Centrifugal liquid phase forming apparatus and method for producing ultra-fine tin-based alloy welding powder

Abstract

The centrifugal liquid phase forming device and method for preparing ultra-fine tin-based alloy welding powder comprises a primary centrifugal device, a condensing device and a secondary centrifugal device; the primary centrifugal device comprises a centrifugal cup and an outer circular cup; the centrifugal cup rotates and the outer circular cup is fixed; a through hole is arranged on the cup wall of the centrifugal cup for the mixed solution to flow out; a rectangular hole is arranged on the cup wall of the outer circular cup; the rectangular hole of the outer circular cup is communicated with the condensing device; and the condensing device is communicated with the secondary centrifugal device. The mixed solution of the molten liquid alloy and the medium oil is injected into the centrifugal cup to be centrifugally mixed; the tiny droplets of the mixed solution centrifuged out of the rectangular hole of the outer circular cup enter the condensing device to be cooled; and the mixed solution of the alloy powder and the medium oil after being cooled enters the secondary centrifugal device to be centrifugally separated. The whole process is in the medium oil, which is simple and efficient; and the alloy particles are prevented from colliding in the forming process, so that the shape and size of the alloy particles are well maintained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic component solder material preparation methods and devices, in particular to the preparation of metal powder, and more particularly to a centrifugal liquid forming device and method for manufacturing ultra-fine tin-based alloy solder powder. BACKGROUND

[0002] With the development of science and technology, the advent of the 5G communication artificial intelligence era, microelectronic and semiconductor packaging technology is widely used in optoelectronic display, intelligent wearable devices, Internet of Things devices. Electronic components are developing towards miniaturization, and the size of chips has been greatly reduced, but the requirements for the power, power consumption and reliability of the device are becoming higher and higher, so the performance requirements for packaging solder materials are also becoming more and more demanding, such as smaller pitch, lower void rate of solder joints, higher electrical reliability around the solder joints, shorter soldering time, lower soldering temperature, etc. Correspondingly, the size of the packaging solder, which is one of the packaging materials for electronic connections, is becoming smaller and smaller, and the solder size is developing from the conventional T3, T4, T5 to smaller solder such as T6, T7, T8, and even later to T9, T10 such ultra-fine solder. Ultra-fine solder is generally applied in the form of solder paste, solder gel or anisotropic conductive adhesive in soldering materials.

[0003] In the prior art, the main production methods of low-melting-point alloys with liquid phase temperature below 300℃ include gas atomization method, centrifugal atomization method, ultrasonic atomization method and ultra-fine liquid forming process. Due to the limitation of motor speed, the harvest rate of ultra-fine powder with finer particle size is low, and the precise sorting of particle powder below 15μm cannot be achieved, resulting in poor sphericity, wide particle size distribution, low content of particles within 10μm, high oxygen content and other defects, which seriously affect the application performance of ultra-fine solder powder.

[0004] Patent Nos. CN102974834A and CN104439259A disclose a centrifugal preparation method for ultra-fine spherical alloy solder powder, which comprises feeding the molten alloy melt into the atomizer in the atomization chamber through the infusion tube, atomizing the alloy melt into small droplets in the atomization chamber filled with inert gas, and then spheroidizing and cooling the droplets, and finally obtaining the product through the grading and screening packaging process. Although this patent can produce T6~T8 ultra-fine solder powder, the harvest rate is low, the sphericity of tin powder is poor, the small droplets spun out by the centrifugal disc collide with each other in the atomization chamber, which may cause sticking, irregular particle powder, and the surface damage of tin powder is more obvious during the screening process. The quality of tin powder seriously affects the application performance of solder paste.

[0005] The patent application with the patent publication number CN113210620A discloses a preparation method and equipment of superfine low-oxygen tin powder. The molten tin ingot is atomized by gas atomization, and then the superfine tin powder is obtained by sorting with a gas flow machine. The tin powder prepared by this method has poor sphericity and obvious sticky band, and the tin powder is damaged by collision and friction during the sorting process, which affects the quality of the tin powder.

[0006] The patent application with the patent publication number CN101985177A discloses a liquid forming process, i.e. a production method of spherical low-melting-point metal powder, which comprises the processes of mixing low-melting-point metal or alloy with hot oil, preliminary dispersion by inert gas, high-power ultrasonic dispersion and emulsification, and filtration separation, etc. This method overcomes the above-mentioned defects, and is an advanced powder production process with high production efficiency, narrow product particle size distribution, low oxygen content, and no need for screening process. However, with the expansion of the market scale of ultra-micro welding powder, the high-power ultrasonic device in this powder production process generates a large amount of heat during work, and cannot work in high-temperature environment for a long time, so it cannot realize high-efficiency continuous production. The above-mentioned scheme cannot meet the market demand and cannot realize continuous production, and the medium used in the production process cannot be recycled, causing waste of materials and increase of loss.

[0007] In this application file, the particle size specifications in the electronic industry standard SJ / T 11391-2019 Tin Alloy Powder for Electronic Product Welding or IPC J-STD-005A-2012 are adopted; the symbols such as T3-T10 represent the particle diameter range signal; the unit is micrometer, i.e. μm;

[0008] The T3 type powder represents that the particle diameter range therein is 25 μm-45 μm;

[0009] The T4 type powder represents that the particle diameter range therein is 20 μm-38 μm;

[0010] The T5 type powder represents that the particle diameter range therein is 15 μm-25 μm;

[0011] The T6 type powder represents that the particle diameter range therein is 5 μm-15 μm;

[0012] The T7 type powder represents that the particle diameter range therein is 2 μm-11 μm;

[0013] The T8 type powder represents that the particle diameter range therein is 2 μm-8 μm;

[0014] The T9 type powder represents that the particle diameter range therein is 1 μm-5 μm;

[0015] The T10 type powder represents that the particle diameter range therein is 1 μm-3 μm. SUMMARY

[0016] The technical scheme of the present application overcomes the shortcomings of low production efficiency, poor sphericity, uneven surface quality and discontinuous production of the prior art, and provides a centrifugal liquid phase forming device for preparing ultra-fine tin-based alloy welding powder.

