Smokeless solder wire and preparation method thereof

Abstract

The invention discloses a smokeless solder wire which comprises a hollow round-strip-shaped solder wire alloy and smokeless scaling powder filled in the solder wire alloy, the mass ratio of the solder wire alloy to the smokeless scaling powder is (97-98): (2-3), the solder wire alloy comprises, by mass, 93-95 parts of tin, 0.3-0.7 part of copper, 0.3-0.7 part of silver, 0.005-0.025 part of antimony and 0.01-0.05 part of bismuth, and the solder wire alloy comprises, by mass, 93-95 parts of tin, 0.3-0.7 part of copper, 0.3-0.7 part of silver, 0.005-0.025 part of antimony and 0.01-0.05 part of bismuth. The smokeless soldering flux comprises 2.1-2.5 parts of an alcohol solvent, 0.05-0.09 part of synthetic resin, 0.05-0.09 part of an organic delustering agent, 0.02-0.06 part of an active agent, 0.06-0.12 part of a cosolvent and 0.004-0.02 part of a corrosion inhibitor, antimony and bismuth are added into a tin solder alloy on the basis of original tin, silver and copper, the moisture capacity of a tin material can be improved, meanwhile, the tin blast problem is restrained, and therefore the tin solder alloy has the advantages of being good in corrosion resistance, good in corrosion resistance and the like. And moreover, the fatigue resistance of the tin solder alloy is improved, the bending resistance degree is high, the ductility is enhanced, the subsequent wire drawing process is facilitated, and the risk that the solder wire is broken is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of smokeless solder wires, in particular to a smokeless solder wire and a preparation method thereof. Background Art

[0002] Solder wire is composed of tin alloy and additives. The alloy components are divided into tin-lead and lead-free additives, which are evenly poured into the middle part of the tin alloy. Different types of solder wires have different additives. The additive part is to improve the auxiliary heat conduction of the solder wire during the welding process, remove oxidation, reduce the surface tension of the material to be welded, remove the oil on the surface of the material to be welded, and increase the welding area. The characteristic of solder wire is that it is a tin alloy wire with a certain length and diameter. It can be used with an electric soldering iron or laser in the welding of electronic components.

[0003] After searching, the patent with application number 202110047440.2 discloses a smokeless solder wire and its preparation method. A smokeless solder wire comprises a tin solder alloy and a smokeless flux filled in the tin solder alloy, the mass ratio of the tin solder alloy and the smokeless flux is (97-98): (2-3), the smokeless flux comprises a smokeless carrier and a flux activator, the mass ratio of the smokeless carrier and the flux activator is (94-96): 5; the smokeless carrier is made of the following raw materials in parts by weight: 40-60 parts of cellulose, 20-30 parts of polyamide wax, and 10-15 parts of ether solvent; the polyamide wax is a mixture of polyamide wax with an acid value of less than 10 mgKOH / g and modified polyamide wax with a density of 0.88-0.9 g / cm3. The smokeless solder wire provided in the application does not generate smoke during soldering, eliminates toxic and harmful gases, and the welded parts are clean and tidy after soldering. The soldering iron tip does not oxidize and turn black, and is not prone to generating tin splashes, and has good wettability.

[0004] The components of the tin solder alloy in the solder wire of the above scheme are tin, silver and copper. The obtained tin solder alloy has poor performance, fatigue resistance needs to be improved, and ductility is poor. It may break during the later wire drawing process. Therefore, we need to propose a smokeless solder wire and a preparation method thereof. Summary of the invention

[0005] The purpose of the present invention is to provide a smokeless solder wire and a preparation method thereof. On the basis of the original tin, silver and copper, antimony and bismuth are added to the tin solder alloy, which can improve the moisture resistance of the tin material, while suppressing the tin plague problem, and improving the fatigue resistance of the tin solder alloy. The bending resistance is strong, the ductility is enhanced, the subsequent wire drawing process is convenient, and the risk of solder wire breakage is reduced, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a smokeless solder wire, comprising a hollow round bar-shaped solder wire alloy and a smokeless soldering flux filled in the solder wire alloy, wherein the mass ratio of the solder wire alloy to the smokeless soldering flux is (97-98):(2-3), and the solder wire alloy comprises 93-95 parts of tin, 0.3-0.7 parts of copper, 0.3-0.7 parts of silver, 0.005-0.025 parts of antimony, and 0.01-0.05 parts of bismuth in terms of mass components; and the smokeless soldering flux comprises 2.1-2.5 parts of an alcohol solvent, 0.05-0.09 parts of a synthetic resin, 0.05-0.09 parts of an organic matting agent, 0.02-0.06 parts of an activator, 0.06-0.12 parts of a co-solvent, and 0.004-0.02 parts of a corrosion inhibitor.

