A nickel-plated lead-free solder wire and its preparation method

Abstract

The present invention relates to the technical field of lead-free solder wire preparation, and specifically relates to a nickel-plated lead-free solder wire and a preparation method thereof. The components of the lead-free solder wire include a lead-free solder and a soldering flux. The lead-free solder includes 120-180 parts by weight of tin, 5-10 parts by weight of copper, 0.5-1.3 parts by weight of silver, and 0.1-0.6 parts by weight of cobalt. The soldering flux includes 1-2 parts by weight of an organic solvent, 2-3 parts by weight of an active agent, 0.2-0.7 parts by weight of a composite corrosion inhibitor, and 3-5 parts by weight of rosin. In the lead-free solder wire of the present invention, the microcapsule corrosion inhibitor in the composite corrosion inhibitor ruptures when heated, releasing the corrosion inhibitor, which can slow down the corrosion rate of the welding residue on the base material, thereby improving the surface insulation resistance effect. At the same time, after the structure of the semi-closed body in the composite corrosion inhibitor collapses, it can cover the welding point position, playing an effect of blocking the erosion of external substances, avoiding corrosion and oxidation of the welding point, and thus improving the welding effect and the stability and durability after welding.

Description

Technical Field

[0001] The present invention relates to the technical field of lead-free solder wire preparation, and specifically to a nickel-plated lead-free solder wire and a preparation method thereof. Background Art

[0002] Lead-free solder wire, also known as environmentally friendly solder wire, is a solder wire made of lead-free alloy and is used for welding electronic components. Lead-free solder wire is more environmentally friendly than leaded solder wire. Leaded solder wire will release harmful lead vapor during the welding process, polluting the environment and endangering human health. Since lead-free solder wire does not contain harmful lead elements, it will not produce harmful lead vapor and is safer and more environmentally friendly. Due to the improvement of environmental protection requirements, lead-free solder wire has gradually replaced leaded solder wire and become the mainstream. Lead-free solder wire is more widely used in the welding of electronic components, especially in the fields of electronic product manufacturing and the electronics industry.

[0003] For various current electronic product components, in order to have a longer service life or rust prevention, nickel is plated on the surface of the components. Generally, the rosin-based lead-free solder wire cannot wet the surface of the nickel-plated layer, resulting in poor welding effect, low product yield, short service life, and even scrapping. For example, the invention patent with the publication number CN107127473A discloses a nickel-plated lead-free solder wire, which includes a lead-free solder wire. The components of the lead-free solder wire include, by weight, 100 - 150 parts of tin, 3 - 11 parts of copper, 0.5 - 1.5 parts of silver, 0.1 - 0.4 parts of cobalt, 5 - 15 parts of rosin, and 3 - 12 parts of additives. The preparation process of this patent is simple. When the prepared solder wire is used to weld parts made of stainless steel or nickel-plated materials, the surface of parts such as stainless steel or nickel-plated materials can be partially eroded, making the solder joints firm and reliable. Although this nickel-plated lead-free solder wire solves the problem of firm solder joints, during the welding process, rosin, additives, etc. splash onto the welding substrate due to uneven distribution, forming residues, and the welding substrate is easily corroded by the welding residues, thus affecting the use. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a nickel-plated lead-free solder wire and a preparation method thereof.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A nickel-plated lead-free solder wire, including a lead-free solder wire, and the components of the lead-free solder wire include a lead-free solder and a soldering flux.

[0007] The lead-free solder includes, by weight, 120 - 180 parts of tin, 5 - 10 parts of copper, 0.5 - 1.3 parts of silver, and 0.1 - 0.6 parts of cobalt.

[0008] The soldering flux includes, by weight, 1 - 2 parts of organic solvent, 2 - 3 parts of activator, 0.2 - 0.7 parts of composite corrosion inhibitor, and 3 - 5 parts of rosin.

[0009] As a further preferred embodiment of the present invention, the organic solvent is one or more of ethylene glycol, propylene glycol methyl ether, and ethylene glycol ethyl ether;

[0010] The activator is one or more of glutaric acid, citric acid, and salicylamide;

[0011] The rosin is one or more of polymerized rosin, disproportionated rosin, and hydrogenated rosin.