[0017] The technical scheme for solving the above technical problems is a centrifugal liquid phase forming device for preparing ultra-fine tin-based alloy welding powder, comprising a primary centrifugal device, a condensing device and a secondary centrifugal device; the primary centrifugal device comprises a centrifugal cup and an outer cup; both the centrifugal cup and the outer cup are hollow; the centrifugal cup is connected with a centrifugal motor M1 for centrifugal rotation, and the outer cup is fixed; a centrifugal cup through hole for mixing solution centrifugation is arranged on the cup wall of the centrifugal cup; the diameter of the outer cup is larger than that of the centrifugal cup, and the outer cup is sleeved on the periphery of the centrifugal cup; an outer cup rectangular hole is arranged on the cup wall of the outer cup; the outer cup rectangular hole is communicated with the condensing device; and the condensing device is communicated with the secondary centrifugal device.

[0018] The primary centrifugal device comprises the coaxially arranged centrifugal cup and outer cup; the cross sections of the outer cup and the centrifugal cup have the same center; the diameter of the centrifugal cup ranges from 50 mm to 300 mm; the cup wall thickness of the centrifugal cup ranges from 1 mm to 5 mm; and the diameter of the centrifugal cup through hole ranges from 0.02 mm to 0.5 mm.

[0019] The width of the outer cup rectangular hole ranges from 2 mm to 5 mm; and the length of the outer cup rectangular hole ranges from 10 mm to 50 mm.

[0020] The outer cup rectangular hole arranged on the cup wall of the outer cup comprises an outer cup rectangular hole A and an outer cup rectangular hole B; the center distance between the outer cup rectangular hole A and the outer cup rectangular hole B is 5 mm to 10 mm; and the outer cup has a heat preservation device for maintaining the temperature balance of the centrifugal cup and the outer cup.

[0021] The centrifugal motor M1 is a high-speed motor, and the motor speed ranges from 1000 rpm to 10000 rpm.

[0022] The condensing device comprises a rectangular-to-round receiving pipe and a condensing pipe; the condensing pipe is used for cooling alloy liquid drops in the mixed liquid into alloy powder; the outer part of the condensing pipe is provided with a pipe sleeve, and cooling oil is arranged between the pipe sleeve and the outer wall of the condensing pipe; one end of the rectangular-to-round receiving pipe is communicated with the outer-cup rectangular hole of the outer cup for receiving the mixed liquid flowing out of the outer-cup rectangular hole; the other end of the rectangular-to-round receiving pipe is communicated with one end of the condensing pipe; the other end of the condensing pipe is communicated with the secondary centrifugal device; or the condensing device comprises a rectangular-to-round receiving pipe, a valve, a condensing pipe A and a condensing pipe B; the condensing pipe A and the condensing pipe B are used for cooling alloy liquid in the mixed liquid into alloy powder; the outer part of the condensing pipe A and the condensing pipe B is provided with a pipe sleeve, and cooling oil is arranged between the pipe sleeve and the outer wall of the condensing pipe A; cooling oil is arranged between the pipe sleeve and the condensing pipe B; the secondary centrifugal device comprises a secondary centrifugal device A and a secondary centrifugal device B; the condensing pipe A is communicated with the secondary centrifugal device A; the condensing pipe B is communicated with the secondary centrifugal device B; one end of the rectangular-to-round receiving pipe is communicated with the outer-cup rectangular hole of the outer cup for receiving the mixed liquid centrifuged out of the outer-cup rectangular hole; the other end of the rectangular-to-round receiving pipe is connected with the valve, and the valve controls the other end of the rectangular-to-round receiving pipe to be communicated with the condensing pipe A or the other end of the rectangular-to-round receiving pipe to be communicated with the condensing pipe B; the centrifugal liquid-phase forming device for preparing ultra-fine tin-based alloy welding powder further comprises a furnace and a reflux pipe; the outer part or the bottom of the furnace is provided with a heating and heat-insulating device, which can be used for melting the solid alloy into liquid alloy; one end of the furnace is communicated with the hollow centrifugal cup for sending the mixed solution of high-temperature medium oil and alloy liquid into the centrifugal cup; one end of the reflux pipe is communicated with the medium oil outlet of the secondary centrifugal device, and the other end of the reflux pipe is communicated with the furnace; the reflux pipe is used for sending the medium oil flowing out of the secondary centrifugal device back to the furnace; the flow regulating device is further arranged between the furnace and the centrifugal cup; the flow regulating device comprises a flow meter A and a flow regulating valve A; the reflux flow regulating device is further arranged between the reflux pipe and the furnace; the reflux flow regulating device comprises a reflux flow meter B and a reflux flow regulating valve B; the secondary centrifugal device comprises a hollow secondary centrifugal device main body; the secondary centrifugal device main body is used for receiving the mixed solution of medium oil and alloy powder output from the condensing device; the medium oil outlet of the secondary centrifugal device is arranged at the upper part of one side of the secondary centrifugal device main body; the secondary centrifugal device main body is further provided with a liquid separation basket for carrying alloy welding powder; the liquid separation basket comprises a filter paper or a non-woven cloth basket; the liquid separation basket rotates at high speed under the drive of the motor M2, a plurality of filtering holes are drilled on the outer circle of the liquid separation basket, the diameter of the filtering holes is 3-5 mm, the rotating speed of the motor M2 is 600-1000 rpm, the liquid separation basket is sleeved with a concentric barrel, i.e., the secondary centrifugal device main body, the oil-liquid suspension in the liquid separation basket overflows from the outer circle holes of the liquid separation basket under the action of centrifugal force, and the alloy welding powder is left in the filter paper or the non-woven cloth basket; the centrifugal cup and the outer cup are made of any one or more of zirconia, alumina and titanium alloy.

[0023] The technical solution to solve the above technical problems is a centrifugal liquid phase forming method for preparing ultra-fine tin-based alloy welding powder, based on the above-mentioned centrifugal liquid phase forming device for preparing ultra-fine tin-based alloy welding powder; comprising the following steps, step B: continuously injecting the mixed solution of molten liquid alloy and medium oil into the centrifugal cup of the first centrifugal device; centrifugal mixing is carried out in the centrifugal cup; the linear speed of the rotation of the centrifugal cup is 5-50 m / s; or the rotation speed of the centrifugal cup is 1000-10000 rpm; step C: the mixed solution of liquid alloy and medium oil centrifuged out from the outer circular cup rectangular hole enters the condensing device for cooling; the cooling temperature range is (T-20) ℃ to (T-50) ℃, where T is the liquidus temperature of the alloy; step D: after cooling in step C, the mixed solution of alloy powder and medium oil enters the secondary centrifugal device for centrifugal separation of the alloy powder and the medium oil.

