A special soldering flux for high-speed tin coating of shingled solder strips

Abstract

The application relates to the technical field of fluxes. The application discloses a special flux for high-speed tin coating of shingled solder strips. The raw material composition of the flux comprises the following components: 1.3-5% of active agent, 0.25-1.5% of surfactant, 2-5% of cosolvent, 0.3-1% of corrosion inhibitor, 0.2-0.5% of film forming agent, and the balance of water; wherein the active agent is composed of alkyl polycarboxylic acid, p-toluenesulfonic acid and sulfosalicylic acid in a weight ratio of (0.5-1):(0.4-2):(0.4-2). The application further discloses a preparation method of the flux. The special flux for high-speed tin coating of shingled solder strips prepared by the application can meet the activation requirement in a short time, effectively slows down tin explosion, reduces surface pores, and improves tin coating quality.

Description

Technical Field

[0001] This application relates to the field of flux technology, and in particular to a flux specifically for high-speed tinning of shingled solder ribbons. Background Technology

[0002] Shingled solder ribbon is a special type of thin and wide busbar, typically over 10mm wide and under 0.15mm thick. Due to the special characteristics of this ribbon, conventional busbar tinning processes cannot meet its production requirements. For a long time, this wide and thin product has primarily been produced using slow tinning processes. However, with increasing pressure to reduce costs at the component level, the cost requirements for accessories and auxiliary materials such as shingled solder ribbon have also increased accordingly. For shingled solder ribbon, the most effective way to reduce costs is to upgrade the tinning process to a high-speed tinning process. In high-speed tinning processes, flux compatibility is crucial.

[0003] Under traditional slow tin plating conditions, the flux has sufficient time to activate, and the contact time between the copper and solder is long, making it easier to form a good copper-tin alloy layer, thus achieving a good tinning effect. In addition, excess active substances also have enough time to decompose and escape, with minimal impact on the tin layer.

[0004] However, in high-speed tin plating processes, the above conditions change. Due to the larger surface area of ​​the shingled solder strips, more flux is applied at high speeds, leading to a significant amount of flux being carried into the tin bath and causing severe solder spattering. Furthermore, after entering the tin bath, unlike standard busbars which can utilize multiple titanium rods for surface cleaning, more flux remains on the copper strip surface. During the cooling process, this residual flux vaporizes and escapes, forming pores on the solder strip surface, thus affecting surface quality. In addition, due to the high speed and short activation time, higher activity is required. Ordinary flux under halogen-free conditions struggles to activate the entire surface quickly enough, resulting in insufficient activity, difficulty in tinning, or numerous pinholes and copper leaks, thus affecting the tinning quality.

[0005] To address these issues, researchers considered using halogenated fluxes with high acid values. However, such fluxes rapidly form large amounts of metal halides within the solder bath, severely impacting solder quality and generating significant amounts of irritating gases, thus affecting the environment and human health.

[0006] Therefore, in order to achieve high-speed tin plating process for shingled solder strips, it is urgent to develop a flux that can meet the activation requirements in a short time, effectively slow down solder spattering, reduce surface porosity, and improve the quality of tin plating. Summary of the Invention

[0007] In order to solve at least one of the above-mentioned technical problems, and to develop a flux that can meet the activation requirements in a short time, effectively slow down solder blasting, reduce surface porosity, and improve the quality of solder coating, this application provides a special flux for high-speed solder coating of shingled solder ribbon.

[0008] On the one hand, the flux for high-speed tinning of shingled solder strips provided in this application comprises, by mass percentage: 1.3% to 5% activator, 0.25% to 1.5% surfactant, 2% to 5% cosolvent, 0.3% to 1% corrosion inhibitor, 0.2% to 0.5% film-forming agent, and the balance being water;

[0009] The active agent is composed of alkyl polycarboxylic acid, p-toluenesulfonic acid and sulfosalicylic acid in a weight ratio of (0.5-1):(0.4-2):(0.4-2).

