Preparation method of copper-nickel-tungsten solder paste and application thereof

Abstract

The present application belongs to the technical field of welding material, and particularly relates to a preparation method of copper-nickel-tungsten solder paste and application thereof. In order to overcome the shortcoming that nano-copper is easy to be oxidized, a new type of copper-nickel-tungsten solder paste is prepared by high-temperature calcination of raw materials such as copper salt, nickel salt, ammonium metatungstate, sugar and flux. The solder paste has high oxidation resistance, can be directly used for welding operation in air atmosphere, provides a more convenient scheme for welding operation, and is conducive to improving the work efficiency of welding operation. Meanwhile, the solder paste overcomes the defect that the existing copper welding material is easy to be oxidized, improves the stability, and has more excellent electrical conductivity and thermal conductivity. In addition, the raw materials used in the present application have a wide source, the preparation process is simple, and the present application has a good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of welding materials technology, specifically relating to a method for preparing copper-nickel-tungsten solder paste and its application. Background Technology

[0002] Currently, copper and copper-based materials are increasingly widely used in electrical components. Their excellent thermal and electrical conductivity, combined with high ductility, creep resistance, and corrosion resistance, makes them the preferred material for current-carrying components. When the particle size of metal particles is in the nanometer range, their specific surface area increases significantly, and their melting point decreases dramatically. When the temperature reaches a certain level, copper nanoparticles can sinter, thereby achieving interconnection structures between metals. However, copper nanoparticles are easily oxidized, and these oxide layers severely hinder the thermal, electrical, and interconnection properties of copper nanoparticles.

[0003] To improve the oxidation resistance of copper solder, researchers have conducted numerous studies. For example, Chinese invention patent CN114210972A discloses a method for preparing a novel nano-copper welding material. This method prevents contact between copper and oxygen by bonding a protective coating film to the surface of copper nanoparticles, thus avoiding agglomeration and improving the oxidation resistance and conductivity of the copper nanoparticles. However, the nano-copper prepared by this method through liquid-phase reduction has a protective film on its surface, and the process of pressing it into copper nanoparticle welding rods needs to be carried out at high temperatures. At high temperatures, the organic layer on the welding surface will decompose, making the nano-copper particles easily oxidized. Chinese invention patent CN113070605A discloses a welding material, its preparation method, and its uses. The welding material provided by this method has a microstructure of small grains or small-angle grain boundaries. The mechanical elongation, fatigue life, and electron migration resistance of this welding material are significantly improved compared to commonly used brazing. However, this method uses spark erosion to prepare small-sized particles, and the process and equipment used are relatively complex. Therefore, further design optimization is necessary to overcome the defect of existing copper welding materials being easily oxidized, while reducing their manufacturing costs. Summary of the Invention

[0004] To overcome the drawback of easy oxidation of nano-copper, the stability of nano-copper is greatly improved by alloying with copper-based particles. At the same time, high-temperature reduction gives the prepared nanoparticles high reliability with high resistance to fatigue fracture and electron migration, which has broad application prospects in the welding field.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a method for preparing copper-nickel-tungsten solder paste, the method comprising the following steps: S1. Dissolve copper salt, nickel salt, ammonium metatungstate and sugar in water respectively, mix them and then add citric acid to dissolve the precipitate. After evaporation and drying, a metal complex is obtained. Finally, the metal complex is calcined at high temperature under an inert atmosphere to obtain copper-nickel-tungsten alloy welding particles. S2. Mix copper-nickel-tungsten alloy welding particles, no-clean flux, solvent and dispersant to obtain solder paste.

[0006] This invention employs an alloy structure design that allows copper to maintain not only high electrical conductivity and excellent oxidation resistance, but also nanoscale particle size, resulting in high reliability with strong resistance to fatigue fracture and electron migration. Furthermore, the preparation process involves only mixing, drying, and high-temperature reduction, making the synthesis route simple and promising for industrial applications.

[0007] Preferably, the copper salt includes (but is not limited to) copper nitrate, copper sulfate, or copper chloride. Copper nitrate is the preferred copper salt.

[0008] Preferably, the nickel salt includes (but is not limited to) nickel nitrate, nickel sulfate, or nickel chloride. Nickel nitrate is a preferred nickel salt.

[0009] Preferably, the sugar includes (but is not limited to) sucrose, glucose, fructose, or maltose. Sucrose is the preferred sugar.

[0010] Preferably, the molar ratio of the copper salt, nickel salt, sugar, and ammonium metatungstate is 1-2:1-2:0.3-0.7:0.1-0.3. More preferably, the molar ratio of the copper salt, nickel salt, sugar, and ammonium metatungstate is 1:1:0.4:0.2.

[0011] Preferably, the ratio of the amount of tungsten to the amount of citric acid in the ammonium metatungstate is 1-2:1.