[0007] Preferably, the alcohol solvent is at least one of ethanol, propanol or isopropanol; the co-solvent is at least one of sodium benzoate, sodium salicylate, p-aminobenzoic acid, niacinamide and acetamide.

[0008] Preferably, the active agent is at least one of succinic acid, adipic acid, malonic acid, glycolic acid, itaconic acid, palmitic acid, malic acid, sebacic acid, glutaric acid, hydroxyacetic acid, benzoate, butyl acetate, ethyl acetate, ethylene glycol phenyl ether, dipropylene glycol methyl ether, tripropylene glycol butyl ether, succinic acid amine, triethanolamine and diethanolamine.

[0009] Preferably, calculated by mass, the solder wire alloy includes 93 parts of tin, 0.3 parts of copper, 0.3 parts of silver, 0.005 parts of antimony, and 0.01 parts of bismuth, and the smokeless flux includes 2.1 parts of alcohol solvent, 0.05 parts of synthetic resin, 0.05 parts of organic matting agent, 0.02 parts of activator, 0.06 parts of co-solvent, and 0.004 parts of corrosion inhibitor.

[0010] Preferably, calculated by mass, the solder wire alloy includes 93.5 parts of tin, 0.4 parts of copper, 0.4 parts of silver, 0.01 parts of antimony, and 0.02 parts of bismuth, and the smokeless flux includes 2.2 parts of alcohol solvent, 0.06 parts of synthetic resin, 0.06 parts of organic matting agent, 0.03 parts of activator, 0.08 parts of co-solvent, and 0.008 parts of corrosion inhibitor.

[0011] Preferably, calculated by mass, the solder wire alloy includes 94 parts of tin, 0.5 parts of copper, 0.5 parts of silver, 0.015 parts of antimony, and 0.03 parts of bismuth, and the smokeless flux includes 2.3 parts of alcohol solvent, 0.07 parts of synthetic resin, 0.07 parts of organic matting agent, 0.04 parts of activator, 0.09 parts of co-solvent, and 0.012 parts of corrosion inhibitor.

[0012] Preferably, calculated by mass, the solder wire alloy includes 94.5 parts of tin, 0.6 parts of copper, 0.6 parts of silver, 0.020 parts of antimony, and 0.04 parts of bismuth, and the smokeless flux includes 2.4 parts of alcohol solvent, 0.08 parts of synthetic resin, 0.08 parts of organic matting agent, 0.05 parts of activator, 0.10 parts of co-solvent, and 0.016 parts of corrosion inhibitor.

[0013] Preferably, calculated by mass, the solder wire alloy includes 95 parts of tin, 0.7 parts of copper, 0.7 parts of silver, 0.025 parts of antimony, and 0.05 parts of bismuth, and the smokeless flux includes 2.5 parts of alcohol solvent, 0.09 parts of synthetic resin, 0.09 parts of organic matting agent, 0.06 parts of activator, 0.12 parts of co-solvent, and 0.02 parts of corrosion inhibitor.

[0014] The present invention also provides a method for preparing a smokeless solder wire, comprising the following steps:

[0015] S1. Preparation and mixing of raw materials: weigh the corresponding mass of tin, copper, silver, antimony and bismuth according to the mass ratio, clean the dust on the metal surface, and then dry it;

[0016] S2. Melting of tin material: Put the dried metal material into a furnace to melt it, and add an antioxidant to cover the surface of the metal material after melting;

[0017] S3, casting of tin material: the molten tin material is poured into a mold and cast into a rod-shaped billet;

[0018] S4. Preparation of smokeless soldering flux: add alcohol solvent into a stirring kettle, then add active agent, synthetic resin, organic matting agent, co-solvent and corrosion inhibitor into the stirring kettle, stir at room temperature until the materials are completely dissolved, and filter;

[0019] S5, extrusion wire drawing: pour the prepared smokeless flux into the rod-shaped blank. Before extrusion, apply a layer of lubricating oil on the surface of the rod-shaped blank. During the extrusion process, the pressure is kept balanced so that the wire drawing speed is always kept uniform.