[0010] By adopting the above technical solution, this application uses specific raw materials and proportions to prepare a flux that can meet the requirements of high-speed tin plating process for shingled copper strips, improve activation effect, effectively reduce solder spatter, reduce surface porosity, and improve tin coating quality. The flux prepared in this application has excellent deoxidation ability, which can remove the oxide layer on the surface of shingled copper strips in a very short time, and also has a good deoxidation effect on slightly discolored copper oxide strips.

[0011] The activator in this application is composed of alkyl polycarboxylic acid, p-toluenesulfonic acid and sulfosalicylic acid in a certain proportion. Only a small amount needs to be added to achieve a good deoxidation effect and meet the activation requirements in a short time. Furthermore, the sulfosalicylic acid will be heated and decomposed into sulfonic acid and salicylic acid the moment it enters the tin furnace, which has the function of continuously protecting the copper surface.

[0012] This application incorporates a corrosion inhibitor to prevent excessive corrosion of the copper base by the activator. The film-forming agent forms a complete film on the copper strip surface, extending the activation time of the activator and surfactant in the solder bath, ensuring the copper strip maintains high wetting effectiveness within the solder for a short time, and forming a complete alloy diffusion layer. Simultaneously, the film-forming agent increases the viscosity of water, reducing the boiling point of the flux upon entering the solder bath, mitigating solder spatter, and preventing porosity due to bubble overflow after the solder strip exits the solder bath. The fluxing agent reduces the surface tension of the solvent, improves the uniformity of solute dissolution in water, inhibits bacterial growth during flux storage, and extends the flux's lifespan.

[0013] Optionally, by weight percentage, the raw material composition includes: 2.5% to 3.5% activator, 0.6% to 1.0% surfactant, 3.5% to 4% cosolvent, 0.6% to 0.8% corrosion inhibitor, 0.3% to 0.4% film-forming agent, and the balance being water.

[0014] Optionally, by weight percentage, its raw material composition includes: 3.0% activator, 0.8% surfactant, 3.8% cosolvent, 0.7% corrosion inhibitor, 0.35% film-forming agent, and the balance being water.

[0015] Optionally, the alkyl polycarboxylic acid is selected from at least one of citric acid, malic acid, succinic acid, and maleic acid.

[0016] By adopting the above technical solution, alkyl polycarboxylic acids help to improve the activation performance of flux, enhance the interaction between flux and copper surface, and improve the activation effect.

[0017] Optionally, the alkyl polycarboxylic acid is selected from at least one of citric acid and malic acid.

[0018] Optionally, the surfactant is composed of ionic surfactant and nonionic surfactant, wherein the weight ratio of ionic surfactant to nonionic surfactant is (0.2-1.2):(0.05-0.3).

[0019] By adopting the above technical solution, ionic surfactants can enhance the activation effect of surfactants, while nonionic surfactants have better wetting properties. The combined effect of both results in superior performance, improving the surface activity and wetting properties of the flux, and further optimizing the tinning effect. This compounding method can better adapt to the tinning requirements of different material surfaces, improving the uniformity and consistency of tinning. The weight ratio of nonionic to ionic surfactants in this application provides better wetting and spreading properties, making the solder ribbon surface smoother and reducing the formation of pinholes and defects.

[0020] Optionally, the ionic surfactant is selected from one of dibromo-butene-diol, sodium alkylbenzene sulfonate, and cyclohexylamine hydrobromide;

[0021] The nonionic surfactant is selected from at least one of polyoxyethylene surfactants, alkynol surfactants, haloalcohol surfactants, and fluorocarbon surfactants;

[0022] The polyoxyethylene surfactant is selected from at least one of octylphenol polyoxyethylene ether and nonylphenol polyoxyethylene ether; the alkynyl alcohol surfactant is selected from at least one of ethynyl alcohol and ethoxylated alkynyl glycol; the haloalcohol surfactant is selected from at least one of trans-2,3-dibromo-2-buten-1,4-diol, 1-bromo-2-butanol, 1-bromo-2-propanol, 3-bromo-1-propanol, 3-bromo-1,2-propanediol, 1,4-dibromo-2-butanol, 1,3-dibromo-2-propanol, 2,3-dibromo-1-propanol, 2,3-dibromo-1,4-butanediol, and 2,3-dibromo-2-buten-1,4-diol; and the fluorocarbon surfactant is fluorocarbon surfactant FS-918.

