A high-moisture halogen-free soldering flux and preparation method thereof

Abstract

The present application relates to the technical field of flux processing. More specifically, it relates to a high-wetting halogen-free flux and a preparation method thereof. The high-wetting halogen-free flux is prepared from the following raw materials by weight percentage: film-forming agent 20-30%, active agent 4-8%, palm wax 5-10%, corrosion inhibitor 0.5-1%, thixotropic agent 2-5%, dimethylamine hydrochloride 0.2-0.6%, rare earth chloride 1-2%, modifier 5-10%, and the remaining amount is solvent. The modifier is obtained by mixing castor oil, stearic acid amide and glycerol. The halogen-free flux prepared by the above compounding formula greatly improves the wettability during the welding process, makes the molten pool more stable, and reduces the occurrence of welding defects. At the same time, the introduction of the modifier, especially the mixture of castor oil, stearic acid amide and glycerol, not only improves the thermal stability of the flux, but also reduces the risk of decomposition of traditional active agents at high temperatures, reduces the release of harmful gases and the formation of residues, and ensures the welding quality.

Description

Technical Field

[0001] This application relates to the technical field of flux processing, and more specifically, to a high-wetting halogen-free flux and a preparation method thereof. Background Art

[0002] During the soldering process of electronic components, halogen-free solder wire flux can provide good soldering quality. Its excellent solderability and connectivity result in plump and bright solder joints with good tin penetration, effectively preventing tin deficiency and short circuits. At the same time, since halogen-free flux does not contain halogen components, it has lower corrosiveness and better environmental protection performance, which meets the requirements for environmental protection and sustainable development in current electronic product production.

[0003] However, it is found during use that the wettability of halogen-free solder wire flux is not as good as that of halogen-containing flux, which can lead to unstable molten pools and an increase in soldering defects during the soldering process. To further improve the wettability of halogen-free solder wire flux, activators such as fatty acids or aromatic acids and their derivatives are added to increase the wettability of halogen-free solder wire flux. However, fatty acids or aromatic acids and their derivatives will decompose or become ineffective at high temperatures, and the gases or residues generated by decomposition have a negative impact on soldering quality, such as causing soldering defects and reducing soldering strength. Summary of the Invention

[0004] To further improve the wettability of halogen-free solder wire flux, this application provides a high-wetting halogen-free flux and a preparation method thereof.

[0005] In the first aspect, this application provides a high-wetting halogen-free flux, adopting the following technical solution:

[0006] A high-wetting halogen-free flux, which is prepared from the following raw materials by weight percentage:

[0007] Film-forming agent 20 - 30%

[0008] Activator 4 - 8%

[0009] Palm wax 5 - 10%

[0010] Corrosion inhibitor 0.5 - 1%

[0011] Thixotropic agent 2 - 5%

[0012] Dimethylamine hydrochloride 0.2 - 0.6%

[0013] Rare earth chloride salt 1 - 2%

[0014] Modifier 5 - 10%

[0015] The remaining amount is solvent

[0016] The modifier is obtained by mixing castor oil, stearic acid amide and glycerol.

[0017] By adopting the above technical solution, the wettability of the halogen-free solder wire flux during the soldering process is greatly improved, the molten pool is more stable, and the occurrence of soldering defects is reduced. At the same time, the introduction of the modifier, especially the mixture of castor oil, stearic acid amide and glycerol, not only improves the thermal stability of the flux, but also reduces the risk of decomposition of traditional activators at high temperatures, reduces the release of harmful gases and the formation of residues, and ensures the soldering quality.

[0018] Components such as castor oil, stearic acid amide and glycerol in the modifier can form a stable compound structure, reducing the decomposition rate of traditional activators at high temperatures. These components are not easily decomposed at high temperatures, can maintain the stability and activity of the flux, and reduce the negative impact of the decomposed gases and residues on the soldering quality. Among them, castor oil has good lubricity and stability, which can enhance the wettability and fluidity of the flux. Stearic acid amide can reduce the interfacial tension between the flux and the metal surface, promoting the spreading and wetting of the flux on the metal surface. Glycerol has hygroscopicity, can keep the flux in a wet state, and together with stearic acid amide, further enhances the wetting performance of the flux. At the same time, the synergistic effect of the activator and the modifier forms a more stable active system, which can maintain good activity even under high-temperature conditions, promote the removal of the oxide film on the metal surface, and enhance the wetting effect.