[0020] S6. Winding: The drawn solder wire is automatically wound on the receiving roller, and the number of turns can be counted under full automatic control when the winding is smooth, and uneven winding can be avoided;

[0021] S7. Inspect packaging and check finished products entering storage.

[0022] Preferably, in S2, the furnace is set as an electric heating furnace. During the melting process of the metal material, hot oil is added to the electric heating furnace, and electric heating is adopted. Active stirring and temperature control can be performed in real time to eliminate poor fusion caused by human factors.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention adds antimony and bismuth to the tin solder alloy on the basis of the original tin, silver and copper, which can improve the moisture resistance of the tin material, suppress the tin plague problem, improve the fatigue resistance of the tin solder alloy, strengthen the bending resistance, enhance the ductility, facilitate the subsequent wire drawing process, and reduce the risk of solder wire breakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] See also Figure 1 The present invention provides a technical solution: a smokeless solder wire, comprising a hollow round solder wire alloy and a smokeless soldering flux filled in the solder wire alloy, wherein the mass ratio of the solder wire alloy to the smokeless soldering flux is (97-98):(2-3), and the solder wire alloy comprises 93-95 parts of tin, 0.3-0.7 parts of copper, 0.3-0.7 parts of silver, 0.005-0.025 parts of antimony, and 0.01-0.05 parts of bismuth in terms of mass components; the smokeless soldering flux comprises 2.1-2.5 parts of an alcohol solvent, 0.05-0.09 parts of a synthetic resin, 0.05-0.09 parts of an organic matting agent, 0.02-0.06 parts of an activator, 0.06-0.12 parts of a co-solvent, and 0.004-0.02 parts of a corrosion inhibitor.

[0029] The alcohol solvent is at least one of ethanol, propanol or isopropanol; the co-solvent is at least one of sodium benzoate, sodium salicylate, p-aminobenzoic acid, niacinamide and acetamide.

[0030] The active agent is at least one of succinic acid, adipic acid, malonic acid, glycolic acid, itaconic acid, palmitic acid, malic acid, sebacic acid, glutaric acid, hydroxyacetic acid, benzoate, butyl acetate, ethyl acetate, ethylene glycol phenyl ether, dipropylene glycol methyl ether, tripropylene glycol butyl ether, succinic acid amine, triethanolamine and diethanolamine.

[0031] Calculated by mass, the solder wire alloy includes 93 parts of tin, 0.3 parts of copper, 0.3 parts of silver, 0.005 parts of antimony, and 0.01 parts of bismuth; the smokeless flux includes 2.1 parts of alcohol solvent, 0.05 parts of synthetic resin, 0.05 parts of organic matting agent, 0.02 parts of activator, 0.06 parts of co-solvent, and 0.004 parts of corrosion inhibitor.

[0032] The present invention also provides a method for preparing a smokeless solder wire, comprising the following steps:

[0033] S1. Preparation and mixing of raw materials: weigh the corresponding mass of tin, copper, silver, antimony and bismuth according to the mass ratio, clean the dust on the metal surface, and then dry it;

[0034] S2. Melting of tin material: Put the dried metal material into a furnace to melt it, and add an antioxidant to cover the surface of the metal material after melting;

[0035] The process of melting tin, copper, silver, antimony and bismuth according to mass ratio to remove impurities and make the required alloy;

[0036] During the smelting process, it should be stirred evenly to remove impurities. After the test and analysis are qualified, it can be used as a casting ingot. When the temperature is raised to the specified temperature, stirring should be started. The stirring speed should be uniform. To ensure that there is no dead angle in the stirring, it is best to install a guide plate about 10-20cm near the bottom of the furnace; depending on the size of the furnace, every 10-20 minutes of stirring, it should be adjusted to stir in the opposite direction; after stirring for about 40 minutes, stop stirring, maintain the temperature in the furnace, and let the alloy in the furnace stand; after standing for 20 minutes, start stirring again, about 10 minutes each time, once in the forward and reverse directions; when the above stirring and standing are completed, slow down the stirring speed, and the operator starts to cast tin cylinders; at this time, the casting liquid temperature of different brands should be strictly followed, and the metal liquid in the furnace must be stirred normally to prevent chemical composition from segregation;