[0023] By adopting the above technical solutions, the wetting ability of nonionic surfactants is outstanding. Only a small amount is needed to significantly improve the wettability of the copper strip surface, ensuring that the activator can be evenly distributed on the copper strip surface. Ionic surfactants can effectively improve the activation effect. Even halogen-containing ionic surfactants are present in very low amounts and decompose and volatilize upon entering the solder bath, leaving no residue in the solder strip and therefore not affecting the reliability of the solder strip.

[0024] Optionally, the co-solvent is selected from at least one of ethylene glycol, glycerol, 2,4-diethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol, 2,5-dimethyl-3-hexyn-2,5-diol, 2,3-dimethyl-2,3-butanediol, diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, 2-methylpentane-2,4-diol, diethylene glycol monohexyl ether, diethylene glycol monobutyl ether, diethylene glycol dibutyl ethyl ether, and triethylene glycol monobutyl ether.

[0025] By adopting the above technical solution, the fluxing agent can effectively dissolve and disperse the components in the flux to form a uniform and stable solution, which helps to improve the coating performance and uniformity of the flux.

[0026] Optionally, the corrosion inhibitor is an imidazole-based corrosion inhibitor.

[0027] By adopting the above technical solution, the corrosion inhibitor of this application can avoid excessive corrosion of the copper base by the activator. However, the content of the corrosion inhibitor should not be too high. If the content of the corrosion inhibitor exceeds 1%, it may weaken the activity and reduce the deoxidation capacity.

[0028] Optionally, the imidazole corrosion inhibitor is selected from one of 2-pentylbenzimidazole, 2-methylbenzimidazole, and benzotriazole.

[0029] By adopting the above technical solution, the corrosion inhibitor selected in this application has a good corrosion inhibition effect on copper materials.

[0030] Optionally, the film-forming agent is PEG-4000 or PEG-6000.

[0031] Optionally, the water is deionized water or distilled water.

[0032] By adopting the above technical solution, this application uses deionized water or distilled water, which reduces the impact of impurities in the water on the performance of the flux and helps to improve the stability and quality of the flux.

[0033] Secondly, this application provides a method for preparing the above-mentioned flux for high-speed tinning of shingled solder strips, comprising the following steps:

[0034] S1. The surfactant is stirred and mixed with water to obtain mixture A; the surfactant and the cosolvent are stirred and mixed to obtain mixture B;

[0035] S2. Mix the mixture A and the mixture B to obtain mixture C;

[0036] S3. Add the film-forming agent to the mixture C, stir and mix to obtain mixture D;

[0037] S4. Add the corrosion inhibitor to the mixture D, stir and mix, let stand, and obtain the special flux for high-speed tinning of shingled solder strips.

[0038] By adopting the above technical solution, the preparation method of this application is simple and convenient to operate, and has high preparation efficiency. This application involves gradual mixing of raw materials, which ensures that the components of the flux are fully mixed and dispersed, forming a uniform and stable solution. The preparation process involves no high-temperature energy-consuming steps, resulting in energy saving, emission reduction, and no pollution.

[0039] In summary, the present invention has at least one of the following beneficial technical effects:

[0040] 1. This application uses specific raw materials and proportions to prepare a flux that can meet the requirements of high-speed tin plating process for shingled solder strips, improve activation effect, effectively slow down solder spattering, reduce surface porosity, and improve tin coating quality.

[0041] 2. The activator in this application is composed of alkyl polycarboxylic acid, p-toluenesulfonic acid and sulfosalicylic acid in a certain proportion. Only a small amount needs to be added to achieve a good deoxidation effect and meet the activation requirements in a short time.

[0042] 3. The flux preparation method of this application is simple and convenient to operate, and has high preparation efficiency. This application involves gradual mixing of raw materials, which enables the flux components to be fully mixed and dispersed, forming a uniform and stable solution. Detailed Implementation

[0043] The present application will be further described in detail below with reference to the embodiments.

