High-wettability halogen-free soldering flux and preparation method thereof

Abstract

The invention relates to the technical field of soldering flux processing, in particular to a high-humidity type halogen-free soldering flux and a preparation method. The high-humidity type halogen-free scaling powder is prepared from, by weight, 20%-30% of a film-forming agent, 4%-8% of an active agent, 5%-10% of palm wax, 0.5%-1% of a corrosion inhibitor, 2%-5% of a thixotropic agent, 0.2%-0.6% of dimethylamine hydrochloride, 1%-2% of chlorinated rare earth salt, 5%-10% of a modifier and the balance solvent, and the modifier is obtained by mixing castor oil, octadecanamide and glycerin. The wettability of the halogen-free soldering flux prepared through the compound formula in the welding process is greatly improved, a molten pool is more stable, and welding defects are reduced. Meanwhile, due to the introduction of the modifier, especially the mixture of castor oil, octadecanamide and glycerol, the thermal stability of the scaling powder is improved, the risk that a traditional active agent is decomposed at high temperature is reduced, release of harmful gas and formation of residues are reduced, and the welding quality is guaranteed.

Description

Technical Field

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

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

[0003] However, during use, it is found that the wettability of halogen-free tin flux is not as good as that of halogen-containing flux, which will lead to unstable molten pool and more welding defects during welding. In order to further improve the wettability of halogen-free tin flux, the wettability of halogen-free tin flux is increased by adding active agents such as fatty acids or aromatic acids and their derivatives. However, fatty acids or aromatic acids and their derivatives will decompose or become ineffective at high temperatures, and the gases or residues produced by the decomposition will have a negative impact on the welding quality, such as welding defects and reduced welding strength. Summary of the invention

[0004] In order to further improve the wettability of halogen-free tin wire soldering flux, the present application provides a high-wetness halogen-free soldering flux and a preparation method thereof.

[0005] In the first aspect, the present application provides a high-wetness halogen-free flux, which adopts the following technical solution: A high-humidity halogen-free soldering flux, wherein the high-humidity halogen-free soldering flux is prepared from the following raw materials in percentage by weight: Film former 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% Chloride rare earth salt 1-2% Modifier 5-10% The rest is solvent The modifier is obtained by mixing castor oil, stearic acid amide and glycerin.

[0006] By adopting the above technical solution, the wettability of halogen-free tin wire flux is greatly improved during the welding process, the molten pool is more stable, and the occurrence of welding defects is reduced. At the same time, the introduction of modifiers, 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 welding quality.

[0007] The castor oil, stearic acid amide and glycerin in the modifier can form a stable compound structure and reduce the decomposition rate of traditional active agents at high temperatures. These ingredients are not easy to decompose at high temperatures, which can maintain the stability and activity of the flux and reduce the negative impact of the gas and residue produced by decomposition on the welding 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, and promote the spreading and wetting of the flux on the metal surface. Glycerin is hygroscopic and can maintain the wet state of the flux. At the same time, it works together with stearic acid amide to further enhance the wetting performance of the flux. At the same time, the synergistic effect of the active agent 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.

[0008] Film formers can form a protective film during the welding process to protect the welding materials from oxidation and corrosion; at the same time, the activator can reduce the surface tension of the welding materials and improve the wettability. The two work together to enable the flux to better wet the welding materials and form a stable molten pool. Palm wax can reduce the friction between the flux and the welding materials, further improve the wettability, and also help reduce spatter and smoke during the welding process. The thixotropic agent gives the flux thixotropy, so that it maintains a certain viscosity when it is stationary, and the viscosity decreases under the action of shear force, which is easy to apply and evenly distribute.

[0009] Chlorinated rare earth salts can refine the weld structure and improve the strength and toughness of the welded joint. At the same time, it can also reduce defects such as cracks and pores during welding and improve welding quality. Dimethylamine hydrochloride has a strong deoxidation ability, which enables it to effectively remove oxides on the metal surface during welding, providing favorable conditions for the wetting and spreading of solder.

[0010] Preferably, the weight ratio of the castor oil, the stearic acid amide and the glycerin is 4:(1-3):(0.5-2.5).

