Multi-point eccentric locking type laser precision welding device for semiconductor lead frame
By using a multi-point eccentric locking laser welding device and inert gas support technology, the problem of inconsistent molten pool morphology in lead frame welding was solved, achieving weld smoothness and stability, and ensuring continuous production in subsequent processes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG MINGSHUN PRECISION MACHINERY TECHNOLOGY CO LTD
- Filing Date
- 2026-03-10
- Publication Date
- 2026-05-15
AI Technical Summary
Existing lead frame welding equipment is prone to inconsistent weld pool morphology when welding thin materials with high thermal conductivity, resulting in weld beads, excess weld height, and hanging beads, which affects the continuous production of subsequent processes.
A multi-point eccentric locking laser welding device is used, combined with non-contact support of inert gas and high-frequency pulsed airflow. Through fluid dynamics and thermal management technology, dynamic stability and morphology control of the molten pool are achieved.
It effectively prevents the formation of weld beads and weld reinforcement, ensures a smooth weld, improves welding quality, prevents weld breakage and jamming, and ensures the smooth progress of subsequent processes.
Smart Images
Figure CN122033434A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lead frame welding, and more specifically, to a multi-point eccentric locking laser precision welding apparatus for semiconductor lead frames. Background Technology
[0002] As a key substrate in semiconductor packaging, the leadframe not only provides robust physical support for the chip but also plays a crucial role in connecting internal and external circuits. Because leadframes are typically made of thin copper alloys with high electrical and thermal conductivity, their precise structure and extremely thin thickness place extremely stringent requirements on mechanical stability and thermal input control during manufacturing.
[0003] In the mass production of integrated circuits, lead frames are typically supplied in roll-to-roll form. To enable continuous operation of subsequent processes such as electroplating, molding, and punching, and to avoid downtime during roll changes, precision splicing of the lead frames must be achieved by laser welding between the end of the old roll and the beginning of the new roll. However, existing technologies have significant drawbacks in handling such precision thin-strip welding: Existing welding equipment mostly uses a simple mechanical clamping structure with single-sided side-blowing protective gas. Because copper alloys have extremely high initial reflectivity to lasers and extremely fast thermal conductivity, high energy density is often required during welding. At extremely thin thicknesses, the molten pool metal is prone to instability under the influence of gravity and surface tension gradient. Single-sided processing without back support often causes the molten metal to collapse downwards, forming a "weld bead," while the front side produces obvious "residual height (protrusion)" due to uneven surface tension. In high-speed continuous production, the residual height at the weld or the back bead can cause the frame to get stuck, scratched, or even break when passing through the plastic sealing mold or electroplating guide rail. Summary of the Invention
[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a multi-point eccentric locking laser precision welding device for semiconductor lead frames.
[0005] To solve the above problems, the present invention adopts the following technical solution.
[0006] A semiconductor lead frame multi-point eccentric locking laser precision welding device includes a machine base, an axial motion platform fixed on the upper part of the machine base, and a laser welding part fixed on the moving end of the axial motion platform. It also includes two slides symmetrically slidably on the upper part of the machine base, multiple eccentric locking parts respectively connected to the upper part of the two slides, a support part fixed on the upper part of the slides and located between the two slides, and an upper gas outlet fixed on the lower part of the laser welding part. The gas outlet of the upper gas outlet faces the support part and outputs inert gas to the welding point. The upper gas outlet has a hollow cavity through which the laser beam passes. The support includes a partition plate fixed to the upper end of the slide and located between two slides, a second movable groove opened on the upper end of the partition plate, a filter screen fixed on the inner wall of the second movable groove, a movable seat located inside the second movable groove, and an exhaust port opened on the upper end of the movable seat. A lower air supply assembly is fixedly connected inside the machine, and the output end of the lower air supply assembly is connected to the input end of the exhaust port through an air supply pipe.
[0007] Furthermore, the movable seat is slidably connected in the second movable groove, and a lead screw drive is rotatably connected in the second movable groove. The lead screw drive is screwed inside the movable seat, and a drive assembly is fixed inside the middle partition, and the output shaft of the drive assembly is connected to the lead screw drive.
[0008] Furthermore, the eccentric locking part includes a pressure plate rotatably connected to the upper end of the slide plate, a bolt screwed inside the pressure plate, and an eccentric clamping assembly disposed on the pressure plate. The upper end of the slide plate is provided with a threaded groove that matches the bolt. The bolt passes through the pressure plate and is screwed into the threaded groove. One side of one of the pressure plates is integrally formed with an extended pressure block for applying pressure to the lead frame welding area.
