Preparation method of low-melting-point alloy powder

Abstract

The invention discloses a preparation method of low-melting-point alloy powder. The preparation method comprises the following steps: (1) preparing a heat-resistant continuous-phase oil dispersant; (2) adding a low-melting-point alloy block and heat-resistant continuous-phase oil into a three-neck flask, heating a mixture of the low-melting-point alloy block and the heat-resistant continuous-phase oil to the melting point of the low-melting-point alloy block to melt the mixture, and adding a heat-resistant continuous-phase oil dispersing agent into the three-neck flask through a pulse type dispersing agent adding device in the heating process; (3) opening the composite stirring device, and stirring the melt in the three-neck flask; and (4) stopping heating the substances in the three-neck flask, keeping a stirring state in the three-neck flask, and cooling the liquid alloy particles and the heat-resistant continuous-phase oil to below the melting point of the low-melting-point alloy to form the low-melting-point alloy particle powder. According to the preparation method of the low-melting-point alloy powder, the low-melting-point alloy powder which is uniform in dispersion and small in particle size distribution range can be prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and specifically relates to a method for preparing low-melting-point alloy powder. Background Art

[0002] With the development of miniaturization of electronic products, the application of surface mount technology has been promoted. Surface mount technology is a technology that directly solders electronic components on the surface of a printed circuit board, and the printing of solder paste is the core link of surface mount technology. As the solder joints of surface mount products become smaller and smaller, the requirements for the printing accuracy and welding reliability of solder paste are getting higher and higher.

[0003] Solder paste mainly consists of alloy powder and flux. The particle size distribution, sphericity, and oxygen content of the alloy powder used in solder paste directly determine the printing accuracy and welding reliability of solder paste. For the preparation of alloy powder, the current mainstream methods include atomization method, rotating disk method, stirring emulsification, etc. Among them, the current stirring emulsification has problems such as uneven dispersion and a wide particle size distribution range.

[0004] Shear emulsification applies a shear force to the molten alloy liquid through a high-speed rotating stirrer to overcome the surface tension of the liquid alloy and disperse the melt into tiny droplets. The single-stage shear emulsification method has insufficient shear strength, resulting in uneven dispersion of the melt and a too wide particle size distribution of the alloy powder. At the same time, in the single-stage shear emulsification method, a surfactant needs to be added to overcome the surface tension of the liquid alloy. However, adding an excessive amount of surfactant will result in high post-treatment costs, and the residues will affect the purity of the alloy powder. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a method for preparing low-melting-point alloy powder, which can produce low-melting-point alloy powder with uniform dispersion and a small particle size distribution range.

[0006] To achieve the above object, the present invention is realized through the following technical solutions: A method for preparing low-melting-point alloy powder, comprising the following steps:

[0007] (1) Prepare a heat-resistant continuous phase oil dispersant;

[0008] (2) Add the low-melting-point alloy block and the heat-resistant continuous phase oil into a three-necked flask, heat the mixture of the low-melting-point alloy block and the heat-resistant continuous phase oil to the melting point of the low-melting-point alloy block to melt it, and add the heat-resistant continuous phase oil dispersant into the three-necked flask through a pulsed dispersant adding device during the heating process;

[0009] (3) Turn on the compound stirring device to stir the melt in the three-necked flask. The compound stirring device includes a multi-stage variable-diameter propeller blade and a conical stator. The stirring of the compound stirring device has multi-stage shearing and emulsifying effects, dispersing the low-melting-point alloy liquid in the three-necked flask into liquid alloy microparticles;

[0010] (4) Stop heating the substance in the three-necked flask. Keep the three-necked flask in a stirring state, and cool the liquid alloy microparticles and the heat-resistant continuous-phase oil below the melting point of the low-melting-point alloy to form low-melting-point alloy microparticle powder.