[0024] The centrifugal liquid phase forming method for preparing ultra-fine tin-based alloy welding powder further comprises step E: collecting the alloy powder obtained in step D, and then washing the collected alloy powder and drying it in a nitrogen protective atmosphere; in step E, the cleaning agent used for cleaning is a degreasing solvent, including any one or more of acetone, ethanol, polypropylene glycol, dichloromethane, and trichloroethylene.

[0025] The mixed solution of molten liquid alloy and medium oil includes a dispersing agent; the dispersing agent includes any one or more of paraffin, polyamide wax, hydrogenated castor oil, and petroleum sulfonate.

[0026] Before step B, it further comprises step A: melting the solid alloy into liquid alloy, and placing the liquid alloy solution in medium oil with a temperature higher than the melting point of the alloy; the medium oil is vegetable oil, including any one of olive oil, peanut oil, soybean oil, castor oil, and rapeseed oil; and it further comprises step F: collecting the medium oil obtained in step D, and sending the medium oil back to step A.

[0027] The centrifugal liquid phase forming method for preparing ultra-fine tin-based alloy welding powder further comprises step E: collecting the alloy powder obtained in step D, and then washing the collected alloy powder and drying it in a nitrogen protective atmosphere; in step E, the cleaning agent used for cleaning is a degreasing solvent, including any one or more of acetone, ethanol, polypropylene glycol, dichloromethane, and trichloroethylene. Liquid alloy The tin-based alloy contains any one or more of Sb, Bi, Cu, Ag, Ni, Co, In, Ge, and Au; or the tin-based alloy contains any one of SnAgCu, SnAg, SnCu, SnSb, SnBi, SnBiAg, SnBiCu, SnAu, and SnIn. Liquid alloy The tin-based alloy contains any one or more of Sb, Bi, Cu, Ag, Ni, Co, In, Ge, and Au; or the tin-based alloy contains any one of SnAgCu, SnAg, SnCu, SnSb, SnBi, SnBiAg, SnBiCu, SnAu, and SnIn.

[0028] Compared with the prior art, one of the beneficial effects of the present application is that the outer circle cup and the outer circle cup rectangular hole thereon are arranged, so that the possibility of collision between the to-be-formed alloy particles in the first centrifugation process is greatly reduced. The to-be-formed alloy particles are in liquid state and have not yet solidified into liquid state, so their external shape is very susceptible to external forces such as collision. In the atomization centrifugation or other centrifugation processes, collision is unavoidable; and in the technical solution of the present application, the alloy after the first centrifugation is in liquid form and enters the outer circle cup together with the medium oil, and then flows into the condensing device through the outer circle cup rectangular hole. The whole process is in the medium oil, and the alloy particle shape and size are well maintained under the surface tension of the liquid alloy; that is, the size of the alloy liquid droplets obtained by atomization after the first centrifugation determines the size of the alloy particles in the cooling process; that is, controlling the size of the alloy liquid droplets can control the size of the finally prepared alloy particles, which is very simple and efficient; and the collision of the alloy particles in the forming process is avoided, further maintaining the shape integrity and size consistency of the alloy particles.

[0029] Compared with the prior art, the second beneficial effect of the present application is that the centrifugal cup and the outer circle cup are coaxially arranged, which ensures the coordination between the centrifugal cup and the outer circle cup, so that the mixed solution of the medium oil and the alloy liquid is uniformly distributed between the outer circle cup and the outer circle cup, thereby being able to be output from the outer circle cup rectangular hole at a stable flow rate; at the same time, the centrifugal cup through hole centrifugally atomizes the isodiametric metal alloy melt liquid droplets, and the liquid metal flow is cut off by the outer circle cup rectangular hole into isodiametric and equal-sized ultra-small droplets, thereby ensuring the consistency and stability of the particles produced in the process.

[0030] Compared with the prior art, the third beneficial effect of the present application is that the multiple outer circle cup rectangular holes are arranged at intervals, which increases the flow rate and also ensures the consistency and stability of the flow rate.

[0031] Compared with the prior art, the fourth beneficial effect of the present application is that the high-speed motor enables the speed of the first centrifugation to sufficiently mix the liquid alloy with the medium oil, thereby ensuring the alloy dispersion degree and the uniformity of the mixing; the liquid alloy can be dispersed to the extent of ultra-small particles, which is very suitable for the preparation of ultra-small particles, and the output of the micro-particles is also more concentrated.

[0032] Compared with the prior art, the fifth beneficial effect of the present application is that the rectangular-to-circular receiving pipe and the condensing pipe are arranged, so that the solidification process of the liquid alloy becomes more controllable.

[0033] Compared with the prior art, the sixth beneficial effect of the present application is that the condensing pipe A and the secondary centrifugation device A are connected to the condensing pipe B and the secondary centrifugation device B; the arrangement of the two sets of cooling and secondary centrifugation devices enables the preparation to be continuously carried out, and the two sets of cooling and secondary centrifugation devices can be switched to ensure that the centrifugal liquid phase forming device for preparing ultra-small tin-based alloy welding powder can continuously operate.

[0034] The seventh advantage of the present application compared with the prior art is that the backflow pipe is arranged so that the medium oil in the backflow pipe can be recycled in the device, avoiding the loss of the medium oil in the process, and the medium oil in the backflow pipe also has part of the energy, avoiding the energy loss of heating from room temperature, and being more energy-saving and environmentally friendly.

[0035] The eighth advantage of the present application compared with the prior art is that the flow regulating device and the backflow flow regulating device enable the flow in the process to be conveniently managed and controlled in real time.

[0036] The ninth advantage of the present application compared with the prior art is that the medium oil outlet in the secondary centrifugal device is arranged at the upper part of one side of the main body of the secondary centrifugal device, facilitating the backflow of the medium oil, improving the system efficiency, and facilitating the taking out of the ultrafine alloy powder by the centrifugal paper or the centrifugal non-woven fabric hanging basket carrying the alloy powder.

[0037] The tenth advantage of the present application compared with the prior art is that the centrifugal cups and the outer round cups made of zirconium oxide, aluminum oxide and titanium alloy are very suitable for high-temperature application scenarios such as alloy melting.