[0009] Furthermore, the eccentric pressing assembly includes an eccentric lever rotatably connected to the pressure plate, a first movable groove opened inside the pressure plate, a movable rod movably inserted into the first movable groove, a limiting part fixed to the upper end of the movable rod and in contact with the eccentric lever, a pressure head fixed to the lower end of the movable rod, and a spring sleeved on the outside of the movable rod and located in the first movable groove, wherein the two ends of the spring are respectively connected to the limiting part and the inner wall of the first movable groove.
[0010] Furthermore, the upper air outlet includes a sleeve fixed to the lower end of the laser welding part, the hollow cavity is opened inside the sleeve, the sleeve has multiple tangential air inlets that are inclined and communicate with the hollow cavity, and the sleeve has multiple air pipe interfaces that are connected to the tangential air inlets on the outside, and the inner wall of the hollow cavity is integrally formed with multiple spiral guide flanges.
[0011] Furthermore, the lower air supply assembly includes an air supply unit fixed inside the machine and a pulse processing unit fixed at the upper end of the machine. The output end of the air supply unit is connected to the input end of the pulse processing unit, and the output end of the pulse processing unit is connected to one end of the air supply pipeline.
[0012] Furthermore, the pulse processing unit includes a housing fixed to the upper part of the machine base, a resonant cavity opened inside the housing, an air supply pipe fixed to the lower part of the housing, an air outlet opened at the upper part of the housing, an ultrasonic transducer fixed inside the housing, and an ultrasonic radiation plate located in the resonant cavity and fixed to the output end of the ultrasonic transducer. One end of the air supply pipe is connected to the output end of the air supply unit, and the air outlet is connected to the air delivery pipe.
[0013] Furthermore, two heat-conducting plates are symmetrically fixed to the upper end of the partition plate, the filter screen is located between the two adjacent heat-conducting plates, and a temperature control anti-warping component is connected inside the machine. Both heat-conducting plates have flow channels inside, the input end of the temperature control anti-warping component is connected to the output end of the flow channel, and the output end is connected to the input end of the flow channel.
[0014] Furthermore, the temperature control anti-warping component includes a circulating pump and a cooling unit fixed inside the machine tool, with the input end of the circulating pump connected to the output end of the cooling unit. The output end of the circulating pump is connected to the input end of the flow channel through a liquid delivery pipe, and the input end of the cooling unit is connected to the output end of the flow channel through a liquid delivery pipe.
[0015] Furthermore, the filter is made of a conductive material that generates heat itself when energized.
[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This scheme has an inert gas exhaust structure above and below the weld. The constant static pressure of inert gas is delivered to the back of the lead frame through the exhaust port to form an air cushion support. The upward support force generated by the static pressure can accurately offset the gravity of the molten metal and the downward jetting force generated by the laser keyhole, preventing the liquid copper liquid from falling and forming weld beads due to its low viscosity and fast thermal conductivity. The downward air pressure generated by the upper exhaust part can effectively flatten the surface of the molten pool. The fluid dynamics are used to generate non-contact physical constraints on the molten pool, thereby solving the problem of morphological consistency of high thermal conductivity thin materials in laser welding without damaging the pre-plating layer of the workpiece, and eliminating the interference of excess height and weld beads on subsequent precision processes.
[0017] (2) The upper air outlet of this scheme adopts a tangential air inlet and a spiral guide flange design, so that the inert gas entering the hollow cavity can form a swirling flow inside the sleeve. The rotating airflow discharged from the hollow cavity and blown towards the weld point can form a high-speed rotating air wall around the weld point. Due to the radial pressure gradient generated by the rotation, a squeezing force towards the center will be generated on the liquid molten pool. This force can forcibly constrain the molten pool that tends to spread to the surroundings, making the weld width narrower. At the same time, the tangential shear force generated when the rotating airflow contacts the surface of the molten pool can break the surface tension steady state that causes the "protrusion" phenomenon. Like a non-contact "rotating iron", it smooths the accumulated molten metal towards the center evenly, making the weld tend to be flat.