[0011] Preferably, the heat-resistant continuous-phase oil is a mineral oil, vegetable oil, or organic solvent with a boiling point higher than that of the low-melting-point alloy block, including one or more of lubricating oil, soybean oil, liquid paraffin, polyethylene glycol, and silicone oil used in combination.

[0012] Preferably, the dispersant is a material that promotes the dissolution of the low-melting-point alloy block and prevents the polymerization of the low-melting-point alloy powder after dispersion, including one or more of Span80, tetra-glycerol condensed castor oil acid ester, sodium dodecyl sulfate, oleic acid, stearic acid, palmitic acid, zinc stearate, and zinc palmitate used in combination.

[0013] Preferably, the compound stirring device includes a vertically arranged stirring shaft, and multi-stage propeller blades are arranged on the stirring shaft from top to bottom, and the sizes of the multi-stage propeller blades are different.

[0014] Preferably, the multi-stage propeller blades are arranged at equal intervals up and down.

[0015] Preferably, the surface of the stirring shaft is provided with a nano-ceramic layer.

[0016] Preferably, the pulsed dispersant adding device includes a dispersant storage syringe and a spraying module. The lower end of the dispersant storage syringe is provided with a discharge pipe, the lower end of the spraying module is provided with a discharge nozzle, the lower end of the discharge pipe is communicated with the discharge nozzle, and a piezoelectric ceramic micro-valve unit for controlling the pulsed spraying and discharging of the spraying module is arranged in the spraying module.

[0017] Preferably, in step (3), the rotation speed of the stirring shaft in the compound stirring device is 2000 r / min, and the stirring time is 5 minutes; in step (4), the rotation speed of the stirring shaft in the compound stirring device is 500 r / min, and the stirring time is 10 minutes.

[0018] Preferably, in step (3), the rotation speed of the stirring shaft in the compound stirring device is 1500 r / min, and the stirring time is 5 minutes; in step (4), the rotation speed of the stirring shaft in the compound stirring device is 500 r / min, and the stirring time is 10 minutes.

[0019] The method for preparing low-melting-point alloy powder provided by the present invention has the following beneficial effects:

[0020] The method for preparing low-melting-point alloy powder of the present invention can prepare low-melting-point alloy powder with uniform dispersion and a small particle size distribution range. The sphericity of the alloy powder is good, which can reduce the amount of dispersant added, reduce the post-treatment cost and reduce the residual influence. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of related equipment in the method for preparing low-melting-point alloy powder of the present invention;

[0022] Figure 2 It is a schematic structural diagram of the compound stirring device in the method for preparing low-melting-point alloy powder of the present invention;

[0023] Figure 3 It is a schematic structural diagram of the pulsed dispersant adding device in the method for preparing low-melting-point alloy powder of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0025] Please refer to Figures 1 to 3 , the present invention provides a technical solution: a method for preparing low-melting-point alloy powder, including the following steps:

[0026] (1) Prepare a heat-resistant continuous phase oil dispersant;

[0027] (2) Add the low-melting-point alloy block and the heat-resistant continuous phase oil into the three-necked flask 1, heat the mixture of the low-melting-point alloy block and the heat-resistant continuous phase oil to the melting point of the low-melting-point alloy block to melt it. Using a dispersant can ensure the stable existence of the dispersed liquid alloy particles in the emulsion. During the heating process, add the heat-resistant continuous phase oil dispersant into the three-necked flask 1 through the pulsed dispersant adding device 2. Using the heat-resistant continuous phase oil can realize the recycling of the oil;

[0028] (3) Turn on the compound stirring device 3 and stir the melt in the three-necked flask 1. The compound stirring device 3 includes a multi-stage variable-diameter propeller blade 301 and a conical stator. The stirring of the compound stirring device 3 has a multi-stage shear emulsification effect, and the low-melting-point alloy liquid in the three-necked flask 1 is dispersed into liquid alloy particles;

[0029] (4) Stop heating the substances in the three-necked flask 1, keep the stirring state in the three-necked flask 1, and cool the liquid alloy particles and the heat-resistant continuous phase oil below the melting point of the low-melting-point alloy to form low-melting-point alloy particle powder.