[0038] The eleventh advantage of the present application compared with the prior art is that the liquid alloy can be fully dispersed to prepare ultrafine particle alloy powder in the first centrifugation, and the liquid alloy can be separated from the medium oil in the second centrifugation, which is a very efficient production method.

[0039] The twelfth advantage of the present application compared with the prior art is that the cleaning can remove the carbon compound oil and fat adhered to the surface of the ultrafine powder, reduce the oxygen content of the ultrafine powder, increase the flowability of the ultrafine powder, form a dense oxide film, and increase the chemical matching stability of the ultrafine powder and the soldering paste.

[0040] The thirteenth advantage of the present application compared with the prior art is that the dispersing agent can effectively reduce the surface tension of the liquid metal, make it suspended in the medium oil with a large difference in density, and the ultrafine liquid droplet particles after centrifugation do not shrink and do not aggregate.

[0041] The fourteenth advantage of the present application compared with the prior art is that the medium oil can be recycled, reducing the loss and energy consumption and improving the overall efficiency of the process. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a schematic view of embodiment one of the centrifugal liquid phase forming device;

[0043] Figure 2 is a front view of the centrifugal cup in the primary centrifugal device;

[0044] Figure 3 is a schematic view of the primary centrifugal device in the main view of the outer cup;

[0045] Figure 4 is a schematic view of the primary centrifugal device in the main view of the outer cup and the centrifugal cup combination state;

[0046] Figure 5 is a schematic view of the primary centrifugal device in the main view of the outer cup and the rectangular-to-circular receiving tube connection;

[0047] Figure 6 is a schematic view of the second embodiment of the centrifugal liquid phase forming device;

[0048] Figures 1 to 6 , wherein the reference numeral 10 is a furnace, the reference numeral 12 is a medium oil, the reference numeral 11 is a metal alloy, the reference numeral 15 is a flow regulating device, the reference numeral 16 is an ultrafine alloy welding powder after powder-liquid separation; the reference numeral 21 is a centrifugal cup, the reference numeral 215 is a through hole of the centrifugal cup; the reference numeral 22 is an outer cup, the reference numeral 225 is a rectangular hole of the outer cup; the reference numeral 23 is a centrifugal motor M1; the reference numeral 31 is a rectangular-to-circular receiving tube, the reference numeral 315 is an ultrafine liquid drop after centrifugation; the reference numeral 32 is a condensing tube, the reference numeral 321 is a condensing tube A, the reference numeral 322 is a condensing tube B; the reference numeral 70 is a secondary centrifugal device B, the reference numeral 50 is a secondary centrifugal device A; the reference numeral 52 is a main body of the secondary centrifugal device, the reference numeral 55 is a medium oil outlet, the reference numeral 53 is a driving motor M2 of the secondary centrifugal device, the reference numeral 54 is a powder-liquid separation basket; the reference numeral 62 is a reflux tube, the reference numeral 63 is a reflux flow regulating device;

[0049] Figure 7 is an SEM image of the prepared ultrafine welding powder in Example 1, wherein the magnification is 1000;

[0050] Figure 8 is an SEM image of the prepared ultrafine welding powder in Example 2, wherein the magnification is 5000;

[0051] Figure 9 is an SEM image of the prepared ultrafine welding powder in Example 3, wherein the magnification is 5000;

[0052] Figure 10 is an SEM image of the prepared ultrafine welding powder in Example 4, wherein the magnification is 8000;

[0053] Figure 11 is an SEM image of the prepared ultrafine welding powder in Example 5, wherein the magnification is 3300;

[0054] Figure 12 is an SEM image of the comparative Example 1, wherein the magnification is 1000;

[0055] Figure 13The image shown is a SEM image of Comparative Example 2, with a magnification of 2000.

[0056] Figure 14 The image shown is a SEM image of Comparative Example 3, with a magnification of 3000.

[0057] Figure 15 The image shown is a SEM image of Comparative Example 4, with a magnification of 2000.

[0058] SEM is an abbreviation for Scanning Electron Microscope. Detailed Implementation

[0059] The contents of this application will be further described in detail below with reference to the accompanying drawings.

[0060] In this application document, wt% means mass percentage and min is the time unit minute.

[0061] like Figures 1 to 5 In one embodiment of a centrifugal liquid phase forming apparatus for preparing ultrafine tin-based alloy solder powder, a primary centrifugation device, a condensation device, and a secondary centrifugation device are shown. The primary centrifugation device includes a centrifuge cup and an outer circular cup. Both the centrifuge cup and the outer circular cup are hollow. The centrifuge cup is connected to a centrifuge motor M1 for centrifugal rotation, and the outer circular cup is fixed. The centrifuge cup wall is provided with a centrifuge cup through hole for centrifuging out the mixed solution. The diameter of the outer circular cup is larger than the diameter of the centrifuge cup, and the outer circular cup is fitted around the periphery of the centrifuge cup. The outer circular cup wall is provided with an outer circular cup rectangular hole. The outer circular cup rectangular hole is connected to the condensation device. The condensation device is connected to the secondary centrifugation device.

[0062] like Figures 1 to 5 In one embodiment of a centrifugal liquid phase forming apparatus for preparing ultrafine tin-based alloy solder powder, a centrifugal cup is used to contain a mixed solution of high-temperature medium oil and alloy liquid; the centrifugal cup can rotate under the drive of an external motor, and drive the mixed solution inside to rotate; under the action of centrifugal force, the mixed solution flows into the outer circular cup through the through hole of the centrifugal cup; the mixed solution in the outer circular cup enters the condensing device through the rectangular hole of the outer circular cup; after centrifugation, the mixed solution is cooled by the condensing device, and the tiny suspended particles in the mixed solution are cooled into alloy powder; the mixed solution containing medium oil and alloy powder enters the secondary centrifugation device for separation of medium oil and alloy powder.

[0063] like Figures 1 to 5In one embodiment of a centrifugal liquid phase forming apparatus for preparing ultrafine tin-based alloy solder powder, the primary centrifugation device includes a centrifugal cup and an outer circular cup arranged coaxially; the cross-sections of the outer circular cup and the centrifugal cup have the same center; the diameter of the centrifugal cup ranges from 50 mm to 300 mm; the wall thickness of the centrifugal cup ranges from 1 mm to 5 mm; and the diameter of the through hole in the centrifugal cup ranges from 0.02 mm to 0.5 mm.

