Water-based soldering flux and its preparation method

Abstract

This application relates to the technical field of soldering fluxes, and specifically discloses an aqueous soldering flux and a preparation method thereof. The aqueous soldering flux is made from the following raw materials in parts by weight: 4-8 parts of an active agent, 6-12 parts of an organic solvent, 3-8 parts of an organic acid, and 80-90 parts of deionized water; the active agent is formed by loading rare earth oxides on fluorinated graphite oxide. The fluorinated graphite in the active agent of this application obtains fluorinated graphite oxide by introducing active oxidation groups, which has good surface activity and dispersibility, can reduce the internal stress of the soldering flux during the soldering process, thereby improving the flow rate and adhesion of soldering, and improving the ability of the soldering flux to improve wettability; at the same time, graphite can improve the corrosion resistance of the weld seam after soldering.

Description

Technical Field

[0001] The present application relates to the technical field of soldering fluxes, and more specifically, to an aqueous soldering flux and a preparation method thereof. Background Art

[0002] Soldering is the main process in electronic assembly, and a soldering flux is an auxiliary material used in soldering. The main function of the soldering flux is to remove oxides on the surface of the solder and the base material to be soldered, making the metal surface reach the necessary cleanliness. It prevents re-oxidation on the surface during soldering, reduces the surface tension of the solder, and improves the soldering performance. The quality of the soldering flux directly affects the quality of electronic products.

[0003] Currently, most of the soldering fluxes used are organic solvent-based soldering fluxes. The active components of this type of soldering flux must be dissolved in organic solvents, and they have disadvantages such as high volatility, flammability, and harm to the body when in use. While water-soluble soldering fluxes use deionized water as a solvent, which is environmentally friendly, safe, and can be better applied to PCB soldering. However, due to the single component of the surfactant used as the active component in the aqueous soldering flux, the wettability and corrosion resistance of this soldering flux are poor.

[0004] Therefore, improving the wettability and corrosion resistance of the active component is of great significance for the development of aqueous soldering fluxes. Summary of the Invention

[0005] In order to improve the wettability and corrosion resistance of the aqueous soldering flux, the present application provides an aqueous soldering flux and a preparation method thereof.

[0006] In a first aspect, the present application provides an aqueous soldering flux, adopting the following technical solution:

[0007] An aqueous soldering flux, comprising raw materials made of the following parts by weight: 4 - 8 parts of an active agent, 6 - 12 parts of an organic solvent, 3 - 8 parts of an organic acid, and 80 - 90 parts of deionized water; the active agent is formed by loading rare earth oxides on fluorinated graphite oxide.

[0008] By adopting the above technical solution, the fluorinated graphite in the active agent is converted into fluorinated graphite oxide by introducing active oxygen groups, which has good surface activity and dispersibility. It can reduce the internal stress of the soldering flux during the soldering process, thereby improving the flow rate and adhesion of the soldering, enhancing the ability of the soldering flux to improve wettability, and reducing the surface tension of the material to be soldered; at the same time, graphite can improve the corrosion resistance of the weld seam after soldering. Rare earth oxides have excellent corrosion resistance. By being loaded on fluorinated graphite oxide, they can not only prevent the agglomeration of fluorinated graphite but also improve the corrosion resistance of the active agent. That is, by adding an appropriate amount of the active agent in the aqueous soldering flux, the wettability and corrosion resistance of the soldering flux can be improved.

[0009] In a specific feasible embodiment, the preparation method of the active agent comprises the following steps:

[0010] Place the concentrated sulfuric acid solution in an ice bath, add 1 part by weight of fluorinated graphite and 0.1 part by weight of graphite oxide, stir and ultrasonicate, and then add 3 - 15 parts by weight of an oxidant to react to obtain a fluorinated and oxidized graphite mixture; filter and dry the fluorinated and oxidized graphite mixture to obtain fluorinated and oxidized graphite;

[0011] Mix the fluorinated and oxidized graphite with deionized water and a surfactant to form a dispersion, and then add a mixture of a soluble rare earth salt solution and an alkaline solution with a molar ratio of 1:2 - 4, and perform a hydrothermal reaction on the mixture to obtain the active agent.