[0030] Preferably, the heat-resistant continuous-phase oil is a mineral oil, vegetable oil, or organic solvent with a boiling point higher than that of the low-melting-point alloy block, including one or more of lubricating oil, soybean oil, liquid paraffin, polyethylene glycol, and silicone oil used in combination.

[0031] Preferably, the dispersant is a material that promotes the dissolution of the low-melting-point alloy block and prevents the aggregation of the low-melting-point alloy powder after dispersion, including one or more of Span80, tetra-glycerol condensed ricinoleate, sodium dodecyl sulfate, oleic acid, stearic acid, palmitic acid, zinc stearate, and zinc palmitate used in combination.

[0032] Preferably, the compound stirring device 3 includes a vertically arranged stirring shaft 302, and multiple-stage propeller blades 301 are arranged on the stirring shaft 302 from top to bottom. The sizes of the multiple-stage propeller blades 301 are different. A motor 303 can be arranged at the top of the stirring shaft 302 to drive the rotation of the stirring shaft 302. When the stirring shaft 302 rotates, the multiple-stage propeller blades 301 rotate accordingly. The rotation of the propeller blades 301 stirs the low-melting-point alloy liquid in the three-necked flask 1 to disperse it into liquid alloy particles. The rotation of the propeller blades 301 generates a shear force on the low-melting-point alloy liquid in the three-necked flask 1. Since the sizes of the multiple-stage propeller blades 301 are different, the shear forces generated on the low-melting-point alloy liquid are also different, and the shear emulsification effect on the low-melting-point alloy liquid is better. Through the action of multiple shear forces, the uniform fragmentation of solder particles can be achieved, and the particle size distribution range can be narrowed. Through the action of multiple shears, the amount of dispersant added can also be reduced, reducing the post-treatment cost and the impact of dispersant residues.

[0033] Preferably, the multiple-stage propeller blades 301 are arranged at equal intervals up and down.

[0034] Preferably, a nano-ceramic layer 304 is provided on the surface of the stirring shaft 302, and the nano-ceramic layer 304 can prevent the stirring shaft 302 from welding with the molten metal.

[0035] Preferably, the pulsed dispersant adding device 2 includes a dispersant storage syringe 201 and an injection module 202. A discharge pipe 203 is provided at the lower end of the dispersant storage syringe 201, and a discharge nozzle 204 is provided at the lower end of the injection module 202. The lower end of the discharge pipe 203 is communicated with the discharge nozzle 204. A piezoelectric ceramic micro-valve unit 205 for controlling the pulsed discharge of the injection module 202 is provided in the injection module 202. Using a piezoelectric ceramic micro-valve to control the addition of the dispersant can improve the accuracy of the dispersant addition amount. The dispersant is added to the dispersant storage syringe 201, passes through the discharge pipe 203 to the discharge nozzle 204, and the piezoelectric ceramic micro-valve unit 205 controls the injection module 202 to spray the dispersant into the three-necked flask 1. The piezoelectric ceramic micro-valve unit 205 controls the injection module 202 to perform pulsed discharge. The intermittent discharge enables the dispersant sprayed into the three-necked flask 1 to have time to be stirred, making the dispersant evenly dispersed.

[0036] Preferably, in step (3), the rotation speed of the stirring shaft 302 in the compound stirring device 3 is 2000 r / min, and the stirring time is 5 minutes; in step (4), the rotation speed of the stirring shaft 302 in the compound stirring device 3 is 500 r / min, and the stirring time is 10 minutes.

[0037] Preferably, in step (3), the rotation speed of the stirring shaft 302 in the compound stirring device 3 is 1500 r / min, and the stirring time is 5 minutes; in step (4), the rotation speed of the stirring shaft 302 in the compound stirring device 3 is 500 r / min, and the stirring time is 10 minutes.

