Apparatus and method for single-filament consumable arc droplet production of tin-based alloy spheres

Abstract

The application relates to a device and a method for preparing tin-based alloy balls by single-wire melting electrode arc droplet, the device comprising an arc power source, a wire feeding unit, a conductive nozzle, a conductive base, a cooling channel and a collecting unit, the wire feeding unit being used for continuously conveying a single tin-based alloy welding wire; the conductive nozzle is electrically connected with one pole of the arc power source, the tin-based alloy welding wire passes through a wire channel in the conductive nozzle, and the tin-based alloy welding wire is electrically connected with one pole of the arc power source by being in contact with the inner wall of the wire channel; the conductive base is electrically connected with the other pole of the arc power source, and the end of the tin-based alloy welding wire can form a molten droplet in a molten state under the action of the arc; the cooling channel is used for cooling and hardening the molten droplet in the molten state into a tin-based alloy ball; and the collecting unit is communicated with the cooling channel and is used for storing the tin-based alloy balls falling from the cooling channel. The welding wire itself is used as a melting electrode, the raw material is integrated with the electrode, foreign impurities such as tungsten and carbon are eliminated from the source, and the appearance quality and yield of the finished product are significantly improved.

Description

Technical Field

[0001] This application relates to the field of metal microsphere preparation technology, and in particular to an apparatus and method for preparing tin-based alloy spheres from single-wire melting electrode arc droplets. Background Technology

[0002] Tin-based alloy balls are indispensable key interconnect materials in the field of high-end electronic packaging, and are widely used in the packaging and soldering of products such as high-density integrated circuits, consumer electronics, automotive electronics, and optoelectronic devices. As electronic devices develop towards miniaturization, high integration, high reliability, and long lifespan, extremely stringent requirements are placed on the sphericity, particle size uniformity, surface finish, internal density, oxygen content, compositional uniformity, and batch stability of tin-based alloy balls.

[0003] Currently, the mainstream technologies for preparing tin-based alloy balls have significant shortcomings: gas atomization and centrifugal atomization equipment require large investments, have complex systems, and consume a lot of energy. They require the entire tin material to be melted, and the high-temperature melt is prone to secondary oxidation. The finished product has a wide particle size distribution and large fluctuations in sphericity, requiring multi-stage sieving and shaping, resulting in high costs and low yields. The uniform droplet method requires extremely high precision, is sensitive to melt temperature and fluidity, is prone to component segregation, has low production efficiency, and is difficult to mass-produce. The mechanical melting and remelting method has poor forming precision, is prone to tailing, ellipsoids, and adhesion, and is only suitable for low-end rough processing. Traditional arc ball making uses non-fusible electrodes such as tungsten electrodes and graphite, which have problems such as burn-off pollution, arc deviation, complex structure, and poor stability in continuous production. The dual-wire arc scheme has defects such as difficulty in aligning the two wires, mutual interference of the arcs, droplet trajectory deviation, and complex control logic, which cannot meet the stable preparation requirements of high-end packaging tin balls. Summary of the Invention

[0004] This application provides an apparatus and method for preparing tin-based alloy balls from droplets produced by a single-wire melting electrode arc. The method uses a single tin-based alloy welding wire as both the melting electrode and the ball-forming material, eliminating the need for a non-melting tungsten electrode. Through a coaxial arc, programmable linkage control, and full-process inertial protection, the method achieves stable droplet detachment and precise ball formation, solving the problems of high pollution, poor forming, difficult control, high cost, and difficulty in continuous mass production associated with traditional technologies.

[0005] On one hand, this application provides an apparatus for preparing tin-based alloy spheres from droplets of a single-wire melting electrode arc, comprising: Arc power source; The wire feeding unit is used to continuously feed a single tin-based alloy welding wire; the tin-based alloy welding wire is pure tin welding wire, tin-bismuth alloy welding wire or tin-silver-copper alloy welding wire, and the purity of the welding wire is ≥99.95%.