[0012] By adopting the above technical solution, on the one hand, by adding an appropriate amount of graphite oxide to the fluorinated graphite, the interaction between graphite sheets is enhanced by means of hydrogen bonding, improving the film-forming property of the soldering flux. At the same time, the addition of an appropriate amount of graphite oxide can maintain the insulation of the film during the subsequent hydrothermal reaction process; on the other hand, fluorinated graphite has hydrophobicity due to the grafting of many F atoms on the graphite. Using ultrasonic treatment, during the propagation of ultrasonic waves, particles in the elastic medium vibrate and transfer energy along the propagation direction, thus generating mechanical effects, thermal effects, and acoustic cavitation phenomena. These phenomena are applied in the ultrasonic treatment process, which can not only depolymerize the aggregates of fluorinated graphite powder particles in concentrated sulfuric acid, but also disperse the fluorinated graphite in concentrated sulfuric acid to obtain a dispersion with relatively uniform particle size. The cavitation effect of ultrasonic waves can also be used to remove the air dissolved or retained in the fluorinated graphite powder, which is conducive to the contact between concentrated sulfuric acid and fluorinated graphite, accelerating the wetting process of concentrated sulfuric acid on fluorinated graphite and facilitating the subsequent reaction. In addition, the cavitation effect of ultrasonic waves can also penetrate the isolation layer covering the fluorinated graphite, promoting the diffusion, intercalation, and reaction of concentrated sulfuric acid into the interior of the fluorinated graphite. The finally obtained fluorinated and oxidized graphite has more oxygen-containing groups, so it has higher activity and dispersibility. Further, loading rare earth oxide nanoparticles on the fluorinated and oxidized graphite layer can not only prevent the agglomeration of fluorinated graphite and improve its dispersibility, but also improve the corrosion resistance of the prepared active agent due to the corrosion inhibition effect of rare earth oxides.

[0013] In a specific feasible embodiment, the preparation method of the fluorinated graphite is: obtained by fluorinating graphene powder with a mixed gas of fluorine gas and nitrogen gas.

[0014] By adopting the above technical solution, since nitrogen has little influence on temperature and plays a dilution role, nitrogen is introduced during the fluorination treatment, making the heat exchange more sufficient after the gas mixture, and performing fluorination surface treatment on graphite, triggering surface medium chemical reactions. On the one hand, it can maintain the high mechanical properties of graphite itself, and on the other hand, it can improve its dispersibility, wettability and corrosion resistance in the flux.

[0015] In a specific feasible embodiment, the fluorine-carbon ratio of the fluorinated graphite is 1.1 - 1.3:1.

[0016] By adopting the above technical solution, if the fluorine-carbon ratio is too low, the thermal stability and lubricating performance of the fluorocarbon graphite are poor; while it is difficult to obtain fluorinated graphite with a relatively high fluorine-carbon ratio, increasing the cost.

[0017] In a specific feasible embodiment, the oxidant is potassium permanganate or a mixture of potassium permanganate and sodium nitrate.

[0018] By adopting the above technical solution, potassium permanganate and sodium nitrate not only introduce oxidation groups into the fluorinated graphite as oxidants, improving the activity and dispersibility of the fluorinated graphite; but also their excessive potassium ions and sodium ions can reduce the melting point and surface tension of the flux, refine the molten droplets, and reduce the free splash degree of the flux during the welding process.

[0019] In a specific feasible embodiment, the surfactant is one or more of stearic acid, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium glycocholate; further, the surfactant is sodium dodecylbenzenesulfonate.

[0020] By adopting the above technical solution, sodium dodecylbenzenesulfonate has a low surface tension, good wetting ability, and excellent foaming performance and high foam stability. Sodium dodecylbenzenesulfonate is neutral, not easily oxidized, easily compounded with various additives, has a low cost, and a mature synthesis process.