[0038] Example 1:

[0039] First, 1.00 g of Span80 and 10.00 ml of heat-resistant continuous phase soybean oil are heated and dissolved to obtain dispersant A; then, 15.00 g of low-melting-point alloy blocks and 150.00 ml of soybean oil are added to the three-necked flask 1, the heating temperature is set to 160 °C, and 1.00 ml of dispersant A is added through the pulsed dispersant adding device 2 during the heating process; after the low-melting-point alloy blocks are melted, the compound stirring device 3 is turned on, the speed of the stirring shaft 302 is set to 2000 r / min, and stirred for 5 minutes; through multi-stage shear emulsification, the low-melting-point alloy liquid is dispersed into liquid alloy microparticles; the heating is stopped, the speed of the stirring shaft 302 is set to 500 r / min, and stirred for 10 min; finally, the liquid alloy microparticles and the heat-resistant continuous phase oil are cooled below the melting point of the low-melting-point alloy to form low-melting-point alloy microparticle powder.

[0040] Example 2:

[0041] First, 0.50 g of zinc stearate and 10.00 ml of heat-resistant continuous-phase lubricating oil were heated and dissolved to obtain dispersant B. Then, 15.00 g of low-melting-point alloy blocks and 150.00 ml of lubricating oil were added to the three-necked flask 1, the heating temperature was set at 160 °C, and 1.00 ml of dispersant B was added through the pulsed dispersant adding device 2 during the heating process. After the low-melting-point alloy blocks melted, the compound stirring device 3 was turned on, the speed of the stirring shaft 302 was set at 1500 r / min, and stirred for 5 minutes. Through multi-stage shear emulsification, the low-melting-point alloy liquid was dispersed into liquid alloy microparticles. The heating was stopped, the speed of the stirring shaft 302 was set at 500 r / min, and stirred for 10 min. Finally, the liquid alloy microparticles and the heat-resistant continuous-phase oil were cooled below the melting point of the low-melting-point alloy to form low-melting-point alloy microparticle powder.

[0042] Example 3:

[0043] First, 0.25 g of tetraglycerol condensed ricinoleate and 10.00 ml of heat-resistant continuous-phase liquid paraffin were heated and dissolved to obtain dispersant C. Then, 15.00 g of low-melting-point alloy blocks and 100.00 ml of liquid paraffin were added to the three-necked flask 1, the heating temperature was set at 160 °C, and 0.50 ml of dispersant C was added through the pulsed dispersant adding device 2 during the heating process. After the low-melting-point alloy blocks melted, the compound stirring device 3 was turned on, the speed of the stirring shaft 302 was set at 1500 r / min, and stirred for 5 minutes. Through multi-stage shear emulsification, the low-melting-point alloy liquid was dispersed into liquid alloy microparticles. The heating was stopped, the speed of the stirring shaft 302 was set at 500 r / min, and stirred for 10 min. Finally, the liquid alloy microparticles and the heat-resistant continuous-phase oil were cooled below the melting point of the low-melting-point alloy to form low-melting-point alloy microparticle powder.

[0044] Example 4:

[0045] First, 0.25 g of sodium dodecyl sulfate and 10.00 ml of heat-resistant continuous-phase silicone oil were heated and dissolved to obtain dispersant D. Then, 15.00 g of low-melting-point alloy blocks and 100.00 ml of silicone oil were added to the three-necked flask 1, the heating temperature was set at 160 °C, and 0.50 ml of dispersant D was added through the pulsed dispersant adding device 2 during the heating process. After the low-melting-point alloy blocks melted, the compound stirring device 3 was turned on, the speed of the stirring shaft 302 was set at 500 r / min, and stirred for 5 minutes. Through multi-stage shear emulsification, the low-melting-point alloy liquid was dispersed into liquid alloy microparticles. The heating was stopped, the speed of the stirring shaft 302 was set at 500 r / min, and stirred for 10 min. Finally, the liquid alloy microparticles and the heat-resistant continuous-phase oil were cooled below the melting point of the low-melting-point alloy to form low-melting-point alloy microparticle powder.