[0018] (3) This scheme is equipped with a pulse processing unit, which can perform high-frequency modulation on the supporting airflow blown towards the weld seam, so that the constant pressure flow becomes a pulsed airflow with high-frequency oscillation. The high-frequency pulsed airflow generates alternating instantaneous peak pressure below the molten pool. This pulsed force field is more effective than static pressure in counteracting the gravity of the molten metal and the downward jetting force of the laser, like a "dynamic air cushion" to steadily support the molten pool within the reference plane. Through the high-frequency mechanical vibration of the ultrasonic transducer, the ultrasonic radiation plate is driven to generate periodic displacement in the flow channel of the lower air supply component, thereby physically modulating the constant pressure inert airflow into a pulse with a specific pressure amplitude. The pulsed airflow acts directly on the bottom of the molten pool, using high-frequency momentum to periodically counteract the downward gravitational component of the molten metal, achieving dynamic mechanical support and forced flattening of the bottom morphology of the molten pool. This effectively prevents the falling and accumulation of high thermal conductivity metal droplets, thus solving the common problem of back-side lumps at the lead frame connector. Furthermore, the micro-stirring effect generated by the high-frequency pulsed flow inside the molten pool can accelerate the aggregation and floating of bubbles inside the liquid metal, allowing them to be quickly discharged before the molten pool solidifies. This ensures the conductivity stability and mechanical consistency at the lead frame connector, effectively preventing brittle fracture of the connector due to porosity.
[0019] (4) This solution is equipped with a temperature control and anti-warping component. The filter screen serves as the bottom support, providing a microscopic physical boundary for the molten pool. This directly prevents the molten metal from falling and forming lumps due to gravity. By heating the filter screen, the temperature difference between the molten copper and the supporting medium is reduced. This prevents uneven shrinkage caused by "sudden cooling" at the bottom of the molten pool due to contact with a cold surface, allowing the molten metal to spread evenly on the filter screen surface instead of accumulating into droplets. The two heat-conducting plates on both sides, together with the cooling liquid, form a thermal enclosure. This intense contrast in heat conduction cuts off the lateral diffusion of heat. This significantly narrows the heat-affected zone. When the molten pool is confined to an extremely narrow area, its total melting volume is reduced, and the volume change caused by thermal expansion and phase transformation is also reduced accordingly, thus suppressing the bulge height from a physical perspective. This layout, with the center hot and the sides cold, establishes a gentle cooling gradient in the center of the weld, while the sides have steep cooling gradients. This can offset some of the shrinkage stress during the cooling process, prevent the lead frame from producing a "wavy" macroscopic deformation at the joint, improve the toughness of the joint, and ensure that the joint will not break during subsequent high-speed punching or electroplating processes. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the laser welding section and the upper air outlet section of the present invention; Figure 3 This is a schematic diagram of the support structure of the present invention; Figure 4 This is a schematic diagram of the partition plate and filter screen structure of the present invention; Figure 5 For the present invention Figure 4 Enlarged schematic diagram of the structure at point A in the middle; Figure 6 This is a schematic diagram of the eccentric locking part structure of the present invention; Figure 7 This is a cross-sectional view of the eccentric locking part of the present invention; Figure 8 This is a schematic diagram of the second movable groove, lead screw drive unit, movable seat, and exhaust port structure of the present invention; Figure 9 For the present invention Figure 8 Enlarged schematic diagram of the structure at point B; Figure 10 This is a schematic diagram of the internal structure of the upper air outlet of the present invention; Figure 11 This is a schematic diagram of the temperature control anti-warping component structure of the present invention; Figure 12 This is a cross-sectional view of the pulse processing unit of the present invention.
[0021] Explanation of the labels in the diagram: 1. Machine base; 2. Slide table; 3. Eccentric locking part; 31. Pressure plate; 32. Bolt; 33. Eccentric lever; 34. Extension pressure block; 35. First movable groove; 36. Spring; 37. Movable rod; 38. Pressure head; 39. Limiting part; 4. Axial motion platform; 41. Laser welding part; 5. Support part; 51. Middle partition plate; 52. Filter screen; 53. Second movable groove; 54. Screw drive part; 55. Moving seat; 551. Exhaust port; 56. Gas pipeline; 6. Upper air outlet; 61. Sleeve; 62. Hollow cavity; 63. Air pipe interface; 64. Tangential air inlet; 65. Spiral guide flange; 7. Temperature control anti-warping component; 71. Heat-conducting plate; 72. Infusion pipeline; 73. Circulation pump; 74. Cooling section; 8. Lower air supply component; 81. Pulse processing section; 811. Housing; 812. Air outlet; 813. Air supply pipeline; 814. Ultrasonic transducer; 815. Ultrasonic radiation plate; 816. Resonant cavity; 82. Air supply section. Detailed Implementation
[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0023] Please see Figures 1 to 12A semiconductor lead frame multi-point eccentric locking laser precision welding device includes a machine base 1, an axial motion platform 4 fixed on the upper end of the machine base 1, and a laser welding part 41 fixed on the moving end of the axial motion platform 4. It also includes two slides 2 symmetrically slidably on the upper end of the machine base 1, multiple eccentric locking parts 3 respectively connected to the upper ends of the two slides 2, a support part 5 fixed to the upper end of the slides 2 and located between the two slides 2, and an upper air outlet 6 fixed to the lower end of the laser welding part 41. The air outlet end of the upper air outlet 6 faces the support part 5 and outputs inert gas to the welding point. A hollow cavity 62 through which the laser beam passes is opened inside the upper air outlet 6. The support part 5 includes a middle partition plate 51 fixed to the upper end of the slide table 2 and located between the two slide tables 2, a second movable groove 53 opened at the upper end of the middle partition plate 51, a filter screen 52 fixed on the inner wall of the second movable groove 53, a movable seat 55 located inside the second movable groove 53, and an exhaust port 551 opened at the upper end of the movable seat 55. The machine base 1 is fixedly connected to a lower air supply assembly 8, and the output end of the lower air supply assembly 8 is connected to the input end of the exhaust port 551 through an air supply pipe 56.