[0044] This application designs a high-speed tinning flux for shingled solder strips. By mass percentage, its raw material composition includes: 1.3%–5% activator, 0.25%–1.5% surfactant, 2%–5% cosolvent, 0.3%–1% corrosion inhibitor, 0.2%–0.5% film-forming agent, and the balance being water.

[0045] The active agent is composed of alkyl polycarboxylic acid, p-toluenesulfonic acid and sulfosalicylic acid in a weight ratio of (0.5-1):(0.4-2):(0.4-2).

[0046] The flux for high-speed tinning of shingled solder ribbons in this application is prepared by the following method, including the following steps:

[0047] S1. The surfactant is stirred and mixed with water to obtain mixture A; the surfactant and the cosolvent are stirred and mixed to obtain mixture B;

[0048] S2. Mix the mixture A and the mixture B to obtain mixture C;

[0049] S3. Add the film-forming agent to the mixture C, stir and mix to obtain mixture D;

[0050] S4. Add the corrosion inhibitor to the mixture D, stir and mix, let stand, and obtain the special flux for high-speed tinning of shingled solder strips.

[0051] This application addresses the problem that existing shingled solder ribbons have insufficient high-speed tinning activity, which easily leads to surface porosity and causes severe tin splattering. The technical solution proposed in this application is as follows.

[0052] This application first proposes a special flux for high-speed tinning of shingled solder ribbon, which can meet the needs of high-speed tinning process of shingled solder ribbon, improve activation effect, effectively reduce solder spatter, reduce surface porosity, and improve tinning quality.

[0053] Secondly, the flux preparation method used in this application is simple and convenient to operate, and has high preparation efficiency. This application involves gradually mixing the raw materials, which allows the various components of the flux to be fully mixed and dispersed, forming a uniform and stable solution.

[0054] The raw materials used in this application are as follows:

[0055] Citric acid: CAS: 77-92-9.

[0056] Malic acid: CAS: 6915-15-7.

[0057] Succinic acid: CAS: 110-15-6.

[0058] Maleic acid: CAS: 110-16-7.

[0059] p-Toluenesulfonic acid: CAS: 104-15-4.

[0060] Sulfosalicylic acid: CAS: 5965-83-3.

[0061] Dibromo-butene-diol: CAS: 3234-02-4.

[0062] Sodium alkylbenzene sulfonate: CAS: 25155-30-0.

[0063] Octylphenol polyoxyethylene ether: CAS: 26636-32-8.

[0064] Nonylphenol polyoxyethylene ether: CAS: 127087-87-0.

[0065] trans-2,3-dibromo-2-butene-1,4-diol: CAS: 21285-46-1.

[0066] Ethylene glycol: CAS: 107-21-1.

[0067] Glycerol: CAS: 56-81-5.

[0068] 2,4-Diethyl-1,5-pentanediol: CAS: 57987-55-0.

[0069] 2,5-Dimethyl-3-hexyn-2,5-diol: CAS: 142-30-3.

[0070] Ethylene glycol monophenyl ether: CAS: 48145-04-6.

[0071] 2-Methylpentane-2,4-diol: CAS: 2163-42-0.

[0072] Diethylene glycol monohexyl ether: CAS: 112-59-4.

[0073] Triethylene glycol monobutyl ether: CAS: 143-22-6.

[0074] 2-Pentylbenzimidazole: CAS: 5851-46-7.

[0075] 2-Methylbenzimidazole: CAS: 615-15-6.

[0076] Benzotriazole: CAS: 95-14-7. Specific Implementation

[0078] Examples 1-5

[0079] Example 1

[0080] This embodiment provides a high-speed tinning flux for shingled solder ribbons. By mass percentage, its raw material composition includes: 1.3% activator, 0.25% surfactant, 5.0% cosolvent, 0.3% corrosion inhibitor, 0.5% film-forming agent, and the balance being water.

[0081] The activator is composed of citric acid, p-toluenesulfonic acid and sulfosalicylic acid in a weight ratio of 0.5:0.4:0.4.

[0082] The surfactant is dibromo-butene-diol, the cosolvent is ethylene glycol, the corrosion inhibitor is 2-pentylbenzimidazole, and the film-forming agent is PEG-4000.