[0064] like Figures 1 to 5 In an embodiment of a centrifugal liquid phase forming apparatus for preparing ultrafine tin-based alloy solder powder, the width of the rectangular hole in the outer cup ranges from 2 mm to 5 mm; the length of the rectangular hole in the outer cup ranges from 10 mm to 50 mm.

[0065] like Figures 1 to 5 In one embodiment of the centrifugal liquid phase forming apparatus for preparing ultrafine tin-based alloy solder powder, the rectangular holes on the outer cup wall include rectangular hole A and rectangular hole B; the center distance between rectangular holes A and B is 5 mm to 10 mm.

[0066] like Figures 1 to 5 In one embodiment of a centrifugal liquid phase forming apparatus for preparing ultrafine tin-based alloy solder powder, the centrifugal motor M1 is a high-speed motor with a speed range of 1000 rpm to 10000 rpm.

[0067] like Figures 1 to 5 In an embodiment of a centrifugal liquid-phase forming apparatus for preparing ultrafine tin-based alloy solder powder, the condensing device includes a rectangular-to-circular receiving pipe and a condensing pipe; the condensing pipe is used to cool the alloy liquid in the mixture into alloy powder; a sleeve is provided on the outside of the condensing pipe, and cooling oil is provided between the sleeve and the outer wall of the condensing pipe; one end of the rectangular-to-circular receiving pipe is connected to the rectangular hole of the outer cup on the outer cup, and is used to receive the mixture flowing out from the rectangular hole of the outer cup; the other end of the rectangular-to-circular receiving pipe is connected to one end of the condensing pipe; the other end of the condensing pipe is connected to a secondary centrifugal device.

[0068] like Figure 6In an embodiment of a centrifugal liquid-phase forming apparatus for preparing ultrafine tin-based alloy solder powder, the condensation device includes a rectangular-to-circular receiving pipe, a valve, condenser A, and condenser B. Condenser A and condenser B are used to cool the alloy liquid in the mixture into alloy powder. Both condenser A and condenser B are externally fitted with sleeves, and cooling oil is disposed between the sleeves and the outer wall of condenser A; cooling oil is also disposed between the sleeves and condenser B. The secondary centrifugation device includes secondary centrifugation device A and secondary centrifugation device B. Condenser A and secondary centrifugation device A are connected; condenser B and secondary centrifugation device B are connected. One end of the rectangular-to-circular receiving pipe is connected to a rectangular hole on an outer circular cup to receive the mixture flowing out from the rectangular hole. The other end of the rectangular-to-circular receiving pipe is connected to the valve, which controls the other end of the rectangular-to-circular receiving pipe to be connected to condenser A, or controls the other end of the rectangular-to-circular receiving pipe to be connected to condenser B. The valve is not shown in the accompanying drawings.

[0069] like Figures 1 to 5 In one embodiment of the centrifugal liquid phase forming apparatus for preparing ultrafine tin-based alloy solder powder, a furnace and a reflux pipe are also included. The furnace is used to melt the solid alloy into a liquid alloy. One end of the furnace is connected to a hollow centrifuge cup for feeding a mixture of high-temperature medium oil and alloy liquid into the centrifuge cup. One end of the reflux pipe is connected to the medium oil outlet of the secondary centrifuge device, and the other end of the reflux pipe is connected to the furnace. The reflux pipe is used to return the medium oil flowing out of the secondary centrifuge device to the furnace.

[0070] like Figures 1 to 5 In one embodiment of the centrifugal liquid phase forming apparatus for preparing ultrafine tin-based alloy solder powder, a flow regulating device is also provided between the furnace and the centrifugal cup; the flow regulating device includes a flow meter A and a flow regulating valve A; a reflux flow regulating device is also provided between the reflux pipe and the furnace; the reflux flow regulating device includes a reflux flow meter B and a reflux flow regulating valve B.

[0071] like Figures 1 to 5 In one embodiment of a centrifugal liquid phase forming apparatus for preparing ultrafine tin-based alloy solder powder, the secondary centrifugal device includes a hollow secondary centrifugal device body; the secondary centrifugal device body is used to receive the medium oil and alloy powder mixed solution output from the condenser; the medium oil outlet of the secondary centrifugal device is located at the upper part of one side of the secondary centrifugal device body; a powder-liquid separation basket for carrying alloy powder is also provided inside the secondary centrifugal device body; the powder-liquid separation basket includes a filter paper or non-woven fabric basket.

[0072] In one embodiment of a centrifugal liquid phase forming apparatus for preparing ultrafine tin-based alloy solder powder, which is not shown in some of the accompanying drawings, the centrifugal cup and the outer circular cup are made of any one or more materials selected from zirconium oxide, alumina, and titanium alloy.

[0073] In some embodiments of the centrifugal liquid phase forming method for preparing ultra-fine solder powder of tin-based alloy, which are not shown in some of the drawings, based on the centrifugal liquid phase forming device for preparing ultra-fine solder powder of tin-based alloy described above, the method comprises the following steps: Step A: melt the solid alloy into a liquid alloy, and place the liquid alloy solution in a medium oil at a temperature higher than the melting point of the alloy; Step B: continuously inject the mixed solution of the molten liquid alloy and the medium oil into the centrifugal cup of a primary centrifugal device; perform centrifugal mixing in the centrifugal cup; the rotation speed of the centrifugal cup is 1000 rpm to 10000 rpm (rpm is revolutions per minute); to Step C: the mixed solution of the liquid alloy and the medium oil overflowing from the outer circular cup rectangular hole enters the condensing device for cooling; the cooling temperature range is (T-20) °C to (T-50) °C, where T is the liquidus temperature of the alloy; Step D: the mixed solution of the alloy powder and the medium oil after cooling in Step C enters a secondary centrifugal device for centrifugal separation of the alloy powder and the medium oil; Step E: collect the alloy powder obtained in Step D, and perform a cleaning step on the collected alloy powder. In Step E, the cleaning agent used for cleaning is a degreasing solvent, including any one or more of acetone, ethanol, polypropylene glycol, dichloromethane, and trichloroethylene. Step F: collect the medium oil obtained in Step D, and send the medium oil back to Step A.

[0074] The mixed solution of the molten liquid alloy and the medium oil includes a dispersing agent; the dispersing agent includes any one or more of paraffin wax, polyamide wax, hydrogenated castor oil, and petroleum sulfonate.