[0024] The movable seat 55 is slidably connected in the second movable groove 53, and a lead screw drive part 54 is rotatably connected in the second movable groove 53. The lead screw drive part 54 is screwed inside the movable seat 55. A drive assembly is fixed inside the partition plate 51, and the output shaft of the drive assembly is connected to the lead screw drive part 54.
[0025] The eccentric locking part 3 includes a pressure plate 31 with one end rotatably connected to the upper end of the slide table 2, a bolt 32 screwed inside the pressure plate 31, and an eccentric pressing assembly set on the pressure plate 31. The upper end of the slide table 2 is provided with a threaded groove that matches the bolt 32. The bolt 32 passes through the pressure plate 31 and is screwed into the threaded groove. One side of one of the pressure plates 31 is integrally formed with an extension pressure block 34 for applying pressure to the lead frame welding area.
[0026] The eccentric clamping assembly includes an eccentric lever 33 rotatably connected to the pressure plate 31, a first movable groove 35 opened inside the pressure plate 31, a movable rod 37 movably inserted into the first movable groove 35, a limiting part 39 fixed to the upper end of the movable rod 37 and in contact with the eccentric lever 33, a pressure head 38 fixed to the lower end of the movable rod 37, and a spring 36 sleeved on the outside of the movable rod 37 and located in the first movable groove 35, with the two ends of the spring 36 respectively connected to the limiting part 39 and the inner wall of the first movable groove 35. like Figure 7As shown, by rotating the eccentric lever 33, the eccentric part of the eccentric lever 33 can press the limiting part 39 downward. The downward movement of the limiting part 39 drives the movable rod 37 and the pressure head 38 to move downward. The pressure head 38 can press and position the lead frame on the slide table 2, realizing the positioning and locking of the lead frame. After rotating the eccentric lever 33 to separate the eccentric part from the limiting part 39, the spring 36 can push the limiting part 39 up and down. The rising of the limiting part 39 drives the pressure head 38 to rise, canceling the positioning and locking of the lead frame.
[0027] By adopting the above technical solution, two slide tables 2 are slidably connected to the machine base 1. The two slide tables 2 can be driven to move by a lead screw, causing them to move towards each other or away from each other. Two lead frames are placed on the two slide tables 2 respectively, and the eccentric locking parts 3 on the slide tables 2 are used to lock and position the lead frames. Then, the two slide tables 2 are driven to move towards each other, bringing the ends of the lead frames on the two slide tables 2 (the end of the old roll and the beginning of the new roll) closer together. Finally, the laser welding part 41 laser-welds the connected ends of the two lead frames. 41 is composed of components such as a laser generator and lenses, which is a mature existing technology and will not be described in detail here. During the laser welding process, the axial motion platform 4 can drive the laser welding part 41 to move. The axial motion platform 4 is a dual-axis motion platform that can perform dual-axis motion in the Z-axis and X-axis. This kind of motion platform is a mature existing technology and will not be described in detail here. The Z-axis motion can drive the laser welding part 41 to rise or fall, thereby adjusting the height of the laser welding part 41. The X-axis motion can drive the laser welding part 41 to move back and forth, thereby realizing mobile welding. The upper air outlet 6 is connected to an external air pipe. Inert gas is discharged from the air pipe and enters the hollow cavity 62. The inert gas is discharged from the hollow cavity 62 and blown towards the solder joint. The resulting downward air pressure can effectively smooth the surface of the molten pool. The lower air supply component 8 supplies inert gas to the moving seat 55 through the air supply pipe 56. The inert gas is discharged from the exhaust port 551 and blown towards the solder joint through the filter screen 52. A constant static pressure of inert gas is delivered to the back of the lead frame through the exhaust port 551 to form an air cushion support. The upward support force generated by the static pressure can accurately counteract the gravity of the molten metal and the downward jetting force generated by the laser keyhole, preventing the liquid copper liquid from falling and forming weld beads due to its low viscosity and fast thermal conductivity. The non-contact physical constraint of the molten pool is generated by fluid dynamics, thereby solving the problem of morphological consistency of high thermal conductivity thin materials in laser bonding without damaging the pre-plating layer of the workpiece, and eliminating the interference of excess height and weld beads on subsequent precision processes.