[0006] The conductive tip is located on the output side of the wire feeding unit and is electrically connected to one pole of the arc power supply. A wire channel running through the conductive tip along the height direction is formed inside the conductive tip. The tin-based alloy welding wire passes through the wire channel and is electrically connected to one pole of the arc power supply by contacting the inner wall of the wire channel. The conductive base is located on the output side of the conductive tip and is electrically connected to the other pole of the arc power supply. An arc working area is formed between the conductive base and the end of the tin-based alloy welding wire. The end of the tin-based alloy welding wire can form a molten droplet in the arc working area. Cooling channel, located on the output side of the conductive base, is used to cool and harden the molten droplets into tin-based alloy balls during their descent. The collection unit is connected to the cooling channel and is used to store tin-based alloy balls falling from the cooling channel.

[0007] In one possible design, the vertical distance between the conductive base and the end of the tin-based alloy welding wire is maintained at 1-3 mm to form a stable localized arc working area at the end of the tin-based alloy welding wire. And / or, the conductive base is a ring-shaped conductive structure, with a clearance hole in the center of the conductive base for the passage of molten droplets, and the conductive base is coaxially arranged with the tin-based alloy welding wire to form an arc circuit in conjunction with the tin-based alloy welding wire.

[0008] In one possible design, an atmosphere protection unit is also included, which provides protective gas to the arc working area and cooling channel. The protective gas flows downward along the cooling channel to form a laminar protective gas curtain that completely envelops the molten droplets.

[0009] The protective gas is high-purity argon or an argon-hydrogen mixture with a hydrogen content of 1%-10% and a gas purity of ≥99.999%. The flow rate of the protective gas is controlled at 5L / min to 20L / min to ensure sufficient oxygen isolation without interfering with the falling trajectory of the molten droplets and the formation of spheres.

[0010] In one possible design, the atmosphere protection unit includes an isolation enclosure and a gas source. The isolation enclosure is located outside the arc working area and is connected to the gas source to maintain an inert gas environment in the arc working area.

[0011] In one possible design, the upper end of the cooling channel is sealed and connected to the isolation cover, and the lower end of the cooling channel is sealed and connected to the collection unit. The length L of the cooling channel satisfies:

[0012] Where t is the time required for the droplet to completely solidify, and v0 is the initial velocity when the droplet falls off.

[0013] In one possible design, the roughness of the inner wall of the cooling channel... ; And / or, the outer wall of the cooling channel is provided with a circulating water cooling jacket to regulate the ambient temperature inside the cooling channel.

[0014] In one possible design, the collection unit is a sealed container with a flexible buffer structure inside.

[0015] The flexible buffer structure is a buffer mesh or a buffer plate. For example, a buffer mesh has its edge connected to the inner wall of a sealed container. The buffer mesh has holes off-center. In its natural state, the buffer mesh hangs down in an arc from the edge to the holes. After the solder ball falls vertically into the buffer mesh along the central axis, it is buffered, slides down the mesh to the holes, and continues to fall into the sealed container, thus preventing the solder ball from being deformed by collision during its natural fall.

[0016] In one possible design, a programmable control unit is also included. The programmable control unit is connected to the arc power supply and the wire feeding unit respectively, and is used to adjust the arc parameters output by the arc power supply and the wire feeding speed of the wire feeding unit in a coordinated manner according to a preset program.

[0017] On the other hand, this application also provides a method for preparing tin-based alloy spheres from single-wire melting electrode arc droplets, characterized in that the apparatus for preparing tin-based alloy spheres from single-wire melting electrode arc droplets as described above is used, and the method includes: S1. Select a single tin-based alloy welding wire as the melting electrode and ball-making material, and clean the surface of the welding wire. S2. Introduce protective gas into the arc working area and cooling channel to create an oxygen-free protective atmosphere; S3. Connect the tin-based alloy welding wire to one pole of the arc power source and connect the conductive base to the other pole of the arc power source. The conductive base and the tin-based alloy welding wire are arranged coaxially to form an arc working area and constitute a complete arc circuit. S4. Start the arc power supply and ignite the consumable electrode arc. The arc is concentrated on the end of the tin-based alloy welding wire, causing the end of the tin-based alloy welding wire to melt and form molten droplets. S5. Based on the law of conservation of volume The pulse frequency f and wire feed speed v are linked and adjusted, where D is the target ball diameter and d is the welding wire diameter. S6. The molten droplets fall and cool to solidify in an inert atmosphere; S7. Collect the cured tin-based alloy balls in a sealed container.

