the precision of the edge processing area.

[0026] In another aspect, the present application also provides a laser micro-drilling and machining method for a metal foil lead frame, which adopts the laser micro-drilling and machining device for a metal foil lead frame according to any one of the above embodiments, and the method comprises the following steps:

[0027] S1, clamping and focusing: clamping the metal foil through a clamp and applying a pre-tension, adjusting the three-axis motion system to focus the laser on the surface of the metal foil;

[0028] S2, image processing and path planning: the design drawing of the lead frame is converted into a binary pixel gray scale image, wherein the pixel value "1" represents a non-processing area, and the pixel value "0" represents a micro-pattern area to be processed; the gray scale image is traversed horizontally and vertically at a scanning interval of 4 mu m, the coordinates of the pixel value changing from "1" to "0" are extracted as the laser opening signal, the coordinates of the pixel value changing from "0" to "1" are extracted as the laser closing signal, and a laser switching instruction sequence is generated;

[0029] S3, multi-directional scanning processing: the laser power, frequency, scanning speed and repeated scanning times are set, 0° direction scanning is performed first, and then 90° direction orthogonal scanning is performed to eliminate shape errors caused by single-direction scanning; during the scanning process, high-precision micro-pattern processing is realized by controlling the laser switching, scanning galvanometer deflection and three-axis running system.

[0030] S4, post-processing: the processed metal foil is immersed in a 15% hydrochloric acid solution for ultrasonic cleaning to remove surface slag and oxide layers, rinsed with pure water after pickling and dried, and finally electroplated.

[0031] Further, the ultrasonic cleaning parameters are 20 kHz frequency and 500 s time length, and the metal foil is dried by an air pump after pickling.

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

[0033] The two-dimensional laser scanning galvanometer is ingeniously mounted on the three-axis mechanical platform, the mechanical system and the laser system are strongly coupled by means of a multi-axis motion controller, the two systems can work cooperatively and give full play to their respective advantages, the dynamic following and precise control of the light path are realized through the carefully designed reflection system, the laser can always act accurately on the processing area, and a powerful guarantee is provided for high-precision processing.

[0034] Further, the deformation of the metal foil is a problem that cannot be ignored during processing. In order to solve this problem, a laser displacement sensor is introduced in the present application, and a special fixture is used. The laser displacement sensor can monitor the deformation of the metal foil in real time during processing, and the special fixture can be adjusted in time according to the monitoring data, so as to effectively suppress the deformation of the metal foil and ensure the stability of the processing quality.

[0035] In summary, the device of the present application has the advantages of compact structure, easy installation and maintenance, stable operation, high processing precision, significant cost-effectiveness, easy operation, excellent processing efficiency and excellent control performance. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

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

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

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

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

[0042] Figure 6 This 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 This is a flowchart of the processing method of the present invention;

[0044] In the diagram: 1. Vibration isolation base; 2. Machining platform; 3. Y-axis moving platform; 4. X-axis moving platform; 5. Z-axis moving platform; 6. Cylinder; 7. Ultraviolet nanosecond pulse laser; 8. Reflection system; 801. First reflecting mirror; 802. Second reflecting mirror; 803. Third reflecting mirror; 804. Fourth reflecting mirror; 805. Fifth reflecting mirror; 9. Scanning galvanometer; 10. Fixture; 101. Clamp; 102. Guide column; 103. Lead screw; 104. Lead screw knob; 105. Slider; 106. Pressure block one; 107. Adjustment knob one; 108. Pressure block two; 109. Adjustment 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 Implementation

[0045] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present application.

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

[0047] Laser micro drilling is a non-contact, high-precision, acid-free and cutting fluid-free clean dry processing method, which has obvious advantages. Among them, nanosecond laser micro drilling removes materials by light-thermal effect through the interaction of high-energy laser beam and materials, which has been widely used in the processing of metal foil micro patterns, providing a new idea for the green processing and preparation of high-precision lead frame micro patterns. However, there are relatively few studies on laser micro drilling of copper alloy foil lead frame at present, and there are still many technical challenges in practical application. However, the existing technology lacks large-area processing capability and effective processing equipment and methods to suppress thermal deformation.

