A method for processing lead-free solder wire

Abstract

This invention discloses a method for processing lead-free solder wire, comprising the following steps: S1: Selecting materials: The first batch of materials includes 20kg of cathode copper, 180kg of tin ingot, and 1kg of zinc chloride; the second batch of materials includes 1000kg of tin ingot and 160kg of tin-copper master alloy; S2: Alloy fusion: The first batch of materials from step S1 is added to an induction furnace for stirring and melting. The product after the first batch of materials is melted and cooled is the tin-copper master alloy. Then, the second batch of materials is added to a tin melting furnace for stirring and melting; S3: Alloy casting: The alloy solution in the tin melting furnace from step S2 is exported to a horizontal continuous casting machine. This invention fills the induction furnace and the tin melting furnace with helium, thereby reducing the amount of oxidized substances in the alloy solution and further ensuring the quality of the alloy solution. By having the upper and lower stirring shafts in the tin melting furnace rotate in opposite directions, the mixing effect of the alloy solution is further improved, indirectly enhancing the quality of the alloy solution.

Description

Technical Field

[0001] This invention relates to the field of lead-free solder wire processing technology, and more specifically, to a method for processing lead-free solder wire. Background Technology

[0002] Lead-free solder wire has good wettability, electrical conductivity, and thermal conductivity, and is easy to tin. Lead-free solder wire has the following characteristics: good wettability, electrical conductivity, and thermal conductivity, easy to tin; no soldering spatter; uniform flux distribution, no broken flux in the solder core; uniform winding without knots, fast tinning speed, and very little residue.

[0003] Currently, the traditional production process of solder wire generally adopts single-hole rosin nozzle extrusion technology. Single-core solder wire is produced through batching, melting, casting, extrusion, rolling, and drawing. This process is relatively mature. However, during its production, the alloy solution is prone to oxide formation, which further leads to poor quality of the alloy solution. This results in excessive slag content in the later products, further causing a low yield of solder wire.

[0004] Therefore, we propose a lead-free solder wire processing method to solve the above problems. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, embodiments of the present invention provide a lead-free solder wire processing method to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for processing lead-free solder wire, comprising the following steps:

[0007] S1: Selecting ingredients: The first batch of materials includes: 20kg cathode copper, 180kg tin ingots, and 1kg zinc chloride; the second batch of materials includes: 1000kg tin ingots and 160kg tin-copper master alloy.

[0008] S2: Alloy fusion: The first batch of material in step S1 is put into an intermediate frequency furnace for stirring and melting. The product after the first batch of material is melted and cooled is a tin-copper intermediate alloy. Then the second batch of material is put into a tin melting furnace for stirring and melting.

[0009] S3: Alloy casting: The alloy solution in the molten tin furnace in step S2 is discharged to the horizontal continuous casting machine. After sufficient cooling, the alloy solution forms a Ф100mm tin cylinder.

[0010] S4: Extrusion molding: Place the tin cylinder from step S3 into the extruder, and then the extruder works to turn the tin cylinder into a Ф12mm tin rod;

[0011] S5: Roll forming: Roll the Ф12mm tin rod from step S4 into a Ф4.4mm tin rod using a rolling mill;

[0012] S6: Finished wire drawing: The tin-copper alloy wire from step S5 is placed into a wire drawing machine for wire drawing. The wire drawing machine has four drawing methods: coarse drawing, medium drawing, fine drawing, and fine drawing. Finally, a solder wire with a diameter of Ф0.5mm is formed.

[0013] S7: Winding, Packaging and Warehousing: The solder wire from step S6 is wound into a coil using a winding machine and then packaged and stored.

[0014] In this device, helium is filled into the medium-frequency furnace and the tin melting furnace to reduce the amount of oxides in the alloy solution, thereby further ensuring the quality of the alloy solution. The inconsistent rotation directions of the upper and lower stirring shafts in the tin melting furnace further improve the mixing effect of the alloy solution, indirectly improving its quality. Simultaneously, the change in rotation speed further enhances the quality of the alloy solution and reduces the formation of oxides. Oxides on the tin cylinders are cleaned using scraping and blowing methods, reducing oxide levels and improving the yield of subsequent tin cylinder processing, thus further increasing the yield of lead-free solder wire. Adding lubricating oil to the die cavity further facilitates smoother tin cylinder discharge, preventing breakage and wear, and further improving the yield of tin cylinders. Through multiple processes of coarse drawing, medium drawing, fine drawing, and precision drawing, 0.5mm solder wire can be formed, further ensuring the quality of the 0.5mm solder wire.