[0018] In one possible design, in step S5, the axial electromagnetic force generated by the pulsed arc... Must meet: ,in To prevent the surface tension from detaching, For the gravity of the molten droplet; surface tension satisfies ,in The diameter of the welding wire. is the surface tension coefficient of tin-based alloys under a protective atmosphere.

[0019] The beneficial effects of this application are as follows: The apparatus for preparing tin-based alloy balls using a single-wire melting electrode arc droplet completely eliminates non-melting electrodes such as tungsten electrodes and graphite, using the welding wire itself as the melting electrode. This integration of raw material and electrode eliminates the introduction of foreign impurities such as tungsten and carbon at the source, resulting in higher purity and more uniform composition in the finished product. The arc energy is highly concentrated in a very small area at the tip of the welding wire, resulting in high thermal efficiency and low overheating risk. It is particularly suitable for low-melting-point, easily oxidized soft solders such as tin-bismuth and tin-silver-copper alloys, avoiding problems such as overheating, spattering, and component segregation. It exhibits strong process compatibility and a wide range of applications.

[0020] By employing a coaxial laminar inert gas curtain, oxygen-free protection is achieved throughout the entire process from wire melting, droplet growth, detachment, cooling to collection. This effectively inhibits high-temperature oxidation, resulting in a finished product with a much lower oxygen content than traditional atomization and droplet methods. The surface is bright and free of oxidation color, and the welding wettability is superior.

[0021] The welding wire, conductive base, cooling channel, and collection unit are arranged coaxially, and the molten droplets fall vertically along the central axis without hitting, rubbing, or sticking to the pipe wall. With the flexible buffer of the collection unit, impact deformation, scratches, and dents are effectively avoided, and the appearance quality and yield of the finished product are significantly improved.

[0022] The monofilament self-consuming structure enables uninterrupted filament feeding and uninterrupted ball formation. Combined with a closed-loop control system, it can operate continuously and stably for a long time. The production process is stable, with low noise and no smoke or dust. It is easy to integrate into automated production lines and meet the needs of large-scale industrial mass production.

[0023] Programmable linkage control enables precise single-pulse single-droplet molding. By simply adjusting the wire feed speed, pulse frequency, and arc parameters, tin-based alloy spheres of different sizes can be precisely customized within a wide range, with highly consistent droplet volume. Combined with a coaxial arc, centered falling, and no offset trajectory, the droplets are fully spherized by surface tension, resulting in near-perfect sphericity and extremely narrow particle size distribution. This eliminates the need for multi-stage sieving and shaping, significantly improving the yield. It meets the usage requirements of different packaging specifications such as BGA, CSP, flip chips, and micro-bumps, offering excellent product flexibility and market adaptability.

[0024] The method for preparing tin-based alloy balls using a single-wire molten electrode arc droplet provided in this application includes all the advantages of the apparatus for preparing tin-based alloy balls using a single-wire molten electrode arc droplet as described in this application. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 A schematic diagram of the apparatus for preparing tin-based alloy spheres from single-wire melting electrode arc droplets provided in an embodiment of this application; Figure 2 This is a schematic diagram of a flexible buffer structure.

[0027] Figure label: 1. Arc power supply; 2. Wire feeding unit; 3. Conductive nozzle; 4. Conductive base; 5. Cooling channel; 6. Collection unit; 7. Isolation cover; 8. Tin-based alloy welding wire; 9. Buffer mesh; 10. Leakage hole; 11. Programmable control unit; 12. Air source; 13. Molten droplet; 14. Tin-based alloy ball. Detailed Implementation

[0028] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] The following is combined Figure 1 This application describes the apparatus for preparing tin-based alloy balls 14 from a single-wire melting electrode arc droplet 13 provided in the embodiments of this application.