[0019] The film-forming agent can form a protective film during the soldering process to protect the soldering materials from oxidation and corrosion; at the same time, the activator can reduce the surface tension of the soldering materials and improve the wettability. The synergistic effect of the two enables the flux to better wet the soldering materials and form a stable molten pool. Palm wax can reduce the friction between the flux and the soldering materials, further improve the wettability, and also helps to reduce spatter and smoke during the soldering process. The thixotropic agent imparts thixotropy to the flux, making it maintain a certain viscosity at rest and reducing the viscosity under the action of shear force, which is convenient for application and uniform distribution.

[0020] Rare earth chloride salts can refine the weld microstructure, improve the strength and toughness of the welded joint. At the same time, it can also reduce defects such as cracks and pores during the soldering process and improve the soldering quality. Dimethylamine hydrochloride has strong deoxidizing ability, which enables it to effectively remove the oxides on the metal surface during the soldering process, providing favorable conditions for the wetting and spreading of the solder.

[0021] Preferably, the weight ratio of the castor oil, the stearic acid amide and the glycerol is 4:(1 - 3):(0.5 - 2.5).

[0022] By adopting the above technical solutions, the dosages of castor oil, stearic acid amide and glycerol are optimized to further improve the wettability and thermal stability of the halogen-free tin wire soldering flux, which helps to reduce the generation of harmful gases during high-temperature soldering, enhance the soldering quality and adjust the performance of the soldering flux, and avoid negative impacts on the environment.

[0023] Preferably, the film-forming agent is obtained by mixing hydrogenated rosin and acrylic resin in a weight ratio of 1:(2.5 - 4).

[0024] By adopting the above technical solutions, the types and dosages of the film-forming agent are optimized, enabling the film-forming agent to form a uniform and dense film on the metal surface, effectively preventing the loss of the soldering flux during high-temperature soldering, and at the same time protecting the soldering surface from oxidation and corrosion. Among them, specific components in hydrogenated rosin have the effect of reducing the surface tension, which helps the solder to wet and spread on the metal surface. The polar groups in acrylic resin can form chemical bonding with the metal surface, further enhancing the wetting effect. The combined use of the two can further improve the wetting performance of the soldering flux, making the soldering process smoother and reducing the generation of soldering defects.

[0025] Preferably, the active agent is composed of fatty alcohol polyoxyethylene ether and 2-ethylimidazole in a weight ratio of 5:(0.5 - 1.5).

[0026] By adopting the above technical solutions, the types and dosages of the active agent are optimized to further improve the wettability and permeability of the halogen-free tin wire soldering flux, which can promote the full contact and combination of the solder and the metal surface, thereby improving the strength and tightness of the solder joint. Among them, fatty alcohol polyoxyethylene ether is a non-ionic surfactant with excellent hydrophilicity and lipophilicity, which can significantly reduce the surface tension of water and improve the wettability and permeability of the solution. After combining with 2-ethylimidazole, it can spread more effectively on the metal surface to form a uniform film, thus improving the wetting effect during soldering.

[0027] Preferably, the corrosion inhibitor is composed of benzotriazole, sulfonated lignin and silicate in a weight ratio of 1:(0.5 - 2):(1 - 3).

[0028] By adopting the above technical solutions, the types and dosages of corrosion inhibitors are optimized to further enhance the protective effect on the surface of the metal to be welded, ensuring that its surface is not oxidized or corroded, which helps to improve the strength and reliability of the welded joint, thereby ensuring the quality of the welded joint. Among them, raw materials such as benzotriazole, sulfonated lignin, and silicate are all non-toxic and harmless and will not cause pollution to the environment. Benzotriazole can form a protective film on the metal surface, effectively isolating the contact between the metal and the surrounding environment, thus preventing oxidation and corrosion. Sulfonated lignin and silicate further isolate the contact between the metal surface and the surrounding environment by forming a protective film, reducing the corrosion risk. These three corrosion inhibitor components act synergistically in the highly humid halogen-free soldering flux to provide comprehensive protection for the metal.

[0029] Preferably, the thixotropic agent includes at least one of polyethylene glycol, polyamide wax, activated clay, and hydrogenated castor oil.