[0012] As a further preferred embodiment of the present invention, the preparation method of the composite corrosion inhibitor is as follows:

[0013] 1) Add copper sulfate solution to deionized water, then successively add polyvinylpyrrolidone aqueous solution and potassium bromide solution, stir well to obtain a precursor solution, then place it in a constant temperature water bath at 80 - 85 °C, and add ascorbic acid solution to the precursor solution under stirring conditions of 80 - 130 r / min. After reacting for 1 - 2 h, centrifuge the obtained product for 5 - 10 min, repeatedly purify it with deionized water and then dry it to obtain flaky copper micro - nano particles;

[0014] 2) Add the flaky copper micro - nano particles to deionized water, ultrasonically disperse them evenly, add citric acid solution, mix well, then add silver nitrate solution, and react at normal temperature under 200 - 300 W for 15 - 30 min. After the reaction ends, centrifuge the obtained product for 5 - 10 min, repeatedly purify it with deionized water and then dry it to obtain porous composite nano - sheets;

[0015] 3) Disperse the porous composite nano - sheets in deionized water to obtain a dispersion liquid, then add silicon carbide nanowires, under ultrasonic action of 300 - 500 W, mechanically stir at 1000 - 2000 r / min for 1 - 2 h, then place it in a vacuum impregnation tank, add corrosion inhibitor microcapsules, evacuate to 100 - 200 Pa, and apply ultrasonic action of 100 - 150 W, process for 15 - 30 min and then release the pressure to atmospheric pressure. After centrifuging and separating the product and drying it, the composite corrosion inhibitor can be obtained.

[0016] As a further preferred embodiment of the present invention, in step 1), the concentration of the copper sulfate solution is 1.0 - 1.3 mol / L;

[0017] The concentration of the polyvinylpyrrolidone aqueous solution is 40 - 60 g / L;

[0018] The concentration of the potassium bromide solution is 0.1 - 0.3 mol / L;

[0019] The concentration of the ascorbic acid solution is 1.5 - 1.8 mol / L;

[0020] The volume ratio of the copper sulfate solution, deionized water, polyvinylpyrrolidone aqueous solution, potassium bromide solution, and ascorbic acid solution is (1 - 3):(5 - 15):(2 - 10):(0.5 - 2.5):(1 - 3);

[0021] The rotation speed of the centrifugation is 8000 - 10000 r / min.

[0022] As a further preferred embodiment of the present invention, in step 2), the concentration of the citric acid solution is 0.1 - 0.2 mol / L;

[0023] The concentration of the silver nitrate solution is 0.2 - 0.3 mol / L;

[0024] The dosage ratio of the flaky copper micro-nanoparticles, deionized water, citric acid solution, and silver nitrate solution is (0.3 - 0.7) g:(8 - 12) mL:(0.1 - 0.2) mL:(0.5 - 0.8) mL;

[0025] The rotation speed of the centrifugation is 8000 - 10000 r / min.

[0026] As a further preferred embodiment of the present invention, in step 3), the dosage ratio of the porous composite nanosheets, deionized water, silicon carbide nanowires, and corrosion inhibitor microcapsules is (5 - 10) g:(120 - 200) mL:(2 - 3) g:(3 - 6) g.

[0027] As a further preferred embodiment of the present invention, the preparation method of the corrosion inhibitor microcapsules is as follows:

[0028] 1) Put lauric acid, xylene, and diethylenetriamine in a container, heat to 170 - 175 °C, react for 3 - 5 h, then raise the temperature to 210 - 216 °C, continue to react for 3 - 5 h. After the reaction is completed, cool to room temperature under vacuum conditions, carry out vacuum distillation and then cool to room temperature to obtain an intermediate. Then add benzyl chloride and react at 80 - 85 °C for 3 - 5 h with stirring by a stirrer, and then perform decolorization and recrystallization to obtain the corrosion inhibitor;

[0029] 2) Dissolve 1.2-2.0 g of gelatin in 50-80 mL of deionized water, heat to 55-60° C. to completely dissolve it, and obtain a gelatin solution. Add 0.3-0.7 g of silicon carbide nanowires and 1.2-2.0 g of chitosan to 50-80 mL of deionized water, stir thoroughly, and then dropwise add to the gelatin solution. After mixing evenly, add acetic acid solution to adjust the pH value to 4.0-4.5, add 0.5-1.2 g of corrosion inhibitor, stir thoroughly for 1-2 hours, and then add 2-3 drops of glutaraldehyde. After the corrosion inhibitor is encapsulated in the microcapsules, dry the microcapsules, and obtain corrosion inhibitor microcapsules.