[0021] In a specific feasible embodiment, the rare earth element in the soluble rare earth salt solution is one of Yb, Er, Sm, Eu, Y, Gd, Dy, Ce; further, the rare earth element in the soluble rare earth salt solution is Ce.

[0022] By adopting the above technical solution, rare earth has a strong affinity with sulfur and oxygen in the weld, generating spherical or ellipsoidal rare earth sulfides, oxides or oxygen-sulfur composite inclusions, significantly improving the sulfide inclusions in the weld; while the density of the compound formed by rare earth cerium and sulfur and oxygen in the weld is about 6.0, which is easy to float and remove in the weld. Therefore, the flux containing rare earth cerium can maximize the corrosion resistance of the flux.

[0023] In a specific feasible embodiment, the organic solvent is a mixture of a low-boiling-point (less than 100 °C) organic solvent, a medium-boiling-point (100 - 150 °C) organic solvent, and a high-boiling-point (150 - 200 °C) organic solvent.

[0024] By adopting the above technical solution, the organic solvent plays a solubilizing role in the flux, which can improve the solubility of the active agent in deionized water and the stability after dispersion. The low-boiling-point solvent is beneficial to preventing the sagging of the weld seam, and it has the advantages of fast volatilization, easy drying, and low viscosity; after the low-boiling-point solvent volatilizes, the medium-boiling-point solvent is beneficial to the leveling of the weld seam to form a dense paint film; the high-boiling-point solvent is beneficial to leveling and can also prevent the weld seam from being damaged due to moisture and low temperature. By combining organic solvents with different boiling points, their synergistic effect can be exerted to improve the stability and welding activity of the flux.

[0025] In a specific feasible embodiment, the low-boiling-point organic solvent is ethanol, the medium-boiling-point organic solvent is butyl acetate, and the high-boiling-point organic solvent is ethylene glycol monobutyl ether; the mass ratio of ethanol, butyl acetate, and ethylene glycol monobutyl ether is 2:(3 - 5):(3 - 5).

[0026] By adopting the above technical solution, the organic solvents are combined in the form of alcohols, esters, and ethers, and can gradually decompose or sublime as the welding process temperature rises, effectively ensuring that the water-based flux plays a soldering role throughout the welding process and can effectively reduce the content of welding residues; at the same time, by selecting specific three organic solvents and controlling their mass ratio, their solubilizing effect can be better exerted.

[0027] In a second aspect, the present application provides a preparation method of a water-based flux, adopting the following technical solution:

[0028] A preparation method of a water-based flux includes the following steps:

[0029] Weigh corresponding weight portions of the organic solvent and part of the deionized water and mix them to form a mixed solution;

[0030] Mix the active agent with the remaining deionized water to form a mixture, and then mix the mixture with the mixed solution.

[0031] By adopting the above technical solution, the active agent of the flux is used as the active part in the solder system and is separately mixed with deionized water and then mixed with the organic solvent, which can maximize the beneficial effects of the activator. The water-based flux prepared in the present application uses deionized water as a solvent, reducing the production cost, achieving the purposes of environmental protection, stability, and safety, and the added active agent has the advantages of improving the wettability and corrosion resistance of the flux.

[0032] In summary, the present application has the following beneficial effects:

[0033] 1. In this application, an active agent is formed by loading rare earth oxides on fluorinated graphite oxide. Fluorinated graphite oxide obtained by introducing oxygen-containing groups into fluorinated graphite has good surface activity and dispersibility, which improves the fluidity and adhesion of welding, making the active agent have good wettability and corrosion resistance. At the same time, by loading rare earth oxides on fluorinated graphite oxide, the corrosion resistance of the obtained active agent is further improved.