[0028] The lead screw drive unit 54 is driven to rotate by the drive assembly (using a servo motor). The rotation of the lead screw drive unit 54 can drive the movable seat 55 to move in the second movable slot 53, so that the movable seat 55 and the exhaust port 551 can follow the welding point. By controlling the servo motor and the X-axis motion unit of the axial motion platform 4 to work synchronously, the synchronous movement of the laser welding part 41 and the movable seat 55 can be achieved. If higher accuracy is required, a position sensor can be added to detect the movement position and stroke of the laser welding part 41 and the movable seat 55, and the data can be fed back to the control unit. The control unit then controls the drive assembly and the axial motion platform 4 to work to adjust their positions, realizing closed-loop adjustment, so that the laser welding part 41 and the movable seat 55 can move synchronously.
[0029] like Figure 2 and Figure 10 As shown, the upper air outlet 6 includes a sleeve 61 fixed to the lower end of the laser welding part 41. The hollow cavity 62 is opened inside the sleeve 61. The sleeve 61 has multiple tangential air inlets 64 that are connected to the hollow cavity 62 and are inclined inside. The sleeve 61 also has multiple air pipe interfaces 63 that are connected to the tangential air inlets 64 on the outside. The inner wall of the hollow cavity 62 is integrally formed with multiple spiral guide flanges 65.
[0030] By adopting the above technical solution, the gas pipe interface 63 is connected to an external gas supply pipe. The inert gas in the gas supply pipe enters the tangential air inlet 64 through the gas pipe interface 63 and enters the hollow cavity 62 tangentially from the tangential air inlet 64. It is guided by the spiral guide flange 65 inside the hollow cavity 62 to form a swirling flow in the hollow cavity 62. The rotating airflow discharged from the hollow cavity 62 and blown towards the weld point can form a high-speed rotating air wall around the weld point. Due to the radial pressure gradient generated by the rotation, it will exert a squeezing force towards the center on the liquid molten pool. This force can forcibly restrain the molten pool that tends to spread outwards, making the weld width narrower. At the same time, the tangential shear force generated when the rotating airflow contacts the surface of the molten pool can break the surface tension steady state that causes the "bulge" phenomenon. Like a non-contact "rotating iron", it evenly smooths the accumulated molten metal towards the center, making the weld tend to be flat.
[0031] like Figure 4 , Figure 11 and Figure 12 As shown, the lower air supply assembly 8 includes an air supply unit 82 fixed inside the machine base 1 and a pulse processing unit 81 fixed at the upper end of the machine base 1. The output end of the air supply unit 82 is connected to the input end of the pulse processing unit 81, and the output end of the pulse processing unit 81 is connected to one end of the air supply pipe 56.
[0032] The pulse processing unit 81 includes a housing 811 fixed to the upper end of the machine base 1, a resonant cavity 816 opened inside the housing 811, an air supply pipe 813 fixed to the lower end of the housing 811, an air outlet 812 opened at the upper end of the housing 811, an ultrasonic transducer 814 fixed inside the housing 811, and an ultrasonic radiation plate 815 located in the resonant cavity 816 and fixed to the output end of the ultrasonic transducer 814. One end of the air supply pipe 813 is connected to the output end of the air supply unit 82, and the air outlet 812 is connected to the air supply pipe 56.