[0083] The preparation method includes the following steps:

[0084] S1. The surfactant is stirred and mixed with water to obtain mixture A; the surfactant and the cosolvent are stirred and mixed to obtain mixture B;

[0085] S2. Mix the mixture A and the mixture B to obtain mixture C;

[0086] S3. Add the film-forming agent to the mixture C, stir and mix to obtain mixture D;

[0087] S4. Add the corrosion inhibitor to the mixture D, stir and mix, let stand, and obtain the special flux for high-speed tinning of shingled solder strips.

[0088] Example 2

[0089] This embodiment provides a high-speed tinning flux for shingled solder ribbons. By mass percentage, its raw material composition includes: 3.5% activator, 0.6% surfactant, 3.5% cosolvent, 0.8% corrosion inhibitor, 0.3% film-forming agent, and the balance being water.

[0090] The activator is composed of citric acid, p-toluenesulfonic acid and sulfosalicylic acid in a weight ratio of 0.6:0.7:0.7.

[0091] The surfactant is dibromo-butene-diol, the cosolvent is ethylene glycol, the corrosion inhibitor is 2-pentylbenzimidazole, and the film-forming agent is PEG-4000.

[0092] The preparation methods of Examples 2 to 5 are the same as those of Example 1.

[0093] Example 3

[0094] This embodiment provides a flux specifically for high-speed tinning of shingled solder ribbons. By mass percentage, its raw material composition includes: 3.0% activator, 0.8% surfactant, 3.8% cosolvent, 0.7% corrosion inhibitor, 0.35% film-forming agent, and the balance being water.

[0095] The activator is composed of citric acid, p-toluenesulfonic acid and sulfosalicylic acid in a weight ratio of 0.7:1:1.

[0096] The surfactant is dibromo-butene-diol, the cosolvent is ethylene glycol, the corrosion inhibitor is 2-pentylbenzimidazole, and the film-forming agent is PEG-4000.

[0097] Example 4

[0098] This embodiment provides a high-speed tinning flux for shingled solder ribbons. By mass percentage, its raw material composition includes: 2.5% activator, 1.0% surfactant, 4.0% cosolvent, 0.6% corrosion inhibitor, 0.4% film-forming agent, and the balance being water.

[0099] The activator is composed of citric acid, p-toluenesulfonic acid and sulfosalicylic acid in a weight ratio of 0.8:1.5:1.5.

[0100] The surfactant is dibromo-butene-diol, the cosolvent is ethylene glycol, the corrosion inhibitor is 2-pentylbenzimidazole, and the film-forming agent is PEG-4000.

[0101] Example 5

[0102] This embodiment provides a high-speed tinning flux for shingled solder ribbons. By mass percentage, its raw material composition includes: 5.0% activator, 1.5% surfactant, 2.0% cosolvent, 1.0% corrosion inhibitor, 0.2% film-forming agent, and the balance being water.

[0103] The activator is composed of citric acid, p-toluenesulfonic acid and sulfosalicylic acid in a weight ratio of 1:2:2.

[0104] The surfactant is dibromo-butene-diol, the cosolvent is ethylene glycol, the corrosion inhibitor is 2-pentylbenzimidazole, and the film-forming agent is PEG-4000.

[0105] Comparative Examples 1-6

[0106] Comparative Example 1

[0107] The difference between Comparative Example 1 and Example 3 is that the activator in Comparative Example 1 is 3.0% citric acid.

[0108] Comparative Example 2

[0109] The difference between Comparative Example 2 and Example 3 is that the activator in Comparative Example 2 is composed of p-toluenesulfonic acid and sulfosalicylic acid in a weight ratio of 1:1.

[0110] Comparative Example 3

[0111] The difference between Comparative Example 3 and Example 3 is that the corrosion inhibitor in Comparative Example 3 is 2% 2-pentylbenzimidazole.

[0112] Comparative Example 4

[0113] The difference between Comparative Example 4 and Example 3 is that the raw materials of Comparative Example 4 do not include a co-solvent.