[0030] By adopting the above technical solutions, the types of thixotropic agents are optimized to further improve the wettability and viscosity of the halogen-free solder wire soldering flux, which can enhance the quality and reliability of the welded joint.

[0031] Preferably, the solvent is obtained by mixing dipentaerythritol ester, diethylene glycol monobutyl ether acetate, and terpineol in a weight ratio of 1:(2 - 3):5.

[0032] By adopting the above technical solutions, by optimizing the types and dosages of solvents, the wetting effect of the halogen-free solder wire soldering flux is further enhanced, ensuring sufficient contact between the solder and the welding material during the welding process, thereby improving the quality and reliability of the welded joint.

[0033] Preferably, the rare earth chloride salt includes at least one of cerium chloride, lanthanum chloride, rubidium chloride, europium chloride, samarium chloride, and scandium chloride.

[0034] By adopting the above technical solutions, the types of rare earth chloride salts are optimized to further improve the wettability between the solder and the welding material, enabling the solder to be more evenly distributed on the welding surface, thereby improving the quality of the welded joint.

[0035] Preferably, the highly humid halogen-free soldering flux is prepared from the following raw materials in weight percentages:

[0036] Film-forming agent 24%

[0037] Activator 5%

[0038] Palm wax 6%

[0039] Corrosion inhibitor 0.5%

[0040] Thixotropic agent 3%

[0041] Dimethylamine hydrochloride 0.3%

[0042] 1% rare earth chloride salt

[0043] 7% modifier

[0044] The remaining amount is the solvent;

[0045] The modifier is obtained by mixing castor oil, stearic acid amide and glycerol in a weight ratio of 4:1.5:1.

[0046] By adopting the above technical solution, the dosage for preparing the high-wetting halogen-free soldering flux is optimized, and further improved. In the second aspect, the present application provides a preparation method of a high-wetting halogen-free soldering flux, adopting the following technical solution:

[0047] A preparation method of a high-wetting halogen-free soldering flux includes the following preparation steps:

[0048] Mix a film-forming agent, an active agent, palm wax, a corrosion inhibitor, a thixotropic agent, dimethylamine hydrochloride, rare earth chloride salt, a modifier and a solvent, and stir evenly to obtain a high-wetting halogen-free soldering flux.

[0049] By adopting the above technical solution, various components are mixed to obtain a high-wetting halogen-free soldering flux, enabling the soldering flux to quickly wet the solder and the welding surface during the welding process, forming a uniform wetting layer. This not only helps the uniform distribution of the solder but also reduces welding defects such as pores and slag inclusions, thereby improving the quality of the welded joint.

[0050] In summary, the present application has the following beneficial effects:

[0051] 1. In the present application, through the synergistic effect of the film-forming agent and the active agent, the surface tension of the welding interface is effectively reduced, promoting the wetting and spreading of the solder on the metal surface. At the same time, the modifier further enhances the wetting performance of the soldering flux, especially remaining stable at high temperatures and not easily decomposing. The modifier is composed of a mixture of castor oil, stearic acid amide and glycerol, and these components have higher thermal stability, reducing decomposition and negative effects at high temperatures. In the present application, through the comprehensive action of components such as the corrosion inhibitor and the thixotropic agent, the welding surface is protected from corrosion, while the fluidity and adhesion of the solder are improved, ultimately enhancing the overall quality and strength of the welded joint. Specific Embodiments

[0052] Examples

[0053] Hydrogenated rosin was purchased from Hubei Yamaide Biopharmaceutical Co., Ltd., with a CAS number of 65997-06-0.

[0054] Acrylic resin was purchased from Jining Jiji New Materials Co., Ltd., with a model of SH-thermoplastic acrylic resin.

[0055] The rosin was purchased from Jinan Yongyue Chemical Co., Ltd. and its model is industrial grade.

[0056] The polyethylene glycol was purchased from Shanghai Dikaiem Industry Co., Ltd., with the brand of Dow and a molecular weight of 4000.

[0057] The polyamide wax was purchased from Shanghai Jianbang Industry Co., Ltd., with the brand of Clariant and the model of Licowax C wax.

[0058] The activated clay was purchased from Lingshou Tianze Mineral Products Processing Factory.