[0033] By adopting the above technical solution, high-frequency elastic mechanical waves are introduced into the path of the inert gas to achieve microscopic dynamic modulation of the transport medium (inert gas). Specifically, the gas supply unit 82 pumps the inert gas into the gas supply pipeline 813. After the gas is discharged from the gas supply pipeline 813 and enters the resonant cavity 816, it first contacts the ultrasonic radiation plate 815. Subsequently, the gas is forced to flow along the gap between the ultrasonic radiation plate 815 and the inner wall of the resonant cavity 816 and enters the main resonant cavity 816. This design can play a certain rectification role, making the airflow distribution into the resonant cavity 816 more uniform. To avoid high-speed airflow directly impacting the resonant region and causing turbulence, the ultrasonic transducer 814 is responsible for converting electrical energy into high-frequency mechanical vibration. Since the ultrasonic transducer 814 is physically connected to the ultrasonic radiating plate 815, the ultrasonic radiating plate 815 will reciprocate at high frequency along with the ultrasonic transducer 814. The large surface area of the ultrasonic radiating plate 815 contacts the gas inside the resonant cavity 816, acting like a speaker diaphragm, pushing and pulling the air to efficiently radiate mechanical vibration energy into the gas medium, forming an ultrasonic sound field. The gas in the resonant cavity 816 passes through the outlet 81... 2. The gas is discharged into the gas supply pipeline 56. By high-frequency modulation of the inert gas, the constant pressure flow is transformed into a pulsed gas flow with high-frequency oscillation. The high-frequency pulsed gas flow generates alternating instantaneous peak pressure below the molten pool. This pulsed force field is more effective than static pressure in counteracting the gravity of the molten metal and the downward jetting force of the laser, acting like a "dynamic air cushion" to steadily support the molten pool within the reference plane. Through the high-frequency mechanical vibration of the ultrasonic transducer 814, the ultrasonic radiation plate 815 is driven to generate periodic displacement within the flow channel of the lower gas supply component 8, thereby physically modulating the constant pressure inert gas flow into a flow with a specific pressure amplitude. Pulsed airflow: This pulsed airflow acts directly on the bottom of the molten pool, using high-frequency momentum to periodically counteract the downward gravitational component of the molten metal, achieving dynamic mechanical support and forced flattening of the bottom morphology of the molten pool. This effectively prevents the falling and accumulation of high thermal conductivity metal droplets, thus solving the common problem of back-side nodules at the lead frame connector. Furthermore, the micro-stirring effect generated by the high-frequency pulsed flow inside the molten pool can accelerate the aggregation and floating of bubbles inside the liquid metal, allowing them to be quickly discharged before the molten pool solidifies. This ensures the conductivity stability and mechanical consistency at the lead frame connector, effectively preventing brittle fracture of the joint due to porosity.
[0034] like Figure 5 , Figure 9 and Figure 11 As shown, two heat-conducting plates 71 are symmetrically fixed to the upper end of the partition plate 51. The filter screen 52 is located between two adjacent heat-conducting plates 71. A temperature control anti-warping component 7 is also connected inside the machine base 1. Flow channels are opened inside the two heat-conducting plates 71. The input end of the temperature control anti-warping component 7 is connected to the output end of the flow channel, and the output end is connected to the input end of the flow channel.
[0035] The temperature control and anti-warping component 7 includes a circulation pump 73 and a cooling section 74 fixed inside the machine base 1. The input end of the circulation pump 73 is connected to the output end of the cooling section 74. The output end of the circulation pump 73 is connected to the input end of the flow channel through a liquid delivery pipe 72. The input end of the cooling section 74 is connected to the output end of the flow channel through a liquid delivery pipe 72.
[0036] The filter 52 is made of conductive material and is used to generate heat itself when energized.
[0037] By adopting the above technical solution, the filter screen 52, as the bottom support, provides a microscopic physical boundary for the molten pool, directly blocking the molten metal from forming lumps due to gravity. Heating the filter screen 52 reduces the temperature difference between the molten copper and the supporting medium, preventing uneven shrinkage caused by "sudden cooling" at the bottom of the molten pool due to contact with a cold surface, allowing the molten metal to spread evenly on the surface of the filter screen 52 instead of accumulating into droplets. Coolant flows inside the flow channel, circulation pump 73, and cooling section 74. The circulation pump 73 circulates the coolant, and the cooling section 74 cools the coolant discharged from the flow channel. The cooled coolant then re-enters the flow channel through the circulation pump 73. This ensures that the two guides... The hot plate 71 has a heat dissipation and cooling effect. The two heat-conducting plates 71 on both sides, together with the coolant, form a thermal enclosure. This intense heat conduction contrast cuts off the lateral diffusion of heat and greatly narrows the heat-affected zone. When the molten pool is confined to an extremely narrow range, its total melting volume is reduced, and the volume change caused by thermal expansion and phase change is also reduced accordingly, thus suppressing the bulge height from a physical perspective. This layout of hot in the middle and cold on both sides establishes a gentle cooling gradient in the center of the weld, while the sides have a steep cooling gradient. This can offset some of the shrinkage stress during the cooling process, prevent the lead frame from producing a "wavy" macroscopic deformation at the joint, improve the toughness of the joint, and ensure that the joint will not break during subsequent high-speed punching or electroplating processes.