[0012] Preferably, the high-temperature calcination temperature is 800℃-1000℃, and the time is 6-9 hours. More preferably, the high-temperature calcination temperature is 900℃, and the time is 7 hours.

[0013] Preferably, the inert gas includes (but is not limited to) nitrogen, argon, or helium. Nitrogen is preferred.

[0014] The second aspect of the present invention provides a copper-nickel-tungsten solder paste prepared by the preparation method described in the first aspect.

[0015] The third aspect of this invention provides the application of the copper-nickel-tungsten solder paste described in the second aspect in metal welding.

[0016] Preferably, the method of applying solder paste to welding is as follows: in an air atmosphere, the above-mentioned copper-nickel-tungsten solder paste is applied between the first substrate and the second substrate, and welding is achieved after sintering.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a novel method for preparing copper-nickel-tungsten solder paste, which is prepared by high-temperature calcination of raw materials such as copper salts, nickel salts, ammonium metatungstate, sugar, and flux. The solder particles prepared by this invention exhibit high oxidation resistance, overcoming the defect of easy oxidation in existing copper soldering materials, thus improving their stability. They also possess superior electrical and thermal conductivity. Furthermore, the alloy soldering material prepared by this invention has small grain characteristics, which significantly improves its fatigue life and electron migration resistance. The method for preparing the alloy soldering material of this invention allows for direct soldering in an air atmosphere, providing a more convenient solution for soldering operations and improving work efficiency. In addition, the raw materials used in the preparation method of this invention are widely available, and it has technical advantages such as simple process, easy control of process parameters, and low cost, showing good prospects for industrial application. Attached Figure Description

[0018] Figure 1 shows the TG curves of copper-nickel-tungsten composite powder and nano-copper powder under air atmosphere. Detailed Implementation

[0019] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0020] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0021] Example 1: A method for preparing a copper-nickel-tungsten solder paste The method includes the following steps: (1) Dissolve copper nitrate, nickel nitrate, ammonium metatungstate and glucose in 600 ml of deionized water respectively. Combine the four solutions and add citric acid to dissolve the precipitate to obtain a mixed salt solution. The molar ratio of copper nitrate, nickel nitrate, sugar and ammonium metatungstate is 1:1:0.4:0.2. The ratio of the amount of tungsten in ammonium metatungstate to the amount of citric acid is 2:1. Then evaporate and dry the mixed salt solution to obtain a metal complex.

[0022] (2) The intermediate product (metal complex) was placed in a tube furnace, nitrogen was introduced, and it was calcined at 900°C for 7 hours. After the reaction, it was annealed and cooled to room temperature. After grinding, alloy welding particles (particle size 50-70 nm) were obtained. (3) The alloy welding particles, YR-ZHG-557 no-clean solder resist, solvent propanol and Pvp dispersant are mixed in a mass ratio of 2:1:5:0.5 to obtain solder paste.

[0023] Example 2: A method for preparing a copper-nickel-tungsten solder paste The method includes the following steps: (1) Dissolve copper nitrate, nickel nitrate, ammonium metatungstate and glucose in deionized water respectively, combine the four solutions and add citric acid to dissolve the precipitate to obtain a mixed salt solution, wherein the molar ratio of copper nitrate, nickel nitrate, sugar and ammonium metatungstate is 2:1:0.4:0.2. Then evaporate the mixed salt solution and dry it to obtain a metal complex.

[0024] (2) The intermediate product (metal complex) was placed in a tube furnace, nitrogen was introduced, and the furnace was calcined at 900°C for 7 hours. After annealing and cooling, alloy welding particles (particle size 50-70 nm) were obtained.

[0025] (3) The alloy welding particles, YR-ZHG-557 no-clean solder resist, solvent propanol and Pvp dispersant are mixed in a mass ratio of 2:1:5:0.5 to obtain solder paste.

[0026] Example 3: A method for preparing a copper-nickel-tungsten solder paste The method includes the following steps: (1) Dissolve copper nitrate, nickel nitrate, ammonium metatungstate and glucose in deionized water respectively, combine the four solutions and add citric acid to dissolve the precipitate to obtain a mixed salt solution, wherein the molar ratio of copper nitrate, nickel nitrate, sugar and ammonium metatungstate is 3:1:0.4:0.2. Then evaporate the mixed salt solution and dry it to obtain a metal complex.

[0027] (2) The intermediate product (metal complex) was placed in a tube furnace, nitrogen was introduced, and the furnace was calcined at 900°C for 7 hours. After annealing and cooling, alloy welding particles (particle size 50-70 nm) were obtained.

[0028] (3) The alloy welding particles, YR-ZHG-557 no-clean solder resist, solvent propanol and Pvp dispersant are mixed in a mass ratio of 2:1:5:0.5 to obtain solder paste.