[0034] 2. In this application, the organic solvent is a mixture of low-boiling organic solvents, medium-boiling organic solvents and high-boiling organic solvents. As the temperature of the welding process rises, the three gradually decompose or biochemize, which can effectively ensure the soldering assistance function of the water-based soldering flux during the entire welding process. At the same time, the content of welding residues can be effectively reduced, achieving a synergistic effect and improving the stability and corrosion resistance of the soldering flux. Specific Embodiments

[0035] The following further elaborates on this application in combination with examples, preparation examples and comparative examples. The raw materials involved in this application can all be obtained commercially.

[0036] Preparation Example 1

[0037] In this preparation example, the active agent is prepared according to the following method:

[0038] (1) Place 0.5 g of graphene powder in a high-pressure reactor, and introduce a mixed gas of fluorine and nitrogen with a volume ratio of 4:1 into the reactor. Fluorinate at a pressure of 50 kPa and a temperature of 300 °C for 5 h to obtain fluorinated graphene powder.

[0039] (2) Add 30 ml of 98 wt% concentrated sulfuric acid solution to a flask, place it in an ice bath, then add 1 g of the above-mentioned fluorinated graphene powder and 0.1 g of graphite oxide to the flask, stir magnetically for 1 h, then ultrasonically treat for 15 min, where the ultrasonic frequency is 55 kHz and the ultrasonic intensity is 0.9 W / cm2. Then place it in an ice bath again and continue to stir for 30 min to form a mixed solution. Slowly add 9 g of potassium permanganate solid to the above-mentioned mixed solution, continue to stir magnetically for 3 h, and then place it in a water bath at 35 °C for constant temperature treatment for 1 h to obtain a fluorinated graphite oxide mixed solution. Add a large amount of deionized water to the obtained fluorinated graphite oxide mixed solution, let it stand and separate layers, and then wash the upper product at a centrifugal speed of 2000 r / min until the pH value of the solution is 7, and vacuum dry at 50 °C for 60 h to obtain fluorinated graphite oxide powder. It is measured by X-ray photoelectron spectroscopy (XPS) that F:O = 1.2:1.

[0040] (3) Mix 30 mg of fluorinated graphite oxide powder with 70 mg of deionized water, add sodium dodecylbenzenesulfonate and ultrasonicate for 3 h to disperse it into a suspension. Then, under magnetic stirring, mix 10 ml of a 0.1 mg / ml cerium nitrate hexahydrate solution with 10 ml of a 0.3 mol / ml ammonia water mixed solution. Next, transfer the mixed solution to a hydrothermal reactor and react at a temperature of 220 °C for 24 h. Finally, wash the mixture with ethanol and deionized water until neutral and dry it under vacuum to obtain the active agent.

[0041] Preparation Example 2

[0042] In this preparation example, the active agent was prepared according to the following method:

[0043] (1) Place 0.5 g of graphene powder in a high-pressure reactor, introduce a mixed gas of fluorine and nitrogen with a volume ratio of 3:1 into the reactor, and fluorinate at a pressure of 10 kPa and a temperature of 300 °C for 2 h to obtain fluorinated graphene powder.

[0044] (2) Add 30 ml of 98 wt% concentrated sulfuric acid solution to a flask and place it in an ice bath. Then add 1 g of the above-mentioned fluorinated graphene powder and 0.1 g of graphite oxide to the flask, stir magnetically for 1 h, and then ultrasonicate for 15 min, where the ultrasonic frequency is 55 kHz and the ultrasonic intensity is 0.9 W / cm2. After that, place it in the ice bath again and continue stirring for 30 min to form a mixed solution. Slowly add 3 g of potassium permanganate solid to the above-mentioned mixed solution, continue magnetic stirring for 3 h, and then keep it in a water bath at 35 °C for 1 h to obtain a fluorinated graphite oxide mixed solution. Add a large amount of deionized water to the obtained fluorinated graphite oxide mixed solution, let it stand for layering, and then wash the upper product at a centrifugal speed of 2000 r / min until the pH value of the solution is 7, and dry it under vacuum at 50 °C for 60 h to obtain fluorinated graphite oxide powder. It is measured by X-ray photoelectron spectroscopy (XPS) that F:O = 1.1:1.