[0030] The apparatus for preparing tin-based alloy balls 14 from single-wire melting electrode arc droplets 13 provided in this application embodiment includes an arc power source 1, a wire feeding unit 2, a conductive nozzle 3, a conductive base 4, a cooling channel 5, and a collection unit 6. The tin-based alloy welding wire 8 is coaxially arranged with the conductive nozzle 3, the conductive base 4, and the cooling channel 5.

[0031] The arc power supply 1 adopts a DC arc power supply 1 or a pulsed DC arc power supply 1. The wire feeding unit 2 is used to continuously feed a single tin-based alloy welding wire 8. Specifically, the wire feeding unit 2 includes two wire feeding rollers. The motor drives the wire feeding rollers to rotate slowly and steadily. The welding wire is pressed into the groove between the two wire feeding rollers, and the welding wire is fed downward under the action of friction. The tin-based alloy welding wire 8 is pure tin welding wire, tin-bismuth alloy welding wire, or tin-silver-copper alloy welding wire, and the purity of the welding wire is ≥99.95%.

[0032] The conductive tip 3 is located below the wire feeding unit 2 and is electrically connected to one pole of the arc power supply 1. A wire channel extending vertically along the height direction is formed inside the conductive tip 3. The diameter of the wire channel is slightly larger than the diameter of the wire; specifically, the diameter difference between the wire channel and the wire is maintained at 0.05-0.15 mm. In this way, the tin-based alloy welding wire 8 can pass smoothly and at a uniform speed through the wire channel. Because the diameter difference between the wire channel and the wire is small, and the wire channel has a certain longitudinal length, the wire does not make point contact when passing through, but rather a line contact along a certain length. Even if there are some gaps in certain areas, a section will always be in contact with the inner wall of the wire channel. This ensures that the conductive tin-based alloy welding wire 8 is in contact with the inner wall of the wire channel and maintains electrical connection with one pole of the arc power supply 1.

[0033] The conductive base 4 is located below the conductive nozzle 3 and is electrically connected to the other pole of the arc power supply 1. An arc working area is formed between the conductive base 4 and the end of the tin-based alloy welding wire 8. When energized, the end of the tin-based alloy welding wire 8 can form a molten droplet 13 in the arc working area.

[0034] In some specific embodiments, the vertical distance between the conductive base 4 and the end of the tin-based alloy welding wire 8 is maintained at 1-3 mm to form a stable localized arc working area at the end of the tin-based alloy welding wire 8. Maintaining the distance at 1-3 mm is beneficial to forming a localized, highly stable arc, which does not drift or extinguish, concentrates heat input, and makes the formation of the molten droplet 13 more stable.

[0035] In some specific embodiments, the conductive base 4 has a ring-shaped conductive structure, and the center of the conductive base 4 is provided with a clearance hole for the molten droplet 13 to pass through. The diameter of the clearance hole is ≥5mm. The conductive base 4 is coaxially arranged with the tin-based alloy welding wire 8 to form an arc circuit in cooperation with the tin-based alloy welding wire 8. The arc force is symmetrical, the molten droplet 13 is subjected to uniform force, the sphericity is higher, the particle size is better consistent, and the finished product qualification rate is effectively improved.

[0036] The cooling channel 5 is located below the conductive base 4 and extends along the height direction. The cooling channel 5 is used to cool and harden the molten droplets 13 into tin-based alloy balls 14 during the falling process.

[0037] In some embodiments, the roughness of the inner wall of the cooling channel 5 By maintaining a low roughness on the inner wall of the cooling channel 5, the protective gas flows in a stable laminar manner, preventing turbulent disturbance of the molten droplets 13 and resulting in more rounded droplets. For example, the cooling channel 5 can be a vertical, sealed quartz glass tube with a smooth, unprotruding inner wall.

[0038] In some embodiments, the outer wall of the cooling channel 5 is provided with a circulating water cooling jacket to regulate the ambient temperature inside the cooling channel 5, thereby preventing the molten droplets 13 from cracking due to rapid cooling or shrinking due to slow cooling, and improving the internal density and batch stability.

[0039] The collection unit 6 is located below and connected to the cooling channel 5, and is used to store the tin-based alloy balls 14 falling from the cooling channel 5. Specifically, the collection unit 6 is a sealed container, such as a stainless steel tank, with a flexible buffer structure inside, which is a buffer net 9 or a buffer plate.