[0011] By adopting the above technical solution, the dosage of castor oil, stearic acid amide and glycerin is optimized, and the wettability and thermal stability of the halogen-free tin wire flux are further improved, which helps to reduce the generation of harmful gases during high-temperature welding, enhance welding quality and adjust the performance of the flux to avoid negative impacts on the environment.

[0012] Preferably, the film-forming agent is obtained by mixing hydrogenated rosin and acrylic resin in a weight ratio of 1:(2.5-4).

[0013] By adopting the above technical solution, the type and amount of the film-forming agent are optimized, so that the film-forming agent can form a uniform and dense film on the metal surface, effectively preventing the loss of the flux during high-temperature welding, and protecting the welding surface from oxidation and corrosion. Among them, the specific components in hydrogenated rosin have the effect of reducing surface tension, which helps the solder to wet and spread on the metal surface. The polar groups in the acrylic resin can form chemical bonds with the metal surface, further enhancing the wetting effect. The combined use of the two can further improve the wetting performance of the flux, making the welding process smoother and reducing the occurrence of welding defects.

[0014] Preferably, the active agent is composed of fatty alcohol polyoxyethylene ether and 2-ethylimidazole in a weight ratio of 5: (0.5-1.5).

[0015] By adopting the above technical solution, the type and amount of the active agent are optimized, the wettability and permeability of the halogen-free tin wire flux are further improved, and the full contact and bonding between the solder and the metal surface can be promoted, thereby improving the strength and sealing of the welded 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, thereby improving the wetting effect during the welding process.

[0016] Preferably, the corrosion inhibitor is composed of benzotriazole, sulfonated lignin and silicate in a weight ratio of 1:(0.5-2):(1-3).

[0017] By adopting the above technical solution, the type and amount of corrosion inhibitor are optimized, the protective effect on the surface of the metal to be welded is further improved, and the surface is guaranteed not to be oxidized and 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 non-toxic and harmless and will not pollute the environment. Benzotriazole can form a protective film on the metal surface, effectively isolating the metal from the surrounding environment, thereby preventing oxidation and corrosion. Sulfonated lignin and silicate further isolate the metal surface from the surrounding environment by forming a protective film, reducing the risk of corrosion. These three corrosion inhibitor components work synergistically in the high-wetting halogen-free flux to provide comprehensive protection for the metal.

[0018] Preferably, the thixotropic agent includes at least one of polyethylene glycol, polyamide wax, activated clay and hydrogenated castor oil.

[0019] By adopting the above technical solution, optimizing the type of thixotropic agent, and further improving the wettability and viscosity of the halogen-free tin wire flux, the quality and reliability of the soldering joint can be improved.

[0020] 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.

[0021] By adopting the above technical solution, the wetting effect of the halogen-free tin wire flux is further enhanced by optimizing the type and amount of the solvent, ensuring sufficient contact between the solder and the welding material during the welding process, thereby improving the quality and reliability of the welding joint.

[0022] Preferably, the rare earth chloride salt includes at least one of cerium chloride, lanthanum chloride, rubidium chloride, europium chloride, samarium chloride and scandium chloride.

[0023] By adopting the above technical solution, the type of rare earth chloride salt is optimized, and the wettability between the solder and the welding material is further improved, so that the solder can be more evenly distributed on the welding surface, thereby improving the quality of the welding joint.

[0024] Preferably, the high wettability halogen-free soldering flux is prepared from the following raw materials in percentage by weight: Film former 24% Active agent 5% Palm wax 6% Corrosion inhibitor 0.5% Thixotropic agent 3% Dimethylamine hydrochloride 0.3% Rare earth chloride 1% Modifier 7% The remaining amount is solvent; The modifier is obtained by mixing castor oil, stearic acid amide and glycerol in a weight ratio of 4:1.5:1.

[0025] By adopting the above technical solution, the amount of the high-wet halogen-free soldering flux is optimized to further improve the second aspect. The present application provides a method for preparing a high-wet halogen-free soldering flux, which adopts the following technical solution: A method for preparing a high-wetting halogen-free soldering flux comprises the following steps: The film former, the activator, the palm wax, the corrosion inhibitor, the thixotropic agent, the dimethylamine hydrochloride, the rare earth chloride salt, the modifier and the solvent are mixed and stirred evenly to obtain a high-wetting type halogen-free soldering flux.