[0114] Comparative Example 5

[0115] The difference between Comparative Example 5 and Example 3 is that the raw materials of Comparative Example 5 do not include film-forming agents.

[0116] Comparative Example 6

[0117] The difference between Comparative Example 6 and Example 3 is that the preparation method of Comparative Example 6 is as follows: the activator, surfactant, cosolvent, corrosion inhibitor, film-forming agent and water are mixed, stirred and allowed to stand to obtain flux.

[0118] Experimental testing

[0119] Testing items and testing methods

[0120] The flux spreading rate is tested according to GB / T 9491-2021 "Fluents for Soldering" to reflect its wetting and spreading characteristics.

[0121] Average number of pores detection: Flux was used to apply tin to the shingled solder strip at high speed. The running speed of the shingled solder strip was 80m / min. The average number of pores per 40 meters was detected.

[0122] The fluxes prepared in Examples 1-5 and Comparative Examples 1-6 were used for high-speed tinning of shingled solder strips. The flux spread rate and the average number of pores in the high-speed tinning of shingled solder strips were tested, and the presence of solder blasting was observed. The test results are shown in Table 1.

[0123] Table 1

[0124] Expansion rate / % Average number of stomata / Tin splattering Example 1 90.2 ≤3 none Example 2 91.4 ≤2 none Example 3 92.7 ≤2 none Example 4 92.0 ≤2 none Example 5 91.1 ≤2 none Comparative Example 1 86.3 ≤5 none Comparative Example 2 87.1 ≤5 none Comparative Example 3 88.5 ≤4 none Comparative Example 4 84.0 ≤7 none Comparative Example 5 90.2 ≤2 have Comparative Example 6 86.6 ≤5 none

[0125] As shown in Table 1, the fluxes prepared in Examples 1-5 exhibit good wetting and spreading properties, effectively reducing porosity on the tinned surface of the shingled solder ribbon, slowing down solder spattering, and improving tinning quality. Even at a running speed of 80 m / min, the shingled solder ribbon can still quickly remove the oxide layer from the copper strip surface, maintaining good wettability and activity after entering the tin bath, thus achieving a good tin plating layer.

[0126] The activator of Comparative Example 1 was a single component citric acid, while the activator of Comparative Example 2 consisted of p-toluenesulfonic acid and sulfosalicylic acid, without citric acid. The wettability and spreadability of the fluxes prepared in Comparative Example 1 and Comparative Example 2 were significantly reduced, and the number of pores on the tin-coated surface of the shingled solder strips increased.

[0127] In Comparative Example 3, the corrosion inhibitor content was 2%, resulting in decreased wettability and increased porosity on the tinned surface of the shingled solder ribbon.

[0128] Comparative Example 4, which does not contain a flux, produces flocculent material with poor uniformity, significantly reduced wetting and spreading properties, and an increased number of pores on the tinned surface of the shingled solder ribbon.

[0129] Comparative Example 5, which does not contain a film-forming agent, resulted in solder spattering during high-speed tinning of shingled solder strips.

[0130] Comparative Example 6 involved mixing all raw materials simultaneously without stepwise mixing, resulting in decreased wetting and spreading properties of the flux and an increase in the number of pores on the tinned surface of the shingled solder strip.

[0131] Examples 6-18

[0132] Example 6

[0133] The difference between Example 6 and Example 3 is that in Example 6, citric acid is replaced with an equal weight of malic acid.

[0134] Example 7

[0135] The difference between Example 7 and Example 3 is that in Example 7, citric acid is replaced with an equal weight of succinic acid.

[0136] Example 8

[0137] The difference between Example 8 and Example 3 is that in Example 8, citric acid is replaced with an equal weight of maleic acid.

[0138] Example 9

[0139] The difference between Example 9 and Example 3 is that the surfactant in Example 9 is octylphenol polyoxyethylene ether.

[0140] Example 10

[0141] The difference between Example 10 and Example 3 is that the surfactant in Example 10 is composed of dibromo-butene-diol and octylphenol polyoxyethylene ether in a weight ratio of 0.2:0.05.