[0040] In some specific embodiments, the flexible buffer structure is a buffer mesh 9. The edge of the buffer mesh 9 is connected to the inner wall of the sealed container. The buffer mesh 9 has a hole 10 at an off-center position. In its natural state, the buffer mesh 9 hangs down in an arc shape from the edge to the hole 10. After the solder ball falls vertically into the buffer mesh 9 along the central axis, it is buffered and slides down the filter to the hole 10 and continues to fall into the sealed container, thereby preventing the solder ball from being deformed by collision when falling naturally.

[0041] In some specific embodiments, the device further includes an atmosphere protection unit, which provides protective gas to the arc working area, cooling channel 5, and collection unit 6. The protective gas flows downward along the cooling channel 5, forming a laminar protective gas curtain that completely surrounds the molten droplets 13. The collection unit 6 is equipped with a one-way valve, which controls the outflow rate of the protective gas to be less than the inflow rate, thereby creating a slight positive pressure inside the arc working area, cooling channel 5, and collection unit 6 to prevent external air from entering. The inert laminar gas curtain covers the entire process of the molten droplets 13 from generation to collection, completely blocking the high-temperature oxidation of the molten droplets 13, resulting in an oxygen content in the finished tin-based alloy balls 14 that is far lower than that of traditional processes.

[0042] Specifically, the atmosphere protection unit includes an isolation cover 7 and a gas source 12. The isolation cover 7 is an arc-shaped cover that is installed outside the arc working area. The isolation cover 7 is connected to the gas source 12. By introducing protective gas into the isolation cover 7, the arc working area is maintained inert gas environment.

[0043] In some embodiments, the protective gas is high-purity argon or an argon-hydrogen mixture, with a hydrogen content of 1%-10% and a gas purity ≥99.999%. The protective gas flow rate is controlled between 5L / min and 20L / min. By controlling the gas flow rate, sufficient oxygen isolation is ensured without interfering with the falling trajectory of the molten droplet 13 and the formation of the ball. The argon-hydrogen mixture can slightly reduce the oxide layer, further improving the surface finish and wettability of the solder ball, thus meeting the requirements of high-end packaging.

[0044] In some specific embodiments, the upper end of the cooling channel 5 is sealed and connected to the isolation cover 7, and the lower end of the cooling channel 5 is sealed and connected to the collection unit 6. The length L of the cooling channel 5 satisfies:

[0045] Where t is the time required for droplet 13 to completely solidify, and v0 is the initial velocity of droplet 13 when it falls off.

[0046] The device also includes a programmable control unit 11, which is connected to the arc power supply 1 and the wire feeding unit 2 respectively, and is used to adjust the arc parameters output by the arc power supply 1 and the wire feeding speed of the wire feeding unit 2 in conjunction with a preset program.

[0047] This application also provides a method for preparing tin-based alloy spheres 14 from single-wire melting electrode arc droplets 13, characterized in that the apparatus for preparing tin-based alloy spheres 14 from single-wire melting electrode arc droplets 13 in the above embodiments is used, and the method includes: S1. Select a single high-purity tin-based alloy welding wire 8 as the melting electrode and ball-forming material. The welding wire material includes pure tin, tin-bismuth alloy, tin-silver-copper alloy, etc., with a purity ≥99.95%. For example, a tin-bismuth alloy welding wire with a diameter of 0.8-1.2mm is selected. Use anhydrous ethanol or a special cleaning agent to degrease and remove oxide scale from the surface of the welding wire, removing oil, oxide layer and impurities to ensure that the welding wire surface is clean, has stable conductivity, and allows for smooth arc initiation.

[0048] S2. Start the atmosphere protection unit and introduce high-purity protective gas into the interior of the isolation cover 7 and the cooling channel 5 to continuously purge and replace the internal air and establish a stable oxygen-free protective environment. The protective gas forms a laminar flow curtain vertically downward along the cooling channel 5, which completely covers the end of the welding wire, the arc working area and the path of the falling droplets 13.