[0059] Example 1

[0060] A high-moisture halogen-free soldering flux is prepared by the following method:

[0061] Mix 300 g of film-forming agent (hydrogenated rosin), 40 g of active agent (fatty alcohol polyoxyethylene ether), 50 g of palm wax, 5 g of corrosion inhibitor (benzotriazole), 20 g of thixotropic agent (polyethylene glycol), 2 g of dimethylamine hydrochloride, 10 g of rare earth chloride (cerium chloride), 50 g of modifier and 523 g of solvent (dipentaerythritol ester), and stir evenly to obtain the high-moisture halogen-free soldering flux.

[0062] The modifier is composed of castor oil, stearic acid amide and glycerol in a weight ratio of 4:1:0.5.

[0063] The differences between Example 2-3 and Example 1 are that the types, dosages of raw materials and experimental parameters for preparing the high-moisture halogen-free soldering flux are different. The specific differences are shown in Table 1:

[0064] Table 1 Types, dosages of raw materials and experimental parameters for preparing the high-moisture halogen-free soldering flux in Examples 1-3

[0065]

[0066]

[0067] Example 4

[0068] A high-moisture halogen-free soldering flux. The difference between this example and Example 1 is that the weight ratio of castor oil, stearic acid amide and glycerol is 4:4:0.5.

[0069] Example 5

[0070] A high-moisture halogen-free soldering flux. The difference between this example and Example 1 is that the weight ratio of castor oil, stearic acid amide and glycerol is 4:1:4.

[0071] Example 6

[0072] A high-moisture halogen-free soldering flux. The difference between this embodiment and Embodiment 1 is that the weight ratio of castor oil, stearic acid amide, and glycerol is 1:1:1.

[0073] Embodiment 7

[0074] A high-moisture halogen-free soldering flux. The difference between this embodiment and Embodiment 1 is that the film-forming agent is obtained by mixing hydrogenated rosin and acrylic resin in a weight ratio of 1:2.5.

[0075] Embodiment 8

[0076] A high-moisture halogen-free soldering flux. The difference between this embodiment and Embodiment 1 is that the film-forming agent is obtained by mixing hydrogenated rosin and acrylic resin in a weight ratio of 1:4.

[0077] Embodiment 9

[0078] A high-moisture halogen-free soldering flux. The difference between this embodiment and Embodiment 1 is that the active agent is composed of fatty alcohol polyoxyethylene ether and 2-ethylimidazole in a weight ratio of 5:0.5.

[0079] Embodiment 10

[0080] A high-moisture halogen-free soldering flux. The difference between this embodiment and Embodiment 7 is that the active agent is composed of fatty alcohol polyoxyethylene ether and 2-ethylimidazole in a weight ratio of 5:1.5.

[0081] Embodiment 11

[0082] A high-moisture halogen-free soldering flux. The difference between this embodiment and Embodiment 9 is that the active agent is composed of fatty alcohol polyoxyethylene ether and 2-ethylimidazole in a weight ratio of 1:1.

[0083] Embodiment 12

[0084] A high-moisture halogen-free soldering flux. The difference between this embodiment and Embodiment 1 is that the corrosion inhibitor is composed of benzotriazole, sulfonated lignin, and silicate in a weight ratio of 1:0.5:1.

[0085] Embodiment 13

[0086] A high-moisture halogen-free soldering flux. The difference between this embodiment and Embodiment 10 is that the corrosion inhibitor is composed of benzotriazole, sulfonated lignin, and silicate in a weight ratio of 1:2:3.

[0087] Embodiment 14

[0088] A high-moisture halogen-free soldering flux. The difference between this embodiment and Embodiment 12 is that the corrosion inhibitor is composed of benzotriazole and silicate in a weight ratio of 1:0.5.

[0089] Example 15

[0090] A high-moisture halogen-free soldering flux. The difference between this example and Example 1 is that the solvent is obtained by mixing dipentaerythritol ester, diethylene glycol monobutyl ether acetate, and terpineol in a weight ratio of 1:2:5.

[0091] Example 16

[0092] A high-moisture halogen-free soldering flux. The difference between this example and Example 13 is that the solvent is obtained by mixing dipentaerythritol ester, diethylene glycol monobutyl ether acetate, and terpineol in a weight ratio of 1:3:5.