[0030] As a further preferred embodiment of the present invention, in step 1), the usage ratio of lauric acid, xylene, diethylenetriamine and benzyl chloride is (40-60) g: (40-60) mL: (24-36) mL: (25-38) mL.

[0031] As a further preferred embodiment of the present invention, in step 2), the concentration of the acetic acid solution is 36-38 wt %.

[0032] A method for preparing a nickel-plated lead-free tin wire, comprising the following steps:

[0033] 1) Mix copper, silver and cobalt, add them into a heating container, heat them into a fluid, and mix them evenly to obtain a premix;

[0034] 2) Add tin to the premix, mix and then use the method of pouring, extrusion and drawing to obtain a semi-finished tin wire;

[0035] 3) Add organic solvent, activator and rosin into the container, dissolve and stir at 150-165℃ until it becomes liquid, then add composite corrosion inhibitor, stir thoroughly, extrude and mix with semi-finished tin wire, and then go through wire drawing process to get the required lead-free tin wire.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] In the present invention, lauric acid, diethylenetriamine and benzyl chloride are used as raw materials to synthesize a quaternary ammonium salt-based corrosion inhibitor. Then, the complex coacervation method is adopted, using gelatin and chitosan as wall materials to encapsulate the corrosion inhibitor, thereby obtaining a microcapsule corrosion inhibitor. When the tin wire is corroded, the microcapsule corrosion inhibitor ruptures in response to external corrosion and releases the encapsulated corrosion inhibitor, thereby slowing down the corrosion damage to the tin wire and improving the corrosion resistance of the tin wire. Moreover, silicon carbide nanowires are added to the wall material of the microcapsule corrosion inhibitor. During the stirring process, the silicon carbide nanowires are intertwined with each other to form a network structure, thereby playing a role in transmitting and dispersing stress in the wall material and enhancing the strength of the wall material, so that the formed microcapsule corrosion inhibitor has a certain resistance to external forces. At the same time, in the present invention, copper sulfate is used as a copper source, and a two-dimensional polygon-shaped flaky copper micro-nano particle is prepared in an aqueous phase by a liquid-phase reduction method. Then, using the flaky copper micro-nano particle as a copper source, a simple and efficient replacement method is adopted, and under the action of normal-temperature ultrasound, a porous composite nanosheet with a two-dimensional structure is prepared. Then, through mechanical stirring under the action of ultrasound, the porous composite nanosheet is fully mixed with the silicon carbide nanowires. The silicon carbide nanowires will be embedded in the pores of the porous composite nanosheet and form countless independent network structures through cross-linking with each other, thereby connecting several porous composite nanosheets to form an irregular semi-closed body. By means of vacuum impregnation, the microcapsule corrosion inhibitor can penetrate into the formed semi-closed body. And the applied ultrasound can, on the one hand, promote the porous composite nanosheets to approach each other, reduce the volume of the semi-closed body, and on the other hand, promote the better penetration of the microcapsule corrosion inhibitor into the semi-closed body, so that the microcapsule corrosion inhibitor can gather in the semi-closed body and closely fit with each other, and it is not easy to overflow from the semi-closed body, thereby obtaining a structurally stable composite corrosion inhibitor. After the composite corrosion inhibitor is fully mixed with an organic solvent, an active agent and rosin, it is coated on the surface of the tin wire to obtain a finished lead-free tin wire. When the lead-free tin wire is used for welding nickel-plated parts, the microcapsule corrosion inhibitor in the composite corrosion inhibitor is heated and ruptured, releasing the corrosion inhibitor, which can slow down the corrosion rate of the welding residue to the substrate material, thereby improving the surface insulation resistance effect. At the same time, with the rupture of the microcapsule sustained-release agent, the structure of the semi-closed body in the composite corrosion inhibitor collapses and returns to the porous composite nanosheet again. These nanosheets can coat the welding point position, playing a role in blocking the erosion of external substances and preventing the welding point from being corroded and oxidized, thereby improving the welding effect and the stability and durability after welding.