[0037] When it is necessary to change the type of tin alloy in the preparation, the tin slag in the furnace must be cleaned with tools to prevent the residual materials from mixing into the next batch of alloys and affecting its alloy composition; the area around the ingot mold field must be clean, and the tin material splashed on the ground must be cleaned and cannot be mixed; when the alloy has been melted into liquid in the furnace, if other cold metal ingots are to be added, they must be dried before adding to prevent the high-temperature molten liquid from splashing and injuring people when it encounters cold; when casting tin alloys with a tin content of <50%, the shrinkage hole at the center of the circle is deep, and the shrinkage hole must be supplemented. The shrinkage hole should be supplemented when the center of the first injection of the molten liquid has not yet solidified, and the surface oxide should be scraped off; the tin cylinder can only be poured out after it is determined that the inside of the tin cylinder has been completely cooled, or after the specified cooling time has arrived. If the inside of the tin cylinder fails to cool and may not be formed, it may cause personal injury; a protective plate must be installed on the ground where the tin cylinder is poured out, and the environment must be kept clean without ash and debris.

[0038] S3, casting of tin material: the molten tin material is poured into a mold and cast into a rod-shaped billet;

[0039] Casting refers to pouring the fused alloy into a forming mold, which is generally cylindrical, so some people also call this semi-finished product a "tin cylinder". The length and thickness of the "tin cylinder" depends on the condition of the press entrance, so that it can be easily put into the extruder for extrusion.

[0040] S4. Preparation of smokeless soldering flux: add alcohol solvent into a stirring kettle, then add active agent, synthetic resin, organic matting agent, co-solvent and corrosion inhibitor into the stirring kettle, stir at room temperature until the materials are completely dissolved, and filter;

[0041] S5, extrusion wire drawing: pour the prepared smokeless flux into the rod-shaped blank. Before extrusion, apply a layer of lubricating oil on the surface of the rod-shaped blank. During the extrusion process, the pressure is kept balanced so that the wire drawing speed is always kept uniform.

[0042] In the entire production process of solder wire, the extrusion process is defined as a special process because in the entire production process, extrusion is a key link that connects the previous and the next. If there are defects or hidden dangers during extrusion, it will directly lead to defects in the solder wire products, and the existence of such hidden dangers is often impossible to make up for in the subsequent wire drawing process, and sometimes it is even impossible to find. Therefore, considering the entire process of solder wire, it is very necessary to control the extrusion process to ensure the production of high-quality products.

[0043] The setting and control of mold temperature is also a critical link in the extrusion process. Under normal circumstances, the mold temperature of lead-free solder wire should be higher than that of tin-lead solder, and can generally be set at around 170°C. The mold temperature of tin-lead solder can generally be set at 90-100°C during extrusion. In winter, it can be slightly increased by 10-20°C to ensure normal wire production.

[0044] The reason why the setting and control of mold temperature is emphasized is that if the mold temperature is not adjusted properly, it will affect the wire drawing effect or cause abnormal wire drawing. Normal wire drawing means that the wire drawing is uniform, there are no deep stripes on the wire surface, no bubbles, etc. If the mold temperature is too high, there will be stripes on the surface when the tin wire is extruded, resulting in an insufficiently smooth surface and easy wire breakage in subsequent wire drawing; if the mold temperature is too low, the pressure increases during extrusion and the wire drawing is slow, which may sometimes cause the rosin hole to shift and not be centered, which may also leave hidden dangers for subsequent processes.

[0045] Regardless of whether the surface of the tin cylinder is peeled or not, a layer of lubricating oil should be applied to the surface of the tin cylinder before it is placed in the extruder to ensure that it can pass smoothly when extruded through the die, reduce the friction between the tin solder and the die hole, and ensure the uniformity of the extruded wire speed, and effectively extend the service life of the die. In the process of rubbing oil, the quality of the oil is more critical. Good quality wetting oil can fully play a lubricating role and has a stronger protective effect. The surface of the extruded tin wire is smooth and has no obvious lines; poor quality lubricating oil has a short service life and the lubricating effect is not ideal. The surface of the extruded tin is not smooth or has obvious lines. Another thing worth noting is that the amount of oil should be moderate, not too little, and of course not too much. It can be fully wiped on the surface of the tin cylinder. If there is too little oil, the effect is not obvious; if there is too much oil, there will be more lubricating oil residue in the die. Under the strong pressure of the extruder, there may be bubbles or dark holes under the surface of the extruded tin wire.