[0048] Therefore, it is urgent 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 limit, realize the high-precision laser micro drilling preparation of large-area metal foil lead frame, and meet the processing needs of ultra-low thickness, high density, high precision and complex micro patterns.

[0049] Therefore, the embodiments of the present application propose a laser micro drilling processing device and method for metal foil lead frame, which converts the lead frame design drawing into a pixel gray scale image and performs binary processing, traverses the entire pixel image according to the set scanning pitch, extracts the coordinates of the points with numerical changes as the basis for laser on / off, so as to ensure the high-quality processing of local micro features and improve the overall performance of the lead frame.

[0050] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Referring to Figures 1 to 5 As shown in the drawings, the present application provides a laser micro drilling processing device for metal foil lead frame, which comprises a vibration isolation base 1, a processing platform 2, a three-axis running system, an ultraviolet nanosecond pulse laser 7, a reflection system 8, a scanning galvanometer 9, a clamp 10 and a control system.

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

[0053] In one embodiment, a gas-floating vibration isolation module is integrated inside the vibration isolation base 1, which can eliminate external vibrations with a frequency of ≥5Hz.

[0054] Specifically, as shown in Figures 1 to 3 , the three-axis operation system includes a Y-axis moving platform 3 arranged on the machining 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 each moving platform.

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

[0056] In one embodiment, the X-axis moving platform 4 is linearly movably connected to the Y-axis moving platform 3 and can smoothly drive the scanning galvanometer 9 to move along the X direction. The X-axis moving platform 4 has a cross-roller guide structure and is linked with the Y-axis platform through a servo motor to realize a machining range of 600×600mm 2 . The X-axis moving platform 4 is equipped with a gravity balance mechanism to eliminate track wear caused by unbalanced load.

[0057] In one embodiment, the Z-axis moving platform 5 is installed on the X-axis moving platform 4 and can smoothly drive the scanning galvanometer 9 to move along the Z-axis direction. The air cylinder 6 is installed on the Z-axis moving platform 5 and can balance the load gravity on the Z-axis to improve the Z-axis movement accuracy. The Z-axis moving platform 5 adopts a closed-loop controlled ball screw to realize a focusing position adjustment accuracy of ±1μm. The scanning galvanometer 9 is installed on the Z-axis moving platform 5 and is driven by the Z-axis moving platform 5 to realize a laser beam focusing function, ensuring that the laser focusing spot always remains on the machining surface.

[0058] Specifically, the ultraviolet nanosecond pulsed laser 7 is mounted on the processing platform 2, and the laser beam is always perpendicularly incident on the inlet of the scanning galvanometer 9 via the reflection system 8. In one specific embodiment, the ultraviolet nanosecond pulsed laser 7 can be a laser emitting device with the following parameters: output wavelength 355nm, pulse energy 2mJ, and repetition frequency adjustable from 1-100kHz. The ultraviolet nanosecond pulsed laser 7 is coupled to the reflection system 8 via optical fiber, and the ultraviolet nanosecond pulsed laser 7 and the reflection system 8 together form a laser optical path system.

[0059] Specifically, 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. Each reflector 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 reflector 801 is fixed to the processing platform 2, and the second to fifth reflectors 805 move with the three-axis motion system to adjust their angles in real time, ensuring that the laser is always perpendicularly incident on the light inlet of the scanning galvanometer 9, with an optical path angle offset error of <5μrad.

[0060] In one specific embodiment, the first reflector 801 and the second reflector 802 are fixedly mounted on a fixed column 12. The fixed column 12 is bolted to the processing platform 2, providing a stable mounting base for the first reflector 801 and the second reflector 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 reflectors can accurately guide the laser beam to the light inlet of the scanning galvanometer 9. To achieve adjustment of the angle of the first reflector 801 and the second reflector 802, the first reflector 801 and the second reflector 802 are equipped with their own self-rotating mechanisms. They are also fixed to the fixed column 12 by adjustable clamps, allowing for 360-degree angle adjustment around the fixed column 12 when needed, and arbitrary adjustment of their vertical position.