[0075] The alloy is a tin-based alloy. Liquid alloy The alloy includes any one or more of Sb, Bi, Cu, Ag, Ni, Co, In, Ge, and Au.

[0076] The alloy is a tin-based alloy. Liquid alloy The alloy includes any one of SnAgCu, SnAg, SnCu, SnSb, SnBi, SnBiAg, SnBiCu, SnAu, and SnIn.

[0077] The medium oil is a plant oil, including any one of olive oil, peanut oil, soybean oil, castor oil, and rapeseed oil.

[0078] Figures 1 to 6In the figure, the number 10 is a furnace, namely a tin furnace, the number 15 is a flow regulating device, in which the flow meter A and the flow regulating valve A are not shown; the number 63 is a backflow flow regulating device, the backflow flow meter B and the backflow flow regulating valve B are not shown in the figure. The alloy of the number 11 is in solid state when it is just put into the furnace, and is melted into liquid alloy in the furnace 10; the liquid alloy 11 is centrifugally dispersed in the centrifugal cup, and then enters the secondary centrifugal device for separation of the alloy and the medium oil after being condensed by the condensing device. The temperature of the medium oil 12 in the furnace is higher than the alloy melting temperature; the temperature of the medium oil 12 in the condensing device and the secondary centrifugal device is lower than the alloy melting temperature.

[0079] The tin-based alloy solder powder of Example 1 is prepared by the centrifugal liquid phase forming method of the ultra-micro tin-based alloy solder powder. The SAC305 tin-based alloy is placed in a tin furnace, namely a melting furnace, high-temperature medium oil is added, the alloy liquid is melted, the temperature is set to 270 degrees, the tin-based alloy solution flows into the rotating centrifugal cup with the high-temperature medium oil, the rotating centrifugal cup has a diameter of 100 millimeters, a cup wall thickness of 5 millimeters, and regular holes of 0.1 millimeters, and rotates at a speed of 4000 rpm. The tin-based alloy solution is ejected from the centrifugal cup through hole and the outer circular cup rectangular hole of the concentric outer circular cup in the form of pulse to form micro metal droplets with equal diameter and size, falls into the rectangular to circular receiving pipe, enters the condensing pipe under the action of the liquid oil medium, and the spherical droplets are cooled below the tin-based alloy liquidus to form spherical powder dispersed in the medium oil. The metal solution flows out from the centrifugal cup through hole, showing equal diameter metal liquid flow, which is cut into small ultra-micro metal droplets by the outer circular cup rectangular hole of the concentric outer circular cup, and the through hole is arranged in array, so that the centrifugal cup through hole flows out a column of metal liquid flow at certain time interval, which is continuously cut by the cup rectangular hole, so that the micro metal droplets with equal diameter and size are ejected in the form of pulse.

[0080] The rear end of the condenser tube is connected with a centrifuge, and the centrifuge is one or more than two in parallel. The medium oil with ultra-fine welding powder suspended is introduced into the centrifuge, a layer of filter paper is attached to the inner side of the centrifuge, the centrifuge is driven by a rotating motor to rotate at high speed, the metal particles with large specific gravity in the suspension are dispersed on the filter paper on the inner wall of the centrifuge under the action of centrifugal force and self gravity, the medium oil with small specific gravity is discharged from the medium oil outlet of the centrifuge and introduced into the tin furnace through the connecting pipe. When the ultra-fine welding powder separated on the filter paper reaches a certain amount, the feed valve of the centrifuge is closed, the suspension is introduced into another centrifuge in parallel for continuous separation operation. During this period, the first centrifuge is collected for ultra-fine welding powder and is prepared for separation again, so that the continuous circulation production of the ultra-fine welding powder centrifugal liquid phase forming is realized. The collected ultra-fine welding powder is cleaned by cleaning agent, dried under nitrogen protection, and then ultra-fine tin-based welding powder 1 is obtained, the proportion of particles with particle size T7 (2-11 um) is 92%, the oxygen content is 420 ppm, the sphericity is good, the powder surface is smooth, and the technical indexes meet the technical indexes of the electronic industry standard, and the SEM of the ultra-fine welding powder is shown in Figure 7 .

[0081] The tin-based alloy welding powder prepared by the centrifugal liquid phase forming method of the ultra-fine tin-based alloy welding powder in example 2, Sn90Sb10 tin-based alloy is added into the tin furnace, i.e. the melting furnace, high-temperature medium oil is added, the alloy liquid is melted, the temperature is set to 280 degrees, the tin-based alloy solution flows into the rotating centrifugal cup with high-temperature medium oil, the rotating centrifugal cup has a diameter of 200 mm, the rotating centrifugal cup has a wall thickness of 3 mm and regular holes of 0.05 mm, the rotating centrifugal cup rotates at a high speed of 4000 rpm, the production process is the same as that in example 1, and ultra-fine tin-based welding powder 2 is obtained, the proportion of particles with particle size T8 (2-8 um) is greater than 95%, the oxygen content is 490 ppm, the sphericity is good, the powder surface is smooth, and the technical indexes meet the technical indexes of the electronic industry standard, and the SEM of the ultra-fine welding powder is shown in Figure 8 .

[0082] The tin-based alloy welding powder prepared by the centrifugal liquid phase forming method of the ultra-fine tin-based alloy welding powder in example 3, Sn42Bi57.6Ag0.4 tin-based alloy is added into the tin furnace 1, i.e. the melting furnace, high-temperature medium oil is added, the alloy liquid is melted, the temperature is set to 190 degrees, the tin-based alloy solution flows into the rotating centrifugal cup with high-temperature medium oil, the rotating centrifugal cup has a diameter of 300 mm, the rotating centrifugal cup has a wall thickness of 1 mm and regular holes of 0.03 mm, the rotating centrifugal cup rotates at a high speed of 1300 rpm. The production process is the same as that in example 1, and ultra-fine tin-based welding powder 3 is obtained, the proportion of particles with particle size T6 (5-15 um) is 93%, the oxygen content is 220 ppm, the sphericity is good, the powder surface is smooth, and the technical indexes meet the technical indexes of the electronic industry standard, and the SEM of the ultra-fine welding powder is shown in Figure 9 .