[0046] S6. Winding: The drawn solder wire is automatically wound on the receiving roller, and the number of turns can be counted under full automatic control when the winding is smooth, and uneven winding can be avoided;

[0047] S7. Inspect packaging and check finished products entering storage.

[0048] In S2, the furnace is set as an electric heating furnace. During the melting process of the metal material, hot oil is added to the electric heating furnace and electric heating is adopted. The furnace can be actively stirred and the temperature can be actively controlled in real time to eliminate poor fusion caused by human factors.

[0049] Example 2

[0050] The difference from Example 1 is

[0051] Calculated by mass, the solder wire alloy includes 93.5 parts of tin, 0.4 parts of copper, 0.4 parts of silver, 0.01 parts of antimony, and 0.02 parts of bismuth; the smokeless flux includes 2.2 parts of alcohol solvent, 0.06 parts of synthetic resin, 0.06 parts of organic matting agent, 0.03 parts of activator, 0.08 parts of co-solvent, and 0.008 parts of corrosion inhibitor.

[0052] Example 3

[0053] The difference from Example 1 is

[0054] Calculated by mass, the solder wire alloy includes 94 parts of tin, 0.5 parts of copper, 0.5 parts of silver, 0.015 parts of antimony, and 0.03 parts of bismuth; the smokeless flux includes 2.3 parts of alcohol solvent, 0.07 parts of synthetic resin, 0.07 parts of organic matting agent, 0.04 parts of activator, 0.09 parts of co-solvent, and 0.012 parts of corrosion inhibitor.

[0055] Example 4

[0056] The difference from Example 1 is

[0057] Calculated by mass, the solder wire alloy includes 94.5 parts of tin, 0.6 parts of copper, 0.6 parts of silver, 0.020 parts of antimony, and 0.04 parts of bismuth; the smokeless flux includes 2.4 parts of alcohol solvent, 0.08 parts of synthetic resin, 0.08 parts of organic matting agent, 0.05 parts of activator, 0.10 parts of co-solvent, and 0.016 parts of corrosion inhibitor.

[0058] Example 5

[0059] The difference from Example 1 is

[0060] Calculated by mass, the solder wire alloy includes 95 parts of tin, 0.7 parts of copper, 0.7 parts of silver, 0.025 parts of antimony, and 0.05 parts of bismuth; the smokeless flux includes 2.5 parts of alcohol solvent, 0.09 parts of synthetic resin, 0.09 parts of organic matting agent, 0.06 parts of activator, 0.12 parts of co-solvent, and 0.02 parts of corrosion inhibitor.

[0061] The specific formula data of five groups of embodiments of the present invention are as follows:

[0062]

[0063]

[0064] In summary, the present invention adds antimony and bismuth to the tin solder alloy on the basis of the original tin, silver and copper, which can improve the moisture resistance of the tin material, while suppressing the tin plague problem, and improving the fatigue resistance of the tin solder alloy. It has strong bending resistance and enhanced ductility, which facilitates subsequent wire drawing processing and reduces the risk of solder wire breakage.

[0065] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A smokeless solder wire, characterized in that: include: A solder wire alloy in the form of a hollow round bar; as well as Smokeless flux filled inside the solder wire alloy; The mass ratio of the solder wire alloy to the smokeless flux is (97-98): (2-3), calculated by mass components: The solder wire alloy comprises 93-95 parts of tin, 0.3-0.7 parts of copper, 0.3-0.7 parts of silver, 0.005-0.025 parts of antimony, and 0.01-0.05 parts of bismuth; The smokeless soldering flux comprises 2.1-2.5 parts of alcohol solvent, 0.05-0.09 parts of synthetic resin, 0.05-0.09 parts of organic matting agent, 0.02-0.06 parts of activating agent, 0.06-0.12 parts of co-solvent and 0.004-0.02 parts of corrosion inhibitor.

2. The smokeless solder wire according to claim 1, characterized in that: The alcohol solvent is at least one of ethanol, propanol or isopropanol; the co-solvent is at least one of sodium benzoate, sodium salicylate, p-aminobenzoic acid, niacinamide and acetamide.