[0038] In the lead-free solder wire of the present invention, the organic solvent can evenly distribute the active agent and the composite corrosion inhibitor in the rosin, avoiding splashing onto the welding substrate during the welding process of nickel-plated parts due to uneven distribution of the active agent, thereby reducing the corrosion of the welding substrate by the welding residues. At the same time, the microcapsule corrosion inhibitor in the composite corrosion inhibitor ruptures when heated, releasing the corrosion inhibitor, which can slow down the corrosion rate of the substrate material by the welding residues, thereby improving the surface insulation resistance effect. At the same time, the semi-closed body in the composite corrosion inhibitor can cover the welding point position after its structure collapses, playing a role in blocking the erosion of external substances and avoiding corrosion and oxidation of the welding point, thereby improving the welding effect and the stability and durability after welding. Specific embodiments

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] In the embodiments of the present invention, the organic solvent is ethylene glycol; the active agent is glutaric acid; the rosin is hydrogenated rosin.

[0041] Embodiment 1: A nickel-plated lead-free solder wire includes a lead-free solder wire, and the components of the lead-free solder wire include a lead-free solder and a flux.

[0042] Among them, the lead-free solder includes 120 parts of tin, 5 parts of copper, 0.5 parts of silver, and 0.1 part of cobalt by weight.

[0043] Among them, the flux includes 1 part of organic solvent, 2 parts of active agent, 0.2 part of composite corrosion inhibitor, and 3 parts of rosin by weight.

[0044] The preparation method of the nickel-plated lead-free solder wire specifically includes the following steps:

[0045] 1) Mix copper, silver, and cobalt and add them to a heating container to heat into a fluid and mix evenly to obtain a premix.

[0046] 2) Add tin to the premix, and after mixing, use the method of perfusion extrusion and drawing to obtain a semi-finished solder wire.

[0047] 3) Add the organic solvent, active agent, and rosin to a container, dissolve and stir at 150 °C until it becomes a liquid, then add the composite corrosion inhibitor, fully stir, and then extrude and mix with the semi-finished solder wire, and then through the wire drawing process, the required lead-free solder wire can be obtained.

[0048] Among them, the preparation method of the composite corrosion inhibitor is as follows:

[0049] 1) Place 40 g of lauric acid, 40 mL of xylene, and 24 mL of diethylenetriamine in a container, heat to 170 °C, react for 3 h, then raise the temperature to 210 °C and continue to react for 3 h. After the reaction is completed, cool to room temperature under vacuum conditions, perform vacuum distillation and then cool to room temperature to obtain an intermediate. Then add 25 mL of benzyl chloride and react at 80 °C for 3 h under stirring of a stirrer. After decolorization and recrystallization, a corrosion inhibitor is obtained;

[0050] 2) Dissolve 1.2 g of gelatin in 50 mL of deionized water, heat to 55 °C to completely dissolve it to obtain a gelatin solution. Then add 0.3 g of silicon carbide nanowires and 1.2 g of chitosan to 50 mL of deionized water, stir well, and then dropwise add it to the gelatin solution. After mixing evenly, add a 36 wt% acetic acid solution to adjust the pH value to 4.0, add 0.5 g of the corrosion inhibitor, stir well for 1 h, add 2 drops of glutaraldehyde. After the corrosion inhibitor is encapsulated into microcapsules, dry to obtain corrosion inhibitor microcapsules;

[0051] 3) Add 1 mL of a 1.0 mol / L copper sulfate solution to 5 mL of deionized water, and then successively add 2 mL of a 40 g / L polyvinylpyrrolidone aqueous solution and 0.5 mL of a 0.1 mol / L potassium bromide solution. After stirring well to obtain a precursor solution, place it in an 80 °C constant temperature water bath, and under stirring conditions of 80 r / min, add 1 mL of a 1.5 mol / L ascorbic acid solution to the precursor solution. After reacting for 1 h, centrifuge the obtained product at 8000 r / min for 5 min, and after repeatedly purifying with deionized water and drying, obtain flaky copper micro-nano particles;