[0049] S3. Tin-based alloy welding wire 8 passes through the welding wire channel. Tin-based alloy welding wire 8 is connected to one pole of arc power supply 1 through conductive tip 3, and conductive base 4 is connected to the other pole of arc power supply 1. Adjust the welding wire and conductive base 4 to be coaxially aligned, and control the vertical distance between the end of the welding wire and the conductive base 4 to be 1-3mm, forming a complete conductive circuit with a very simple structure and no non-molten tungsten electrode, providing a basis for stable arc initiation.

[0050] S4. Start the arc power supply 1 and ignite a stable consumable electrode arc between the end of the welding wire and the conductive base 4. The arc energy is highly concentrated on the end of the welding wire, which locally and rapidly heats the welding wire to above the melting point, causing the metal to continue to melt. Under the combined action of surface tension, arc force and gravity, the molten metal gathers to form a regular shape and a rounded outline of molten spherical droplet 13, without splashing, drawing wire, or deflection.

[0051] S5. Due to the volume conservation of the target solder ball volume and the molten solder wire volume, that is... In the formula: D is the target solder ball diameter, d is the solder wire diameter, v is the wire feed speed, and f is the pulse frequency. Therefore, the target solder ball diameter can be controlled by adjusting the pulse frequency f and the wire feed speed v in conjunction with the programmable control unit 11. Simultaneously, the pulse arc parameters can be adjusted via programmable control to ensure that the axial electromagnetic force satisfies: ,in σ represents the surface tension, Fg represents the gravity of droplet 13, and σ represents the surface tension coefficient of the tin-based alloy under a protective atmosphere, ensuring that droplet 13 can overcome surface tension and fall off stably without tailing, adhesion, or splashing.

[0052] S6. The molten droplet 13 falls vertically along the central axis of the cooling channel 5, and dissipates heat, cools down and solidifies under the protection of the inert laminar flow air curtain throughout the process. The cooling channel 5 provides sufficient stroke and controllable cooling rate to ensure that the molten droplet 13 gradually hardens during the falling process, maintaining high sphericity, high density, no internal defects and no oxidation discoloration.

[0053] S7. The fully cured tin-based alloy spheres 14 enter the collection unit 6. After being protected by the internal flexible buffer structure, they are sealed and collected in the container. The collection process is completely isolated from air to avoid collision deformation and secondary oxidation, and finally obtains tin-based alloy spheres 14 with high sphericity, uniform particle size, smooth surface, low oxygen and high purity.

[0054] The preparation method of this application employs a DC pulsed arc power supply 1, with the arc operating in a low-power, stable combustion range to suit the low melting point characteristics of tin-based alloys and avoid localized overheating and spatter. The pulse current is set with a base current and a peak current. The base current maintains continuous and stable arc combustion, while the peak current concentrates heating the end of the welding wire to achieve concentrated melting and droplet detachment. The pulse frequency and wire feed speed are synchronously matched, ensuring that the droplet 13 completes a stable detachment once per pulse cycle, achieving precise control of a single pulse and a single droplet 13. The wire feed speed adopts a uniform continuous feed mode, matching the wire feed speed with the arc heat input to ensure a complete balance between the welding wire melting rate and the feed rate, achieving continuous and uninterrupted ball formation.

[0055] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not 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 application.

[0056] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0057] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0058] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0059] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An apparatus for preparing tin-based alloy spheres from single-wire melting electrode arc droplets, characterized in that, include: Arc power source; A wire feeding unit, wherein the wire feeding unit is used to continuously feed a single tin-based alloy welding wire; A conductive tip is disposed on the output side of the wire feeding unit and electrically connected to one pole of the arc power supply. A welding wire channel extending along the height direction is formed inside the conductive tip. Tin-based alloy welding wire passes through the welding wire channel and is electrically connected to one pole of the arc power supply by contacting the inner wall of the welding wire channel. A conductive base is disposed on the output side of the conductive nozzle and electrically connected to the other pole of the arc power supply. An arc working area is formed between the conductive base and the end of the tin-based alloy welding wire. The end of the tin-based alloy welding wire can form a molten droplet in the arc working area. A cooling channel is provided on the output side of the conductive base, and the cooling channel is used to cool and harden the molten droplets into tin-based alloy balls during the falling process; A collection unit, which is connected to the cooling channel, is used to store tin-based alloy balls falling from the cooling channel.