[0038] Operating Instructions: Two slide tables 2 are slidably connected to the machine base 1. The two slide tables 2 are driven by a lead screw, allowing them to move towards or away from each other. Two lead frames are placed on the two slide tables 2 respectively. The eccentric locking parts 3 on the slide tables 2 are then used to lock and position the lead frames. The two slide tables 2 are then driven to move towards each other, bringing the ends of the lead frames (the end of the old roll and the beginning of the new roll) closer together. The laser welding part 41 is used to laser weld the connected ends of the two lead frames. An external air supply pipe is connected to the air pipe interface 63 to supply air to the machine. Inert gas from the trachet enters the tangential inlet 64 through the trachet interface 63, and then tangentially enters the hollow cavity 62 from the tangential inlet 64. It is guided by the spiral guide flange 65 inside the hollow cavity 62, forming a swirling flow within the cavity. The rotating airflow exiting the hollow cavity 62 and blowing towards the weld point creates a high-speed rotating air wall around the weld point, and the resulting downward air pressure effectively smooths the surface of the molten pool. The gas supply unit 82 pumps the inert gas into the gas supply line 813. After exiting the gas supply line 813 and entering the resonant cavity 816, the gas first interacts with the ultrasonic radiation plate. Upon contact at 815, the gas is forced to flow along the gap between the ultrasonic radiating plate 815 and the inner wall of the resonant cavity 816, entering the main resonant cavity 816. The ultrasonic transducer 814 is responsible for converting electrical energy into high-frequency mechanical vibration. Because the ultrasonic transducer 814 is physically connected to the ultrasonic radiating plate 815, the ultrasonic radiating plate 815 will reciprocate at high frequency along with the ultrasonic transducer 814. The larger surface of the ultrasonic radiating plate 815 contacts the gas inside the resonant cavity 816, acting like the diaphragm of a loudspeaker, pushing and pulling the air to transfer the mechanical vibration energy. The ultrasonic sound field is efficiently radiated into the gas medium. By high-frequency modulation of the inert gas, the constant pressure flow is transformed into a pulsed airflow with high-frequency oscillation. The pulsed airflow enters the movable seat 55 through the gas supply pipe 56. The inert gas is discharged from the exhaust port 551 and blown towards the solder joint through the filter screen 52. Constant static pressure inert gas is delivered to the back of the lead frame through the exhaust port 551 to form an air cushion support. The upward support force generated by the static pressure can accurately counteract the gravity of the molten metal and the downward jetting force generated by the laser keyhole, preventing the liquid copper liquid from falling and forming a weld bead due to its low viscosity and fast heat conduction.
[0039] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.
Claims
1. A semiconductor lead frame multi-point eccentric locking laser precision welding device, comprising a machine base (1), an axial motion platform (4) fixed on the upper end of the machine base (1), and a laser welding part (41) fixed on the moving end of the axial motion platform (4), characterized in that: It also includes two slides (2) symmetrically slidably connected to the upper end of the machine base (1), multiple eccentric locking parts (3) respectively connected to the upper end of the two slides (2), a support part (5) fixed to the upper end of the slides (2) and located between the two slides (2), and an upper air outlet (6) fixed to the lower end of the laser welding part (41). The air outlet end of the upper air outlet (6) faces the support part (5) and outputs inert gas to the welding point. The upper air outlet (6) has a hollow cavity (62) through which the laser beam passes. The support part (5) includes a partition plate (51) fixed on the upper end of the slide (2) and located between the two slides (2), a second movable groove (53) opened on the upper end of the partition plate (51), a filter screen (52) fixed on the inner wall of the second movable groove (53), a movable seat (55) located inside the second movable groove (53), and an exhaust port (551) opened on the upper end of the movable seat (55). The machine base (1) is fixedly connected to a lower air supply assembly (8), and the output end of the lower air supply assembly (8) is connected to the input end of the exhaust port (551) through an air supply pipe (56).