[0052] 4) Add 0.3 g of flaky copper micro-nano particles to 8 mL of deionized water, disperse evenly by ultrasonic wave, add 0.1 mL of a 0.1 mol / L citric acid solution, mix well, then add 0.5 mL of a 0.2 mol / L silver nitrate solution, and react at 200 W at room temperature for 15 min. After the reaction is completed, centrifuge the obtained product at 8000 r / min for 5 min, and after repeatedly purifying with deionized water and drying, obtain porous composite nano-sheets;

[0053] 5) Disperse 5 g of porous composite nano-sheets in 120 mL of deionized water to obtain a dispersion liquid, then add 2 g of silicon carbide nanowires, under ultrasonic action of 300 W, mechanically stir at 1000 r / min for 1 h, then place it in a vacuum impregnation tank, add 3 g of corrosion inhibitor microcapsules, evacuate to 100 Pa, and apply ultrasonic action of 100 W. After treating for 15 min, release the pressure to atmospheric pressure, centrifuge the product and then dry it to obtain a composite corrosion inhibitor.

[0054] Example 2: A nickel-plated lead-free solder wire, including a lead-free solder wire, and the components of the lead-free solder wire include a lead-free solder and a flux;

[0055] Among them, the lead-free solder includes 150 parts of tin, 8 parts of copper, 0.8 parts of silver, and 0.3 parts of cobalt by weight;

[0056] Among them, the flux includes 1.5 parts of organic solvent, 2.5 parts of active agent, 0.5 part of composite corrosion inhibitor, and 4 parts of rosin by weight.

[0057] The preparation method of the nickel-plated lead-free solder wire specifically includes the following steps:

[0058] 1) Mix copper, silver, and cobalt and add them to a heating container to be heated into a fluid and mix evenly to obtain a premix;

[0059] 2) Add tin to the premix, and after mixing, use the method of perfusion extrusion and drawing to obtain a semi-finished solder wire;

[0060] 3) Add the organic solvent, active agent, and rosin to a container, dissolve and stir at 155 °C until it becomes a liquid, then add the composite corrosion inhibitor, stir well, and then perform extrusion mixing with the semi-finished solder wire, and then through the wire drawing process, the required lead-free solder wire can be obtained.

[0061] Among them, the preparation method of the composite corrosion inhibitor is as follows:

[0062] 1) Place 50 g of lauric acid, 50 mL of xylene, and 30 mL of diethylenetriamine in a container, heat to 172 °C, react for 4 h, then raise the temperature to 215 °C and continue to react for 4 h. After the reaction is completed, cool to room temperature under vacuum conditions, perform vacuum distillation and then cool to room temperature to obtain an intermediate, and then add 30 mL of benzyl chloride and react at 82 °C for 4 h under stirring of a stirrer, and then through decolorization and recrystallization, a corrosion inhibitor is obtained;

[0063] 2) Dissolve 1.6 g of gelatin in 70 mL of deionized water, heat to 57 °C to completely dissolve it to obtain a gelatin solution. Then add 0.5 g of silicon carbide nanowires and 1.8 g of chitosan to 70 mL of deionized water, stir well, then dropwise add it to the gelatin solution, mix evenly, add acetic acid solution with a concentration of 37 wt% to adjust the pH value to 4.5, add 0.7 g of the corrosion inhibitor, stir well for 1.5 h, then add 3 drops of glutaraldehyde, wait until the corrosion inhibitor is microencapsulated therein, and after drying, a corrosion inhibitor microcapsule is obtained;

[0064] 3) Add 2 mL of copper sulfate solution with a concentration of 1.2 mol / L to 10 mL of deionized water, then successively add 8 mL of polyvinylpyrrolidone aqueous solution with a concentration of 50 g / L and 1.5 mL of potassium bromide solution with a concentration of 0.2 mol / L. After stirring well, a precursor solution is obtained. Then, place it in a constant temperature water bath at 83 °C and, under the stirring condition of 100 r / min, add 2 mL of ascorbic acid solution with a concentration of 1.7 mol / L to the precursor solution. After reacting for 1.5 h, centrifuge the obtained product at 9000 r / min for 8 min, and after repeated purification with deionized water, dry it to obtain flaky copper micro-nano particles;