3. The smokeless solder wire according to claim 1, characterized in that: The active agent is at least one of succinic acid, adipic acid, malonic acid, glycolic acid, itaconic acid, palmitic acid, malic acid, sebacic acid, glutaric acid, hydroxyacetic acid, benzoate, butyl acetate, ethyl acetate, ethylene glycol phenyl ether, dipropylene glycol methyl ether, tripropylene glycol butyl ether, succinic acid amine, triethanolamine and diethanolamine.

4. The smokeless solder wire according to claim 1, characterized in that: Calculated by mass, the solder wire alloy includes 93 parts of tin, 0.3 parts of copper, 0.3 parts of silver, 0.005 parts of antimony, and 0.01 parts of bismuth; the smokeless flux includes 2.1 parts of alcohol solvent, 0.05 parts of synthetic resin, 0.05 parts of organic matting agent, 0.02 parts of activator, 0.06 parts of co-solvent, and 0.004 parts of corrosion inhibitor.

5. The smokeless solder wire according to claim 1, characterized in that: Calculated by mass, the solder wire alloy includes 93.5 parts of tin, 0.4 parts of copper, 0.4 parts of silver, 0.01 parts of antimony, and 0.02 parts of bismuth; the smokeless flux includes 2.2 parts of alcohol solvent, 0.06 parts of synthetic resin, 0.06 parts of organic matting agent, 0.03 parts of activator, 0.08 parts of co-solvent, and 0.008 parts of corrosion inhibitor.

6. The smokeless solder wire according to claim 1, characterized in that: Calculated by mass, the solder wire alloy includes 94 parts of tin, 0.5 parts of copper, 0.5 parts of silver, 0.015 parts of antimony, and 0.03 parts of bismuth; the smokeless flux includes 2.3 parts of alcohol solvent, 0.07 parts of synthetic resin, 0.07 parts of organic matting agent, 0.04 parts of activator, 0.09 parts of co-solvent, and 0.012 parts of corrosion inhibitor.

7. The smokeless solder wire according to claim 1, characterized in that: Calculated by mass, the solder wire alloy includes 94.5 parts of tin, 0.6 parts of copper, 0.6 parts of silver, 0.020 parts of antimony, and 0.04 parts of bismuth; the smokeless flux includes 2.4 parts of alcohol solvent, 0.08 parts of synthetic resin, 0.08 parts of organic matting agent, 0.05 parts of activator, 0.10 parts of co-solvent, and 0.016 parts of corrosion inhibitor.

8. The smokeless solder wire according to claim 1, characterized in that: Calculated by mass, the solder wire alloy includes 95 parts of tin, 0.7 parts of copper, 0.7 parts of silver, 0.025 parts of antimony, and 0.05 parts of bismuth; the smokeless flux includes 2.5 parts of alcohol solvent, 0.09 parts of synthetic resin, 0.09 parts of organic matting agent, 0.06 parts of activator, 0.12 parts of co-solvent, and 0.02 parts of corrosion inhibitor.

9. A method for preparing a smokeless solder wire according to any one of claims 1 to 8, characterized in that: The steps include: S1. Preparation and mixing of raw materials: weigh the corresponding mass of tin, copper, silver, antimony and bismuth according to the mass ratio, clean the dust on the metal surface, and then dry it; S2. Melting of tin material: Put the dried metal material into a furnace to melt it, and add an antioxidant to cover the surface of the metal material after melting; S3, casting of tin material: the molten tin material is poured into a mold and cast into a rod-shaped billet; S4. Preparation of smokeless soldering flux: add alcohol solvent into a stirring kettle, then add active agent, synthetic resin, organic matting agent, co-solvent and corrosion inhibitor into the stirring kettle, stir at room temperature until the materials are completely dissolved, and filter; S5, extrusion wire drawing: pour the prepared smokeless flux into the rod-shaped blank. Before extrusion, apply a layer of lubricating oil on the surface of the rod-shaped blank. During the extrusion process, the pressure is kept balanced so that the wire drawing speed is always kept uniform. S6. Winding: The solder wire after drawing is automatically wound on the receiving roller, and the number of turns can be counted under full automatic control when the winding is flat, and uneven winding can be avoided; S7. Inspect packaging and check finished products entering storage.

10. The method for preparing a smokeless solder wire according to claim 9, characterized in that: In S2, the furnace is set as an electric heating furnace. During the melting process of the metal material, hot oil is added to the electric heating furnace and electric heating is adopted. The furnace can be actively stirred and the temperature can be actively controlled in real time to eliminate poor fusion caused by human factors.

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