[0142] Example 11

[0143] The difference between Example 11 and Example 10 is that the surfactant in Example 11 is composed of dibromo-butene-diol and octylphenol polyoxyethylene ether in a weight ratio of 0.8:0.15.

[0144] Example 12

[0145] The difference between Example 12 and Example 10 is that the surfactant in Example 12 is composed of dibromo-butene-diol and octylphenol polyoxyethylene ether in a weight ratio of 1.2:0.2.

[0146] Example 13

[0147] The difference between Example 13 and Example 11 is that in Example 13, dibromo-butene-diol is replaced with an equal amount of sodium alkylbenzene sulfonate; and octylphenol polyoxyethylene ether is replaced with nonylphenol polyoxyethylene ether and trans-2,3-dibromo-2-butene-1,4-diol in a weight ratio of 1:1, wherein the sum of the weights of nonylphenol polyoxyethylene ether and trans-2,3-dibromo-2-butene-1,4-diol is equal to the weight of octylphenol polyoxyethylene ether.

[0148] Example 14

[0149] The difference between Example 14 and Example 3 is that the cosolvent in Example 14 is glycerol and 2,4-diethyl-1,5-pentanediol in a weight ratio of 1:1.

[0150] Example 15

[0151] The difference between Example 15 and Example 3 is that the cosolvent in Example 15 is ethylene glycol monophenyl ether and diethylene glycol monohexyl ether in a weight ratio of 1:1.

[0152] Example 16

[0153] The difference between Example 16 and Example 3 is that the cosolvent in Example 16 is 2,5-dimethyl-3-hexyn-2,5-diol, 2-methylpentane-2,4-diol and triethylene glycol monobutyl ether in a weight ratio of 1:1:1.

[0154] Example 17

[0155] The difference between Example 17 and Example 3 is that the corrosion inhibitor in Example 17 is composed of 2-methylbenzimidazole and benzotriazole in a weight ratio of 1:1.

[0156] Example 18

[0157] The difference between Example 18 and Example 3 is that the film-forming agent in Example 18 is PEG-6000.

[0158] The fluxes prepared in Examples 6 to 18 were used for high-speed tinning of shingled solder strips. The flux spread rate and the average number of pores in the high-speed tinning of shingled solder strips were tested, and the presence of solder blasting was observed. The test results are shown in Table 2.

[0159] Table 2

[0160] Expansion rate / % Average number of stomata / Tin splattering Example 6 92.8 ≤2 none Example 7 92.5 ≤2 none Example 8 92.4 ≤2 none Example 9 93.0 ≤2 none Example 10 94.7 ≤1 none Example 11 95.1 ≤1 none Example 12 94.9 ≤1 none Example 13 95.3 ≤1 none Example 14 93.6 ≤1 none Example 15 93.8 ≤1 none Example 16 94.2 ≤1 none Example 17 93.3 ≤1 none Example 18 92.4 ≤2 none

[0161] As can be seen from the test results in Table 2, replacing citric acid with malic acid in Example 6 did not significantly change the wettability and spreadability of the flux or the number of pores on the tinned surface of the shingled solder ribbon.

[0162] In Example 7, citric acid was replaced with succinic acid, and in Example 8, citric acid was replaced with maleic acid. The wetting and spreading properties of the resulting flux decreased.

[0163] The difference between Examples 9 and 10 and Example 3 lies in the composition of the surfactant. In Example 9, the surfactant is octylphenol polyoxyethylene ether, and the wettability and porosity of the flux and the number of pores on the tin-coated surface of the shingled solder ribbon do not change much. In Example 10, a compound surfactant of dibromo-butene-diol and octylphenol polyoxyethylene ether is used, and the wettability and spreadability of the flux are significantly improved.

[0164] The difference between Examples 11 and 12 and Example 10 is that the weight ratio of dibromo-butene-diol and octylphenol polyoxyethylene ether is different. Among them, the flux prepared in Example 11 has the best wetting and spreading properties.

[0165] Compared with Example 11, the flux prepared in Example 13 has higher wetting and spreading properties.