[0065] 4) Add 0.5 g of flaky copper micro-nano particles to 10 mL of deionized water. After ultrasonic dispersion, add 0.2 mL of citric acid solution with a concentration of 0.2 mol / L. After mixing well, add 0.7 mL of silver nitrate solution with a concentration of 0.3 mol / L and react at room temperature with 300 W for 25 min. After the reaction ends, centrifuge the obtained product at 9000 r / min for 8 min, and after repeated purification with deionized water, dry it to obtain porous composite nano-sheets;

[0066] 5) Disperse 7 g of porous composite nano-sheets in 160 mL of deionized water to obtain a dispersion liquid, then add 2.5 g of silicon carbide nanowires. Under the action of 400 W ultrasonic waves, mechanically stir at 1500 r / min for 1.5 h, then place it in a vacuum impregnation tank, add 5 g of corrosion inhibitor micro-capsules, evacuate to 150 Pa, and apply 150 W ultrasonic wave action. After treating for 25 min, release the pressure to atmospheric pressure. After centrifuging and separating the product, dry it to obtain a composite corrosion inhibitor.

[0067] Example 3: A nickel-plated lead-free solder wire, including a lead-free solder wire, and the components of the lead-free solder wire include a lead-free solder and a flux;

[0068] Among them, the lead-free solder includes 180 parts of tin, 10 parts of copper, 1.3 parts of silver, and 0.6 parts of cobalt by weight;

[0069] Among them, the flux includes 2 parts of organic solvent, 3 parts of active agent, 0.7 part of composite corrosion inhibitor, and 5 parts of rosin by weight.

[0070] The preparation method of the nickel-plated lead-free solder wire specifically includes the following steps:

[0071] 1) Mix copper, silver, and cobalt and add them to a heating container to heat into a fluid and mix evenly to obtain a premix;

[0072] 2) Add tin to the premix, and after mixing, use the method of perfusion extrusion and drawing to obtain a semi-finished solder wire;

[0073] 3) Add organic solvents, surfactants, and rosin into a container, dissolve and stir at 165 °C until it becomes a liquid. Then add a composite corrosion inhibitor, fully stir, and extrude and mix with semi-finished tin wire. After that, through the wire drawing process, the required lead-free tin wire can be obtained.

[0074] Among them, the preparation method of the composite corrosion inhibitor is as follows:

[0075] 1) Place 60 g of lauric acid, 60 mL of xylene, and 36 mL of diethylenetriamine in a container, heat to 175 °C, react for 5 h, then raise the temperature to 216 °C and continue to react for 5 h. After the reaction is completed, cool to room temperature under vacuum conditions, carry out vacuum distillation and then cool to room temperature to obtain an intermediate. Then add 38 mL of benzyl chloride and react at 85 °C for 5 h under stirring by a stirrer. After decolorization and recrystallization, a corrosion inhibitor is obtained;

[0076] 2) Dissolve 2.0 g of gelatin in 80 mL of deionized water, heat to 60 °C to completely dissolve it to obtain a gelatin solution. Then add 0.7 g of silicon carbide nanowires and 2.0 g of chitosan to 80 mL of deionized water, fully stir, and dropwise add it into the gelatin solution. After mixing evenly, add an acetic acid solution with a concentration of 38 wt% to adjust the pH value to 4.5, add 1.2 g of the corrosion inhibitor, fully stir for 2 h, then add 3 drops of glutaraldehyde. Wait until the corrosion inhibitor is microencapsulated therein, and after drying, a corrosion inhibitor microcapsule is obtained;

[0077] 3) Add 3 mL of a copper sulfate solution with a concentration of 1.3 mol / L to 15 mL of deionized water, then successively add 10 mL of an aqueous polyvinylpyrrolidone solution with a concentration of 60 g / L and 2.5 mL of a potassium bromide solution with a concentration of 0.3 mol / L. After fully stirring, a precursor solution is obtained. Then place it in a constant temperature water bath at 85 °C and, under the stirring condition of 130 r / min, add 3 mL of an ascorbic acid solution with a concentration of 1.8 mol / L to the precursor solution. After reacting for 2 h, centrifuge the obtained product at 10000 r / min for 10 min, and after repeatedly purifying with deionized water and drying, flaky copper micro-nanoparticles are obtained;