[0015] In a preferred embodiment, in step S2, helium is filled into the intermediate frequency furnace and the tin melting furnace, and the flow rate of helium into the intermediate frequency furnace and the tin melting furnace is 1000ml / min-2000ml / min. In step S2, the stirring temperature in the intermediate frequency furnace is 550℃-600℃, and then electromagnetic stirring is performed. In step S2, the stirring temperature in the tin melting furnace is 360℃-380℃, and then the fusion is carried out by forward and reverse stirring with a motor.

[0016] In a preferred embodiment, in step S2, the electromagnetic stirring speed is 2000 rpm. In step S2, during the stirring of the molten tin furnace motor, the stirring shaft on the motor is divided into an upper stirring shaft and a lower stirring shaft. The rotation direction of the upper stirring shaft is the same as the rotation direction of the motor drive shaft. A transmission unit is provided between the upper and lower stirring shafts. The transmission unit enables the upper and lower stirring shafts to rotate in opposite directions. The stirring speed of the motor in both directions is 3000 rpm. During the stirring of the molten tin furnace motor, the motor should be adjusted to stir in the opposite direction every 15-25 minutes. After stirring for about 30 minutes, stirring is stopped, the temperature inside the furnace is maintained, and the alloy inside the furnace is allowed to stand. After standing for 15 minutes, stirring is restarted, each time for about 10 minutes, once in both directions.

[0017] In a preferred embodiment, in step S3, the casting temperature of the horizontal continuous casting machine is between 320°C and 340°C. After the tin cylinder has cooled, the oxides on the tin cylinder are cleaned by scraping and blowing. The scraper is circular and made of alloy material. The gas used to blow the oxides is nitrogen.

[0018] In a preferred embodiment, in step S4, a die cavity with a diameter of φ12mm is used, wherein the barrel temperature is 85℃-95℃, the flux temperature during extrusion is 150±10℃, and nitrogen pressurization is used for injection.

[0019] In a preferred embodiment, in step S4, lubricating oil is added to the die cavity, and the lubricating oil is added at a rate of 20 drops / min to 40 drops / min.

[0020] In a preferred embodiment, in step S5, during the rolling of the solder rod, the rollers and the solder rod are sprayed with cooling water and air cooling. Part of the cooling water nozzle is located above the rollers and the solder rod, and the other part is located to one side of the air nozzle. With the assistance of the air nozzle, the cooling water can be turned into water mist, thereby improving the cooling effect.

[0021] In a preferred embodiment, in step S5, the rolling deformation sequence is: 12mm-11mm-10.5mm-9.2mm-8.3mm-7.8mm-6.9mm-6.1mm-5.3mm-5.0mm-4.8mm-4.6mm-4.4mm. After 13 rolling passes on the rolling mill, a 4.4mm tin rod is finally formed.

[0022] In a preferred embodiment, in step S6, the rough drawing process using the Talen wire drawing method can directly draw the tin rod from a thickness of 4.4mm to a thickness of 2.135mm, forming a tin-copper alloy. Based on the ductility and wire diameter of the SnCu0.7 alloy rod, the draw coefficient is designed to be 0.832, with 13 drawing passes, and the drawing die arrangement sequence is as follows:

[0023] 4.40mm-4.2mm-4.124mm-3.769mm-3.650mm-3.539mm-3.435mm-3.336mm-3.227mm-2.943mm-2.532mm-2.321mm-2.135mm;

[0024] The rough drawing equipment is a medium-sized water tank wire drawing machine, which uses a high crystal mold for wire drawing and propylene glycol as the wire drawing fluid. The temperature of the wire drawing fluid should be controlled at 70℃-90℃.

[0025] The intermediate drawing process, using Taren wire drawing, allows the tin rod to be drawn directly from a 2.135mm diameter to a 1.86mm diameter tin-copper alloy. Based on the ductility and wire diameter of the SnCu0.7 alloy rod, the draw coefficient is designed to be 0.923, with 6 drawing passes and the drawing die arrangement sequence as follows:

[0026] 2.135mm-1.932mm-1.901mm-1.889mm-1.876mm-1.86mm;

[0027] The medium-sized drawing equipment is a small water tank drawing machine, which uses a high crystal mold drawing die and propylene glycol as the drawing fluid. The temperature of the drawing fluid can be controlled to be maintained at 75℃-85℃.