[0045] (3) Mix 30 mg of fluorinated graphite oxide powder with 70 mg of deionized water, add sodium dodecylbenzenesulfonate and ultrasonicate for 2 h to disperse it into a suspension. Then, under magnetic stirring, mix 10 ml of a 0.1 mg / ml cerium nitrate hexahydrate solution with 10 ml of a 0.2 mol / ml ammonia water mixed solution. Next, transfer the mixed solution to a hydrothermal reactor and react at a temperature of 200 °C for 20 h. Finally, wash the mixture with ethanol and deionized water until neutral and dry it under vacuum to obtain the active agent.

[0046] Preparation Example 3

[0047] In this preparation example, the active agent was prepared according to the following method:

[0048] (1) Place 0.5 g of graphene powder in a high-pressure reactor, and introduce a mixed gas of fluorine and nitrogen with a volume ratio of 5:1 into the reactor. Fluorinate it at a pressure of 100 kPa and a temperature of 500 °C for 8 h to obtain fluorinated graphene powder;

[0049] (2) Add 30 ml of 98 wt% concentrated sulfuric acid solution to a flask, place it in an ice bath, and then add 1 g of the above-mentioned fluorinated graphene powder and 0.1 g of graphite oxide to the flask. Stir magnetically for 1 h, then perform ultrasonic treatment for 15 min, where the ultrasonic frequency is 55 kHz and the ultrasonic intensity is 0.9 W / cm2. Then place it in an ice bath again and continue stirring for 30 min to form a mixed solution; Slowly add 9 g of potassium permanganate and 5 g of sodium nitrate solid to the above-mentioned mixed solution, continue magnetic stirring for 3 h, and then place it in a water bath at 35 °C for constant temperature treatment for 1 h to obtain a fluorinated graphite oxide mixed solution; Add a large amount of deionized water to the obtained fluorinated graphite oxide mixed solution, let it stand for stratification, and then wash the upper product at a centrifugal speed of 2000 r / min until the pH value of the solution is 7. Dry it in vacuum at 50 °C for 60 h to obtain fluorinated graphite oxide powder. It is measured by X-ray photoelectron spectroscopy (XPS) that F:O = 1.3:1;

[0050] (3) Take 30 mg of fluorinated graphite oxide powder and mix it with 70 mg of deionized water, add sodium dodecylbenzenesulfonate and perform ultrasonic treatment for 2 h to disperse it into a suspension. Then, under magnetic stirring, mix 10 ml of a 0.1 mg / ml cerium nitrate hexahydrate solution and 10 ml of a 0.4 mol / ml ammonia water solution; Then transfer the mixed solution to a hydrothermal reactor and react at a temperature of 250 °C for 30 h. Finally, wash the mixture with ethanol and deionized water until it is neutral and dry it in vacuum to obtain an active agent.

[0051] Preparation Example 4

[0052] In this preparation example, the active agent is prepared according to the following method:

[0053] (1) Place 0.5 g of graphene powder in a high-pressure reactor, and introduce a mixed gas of fluorine and nitrogen with a volume ratio of 4:1 into the reactor. Fluorinate it at a pressure of 50 kPa and a temperature of 300 °C for 5 h to obtain fluorinated graphene powder.

[0054] Preparation Example 5

[0055] In this preparation example, the active agent is prepared according to the following method:

[0056] (1) Place 0.5 g of graphene powder in a high-pressure reactor, and introduce a mixed gas of fluorine and nitrogen with a volume ratio of 4:1 into the reactor. Fluorinate it at a pressure of 50 kPa and a temperature of 300 °C for 5 h to obtain fluorinated graphene powder;