[0078] 4) Add 0.7 g of flaky copper micro-nanoparticles to 12 mL of deionized water, ultrasonically disperse evenly, add 0.2 mL of a citric acid solution with a concentration of 0.2 mol / L, fully mix evenly, then add 0.8 mL of a silver nitrate solution with a concentration of 0.3 mol / L, and react at 300 W at room temperature for 30 min. After the reaction is completed, centrifuge the obtained product at 10000 r / min for 10 min, and after repeatedly purifying with deionized water and drying, porous composite nanosheets are obtained;

[0079] 5) Disperse 10 g of porous composite nanosheets in 200 mL of deionized water to obtain a dispersion liquid, then add 3 g of silicon carbide nanowires, under the action of 500 W ultrasonic wave, mechanically stir at 2000 r / min for 2 h, then place it in a vacuum impregnation tank, add 6 g of inhibitor microcapsules, evacuate to 200 Pa, and apply 150 W ultrasonic wave. After treating for 30 min, release the pressure to atmospheric pressure. Centrifuge and dry the product to obtain the composite inhibitor.

[0080] Comparative Example 1: This comparative example is basically the same as Example 1, except that it does not contain the composite inhibitor.

[0081] Comparative Example 2: This comparative example is basically the same as Example 1, except that in the preparation of the composite inhibitor, steps 1 - 2) are omitted.

[0082] Comparative Example 3: This comparative example is basically the same as Example 1, except that in the preparation of the composite inhibitor, step 3) is omitted.

[0083] Comparative Example 4: This comparative example is basically the same as Example 1, except that in the preparation of the composite inhibitor, step 4) is omitted.

[0084] Comparative Example 5: This comparative example is basically the same as Example 1, except that in the preparation of the composite inhibitor, steps 3 - 5) are omitted.

[0085] Testing experiment:

[0086] Perform insulation performance testing on the lead - free solder wires prepared by each example and comparative example of the present invention, and the data are as follows in the table:

[0087]

[0088] It can be seen from the above table that the lead - free solder wires in the examples of the present invention can effectively slow down the corrosion rate of the matrix material by welding residues and avoid corrosion and oxidation at the welding points, thereby improving the surface insulation resistance effect.

[0089] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, according to the content of this specification, many modifications and changes can be made. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the relevant technical field can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A nickel-plated lead-free tin wire, comprising a lead-free solder wire, characterized in that: The lead-free solder wire components include lead-free solder and flux; The lead-free solder comprises 120-180 parts of tin, 5-10 parts of copper, 0.5-1.3 parts of silver and 0.1-0.6 parts of cobalt in parts by weight; The soldering flux comprises, by weight, 1-2 parts of an organic solvent, 2-3 parts of an activator, 0.2-0.7 parts of a composite corrosion inhibitor and 3-5 parts of rosin; The organic solvent is one or more of ethylene glycol, propylene glycol methyl ether, and ethylene glycol ethyl ether; The active agent is one or more of glutaric acid, citric acid, and salicylamide; The rosin is one or more of polymerized rosin, disproportionated rosin, and hydrogenated rosin; The preparation method of the composite corrosion inhibitor is as follows: 1) Add copper sulfate solution to deionized water, then add polyvinyl pyrrolidone aqueous solution and potassium bromide solution in sequence, stir thoroughly to obtain a precursor solution, then place in a constant temperature water bath at 80-85°C, add ascorbic acid solution to the precursor solution under stirring conditions of 80-130r / min, react for 1-2h, centrifuge the obtained product for 5-10min, purify repeatedly with deionized water and dry to obtain flaky copper micro-nano particles; 2) Add the flaky copper micro-nanoparticles to deionized water, disperse them uniformly by ultrasonication, add the citric acid solution, mix them thoroughly, then add the silver nitrate solution, react at 200-300W at room temperature for 15-30min, after the reaction is completed, centrifuge the obtained product for 5-10min, purify it repeatedly with deionized water and dry it to obtain a porous composite nanosheet; 3) The porous composite nanosheets are dispersed in deionized water to obtain a dispersion, and then silicon carbide nanowires are added. Under 300-500W ultrasonic action, the dispersion is mechanically stirred at 1000-2000r / min for 1-2h, and then placed in a vacuum impregnation tank, and corrosion inhibitor microcapsules are added. The dispersion is evacuated to 100-200Pa, and 100-150W ultrasonic action is applied. After treating for 15-30min, the pressure is released to normal pressure, and the product is centrifuged and dried to obtain a composite corrosion inhibitor.