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

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

[0063] In the above structure, telescopic rod 14 and telescopic rod 16 are used to fine-tune the position of the reflector, adjusting its forward and backward position through telescopic movement. This design allows for dynamic adjustment of the laser beam path during processing to compensate for beam path deviations caused by mechanical movement or environmental changes. The telescopic range and precision of the telescopic rods are designed according to the requirements of laser processing, ensuring that the laser beam can always be accurately focused on the processing area. Through the above structural design and adjustment method, the reflection system 8 can achieve dynamic tracking and precise control of the laser beam path, ensuring that the laser beam is always perpendicularly incident on the inlet of the scanning galvanometer 9, thus providing a strong guarantee for high-precision processing.

[0064] Specifically, the scanning galvanometer 9 is mounted on the Z-axis moving platform 5 and driven by the Z-axis moving platform 5 to realize the laser beam focusing function and ensure that the laser focused spot is always kept on the processing surface.

[0065] In one specific embodiment, the scanning galvanometer 9 employs a combination of a high-speed galvanometer motor (deflection speed ≥2m / s) and an f-θ lens, with a focused spot diameter of 5-10μm (adjustable). It is rigidly connected to the Z-axis moving platform 5 via an aviation connector, and the galvanometer base is equipped with heat dissipation fins, achieving a temperature control accuracy of ±0.5℃. Its working principle is as follows: receiving commands from a multi-axis motion controller, it coordinates with the X-axis moving platform 4 and the Y-axis moving platform 3 to achieve a composite processing mode of "local galvanometer processing + large-format splicing of the mechanical platform," thereby reducing processing errors.

[0066] Specifically, the control system includes an image processing module comprising a host computer and a slave computer. The host computer converts the CAD drawing into a binary grayscale image (4μm / pixel) and generates a laser switching command sequence. The slave computer, through an FPGA controller, synchronously coordinates three-axis motion (500Hz refresh rate), laser parameters (pulse synchronization error <10ns), and galvanometer deflection to achieve 0° / 90° bidirectional scanning path filling. A PID-feedforward composite control algorithm is employed, achieving a position tracking error of <0.3μm.

[0067] In one specific embodiment, such as Figure 4As shown, the clamp 10 mainly consists of a clamping base 101, guide posts 102, a lead screw 103, a slider 105, a pressure block, and an adjusting knob. The clamping base 101 is an upward-opening U-shaped structure, including a base plate and two vertical plates fixed to the base plate, forming a stable support frame. Two guide posts 102 are horizontally installed between the two vertical plates, and the slider 105 is slidably sleeved on the guide posts 102 to ensure the straightness and stability of its movement trajectory. The two ends of the lead screw 103 are rotatably connected to the vertical plates through bearings, with one end extending out of the vertical plate and connected to a manual knob for driving the lead screw 103 to rotate. The slider 105 is threadedly engaged with the lead screw 103. When the lead screw 103 is rotated, the slider 105 can reciprocate along the guide posts 102 to achieve the clamping or releasing function.

[0068] A pressure block 106 is fixed above the slider 105, and a pressure block 2 108 is installed above the corresponding side upright plate, together forming a clamping surface. The vertical gap between pressure block 106 and slider 105 is controlled by adjusting knob 107, and the gap between pressure block 2 108 and upright plate is adjusted by adjusting knob 2 109, thus accommodating objects of different thicknesses. In addition, a laser displacement sensor 11 is integrated inside the clamping base 101 to monitor displacement changes in real time during the clamping process, ensuring clamping accuracy and stability. The lead screw 103 drives slider 105 to move along guide post 102 by rotation, realizing the clamping or releasing action of pressure block 106 and pressure block 2 108. The laser displacement sensor 11 monitors the thermal deformation of the metal foil to provide feedback on its real-time clamping status, supporting high-precision clamping control.

[0069] In one specific embodiment, the first pressure block 106 and the second pressure block 108 are made of tungsten carbide. The gap can be finely adjusted by adjusting the first knob 107 and the second knob 109 to a margin of ±0.01mm. The laser displacement sensor 11 is integrated into the inner side of the vertical plate of the clamp 101. It adopts the confocal white light principle to monitor the deformation of the metal foil in real time and feed it back to the control system. The pre-tension is dynamically adjusted to suppress thermal deformation and keep the deformation of the processing area within ±1μm.