[0166] The difference between Examples 14-16 and Example 3 lies in the choice of flux. The fluxes prepared in Examples 14 and 15 have improved wetting and spreading properties, while the flux prepared in Example 16 has the best wetting and spreading properties.

[0167] The corrosion inhibitor in Example 17 was a combination of 2-methylbenzimidazole and benzotriazole, which improved the wetting and spreading properties of the flux.

[0168] The film-forming agent in Example 18 was PEG-6000, and the wettability and spreadability of the resulting flux decreased.

[0169] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A flux specifically for high-speed tinning of shingled solder strips, characterized in that, The raw material composition, by mass percentage, includes: 1.3%~5% activator, 0.25%~1.5% surfactant, 2%~5% cosolvent, 0.3%~1% corrosion inhibitor, 0.2%~0.5% film-forming agent, and the balance being water; wherein, the activator is composed of alkyl polycarboxylic acid, p-toluenesulfonic acid, and sulfosalicylic acid in a weight ratio of (0.5~1):(0.4~2):(0.4~2); the alkyl polycarboxylic acid is selected from one of citric acid, malic acid, succinic acid, and maleic acid; the surfactant is composed of ionic surfactant and nonionic surfactant; the ionic surfactant is selected from one of sodium alkylbenzenesulfonate and cyclohexylamine hydrobromide; the nonionic surfactant is selected from at least one of polyoxyethylene surfactant, alkynol surfactant, haloalcohol surfactant, and fluorocarbon surfactant; the corrosion inhibitor is an imidazole corrosion inhibitor.

2. The flux for high-speed tinning of shingled solder strips according to claim 1, characterized in that, By mass percentage, its raw material composition includes: 2.5%~3.5% activator, 0.6%~1.0% surfactant, 3.5%~4% cosolvent, 0.6%~0.8% corrosion inhibitor, 0.3%~0.4% film-forming agent, and the balance being water.

3. The flux for high-speed tinning of shingled solder strips according to claim 1, characterized in that, The weight ratio of the ionic surfactant to the nonionic surfactant is (0.2~1.2):(0.05~0.3).

4. The flux for high-speed tinning of shingled solder strips according to claim 1, characterized in that, The polyoxyethylene surfactant is selected from at least one of octylphenol polyoxyethylene ether and nonylphenol polyoxyethylene ether; the alkynyl alcohol surfactant is selected from at least one of ethynyl alcohol and ethoxylated alkynyldiol; the haloalcohol surfactant is selected from at least one of 1-bromo-2-butanol, 1-bromo-2-propanol, 3-bromo-1-propanol, 3-bromo-1,2-propanediol, 1,4-dibromo-2-butanol, 1,3-dibromo-2-propanol, 2,3-dibromo-1-propanol, 2,3-dibromo-1,4-butanediol, and 2,3-dibromo-2-butene-1,4-diol; and the fluorocarbon surfactant is fluorocarbon surfactant FS-918.

5. The flux for high-speed tinning of shingled solder strips according to claim 1, characterized in that, The co-solvent is selected from at least one of ethylene glycol, glycerol, 2,4-diethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol, 2,5-dimethyl-3-hexyn-2,5-diol, 2,3-dimethyl-2,3-butanediol, diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, 2-methylpentane-2,4-diol, diethylene glycol monohexyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether.

6. The flux for high-speed tinning of shingled solder strips according to claim 1, characterized in that, The imidazole corrosion inhibitor is selected from 2-pentylbenzimidazole and 2-methylbenzimidazole.

7. The flux for high-speed tinning of shingled solder strips according to claim 1, characterized in that, The film-forming agent is PEG-4000 or PEG-6000.

8. A method for preparing the flux for high-speed tinning of shingled solder strips as described in claim 1, characterized in that, Includes the following steps: S1. The surfactant is stirred and mixed with water to obtain mixture A; the surfactant and the cosolvent are stirred and mixed to obtain mixture B; S2. Mix the mixture A and the mixture B to obtain mixture C; S3. Add the film-forming agent to the mixture C, stir and mix to obtain mixture D; S4. Add the corrosion inhibitor to the mixture D, stir and mix, let stand, and obtain the special flux for high-speed tinning of shingled solder strips.