[0083] The tin-based alloy solder powder of Example 4 prepared by the centrifugal liquid phase forming method of the super-fine tin-based alloy solder powder is Sn96.5Ag3Cu0.5. The tin-based alloy is added into tin furnace 1, i.e., a melting furnace, with high-temperature medium oil to melt the alloy liquid. The temperature is set to 270 degrees. The tin-based alloy solution flows into a rotating centrifugal cup with the high-temperature medium oil. The rotating centrifugal cup has a diameter of 400 millimeters, a cup wall thickness of 5 millimeters, and regular openings of 0.02 millimeters. The rotating centrifugal cup rotates at a high speed of 2000 rpm. The production process is the same as that of Example 1. The super-fine tin-based solder powder 4 is obtained. After testing, the particles with a particle size T9 (1-5 um) account for 92%. The oxygen content is 750 ppm. The sphericity is good. The powder surface is smooth, which meets the technical indicators of the electronic industry standards. The SEM of the super-fine solder powder is shown in Figure 10 .

[0084] The tin-based alloy solder powder of Example 5 prepared by the centrifugal liquid phase forming method of the super-fine tin-based alloy solder powder is Sn90.5Ag3Cu0.5Bi6. The tin-based alloy is added into tin furnace 1, i.e., a melting furnace, with high-temperature medium oil to melt the alloy liquid. The temperature is set to 270 degrees. The tin-based alloy solution flows into a rotating centrifugal cup with the high-temperature medium oil. The rotating centrifugal cup has a diameter of 500 millimeters, a cup wall thickness of 8 millimeters, and regular openings of 0.02 millimeters. The rotating centrifugal cup rotates at a high speed of 2000 m / s. The production process is the same as that of Example 1. The super-fine tin-based solder powder 5 is obtained. After testing, the particles with a particle size T10 (1-3 um) account for 90%. The oxygen content is 960 ppm. The sphericity is good. The powder surface is smooth, which meets the technical indicators of the electronic industry standards. The SEM of the super-fine solder powder is shown in Figure 11 .

[0085] Comparative Example 1: The centrifugal process super-fine solder powder SAC305 T6 sold on the market is taken. The particles with a particle size distribution (5-15 um) account for 90%. The tin powder surface is observed by scanning electron microscopy. There are obvious damages and a large number of irregular shaped particles. The SEM is shown in Figure 12 .

[0086] Comparative Example 2: The liquid phase forming process super-fine solder powder SAC305 T7 sold on the market is taken. The particles with a particle size distribution (2-11 um) account for 91%. The tin powder surface is observed by scanning electron microscopy. There are damages and uneven states. The SEM is shown in Figure 13 .

[0087] Comparative Example 3: The centrifugal atomization airflow sorting process super-fine solder powder SAC305 T7 sold on the market is taken. The particles with a particle size distribution (2-11 um) account for 92%. The tin powder surface is observed by scanning electron microscopy. There are irregular shaped particles, and the tin powder surface is not smooth and flat. The SEM is shown in Figure 14 .

[0088] Comparative Example 4: The ultra-fine solder powder SAC305 T9 of a foreign market gas-atomized gas flow sorting process was taken, the particle ratio of the particle size distribution (1-5 um) was 77%, the tin powder surface was obviously damaged under the scanning electron microscope observation, and a small amount of irregular irregular particles existed, as shown in SEM Figure 15 .

[0089] A centrifugal liquid forming device and method for preparing ultra-fine tin-based alloy solder powder are provided in the application. The high-efficiency centrifugal atomization technology and the high-product-quality liquid forming process are combined together to realize continuous and efficient preparation of high-quality ultra-fine solder powder, and the medium auxiliary materials in the production process can be recycled, saving production cost and providing production efficiency.

[0090] The above is only an embodiment of the application, and does not limit the patent scope of the application. Any equivalent structure or equivalent process transformation using the content of the application specification and drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the application.

Claims

1. A centrifugal liquid phase forming device for preparing ultra-fine tin-based alloy welding powder, characterized in that it comprises a primary centrifugal device, a condensing device and a secondary centrifugal device; the primary centrifugal device comprises a centrifugal cup and an outer circular cup; both the centrifugal cup and the outer circular cup are hollow; the centrifugal cup is connected with a centrifugal motor M1 for centrifugal rotation, and the outer circular cup is fixed; a through hole is arranged on the cup wall of the centrifugal cup for the outflow of the mixed solution; the diameter of the outer circular cup is larger than that of the centrifugal cup, and the outer circular cup is sleeved on the periphery of the centrifugal cup; a rectangular hole is arranged on the cup wall of the outer circular cup; the rectangular hole of the outer circular cup is communicated with the condensing device; the condensing device is communicated with the secondary centrifugal device; the primary centrifugal device comprises the centrifugal cup and the outer circular cup arranged coaxially; the cross sections of the outer circular cup and the centrifugal cup have the same center; the condensing device comprises a rectangular-to-circular receiving pipe and a condensing pipe; the condensing pipe is used for cooling alloy liquid drops in the mixed solution into alloy powder; a pipe sleeve is arranged outside the condensing pipe, and cooling oil is arranged between the pipe sleeve and the outer wall of the condensing pipe; one end of the rectangular-to-circular receiving pipe is communicated with the rectangular hole of the outer circular cup on the outer circular cup for receiving the mixed solution flowing out of the rectangular hole of the outer circular cup; the other end of the rectangular-to-circular receiving pipe is communicated with one end of the condensing pipe; the other end of the condensing pipe is communicated with the secondary centrifugal device; or the condensing device comprises a rectangular-to-circular receiving pipe, a valve, a condensing pipe A and a condensing pipe B; the condensing pipe A and the condensing pipe B are used for cooling alloy liquid in the mixed solution into alloy powder; a pipe sleeve is arranged outside each of the condensing pipe A and the condensing pipe B, and cooling oil is arranged between the pipe sleeve and the outer wall of the condensing pipe A; cooling oil is arranged between the pipe sleeve and the condensing pipe B; the secondary centrifugal device comprises a secondary centrifugal device A and a secondary centrifugal device B; the condensing pipe A is communicated with the secondary centrifugal device A; the condensing pipe B is communicated with the secondary centrifugal device B; one end of the rectangular-to-circular receiving pipe is communicated with the rectangular hole of the outer circular cup on the outer circular cup for receiving the mixed solution flowing out of the rectangular hole of the outer circular cup; the other end of the rectangular-to-circular receiving pipe is connected with the valve; the valve controls the other end of the rectangular-to-circular receiving pipe to be communicated with the condensing pipe A or the condensing pipe B; the centrifugal liquid phase forming device for preparing ultra-fine tin-based alloy welding powder further comprises a furnace and a reflux pipe; the furnace is provided with a heating and heat preservation device outside or at the bottom, which can be used for melting solid alloy into liquid alloy; one end of the furnace is communicated with the hollow centrifugal cup for sending the mixed solution of high-temperature medium oil and alloy liquid into the centrifugal cup; one end of the reflux pipe is communicated with the medium oil outlet of the secondary centrifugal device, and the other end of the reflux pipe is communicated with the furnace; the reflux pipe is used for sending the medium oil flowing out of the secondary centrifugal device back to the furnace; a flow adjusting device is further arranged between the furnace and the centrifugal cup; the flow adjusting device comprises a flow meter A and a flow adjusting valve A; a reflux flow adjusting device is further arranged between the reflux pipe and the furnace; the reflux flow adjusting device comprises a reflux flow meter B and a reflux flow adjusting valve B. ​ ​ ​ ​ ​ ​ ​ The secondary centrifugal device comprises a hollow secondary centrifugal device body; the secondary centrifugal device body is used for receiving the mixed solution of the medium oil and the alloy powder output from the condensing device; the medium oil outlet of the secondary centrifugal device is arranged at the upper part of one side of the secondary centrifugal device body; the secondary centrifugal device body is internally provided with a powder-liquid separation basket for carrying the alloy welding powder; the powder-liquid separation basket comprises a filter paper or a non-woven cloth basket; the powder-liquid separation basket rotates at a high speed under the drive of the motor M2; a plurality of filtering small holes are drilled on the outer circle of the powder-liquid separation basket; the diameter of the filtering small holes is 3-5 mm; the rotating speed of the motor M2 is 600-1000 rpm; the powder-liquid separation basket is externally sleeved with a concentric barrel, i.e. the secondary centrifugal device body; the oil-liquid suspension in the powder-liquid separation basket overflows from the outer circle holes of the powder-liquid separation basket under the action of the centrifugal force; and the alloy welding powder is left in the filter paper or the non-woven cloth basket.