2. The semiconductor lead frame multi-point eccentric locking laser precision welding device according to claim 1, characterized in that: The movable seat (55) is slidably connected in the second movable groove (53), and a lead screw drive unit (54) is rotatably connected in the second movable groove (53). The lead screw drive unit (54) is screwed inside the movable seat (55). A drive assembly is fixed inside the middle partition plate (51), and the output shaft of the drive assembly is connected to the lead screw drive unit (54).
3. The semiconductor lead frame multi-point eccentric locking laser precision welding device according to claim 1, characterized in that: The eccentric locking part (3) includes a pressure plate (31) rotatably connected to the upper end of the slide (2), a bolt (32) screwed inside the pressure plate (31), and an eccentric clamping assembly set on the pressure plate (31). The upper end of the slide (2) is provided with a threaded groove that matches the bolt (32). The bolt (32) passes through the pressure plate (31) and is screwed into the threaded groove. One side of one of the pressure plates (31) is integrally formed with an extended pressure block (34) for applying pressure to the lead frame welding area.
4. The semiconductor lead frame multi-point eccentric locking laser precision welding device according to claim 3, characterized in that: The eccentric clamping assembly includes an eccentric lever (33) rotatably connected to the pressure plate (31), a first movable groove (35) opened inside the pressure plate (31), a movable rod (37) movably inserted into the first movable groove (35), a limiting part (39) fixed to the upper end of the movable rod (37) and in contact with the eccentric lever (33), a pressure head (38) fixed to the lower end of the movable rod (37), and a spring (36) sleeved on the outside of the movable rod (37) and located in the first movable groove (35), with the two ends of the spring (36) respectively connected to the limiting part (39) and the inner wall of the first movable groove (35).
5. The semiconductor lead frame multi-point eccentric locking laser precision welding device according to claim 1, characterized in that: The upper air outlet (6) includes a sleeve (61) fixed to the lower end of the laser welding part (41). The hollow cavity (62) is opened inside the sleeve (61). The sleeve (61) has multiple tangential air inlets (64) that communicate with the hollow cavity (62) at an angle inside. The sleeve (61) also has multiple air pipe interfaces (63) that communicate with the tangential air inlets (64) on the outside. The inner wall of the hollow cavity (62) is integrally formed with multiple spiral guide flanges (65).
6. The semiconductor lead frame multi-point eccentric locking laser precision welding device according to claim 1, characterized in that: The lower air supply assembly (8) includes an air supply unit (82) fixed inside the machine base (1) and a pulse processing unit (81) fixed on the upper end of the machine base (1). The output end of the air supply unit (82) is connected to the input end of the pulse processing unit (81), and the output end of the pulse processing unit (81) is connected to one end of the air supply pipeline (56).
7. The semiconductor lead frame multi-point eccentric locking laser precision welding device according to claim 6, characterized in that: The pulse processing unit (81) includes a housing (811) fixed to the upper end of the machine base (1), a resonant cavity (816) opened inside the housing (811), an air supply pipe (813) fixed to the lower end of the housing (811), an air outlet (812) opened at the upper end of the housing (811), an ultrasonic transducer (814) fixed inside the housing (811), and an ultrasonic radiation plate (815) located in the resonant cavity (816) and fixed to the output end of the ultrasonic transducer (814). One end of the air supply pipe (813) is connected to the output end of the air supply unit (82), and the air outlet (812) is connected to the air delivery pipe (56).
8. The semiconductor lead frame multi-point eccentric locking laser precision welding device according to claim 1, characterized in that: Two heat-conducting plates (71) are symmetrically fixed to the upper end of the partition plate (51). The filter screen (52) is located between two adjacent heat-conducting plates (71). The machine base (1) is also connected to a temperature control anti-warping component (7). The two heat-conducting plates (71) are provided with flow channels. The input end of the temperature control anti-warping component (7) is connected to the output end of the flow channel, and the output end is connected to the input end of the flow channel.
9. The semiconductor lead frame multi-point eccentric locking laser precision welding device according to claim 8, characterized in that: The temperature control anti-warping component (7) includes a circulation pump (73) and a cooling section (74) fixed inside the machine (1). The input end of the circulation pump (73) is connected to the output end of the cooling section (74). The output end of the circulation pump (73) is connected to the input end of the flow channel through a liquid delivery pipe (72). The input end of the cooling section (74) is connected to the output end of the flow channel through a liquid delivery pipe (72).
10. The semiconductor lead frame multi-point eccentric locking laser precision welding device according to claim 9, characterized in that: The filter (52) is made of conductive material and is used to generate heat itself when energized.