[0026] By adopting the above technical solution, various components are mixed to obtain a high-wetting halogen-free flux, which enables the flux to quickly wet the solder and the welding surface during the welding process to form a uniform wetting layer. This not only helps to evenly distribute the solder, but also reduces welding defects such as pores and slag inclusions, thereby improving the quality of the welded joint.

[0027] In summary, this application has the following beneficial effects: 1. In this application, the synergistic effect of the film-forming agent and the activator effectively reduces the surface tension of the welding interface, and promotes the wetting and spreading of the solder on the metal surface. At the same time, the modifier further enhances the wetting performance of the flux, especially it can remain stable at high temperatures and is not easy to decompose. The modifier is a mixture of castor oil, stearic acid amide and glycerol. These ingredients have higher thermal stability and reduce decomposition and negative effects at high temperatures. In this application, the combined effect of corrosion inhibitors, thixotropic agents and other ingredients is also used to protect the welding surface from corrosion, while improving the fluidity and adhesion of the solder, and ultimately improving the overall quality and strength of the welded joint. DETAILED DESCRIPTION Example

[0028] Hydrogenated rosin was purchased from Hubei Yamade Biopharmaceutical Co., Ltd. with a CAS number of 65997-06-0.

[0029] Acrylic resin was purchased from Jining Juji New Materials Co., Ltd., and the model number is SH-thermoplastic acrylic resin.

[0030] Rosin was purchased from Jinan Yongyue Chemical Co., Ltd. and the model was industrial grade.

[0031] Polyethylene glycol was purchased from Shanghai Tichem Industrial Co., Ltd. The brand is Dow and the molecular weight is 4000.

[0032] Polyamide wax was purchased from Shanghai Jianbang Industrial Co., Ltd. The brand is Clariant and the model is Licowax C wax.

[0033] The activated clay was purchased from Tianze Mineral Products Processing Plant in Lingshou County.

[0034] Example 1 A high-wetting halogen-free soldering flux is prepared by the following method: Mix 300g of film-forming agent (hydrogenated rosin), 40g of activator (fatty alcohol polyoxyethylene ether), 50g of palm wax, 5g of corrosion inhibitor (benzotriazole), 20g of thixotropic agent (polyethylene glycol), 2g of dimethylamine hydrochloride, 10g of rare earth chloride (cerium chloride), 50g of modifier and 523g of solvent (dipentaerythritol ester), stir well to obtain a high-wetting halogen-free flux.

[0035] The modifier is composed of castor oil, stearic acid amide and glycerin in a weight ratio of 4:1:0.5.

[0036] The difference between Example 2-3 and Example 1 is that the types of raw materials, amounts and experimental parameters for preparing the high-wetting halogen-free flux are different. The specific differences are shown in Table 1: Table 1 Raw material types, dosages and experimental parameters for preparing high-wetting halogen-free flux in Examples 1-3 Example 4 A high-wetting 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 4:4:0.5.

[0037] Example 5 A high-wetting 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 4:1:4.

[0038] Example 6 A high-wetting 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.

[0039] Example 7 A high-wetting 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.

[0040] Example 8 A high-wetting 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.

[0041] Example 9 A high-wetting halogen-free soldering flux, the difference between this embodiment and embodiment 1 is that the activator is composed of fatty alcohol polyoxyethylene ether and 2-ethylimidazole in a weight ratio of 5:0.5.

[0042] Example 10 A high-wetting halogen-free soldering flux. The difference between this embodiment and embodiment 7 is that the activator is composed of fatty alcohol polyoxyethylene ether and 2-ethylimidazole in a weight ratio of 5:1.5.

[0043] Embodiment 11 A high-wetting halogen-free soldering flux. The difference between this embodiment and embodiment 9 is that the activator is composed of fatty alcohol polyoxyethylene ether and 2-ethylimidazole in a weight ratio of 1:1.

[0044] Example 12 A high-wetting 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.

[0045] Embodiment 13 A high-wetting 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.

[0046] Embodiment 14 A high-wetting 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.