[0057] (2) Add 30 ml of 98 wt% concentrated sulfuric acid solution into a flask, place it in an ice bath, then add 1 g of the above-mentioned fluorinated graphene powder and 0.1 g of graphite oxide into the flask, stir magnetically for 1 h, then perform ultrasonic treatment for 15 min, where the ultrasonic frequency is 55 kHz and the ultrasonic intensity is 0.9 W / cm2. After that, place it in the ice bath again and continue to stir for 30 min to form a mixed solution; slowly add 9 g of solid potassium permanganate into the above-mentioned mixed solution, continue to stir magnetically for 3 h, then place it in a water bath at 35 °C for constant temperature treatment for 1 h to obtain a fluorinated graphite oxide mixed solution; add a large amount of deionized water into the obtained fluorinated graphite oxide mixed solution, let it stand and separate layers, then wash the upper product at a centrifugal speed of 2000 r / min until the pH value of the solution is 7, and dry it in vacuum at 50 °C for 60 h to obtain fluorinated graphite oxide powder. It is measured by X-ray photoelectron spectroscopy (XPS) that F:O = 1.2:1.

[0058] Preparation Example 6

[0059] In this preparation example, the active agent is prepared according to the following method:

[0060] (1) Place 0.5 g of graphene powder in a high-pressure reaction kettle, introduce a mixed gas of fluorine and nitrogen with a volume ratio of 4:1 into the kettle, and fluorinate it at a pressure of 50 kPa and a temperature of 300 °C for 5 h to obtain fluorinated graphene powder;

[0061] (2) Take 30 mg of fluorinated graphite powder and mix it with 70 mg of deionized water, add sodium dodecylbenzenesulfonate and perform ultrasonic treatment for 3 h to disperse it into a suspension. Then, under magnetic stirring, mix a 10 ml solution of 0.1 mg / ml cerium nitrate hexahydrate with a 10 ml solution of 0.3 mol / ml ammonia water; then transfer the mixed solution to a hydrothermal reaction kettle and react at a temperature of 220 °C for 24 h. Finally, wash the mixture with ethanol and deionized water until it is neutral, and dry it in vacuum to obtain the active agent.

[0062] Example

[0063] Example 1

[0064] In this example, the water-based soldering flux includes the following components: 6 Kg of active agent, 9 Kg of organic solvent (1.8 Kg of ethanol + 3.6 Kg of butyl acetate + 3.6 Kg of ethylene glycol monobutyl ether), 5 Kg of hydroxybutanedioic acid, and 85 Kg of deionized water, where the active agent is obtained from Preparation Example 1.

[0065] In this example, the water-based soldering flux is prepared according to the following steps:

[0066] (1) Weigh the corresponding weight portions of ethanol, butyl acetate, and ethylene glycol monobutyl ether, mix them evenly, and stir and mix them evenly with half of the mass of deionized water to form a mixed solution;

[0067] (2) Weigh the corresponding weight portions of the active agent and the other half weight portion of deionized water, stir and mix them evenly to form a mixture;

[0068] (3) Stir and mix the above-mentioned mixed liquid and the mixture evenly.

[0069] Example 2

[0070] The difference between this example and Example 1 is that the active agent used in this example is obtained from Preparation Example 2.

[0071] Example 3

[0072] The difference between this example and Example 1 is that the active agent used in this example is obtained from Preparation Example 3.

[0073] Example 4

[0074] The difference between this example and Example 1 is that in this example, the water-based soldering flux includes the following components: 4 Kg of active agent, 6 Kg of organic solvent (1.2 Kg of ethanol + 2.4 Kg of butyl acetate + 2.4 Kg of ethylene glycol monobutyl ether), 5 Kg of hydroxybutanedioic acid, and 90 Kg of deionized water, and the active agent used is obtained from Preparation Example 1.

[0075] Example 5

[0076] The difference between this example and Example 1 is that in this example, the water-based soldering flux includes the following components: 8 Kg of active agent, 12 Kg of organic solvent (1.2 Kg of ethanol + 2.4 Kg of butyl acetate + 2.4 Kg of ethylene glycol monobutyl ether), 5 Kg of hydroxybutanedioic acid, and 80 Kg of deionized water, and the active agent used is obtained from Preparation Example 1.