[0093] Example 17

[0094] A high-moisture halogen-free soldering flux is prepared by the following method:

[0095] Mix 240 g of film-forming agent (hydrogenated rosin), 50 g of active agent (fatty alcohol polyoxyethylene ether), 60 g of palm wax, 5 g of corrosion inhibitor (benzotriazole), 30 g of thixotropic agent (polyethylene glycol), 3 g of dimethylamine hydrochloride, 10 g of rare earth chloride salt (cerium chloride), 70 g of modifier, and 532 g of solvent (dipentaerythritol ester), and stir evenly to obtain a high-moisture halogen-free soldering flux.

[0096] The modifier is composed of castor oil, stearic acid amide, and glycerin in a weight ratio of 4:1.5:1.

[0097] Comparative Example

[0098] Comparative Example 1

[0099] A high-moisture halogen-free soldering flux. The difference between this comparative example and Example 1 is that succinic acid is used instead of the modifier.

[0100] Comparative Example 2

[0101] A high-moisture halogen-free soldering flux. The difference between this comparative example and Example 1 is that the modifier is composed of castor oil and stearic acid amide in a weight ratio of 4:1.

[0102] Comparative Example 3

[0103] A high-moisture halogen-free soldering flux. The difference between this comparative example and Example 1 is that the modifier is composed of castor oil and glycerin in a weight ratio of 4:0.5.

[0104] Comparative Example 4

[0105] A high-moisture halogen-free soldering flux. The difference between this comparative example and Example 1 is that the modifier is composed of stearic acid amide and glycerin in a weight ratio of 1:0.5.

[0106] Comparative Example 5

[0107] A high-moisture halogen-free flux. The difference between this comparative example and Example 1 is that paraffin wax is used instead of palm wax.

[0108] Comparative Example 6

[0109] A high-moisture halogen-free flux. The difference between this comparative example and Example 1 is that zinc chloride is used instead of cerium chloride.

[0110] Comparative Example 7

[0111] A high-moisture halogen-free flux. The difference between this comparative example and Example 1 is that [so-and-so] is used instead of dimethylamine hydrochloride.

[0112] Testing method / Experimental method

[0113] Purchase the bismuth-tin alloy powder solder from Hunan Xinen New Materials Co., Ltd. According to the conventional proportion of solder and flux for solder paste, prepare solder paste by combining the high-moisture halogen-free fluxes prepared in Examples 1-17 and Comparative Examples 1-7 respectively. Test the welding performance of the fluxes prepared in Examples 1-17 and Comparative Examples 1-2 according to the methods specified in the standards of GB / T11364-2008, SJ / T11389-2009, GB / T 9491-2002 and IPC-SA-61. The results are shown in Table 2:

[0114] Table 2 Experimental results of Examples 1-17 and Comparative Examples 1-7

[0115]

[0116]

[0117] It can be seen from the experimental results of Examples 1-17 and Comparative Examples 1-7 that the halogen-free flux prepared by the formula in this application has the characteristics of high wettability, no corrosion and no residue, can effectively inhibit the formation of solder bridges, make the solder joints bright and full, and has high solder joint reliability, and can effectively improve the welding quality.

[0118] Comparing Example 1 with Comparative Examples 1-4, the wettability of Comparative Examples 1-4 is inferior to that of Example 1. Corrosion and residue phenomena occur in Comparative Example 1, and residue phenomenon occurs in Comparative Example 3. Moreover, the solder joint brightness of Comparative Examples 1-4 is average, indicating that by preparing a modifier with sesame oil, stearic acid amide and glycerol in this application and then using it in the flux, the wettability and welding quality of the flux can be effectively improved.

[0119] Comparing Example 1 with Comparative Examples 5-7, the wettability of Comparative Examples 5-7 is inferior to that of Example 1. Residual phenomena occurred in Comparative Examples 5-7, solder bridge phenomena occurred in Comparative Examples 6-7, the solder joint brightness of Comparative Example 5 was poor, and the solder joint brightness of Comparative Examples 6-7 was average. This shows that preparing a soldering flux by adding palm wax, dimethylamine hydrochloride, and rare earth chloride salts is beneficial to improving the wettability and soldering quality of the soldering flux.

[0120] Comparing Example 1 with Examples 4-5, the wettability of Examples 4-5 is inferior to that of Example 1. This shows that by optimizing the weight ratio of castor oil, stearamide, and glycerol, the wettability of the soldering flux can be further improved.

[0121] Comparing Example 1 with Examples 7-8, the wettability of Examples 7-8 is better than that of Example 1. This shows that preparing a film-forming agent by mixing hydrogenated rosin and acrylic resin in a specific ratio is beneficial to improving the wettability of the soldering flux.