[0047] Embodiment 15 A high-wetting halogen-free soldering flux, the difference between this embodiment and embodiment 1 is that the solvent is obtained by mixing dipentaerythritol ester, diethylene glycol monobutyl ether acetate and pineneol in a weight ratio of 1:2:5.

[0048] Example 16 A high-wetting halogen-free soldering flux. The difference between this embodiment and embodiment 13 is that the solvent is obtained by mixing dipentaerythritol ester, diethylene glycol monobutyl ether acetate and pineneol in a weight ratio of 1:3:5.

[0049] Embodiment 17 A high-wetting halogen-free soldering flux is prepared by the following method: Mix 240g of film-forming agent (hydrogenated rosin), 50g of activator (fatty alcohol polyoxyethylene ether), 60g of palm wax, 5g of corrosion inhibitor (benzotriazole), 30g of thixotropic agent (polyethylene glycol), 3g of dimethylamine hydrochloride, 10g of rare earth chloride (cerium chloride), 70g of modifier and 532g of solvent (dipentaerythritol ester), stir well to obtain a high-wetting halogen-free flux.

[0050] The modifier is composed of castor oil, stearic acid amide and glycerin in a weight ratio of 4:1.5:1.

[0051] Comparative Example Comparative Example 1 A high-wetting halogen-free soldering flux. The difference between this comparative example and Example 1 is that succinic acid is used instead of the modifier.

[0052] Comparative Example 2 A high-wetting 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.

[0053] Comparative Example 3 A high-wetting 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.

[0054] Comparative Example 4 A high-wetting halogen-free soldering flux. The difference between this comparative example and Example 1 is that the modifier is composed of stearic acid amide and glycerol in a weight ratio of 1:0.5.

[0055] Comparative Example 5 A high-wetting halogen-free soldering flux. The difference between this comparative example and Example 1 is that paraffin wax is used instead of palm wax.

[0056] Comparative Example 6 A high-wetting halogen-free soldering flux. The difference between this comparative example and Example 1 is that zinc chloride is used instead of cerium chloride.

[0057] Comparative Example 7 A high-wetting halogen-free soldering flux. The difference between this comparative example and Example 1 is that a certain compound is used instead of dimethylamine hydrochloride.

[0058] Detection method / test method Bismuth-tin alloy powder solder was purchased from Hunan XiNeng New Materials Co., Ltd., and solder paste was prepared according to the proportion of solder and flux in conventional solder paste, respectively, in combination with the high-wetting halogen-free flux prepared in Examples 1-17 and Comparative Examples 1-7. The soldering performance of the flux prepared in Examples 1-17 and Comparative Examples 1-2 was tested according to the methods specified in GB / T11364-2008, SJ / T11389-2009, GB / T 9491-2002 and IPC-SA-61 standards. The results are shown in Table 2: Table 2 Experimental results of Examples 1-17 and Comparative Examples 1-7 It can be seen from the experimental results of Examples 1-17 and Comparisons 1-7 that the halogen-free flux prepared by the formula in the present application has the characteristics of high wetting, no corrosion, and no residue, can effectively inhibit the formation of tin bridges, make the solder joints bright and full, the solder joints have high reliability, and can effectively improve the welding quality.

[0059] Comparing Example 1 with Comparative Examples 1-4, the wettability of Comparative Examples 1-4 is not as good as that of Example 1. Corrosion and residue phenomena occur in Comparative Example 1, and residue phenomena occur in Comparative Example 3. In addition, the brightness of the solder joints of Comparative Examples 1-4 is average, indicating that in the present application, by preparing a modifier with sesame oil, stearic acid amide and glycerin and then using it in the flux, the wettability and welding quality of the flux can be effectively improved.

[0060] Comparing Example 1 with Comparative Examples 5-7, the wettability of Comparative Examples 5-7 is not as good as that of Example 1. Comparative Examples 5-7 all have residual phenomena, and Comparative Examples 6-7 have tin bridge phenomena. The brightness of the solder joints in Comparative Example 5 is poor, and the brightness of the solder joints in Comparative Examples 6-7 is average. This shows that preparing the flux by adding palm wax, dimethylamine hydrochloride, and rare earth chloride salt is beneficial to improving the wettability of the flux and the welding quality.