[0077] Example 6

[0078] The difference between this example and Example 1 is that in this example, the water-based soldering flux includes the following components: 6 Kg of active agent, 9 Kg of organic solvent (1.8 Kg of ethanol + 2.7 Kg of butyl acetate + 4.5 Kg of ethylene glycol monobutyl ether), 5 Kg of hydroxybutanedioic acid, and 85 Kg of deionized water, and the active agent used is obtained from Preparation Example 1.

[0079] Example 7

[0080] The difference between this example and Example 1 is that in this example, the water-based soldering flux includes the following components: 6 Kg of active agent, 9 Kg of organic solvent (1.8 Kg of ethanol + 4.5 Kg of butyl acetate + 2.7 Kg of ethylene glycol monobutyl ether), 5 Kg of hydroxybutanedioic acid, and 85 Kg of deionized water, and the active agent used is obtained from Preparation Example 1.

[0081] Comparative Example

[0082] Comparative Example 1

[0083] In this comparative example, the water-based soldering flux comprises the following components: 6 Kg of active agent, 9 Kg of organic solvent (1.8 Kg of ethanol + 3.6 Kg of butyl acetate + 3.6 Kg of ethylene glycol monobutyl ether), 5 Kg of hydroxybutanedioic acid, and 85 Kg of deionized water, wherein the active agent is obtained from Preparation Example 4.

[0084] Comparative Example 2

[0085] In this comparative example, the water-based soldering flux comprises the following components: 6 Kg of active agent, 9 Kg of organic solvent (1.8 Kg of ethanol + 3.6 Kg of butyl acetate + 3.6 Kg of ethylene glycol monobutyl ether), 5 Kg of hydroxybutanedioic acid, and 85 Kg of deionized water, wherein the active agent is obtained from Preparation Example 5.

[0086] Comparative Example 3

[0087] In this comparative example, the water-based soldering flux comprises the following components: 6 Kg of active agent, 9 Kg of organic solvent (1.8 Kg of ethanol + 3.6 Kg of butyl acetate + 3.6 Kg of ethylene glycol monobutyl ether), 5 Kg of hydroxybutanedioic acid, and 85 Kg of deionized water, wherein the active agent is obtained from Preparation Example 6.

[0088] Performance Detection Test Method

[0089] I. Corrosion Resistance Test

[0090] Take a PCB board of 0.2 mm×40 mm×40 mm as the welding board, the solder is Sn99.3Cu0.7, and the soldering fluxes used are those of each example and comparative example. Use the solder and the soldering flux to weld the welding board. After welding, count the number and volume of pores on each board. The test results are shown in Table 1.

[0091] II. Wettability

[0092] Immerse the metal sheet specimen into the molten solder, measure the load curve during lifting, and obtain the wetting time and the wetting force after correction of the buoyancy according to this load curve. The wetting force refers to the resultant force of the force exerted on the specimen when it is vertically immersed in the molten solder and the buoyancy when it is immersed. The metal sheet specimen used is a copper sheet (grade T2) with a specification of 10 mm×30 mm×0.3 mm. Pretreat the copper sheet specimen according to the method of 《GB / T223.32-2008》. Use Sn99.3Cu0.7 lead-free solder in the solder bath, the test temperature is 270 °C, the speed is 5 mm / s, the immersion depth is 7 mm, and the holding time is 10 s. The test results are shown in Table 1.

[0093] Table 1 Performance Detection Data Table of Examples 1-7 and Comparative Examples 1-3

[0094]

[0095]

[0096] Combined with Examples 1-7 and Comparative Example 1 and Table 1, it can be seen that when the water-based soldering fluxes of Examples 1-7 are applied to welding, their corrosion resistance and wettability are better than those of Comparative Example 1, indicating that the water-based soldering flux prepared in this application uses deionized water as a solvent, reducing the production cost, achieving the purposes of environmental protection, stability and safety, and the added active agent has the advantages of improving the wettability and corrosion resistance of the soldering flux. In particular, the active agent of this application loads rare earth oxides through fluorinated graphene oxide, has high welding activity, can effectively prevent oxidation, improves the wetting effect of the soldering flux on the material to be soldered, and reduces the surface tension of the material to be soldered.