[0122] Comparing Example 1 with Example 9, the wettability of Example 9 is better than that of Example 1;

[0123] Comparing Example 7 with Example 10, the wettability of Example 10 is better than that of Example 7;

[0124] Comparing Example 9 with Example 11, the wettability of Example 9 is better than that of Example 11;

[0125] From Examples 1, 9, 10, and 11, it can be seen that preparing an active agent by mixing fatty alcohol polyoxyethylene ether and 2-ethylimidazole in a specific ratio is beneficial to improving the wettability of the soldering flux.

[0126] Comparing Example 1 with Example 12, the wettability of Example 12 is better than that of Example 1;

[0127] Comparing Example 10 with Example 13, the wettability of Example 13 is better than that of Example 10;

[0128] Comparing Example 12 with Example 14, the wettability of Example 12 is better than that of Example 14; <(

[0129] From Examples 1, 12, 13, and 14, it can be seen that preparing a corrosion inhibitor by mixing benzotriazole and silicate in a specific ratio is beneficial to improving the wettability of the soldering flux.

[0130] Comparing Example 1 with Example 15, the wettability of Example 15 is better than that of Example 1;

[0131] Comparing Example 16 with Example 13, the wettability of Example 16 is better than that of Example 13;

[0132] As can be seen from Examples 1, 15, and 16, preparing a solvent by mixing dipentaerythritol ester, diethylene glycol monobutyl ether acetate, and terpineol in specific proportions is beneficial to improving the wettability of the soldering flux.

[0133] Comparing Example 1 with Example 17, the wettability of Example 17 is better than that of Example 1, indicating that further optimizing the raw material dosage for preparing the high-wetting halogen-free soldering flux is beneficial to improving the wettability of the soldering flux.

[0134] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A high-moisture type halogen-free soldering flux, characterized in that, The high-moisture halogen-free flux is prepared from the following raw materials by weight percentage: Film-forming agent 20-30% Activator 4-8% Palm wax 5-10% Corrosion inhibitor 0.5-1% Thixotropic agent 2-5% Dimethylamine hydrochloride 0.2-0.6% Rare earth chloride salt 1-2% Modifier 5-10% The balance is solvent The modifier is obtained by mixing castor oil, stearic acid amide and glycerol; The weight ratio of the castor oil, the stearic acid amide and the glycerol is 4:1-3:0.5-2.5; The film-forming agent is obtained by mixing hydrogenated rosin and acrylic resin in a weight ratio of 1:2.5-4; The activator is composed of fatty alcohol polyoxyethylene ether and 2-ethylimidazole in a weight ratio of 5:0.5-1.5; The corrosion inhibitor is composed of benzotriazole, sulfonated lignin and silicate in a weight ratio of 1:0.5-2:1-3; The solvent is obtained by mixing dipentaerythritol ester, diethylene glycol monobutyl ether acetate and terpineol in a weight ratio of 1:2-3:

5.

2. The water-wettable halogen-free flux according to claim 1, wherein: The thixotropic agent includes at least one of polyethylene glycol, polyamide wax, activated clay and hydrogenated castor oil.

3. The water-wettable halogen-free soldering flux according to claim 1, wherein: The rare earth chloride salt includes at least one of cerium chloride, lanthanum chloride, rubidium chloride, europium chloride, samarium chloride and scandium chloride.

4. The water-wettable halogen-free soldering flux according to claim 1, wherein: The high-moisture halogen-free flux is prepared from the following raw materials by weight percentage: Film-forming agent 24% Activator 5% Palm wax 6% Corrosion inhibitor 0.5% Thixotropic agent 3% Dimethylamine hydrochloride 0.3% Rare earth chloride salt 1% Modifier 7% The balance is solvent The modifier is obtained by mixing castor oil, stearic acid amide and glycerol in a weight ratio of 4:1.5:

1.

5. A preparation method of the high-moisture-resistant halogen-free soldering flux according to any one of claims 1-4, characterized in that, It includes the following preparation steps: Mix the film-forming agent, activator, palm wax, corrosion inhibitor, thixotropic agent, dimethylamine hydrochloride, rare earth chloride salt, modifier and solvent, and stir evenly to obtain the high-moisture halogen-free flux.

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