2. The apparatus for preparing tin-based alloy spheres from single-wire melting electrode arc droplets according to claim 1, characterized in that, The vertical distance between the conductive base and the end of the tin-based alloy welding wire is maintained at 1-3 mm to form a stable localized arc working area at the end of the tin-based alloy welding wire. And / or, the conductive base has an annular conductive structure, the center of the conductive base is provided with a clearance hole for the passage of molten droplets, and the conductive base is coaxially arranged with the tin-based alloy welding wire to form an arc circuit in cooperation with the tin-based alloy welding wire.

3. The apparatus for preparing tin-based alloy spheres from single-wire melting electrode arc droplets according to claim 1 or 2, characterized in that, It also includes an atmosphere protection unit, which provides protective gas to the arc working area and the cooling channel. The protective gas flows downward along the cooling channel to form a laminar protective gas curtain that completely envelops the molten droplets.

4. The apparatus for preparing tin-based alloy spheres from single-wire melting electrode arc droplets according to claim 3, characterized in that, The atmosphere protection unit includes an isolation cover and a gas source. The isolation cover is located outside the arc working area and is connected to the gas source to maintain an inert gas environment in the arc working area.

5. The apparatus for preparing tin-based alloy spheres from single-wire melting electrode arc droplets according to claim 4, characterized in that, The upper end of the cooling channel is sealed and connected to the isolation cover, and the lower end of the cooling channel is sealed and connected to the collection unit. The length L of the cooling channel satisfies: Where t is the time required for the droplet to completely solidify, and v0 is the initial velocity when the droplet falls off.

6. The apparatus for preparing tin-based alloy spheres from single-wire melting electrode arc droplets according to claim 1 or 2, characterized in that, The inner wall roughness of the cooling channel ; And / or, the outer wall of the cooling channel is provided with a circulating water cooling jacket for regulating the ambient temperature inside the cooling channel.

7. The apparatus for preparing tin-based alloy spheres from single-wire melting electrode arc droplets according to claim 1 or 2, characterized in that, The collection unit is a sealed container with a flexible buffer structure inside.

8. The apparatus for preparing tin-based alloy spheres from single-wire melting electrode arc droplets according to claim 1 or 2, characterized in that, It also includes a programmable control unit, which is connected to the arc power supply and the wire feeding unit respectively, and is used to adjust the arc parameters output by the arc power supply and the wire feeding speed of the wire feeding unit in conjunction according to a preset program.

9. A method for preparing tin-based alloy spheres from droplets formed by a single-wire melting electrode arc, characterized in that, The apparatus for preparing tin-based alloy spheres using the single-wire melting electrode arc droplet according to any one of claims 1-8, the method comprising: S1. Select a single tin-based alloy welding wire as the melting electrode and ball-making material, and clean the surface of the welding wire. S2. Introduce protective gas into the arc working area and cooling channel to create an oxygen-free protective atmosphere; S3. Connect the tin-based alloy welding wire to one pole of the arc power source and connect the conductive base to the other pole of the arc power source, wherein the conductive base and the tin-based alloy welding wire are arranged coaxially to form an arc working area and constitute a complete arc circuit. S4. Start the arc power supply and ignite the consumable electrode arc. The arc is concentrated on the end of the tin-based alloy welding wire, causing the end of the tin-based alloy welding wire to melt and form molten droplets. S5. Based on the law of conservation of volume The pulse frequency f and wire feed speed v are linked and adjusted, where D is the target ball diameter and d is the welding wire diameter. S6. The molten droplets fall and cool to solidify in an inert atmosphere; S7. Collect the cured tin-based alloy balls in a sealed container.

10. The method for preparing tin-based alloy spheres from single-wire melting electrode arc droplets according to claim 9, characterized in that, In step S5, the axial electromagnetic force generated by the pulsed electric arc Must meet: ,in To prevent the surface tension from detaching, The surface tension satisfies the gravity of the molten droplet; ,in The diameter of the welding wire. is the surface tension coefficient of tin-based alloys under a protective atmosphere.

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