2. The centrifugal liquid phase forming apparatus for preparing ultra-fine tin-based alloy welding powder according to claim 1, wherein The diameter of the centrifugal cup ranges from 50 mm to 300 mm; the thickness of the cup wall of the centrifugal cup ranges from 1 mm to 5 mm; and the diameter of the through hole of the centrifugal cup ranges from 0.02 mm to 0.5 mm.

3. The centrifugal liquid phase forming apparatus for preparing ultra-fine tin-based alloy welding powder according to claim 1, wherein The width of the outer circle cup rectangular hole ranges from 2 mm to 5 mm; and the length of the outer circle cup rectangular hole ranges from 10 mm to 50 mm.

4. The centrifugal liquid phase forming apparatus for preparing ultra-fine tin-based alloy welding powder according to claim 1, wherein The outer circle cup rectangular holes arranged on the cup wall of the outer circle cup comprise outer circle cup rectangular hole A and outer circle cup rectangular hole B; the center distance between the outer circle cup rectangular hole A and the outer circle cup rectangular hole B is 5-10 mm; the outer circle cup is externally provided with a heat preservation device for maintaining the temperature balance of the centrifugal cup and the outer circle cup; and the centrifugal motor M1 is a high-speed motor with a rotating speed ranging from 1000 rpm to 10000 rpm.

5. The centrifugal liquid forming apparatus for preparing ultra-fine tin-based alloy welding powder according to claim 1, wherein The centrifugal cup and the outer circle cup are made of any one or more of zirconium oxide, aluminum oxide and titanium alloy.

6. A centrifugal liquid phase forming method for preparing ultra-fine tin-based alloy welding powder, characterized in that, The centrifugal liquid phase forming device for preparing ultra-fine tin-based alloy welding powder according to any one of claims 1-5; comprises the following steps, Step A: melting the solid alloy into a liquid alloy, and placing the liquid alloy solution in a medium oil with a temperature higher than the melting point of the alloy; Step B: continuously injecting the mixed solution of the melted liquid alloy and the medium oil into the centrifugal cup of the primary centrifugal device; performing centrifugal mixing in the centrifugal cup; the rotating linear speed of the centrifugal cup is 5-50 m / s; or the rotating speed of the centrifugal cup ranges from 1000 rpm to 10000 rpm; Step C: the mixed solution of the liquid alloy and the medium oil centrifuged out from the outer circle cup rectangular hole enters the condensing device for cooling; the cooling temperature ranges from (T-20) ℃ to (T-50) ℃, wherein T is the liquid phase temperature of the alloy; Step D: after the cooling in Step C, the mixed solution of the alloy powder and the medium oil enters the secondary centrifugal device for centrifugal separation of the alloy powder and the medium oil; Step E: collecting the alloy powder obtained in Step D, and then washing the collected alloy powder and drying the washed alloy powder in a nitrogen protection atmosphere; Step F: collecting the medium oil obtained in Step D, and sending the medium oil back to Step A.

7. The centrifugal liquid forming method for preparing ultra-fine tin-based alloy welding powder according to claim 6, characterized in that, In Step E, the washing agent used for washing is a degreasing solvent, which comprises any one or more of acetone, ethanol, polypropylene alcohol, dichloromethane and trichloroethylene.

8. The centrifugal liquid forming method for preparing ultra-fine tin-based alloy welding powder according to claim 6, characterized in that, The dispersing agent includes any one or more of paraffin wax, polyamide wax, hydrogenated castor oil, petroleum sulfonate.

9. The centrifugal liquid forming method for preparing ultra-fine tin-based alloy welding powder according to claim 6, wherein, The medium oil in step A is vegetable oil, including any one of olive oil, peanut oil, soybean oil, castor oil, rapeseed oil.

10. The centrifugal liquid forming method of preparing ultra-fine tin-based alloy welding powder according to claim 6, wherein The liquid alloy is a tin-based alloy, which contains any one or more of Sb, Bi, Cu, Ag, Ni, Co, In, Ge, Au. Or the liquid alloy is a tin-based alloy, which includes any one of SnAgCu, SnAg, SnCu, SnSb, SnBi, SnBiAg, SnBiCu, SnAu, SnIn.

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