[0046] The low-melting-point alloy microparticle powders prepared in the above four embodiments were tested to obtain the performance data of the low-melting-point alloy microparticle powders prepared in different embodiments, as shown in the following table:

[0047]

[0048] It can be seen from the above table that the low-melting-point alloy microparticle powders prepared by the method of the present invention have good performance in terms of the addition amount of the dispersant, oxygen content, sphericity and particle size distribution range, and have advantages over the traditional preparation methods.

[0049] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.

Claims

1. A method for preparing low melting point alloy powder, characterized in that: The following steps are involved: (1) preparing a heat-resistant continuous phase oil dispersant; (2) adding a low melting point alloy block and a heat-resistant continuous phase oil into a three-necked flask, heating the mixture of the low melting point alloy block and the heat-resistant continuous phase oil to the melting point of the low melting point alloy block to melt it, and adding a heat-resistant continuous phase oil dispersant into the three-necked flask through a pulse dispersant adding device during the heating process; (3) turning on the composite stirring device to stir the melt in the three-necked flask. The composite stirring device includes a multi-stage variable diameter propeller blade and a conical stator. The composite stirring device has a multi-stage shearing and emulsifying effect, so that the low melting point alloy liquid in the three-necked flask is dispersed into liquid alloy particles. (4) Stop heating the contents of the three-necked flask and keep stirring the flask to cool the liquid alloy particles and the heat-resistant continuous phase oil to below the melting point of the low-melting-point alloy to form low-melting-point alloy particle powder.

2. The method for preparing low melting point alloy powder according to claim 1, characterized in that: The heat-resistant continuous phase oil is a mineral oil, vegetable oil, or organic solvent having a boiling point higher than that of the low-melting-point alloy block, including a mixture of one or more of lubricating oil, soybean oil, liquid paraffin, polyethylene glycol, and silicone oil.

3. The method for preparing low melting point alloy powder according to claim 1, characterized in that: The dispersant is a material that promotes the dissolution of low melting point alloy blocks and prevents the aggregation of low melting point alloy powder after dispersion, including a mixture of one or more of Span80, tetraglycerol condensed ricinoleate, sodium lauryl sulfate, oleic acid, stearic acid, palmitic acid, zinc stearate and zinc palmitate.

4. The method for preparing low melting point alloy powder according to claim 1, characterized in that: The composite stirring device comprises a vertically arranged stirring shaft, on which a plurality of propeller blades are arranged from top to bottom, and the plurality of propeller blades have different sizes.

5. The method for preparing low melting point alloy powder according to claim 4, characterized in that: The multi-stage propeller blades are arranged at equal intervals up and down.

6. The method for preparing low melting point alloy powder according to claim 5, characterized in that: The surface of the stirring shaft is provided with a nano ceramic layer.

7. The method for preparing low melting point alloy powder according to claim 6, characterized in that: The pulse dispersant addition device includes a dispersant storage syringe and an injection module. The lower end of the dispersant storage syringe is provided with a discharge pipe, and the lower end of the injection module is provided with a discharge nozzle. The lower end of the discharge pipe is connected to the discharge nozzle. The injection module is provided with a piezoelectric ceramic microvalve unit for controlling the pulse discharge of the injection module.

8. The method for preparing low melting point alloy powder according to claim 4, characterized in that: In step (3), the rotation speed of the stirring shaft in the composite stirring device is 2000 r / min, and the stirring time is 5 minutes; in step (4), the rotation speed of the stirring shaft in the composite stirring device is 500 r / min, and the stirring time is 10 minutes.

9. The method for preparing low melting point alloy powder according to claim 4, characterized in that: In step (3), the rotation speed of the stirring shaft in the composite stirring device is 1500 r / min, and the stirring time is 5 minutes; in step (4), the rotation speed of the stirring shaft in the composite stirring device is 500 r / min, and the stirring time is 10 minutes.

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