[0061] Comparing Example 1 with Examples 4-5, the wettability of Examples 4-5 is not as good as that of Example 1, indicating that the wettability of the flux can be further improved by optimizing the weight ratio of castor oil, stearic acid amide and glycerol.

[0062] Comparing Example 1 with Examples 7-8, the wettability of Examples 7-8 is better than that of Example 1, indicating that preparing the film-forming agent with hydrogenated rosin and acrylic resin in a specific ratio is beneficial to improving the wettability of the flux.

[0063] By comparing Example 1 with Example 9, the wettability of Example 9 is better than that of Example 1; Comparing Example 7 with Example 10, the wettability of Example 10 is better than that of Example 7; Comparing Example 9 with Example 11, the wettability of Example 9 is better than that of Example 11; It can be seen from Examples 1, 9, 10 and 11 that preparing the activator by mixing fatty alcohol polyoxyethylene ether and 2-ethylimidazole in a specific ratio is beneficial to improving the wettability of the soldering flux.

[0064] By comparing Example 1 with Example 12, the wettability of Example 12 is better than that of Example 1; By comparing Example 10 with Example 13, the wettability of Example 13 is better than that of Example 10; By comparing Example 12 with Example 14, the wettability of Example 12 is better than that of Example 14; It can be seen from Examples 1, 12, 13 and 14 that the wettability of the flux can be improved by preparing the corrosion inhibitor by using benzotriazole and silicate in a specific ratio.

[0065] By comparing Example 1 with Example 15, the wettability of Example 15 is better than that of Example 1; Comparing Example 16 with Example 13, the wettability of Example 16 is better than that of Example 13; It can be seen from Examples 1, 15 and 16 that preparing the solvent by using dipentaerythritol ester, diethylene glycol monobutyl ether acetate and terpineol in a specific ratio is beneficial to improving the wettability of the soldering flux.

[0066] Comparing Example 1 with Example 17, the wettability of Example 17 is better than that of Example 1, indicating that further optimizing the amount of raw materials used in preparing the high-wetting halogen-free flux is beneficial to improving the wettability of the flux.

[0067] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A high-humidity halogen-free flux, characterized in that: The high-humidity halogen-free soldering flux is prepared from the following raw materials in percentage by weight: Film former 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% The rest is solvent The modifier is obtained by mixing castor oil, stearic acid amide and glycerin.

2. A high-humidity halogen-free soldering flux according to claim 1, characterized in that: The weight ratio of the castor oil, the stearic acid amide and the glycerin is 4:(1-3):(0.5-2.5).

3. The high-humidity halogen-free soldering flux according to claim 1, characterized in that: The film-forming agent is obtained by mixing hydrogenated rosin and acrylic resin in a weight ratio of 1:(2.5-4).

4. The high-humidity halogen-free soldering flux according to claim 1, characterized in that: The active agent is composed of fatty alcohol polyoxyethylene ether and 2-ethylimidazole in a weight ratio of 5: (0.5-1.5).

5. The high-humidity halogen-free soldering flux according to claim 1, characterized in that: The corrosion inhibitor is composed of benzotriazole, sulfonated lignin and silicate in a weight ratio of 1: (0.5-2): (1-3).

6. The high-humidity halogen-free soldering flux according to claim 1, characterized in that: The thixotropic agent includes at least one of polyethylene glycol, polyamide wax, activated clay and hydrogenated castor oil.

7. The high-humidity halogen-free soldering flux according to claim 1, characterized in that: The solvent is obtained by mixing dipentaerythritol ester, diethylene glycol monobutyl ether acetate and pineneol in a weight ratio of 1: (2-3):

5.

8. The high-humidity halogen-free soldering flux according to claim 1, characterized in that: The rare earth chloride salt includes at least one of cerium chloride, lanthanum chloride, rubidium chloride, europium chloride, samarium chloride and scandium chloride.

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

1.

10. A method for preparing the high-wetness halogen-free soldering flux according to any one of claims 1 to 9, characterized in that: The method comprises the following preparation steps: The film former, the activator, the palm wax, the corrosion inhibitor, the thixotropic agent, the dimethylamine hydrochloride, the rare earth chloride salt, the modifier and the solvent are mixed and stirred evenly to obtain a high-wetting type halogen-free soldering flux.

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