[0070] The working principle of the fixture 10 is as follows: Rotating the lead screw knob 104 drives the lead screw 103 to rotate, which in turn drives the slider 105 to move along the guide post 102, causing the first pressure block 106 and the second pressure block 108 to move closer or further apart, thus clamping or releasing the workpiece. Adjusting knobs 107 and 109 can finely adjust the vertical position of the two pressure blocks to ensure parallel clamping surfaces and uniform pressure distribution. The laser displacement sensor 11 provides real-time feedback on the clamping status, offering data support for high-precision clamping. This structure is rationally designed, easy to operate, and suitable for applications requiring high clamping accuracy.

[0071] Reference Figures 6 to 7As shown in the embodiments of the present invention, a laser micro-drilling method for metal foil lead frames is also proposed. Using the laser micro-drilling apparatus for metal foil lead frames described in any of the above embodiments, the method includes the following steps:

[0072] S1. Mounting and focusing

[0073] S11. Fixture 10 Installation and Pre-tension Application: Use a special fixture 10 to clamp both ends of the metal foil to ensure that the metal foil is flat and without looseness; apply pre-tension through the lead screw 103 mechanism of the fixture 10 to suppress thermal deformation that may occur during 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 is monitored in real time by 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 precisely align the focused spot of the ultraviolet nanosecond pulse laser 7 with the upper surface of the metal foil; the scanning galvanometer 9, in coordination with the Z-axis movement, ensures that the laser beam can maintain the best focusing state in different processing areas, and the spot diameter can be adjusted within the range of 5–10 μm;

[0075] S13. Large-format splicing processing: For areas exceeding the single galvanometer scanning area, the three-axis motion system is used to adjust the movement platforms of each axis, employing a "local processing + mechanical splicing" method to complete the fabrication of large-format lead frames. The processing area can reach 600×600mm. 2 .

[0076] S2, Image Processing and Path Planning

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

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

[0079] Laser activated; pixel value changes from "1" to "0", indicating the start of processing the micro-pattern edges;

[0080] Laser off; pixel value changes from "0" to "1", indicating 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 of the micro-pattern (±0.5μm).

[0082] S3, Multi-directional scanning processing

[0083] S31. Parameter settings: The laser power (e.g., 2mJ / pulse), frequency (adjustable from 1 to 100kHz), scanning speed (maximum 500mm / s), and number of repeated scans (adjusted according to the material removal depth) can be set via the host computer.

[0084] S32. Bidirectional scanning strategy: Use 0° and 90° orthogonal parallel contour paths to fill the scan.

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

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

[0087] S33. Real-time monitoring and adjustment: The laser displacement sensor 11 provides feedback on the real-time deformation data of the metal foil, dynamically adjusting the pre-tension or laser parameters to ensure consistent ablation depth.

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

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

[0090] S42. Electroplating process: Electroplating (such as gold or silver plating) is performed on the cleaned and dried lead frame to enhance its conductivity and oxidation resistance, meeting the requirements of semiconductor packaging.

[0091] This invention achieves high-precision, large-format, and green fabrication of metal foil lead frames through a series of innovative technical means, providing a reliable process solution for integrated circuit packaging. Specifically, the closed-loop control technology using pre-tension and laser displacement sensor 11 effectively solves the focus drift problem caused by heat accumulation in traditional laser processing, significantly suppressing thermal deformation. Simultaneously, the combination of binarized image processing and bidirectional scanning strategy significantly improves the processing accuracy of micron-level features (such as narrow slits and through-holes), ensuring high-precision processing results. Furthermore, compared to wet etching, dry laser processing eliminates the need for chemical etching solutions, significantly reducing environmental pollution and increasing processing efficiency by more than 50%, combining the advantages of environmental friendliness and high efficiency. This method also has good scalability and can be adapted to other ultrathin metal materials, such as stainless steel foil and titanium foil, making it widely applicable to MEMS devices, flexible electronics, and other fields.