[0029] Example 4: A method for preparing a copper-nickel-tungsten solder paste The method includes the following steps: (1) Dissolve copper nitrate, nickel nitrate, ammonium metatungstate and glucose in deionized water, combine the four solutions and add citric acid to dissolve the precipitate to obtain a mixed salt solution, wherein the molar ratio of copper nitrate, nickel nitrate, sugar and ammonium metatungstate is 3:1:0.4:0.1. Then evaporate the mixed salt solution and dry it to obtain a metal complex.

[0030] (2) The intermediate product (metal complex) was placed in a tube furnace, nitrogen was introduced, and the furnace was calcined at 900°C for 7 hours. After annealing and cooling, alloy welding particles (particle size 50-70 nm) were obtained.

[0031] (3) The alloy welding particles, YR-ZHG-557 no-clean solder resist, solvent propanol and Pvp dispersant are mixed in a mass ratio of 2:1:5:0.5 to obtain solder paste.

[0032] Comparative Example 1: A method for preparing a copper welding material Solder paste is prepared by mixing copper particles (the raw material for solder), no-clean flux, propanol (the solvent), and dispersant in a mass ratio of 2:1:5:0.5.

[0033] Experimental Example: Performance Testing of Welding Materials The prepared solder paste (taking Example 1 and Comparative Example 1 as examples) was screen printed on a copper substrate to form an 80 μm layer of solder paste. Then another copper plate was added on top of the solder paste. After preheating at 60°C for 5 min, it was then kept at 280°C and 10 MPa pressure in air for 30 min.

[0034] The TG spectra of Example 1 and Comparative Example 1 are as follows: Figure 1 As shown, the alloy particles of Example 1 begin to oxidize at 380°C, indicating that the formed alloy structure improves the thermal stability of the particles. Observations revealed that the alloy particles only increased in weight by 2.71% relative to their initial weight, and even at 600°C, they continued to increase in weight at a slow rate, without being completely oxidized. Compared to pure copper particles, they exhibit superior oxidation resistance. Furthermore, the thermal conductivity of the alloy particles of Example 1 at 300K is 1.237 ± 0.001 W / m. -1 K -1 The resistivity of the alloy particles is 30 μΩ·cm, while the thermal conductivity of the nano-copper powder is 1.21 W / (m·k) and the resistivity is 10 μΩ·cm, indicating that the alloy particles have excellent electrical and thermal conductivity. Furthermore, shear strength tests were performed on the joints formed by solder paste sintering. The shear strength of the alloy particles in Example 1 was 10.2 MPa, while that of the nano-copper powder was 8.4 MPa, indicating that the alloy particles have excellent bonding performance.

[0035] In addition, the alloy particles of Examples 2-4 also exhibit similar thermal stability, electrical conductivity, and shear strength.

[0036] In summary, the solder paste prepared by this invention exhibits high antioxidant properties and can be directly soldered in an air atmosphere, providing a more convenient solution for soldering operations and improving work efficiency. Furthermore, the raw materials used in this invention are widely available, the preparation process is simple, and it has promising prospects for industrial application.

[0037] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing a copper-nickel-tungsten solder paste, characterized in that, Includes the following steps: S1. Copper salt, nickel salt, ammonium metatungstate, and sugar are dissolved separately in water, mixed, and then citric acid is added to dissolve the precipitate. After evaporation and drying, a metal complex is obtained. Finally, the metal complex is calcined at high temperature under an inert atmosphere to obtain copper-nickel-tungsten alloy welding particles. The molar ratio of copper salt, nickel salt, sugar, and ammonium metatungstate is 1-2:1-2:0.3-0.7:0.1-0.

3. The high-temperature calcination temperature is 800℃-1000℃, and the time is 6-9 hours. S2. Mix copper-nickel-tungsten alloy welding particles, no-clean flux, solvent and dispersant to obtain solder paste.

2. The method for preparing a copper-nickel-tungsten solder paste according to claim 1, characterized in that, The copper salts include copper nitrate, copper sulfate, or copper chloride.

3. The method for preparing a copper-nickel-tungsten solder paste according to claim 1, characterized in that, The nickel salts include nickel nitrate, nickel sulfate, or nickel chloride.

4. The method for preparing a copper-nickel-tungsten solder paste according to claim 1, characterized in that, The sugars include sucrose, glucose, fructose, or maltose.

5. The method for preparing a copper-nickel-tungsten solder paste according to claim 1, characterized in that, The ratio of the amount of tungsten to the amount of citric acid in the ammonium metatungstate is 1-2:

1.

6. Copper-nickel-tungsten solder paste prepared by any one of claims 1-5.

7. The application of the copper-nickel-tungsten solder paste according to claim 6 in metal welding.

8. The application according to claim 7, characterized in that, The method of applying solder paste to welding is as follows: in an air atmosphere, the copper-nickel-tungsten solder paste of claim 6 is applied between the first substrate and the second substrate, and welding is achieved after sintering.

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