2. The nickel-plated lead-free tin wire according to claim 1, characterized in that: In step 1), the concentration of the copper sulfate solution is 1.0-1.3 mol / L; The concentration of the polyvinyl pyrrolidone aqueous solution is 40-60 g / L; The concentration of the potassium bromide solution is 0.1-0.3 mol / L; The concentration of the ascorbic acid solution is 1.5-1.8 mol / L; The volume ratio of the copper sulfate solution, deionized water, polyvinyl pyrrolidone aqueous solution, potassium bromide solution and ascorbic acid solution is (1-3): (5-15): (2-10): (0.5-2.5): (1-3); The centrifugal speed is 8000-10000r / min.

3. The nickel-plated lead-free tin wire according to claim 1, characterized in that: In step 2), the concentration of the citric acid solution is 0.1-0.2 mol / L; The concentration of the silver nitrate solution is 0.2-0.3 mol / L; The usage ratio of the flaky copper micro-nano particles, deionized water, citric acid solution, and silver nitrate solution is (0.3-0.7) g: (8-12) mL: (0.1-0.2) mL: (0.5-0.8) mL; The centrifugal speed is 8000-10000r / min.

4. The nickel-plated lead-free tin wire according to claim 1, characterized in that: In step 3), the usage ratio of the porous composite nanosheet, deionized water, silicon carbide nanowires, and corrosion inhibitor microcapsules is (5-10) g: (120-200) mL: (2-3) g: (3-6) g.

5. The nickel-plated lead-free tin wire according to claim 1, characterized in that: The preparation method of the corrosion inhibitor microcapsule is as follows: 1) Place lauric acid, xylene and diethylenetriamine in a container, heat to 170-175°C, react for 3-5 hours, then heat to 210-216°C, continue to react for 3-5 hours, after the reaction is completed, cool to room temperature under vacuum conditions, perform reduced pressure distillation and cool to room temperature to obtain an intermediate, then add benzyl chloride, react at 80-85°C for 3-5 hours under stirring, and then decolorize and recrystallize to obtain a corrosion inhibitor; 2) Dissolve 1.2-2.0 g of gelatin in 50-80 mL of deionized water, heat to 55-60° C. to completely dissolve it, and obtain a gelatin solution. Add 0.3-0.7 g of silicon carbide nanowires and 1.2-2.0 g of chitosan to 50-80 mL of deionized water, stir thoroughly, and then dropwise add to the gelatin solution. After mixing evenly, add acetic acid solution to adjust the pH value to 4.0-4.5, add 0.5-1.2 g of corrosion inhibitor, stir thoroughly for 1-2 hours, and then add 2-3 drops of glutaraldehyde. After the corrosion inhibitor is encapsulated in the microcapsules, dry the microcapsules, and obtain corrosion inhibitor microcapsules.

6. The nickel-plated lead-free tin wire according to claim 5, characterized in that: In step 1), the usage ratio of lauric acid, xylene, diethylenetriamine and benzyl chloride is (40-60) g: (40-60) mL: (24-36) mL: (25-38) mL.

7. The nickel-plated lead-free tin wire according to claim 5, characterized in that: In step 2), the concentration of the acetic acid solution is 36-38 wt %.

8. A method for preparing a nickel-plated lead-free tin wire according to any one of claims 1 to 7, characterized in that: The specific steps include: 1) Mix copper, silver and cobalt, add them into a heating container, heat them into a fluid, and mix them evenly to obtain a premix; 2) Add tin to the premix, mix and then use the method of pouring, extruding and drawing to obtain a semi-finished tin wire; 3) Add organic solvent, activator and rosin into the container, dissolve and stir at 150-165℃ until it becomes liquid, then add composite corrosion inhibitor, stir thoroughly, extrude and mix with semi-finished tin wire, and then go through wire drawing process to get the required lead-free tin wire.

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