[0097] Combined with Example 1 and Comparative Example 2 and Table 1, it can be seen that in this application, an activator is further formed by combining with rare earth oxides on the basis of fluorinated graphene oxide. Rare earth oxides have good corrosion resistance. Loading rare earth oxide nanoparticles on the fluorinated graphene oxide layer can not only prevent the aggregation of fluorinated graphite, improve its dispersibility, but also improve its uniformity in the active agent, thereby improving the corrosion resistance and wettability in the soldering flux with the action of the active agent.

[0098] Combined with Example 1 and Comparative Example 3 and Table 1, it can be seen that in this application, fluorinated graphite is oxidized and then loaded with rare earth oxides. Fluorinated graphite has hydrophobicity because many F atoms are grafted on the graphite. In this application, ultrasonic treatment is used to treat fluorinated graphite and introduce oxygen-containing groups, so that fluorinated graphene oxide has higher activity and dispersibility than fluorinated graphite, and can improve the wettability and corrosion resistance of the active agent prepared therefrom.

[0099] This specific embodiment is only an interpretation of this application, and it is not a limitation of this application. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as it is within the scope of the claims of this application, it is protected by the patent law.

Claims

1. A water-based soldering flux, characterized in that, It is made from the following raw materials in parts by weight: 4 - 8 parts of surfactant, 6 - 12 parts of organic solvent, 3 - 8 parts of organic acid, and 80 - 90 parts of deionized water; the surfactant is formed by loading rare earth oxides on fluorinated graphite oxide; the preparation method of the surfactant includes the following steps: Place the concentrated sulfuric acid solution in an ice bath, add 1 part by weight of fluorinated graphite and 0.1 part by weight of graphite oxide, stir and ultrasonicate, then add 3 - 15 parts by weight of an oxidizing agent to react to obtain a fluorinated graphite oxide mixture; filter and dry the fluorinated graphite oxide mixture to obtain fluorinated graphite oxide; Mix the fluorinated graphite oxide with deionized water and a surfactant to form a dispersion, then add a mixture formed by a soluble rare earth salt solution and an alkaline solution with a molar ratio of 1:2 - 4, and perform a hydrothermal reaction on the mixture to obtain the surfactant; the fluorine - carbon ratio of the fluorinated graphite is 1.1 - 1.3:

1.

2. The water-based soldering flux according to claim 1, characterized in that, The preparation method of the fluorinated graphite is: it is obtained by fluorinating graphene powder with a mixed gas of fluorine gas and nitrogen gas.

3. The water-based soldering flux according to claim 1, wherein, The oxidizing agent is potassium permanganate or a mixture of potassium permanganate and sodium nitrate.

4. The water-based soldering flux according to claim 1, wherein The surfactant is one or more of stearic acid, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium glycocholate.

5. The water-based soldering flux according to claim 1, wherein The rare earth element in the soluble rare earth salt solution is one of Yb, Er, Sm, Eu, Y, Gd, Dy, and Ce.

6. The water-based soldering flux according to claim 1, wherein, The organic solvent is a mixture of a low - boiling organic solvent with a boiling point less than 100°C, a medium - boiling organic solvent with a boiling point of 100 - 150°C, and a high - boiling organic solvent with a boiling point of 150 - 200°C.

7. The water-based soldering flux according to claim 6, characterized in that, The low - boiling organic solvent is ethanol, the medium - boiling organic solvent is butyl acetate, and the high - boiling organic solvent is ethylene glycol monobutyl ether; the mass ratio of ethanol, butyl acetate, and ethylene glycol monobutyl ether is 2:(3 - 5):(3 - 5).

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