[0092] In summary, the apparatus and method for machining metal foil lead frames based on optomechanical coupling multi-axis linkage laser micro-drilling of the present invention, with its unique advantages, demonstrates broad application prospects in the field of electronic manufacturing. It not only effectively solves many problems in traditional lead frame fabrication but also meets 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 future lead frame machining, driving technological progress and industrial upgrading in the electronic manufacturing industry.

[0093] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0094] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A laser micro-drilling processing device for a metal foil lead frame, characterized in that, include: Processing platform (2); The fixture (10), located on the processing platform (2), includes: a clamping base (101), which is an upward-opening U-shaped structure, including a base plate and two upright plates; two guide columns (102), which are horizontally installed between the two upright plates; a lead screw (103), which is rotatably connected to the upright plates at both ends, and one end is connected to a lead screw knob (104); a slider (105), which is slidably sleeved on the two guide columns (102) and threadedly engaged with the lead screw (103); a pressure block one (106) and a pressure block two (108), which are movably connected to the slider (105) and one side upright plate respectively through an adjustment knob, for forming a clamping clamp from both ends of the metal foil; the fixture (10) clamps both ends of the metal foil and applies a pre-tension force, and the fixture (10) monitors the thermal deformation of the metal foil in real time through a laser displacement sensor (11); The three-axis motion system includes a Y-axis moving platform (3) mounted on the machining 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. The scanning galvanometer (9) is fixed to the Z-axis moving platform (5) and achieves three-dimensional motion through the three-axis running system; An ultraviolet nanosecond pulsed laser (7) is fixed on the processing platform (2) and the laser is vertically transmitted to the light inlet of the scanning galvanometer (9) through the reflection system (8); 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), the position and angle of each reflector being adjustable.

2. The laser micro-drilling processing device for metal foil lead frames according to claim 1, characterized in that, The first reflector (801) and the second reflector (802) are respectively fixed on the same fixed column (12) by 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 a self-rotating mechanism.

3. The laser micro-drilling processing device for metal foil lead frames according to claim 1, characterized in that, The third reflector (803) is fixed at the top of the vertically arranged telescopic rod (14), and the bottom of the telescopic rod (14) is fixed on the connecting plate (13). The connecting plate (13) is fixedly connected to the X-axis moving platform (4), and the position is finely adjusted in the height direction through the telescopic rod (14).

4. The laser micro-drilling apparatus for metal foil lead frames according to claim 1, characterized in that, The fourth reflector (804) is connected to the second connecting plate (15) via a horizontally set telescopic rod (16). The second connecting plate (15) is fixedly connected to the Z-axis moving platform (5). The position of the telescopic rod (16) is finely adjusted in the Y-axis direction.

5. A laser micro-drilling method for metal foil lead frames, employing the laser micro-drilling apparatus for metal foil lead frames as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Clamping and focusing: Clamp the metal foil with the clamp (10) and apply a pre-tension force, and adjust the three-axis motion system to focus the laser on the surface of the metal foil; S2. Image Processing and Path Planning: The design drawings of the lead frame are converted into a binary pixel grayscale image, where a pixel value of "1" represents a non-processed area and a pixel value of "0" represents a micro-pattern area to be processed; the grayscale image is traversed horizontally and vertically at a scanning interval of 4 μm, and the coordinates of the pixel values ​​changing from "1" to "0" are extracted as laser turn-on signals, and the coordinates changing from "0" to "1" are used as laser turn-off signals, generating a laser switch command sequence; S3. Multi-directional scanning processing: Set the laser power, frequency, scanning speed and number of repeated scans. First, perform a 0° direction scan, and then perform a 90° direction orthogonal scan 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 running system. S4. Post-treatment: The processed metal foil is immersed in a 15% hydrochloric acid solution for ultrasonic cleaning to remove surface slag and oxide layer. After pickling, it is rinsed with pure water and dried, and finally electroplated.

6. The laser micro-drilling method for metal foil lead frames according to claim 5, characterized in that, The ultrasonic cleaning parameters are 20 kHz frequency and 500s duration. After acid washing, the metal foil is dried by an air pump.

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