[0028] Fine drawing, using Talen wire drawing, can directly draw tin rods from a thickness of 1.86mm to a thickness of 0.935mm in tin-copper alloy. Based on the ductility and wire diameter of the SnCu0.7 alloy rod, the draw coefficient is designed to be 0.965, with 12 drawing passes, and the drawing die arrangement sequence is as follows:

[0029] 1.86mm-1.735mm-1.695mm-1.634mm-1.596mm-1.478mm-1.423mm-1.321mm-1.221mm-1.145mm-0.998mm-0.935mm;

[0030] The fine drawing equipment is a small water tank wire drawing machine, which uses a high crystal mold for wire drawing and propylene glycol as the wire drawing fluid. The temperature of the wire drawing fluid should be controlled at 70℃-80℃.

[0031] Fine drawing via Talen wire drawing can directly draw tin rods from 0.935mm to 0.5mm in diameter to form a tin-copper alloy. Based on the ductility and wire diameter of the SnCu0.7 alloy rod, the draw coefficient is designed to be 0.89, with 8 drawing passes and the drawing die arrangement sequence being: 0.935mm-0.895mm-0.835mm-0.795mm-0.736mm-0.585mm-0.525mm-0.5mm.

[0032] The fine drawing equipment is a miniature water tank wire drawing machine, which uses a high crystal mold for wire drawing and propylene glycol as the wire drawing fluid. The temperature of the wire drawing fluid is controlled to be maintained at 70℃-80℃.

[0033] The technical effects and advantages of this invention are as follows:

[0034] 1. In this invention, helium is filled into the medium-frequency furnace and the tin melting furnace to reduce the amount of oxidized substances in the alloy solution, thereby further ensuring the quality of the alloy solution.

[0035] 2. By having the upper and lower stirring shafts in the tin melting furnace rotate in opposite directions, the mixing effect of the alloy solution can be improved, indirectly increasing the quality of the alloy solution. At the same time, by changing the rotation speed, the quality of the alloy solution can be further improved, reducing the occurrence of oxides.

[0036] 3. The oxides on the tin cylinders are cleaned by scraping and blowing, which reduces the oxides on the tin cylinders and improves the yield of subsequent tin cylinder processing, thereby further improving the yield of lead-free solder wire.

[0037] 4. By adding lubricating oil to the die cavity, the solder cylinder can be ejected more smoothly, thus avoiding breakage and wear of the solder cylinder and further improving the yield of solder cylinders.

[0038] 5. Through multiple processes of coarse drawing, medium drawing, fine drawing and fine drawing, Ф0.5mm solder wire can be formed, further ensuring the quality of Ф0.5mm solder wire. Detailed Implementation

[0039] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] A method for processing lead-free solder wire includes the following steps:

[0041] S1: Selecting ingredients: The first batch of materials includes: 20kg cathode copper, 180kg tin ingots, and 1kg zinc chloride; the second batch of materials includes: 1000kg tin ingots and 160kg tin-copper master alloy.

[0042] S2: Alloy Fusion: The first batch of material from step S1 is added to an induction furnace for stirring and melting. The product after the first batch of material melts and cools is a tin-copper intermediate alloy. Then, the second batch of material is added to a tin-melting furnace for stirring and melting. In step S2, helium is filled into the induction furnace and the tin-melting furnace at a flow rate of 1000ml / min-2000ml / min. In step S2, the stirring temperature in the induction furnace is 550℃-600℃, followed by electromagnetic stirring. In step S2, the stirring temperature in the tin-melting furnace is 360℃-380℃, followed by forward and reverse stirring with a motor. In step S2, the electromagnetic stirring speed is 2000 rpm. In step S2, during the stirring of the molten tin furnace by the motor, the stirring shaft on the motor is divided into an upper stirring shaft and a lower stirring shaft. The rotation direction of the upper stirring shaft is the same as the rotation direction of the motor drive shaft. A transmission unit is provided between the upper and lower stirring shafts. The transmission unit can make the upper and lower stirring shafts rotate in opposite directions. The speed of the motor stirring in both directions is 3000 rpm. During the stirring of the molten tin furnace by the motor, the motor should be adjusted to stir in the opposite direction every 15-25 minutes. After stirring for about 30 minutes, stop stirring, maintain the temperature inside the furnace, and let the alloy in the furnace stand. After standing for 15 minutes, start stirring again, each time for about 10 minutes, once in both directions.

[0043] S3: Alloy casting: The alloy solution in the molten tin furnace in step S2 is transferred to a horizontal continuous casting machine. After sufficient cooling, the alloy solution forms a Ф100mm tin cylinder. In step S3, the casting temperature of the horizontal continuous casting machine is between 320℃ and 340℃. After the tin cylinder has cooled, the oxides on the tin cylinder are cleaned by scraping and blowing. The scraper is circular and made of alloy material. The gas used to blow the oxides is nitrogen.

[0044] S4: Extrusion molding: The tin cylinder from step S3 is placed into the extruder, and then the extruder operates to turn the tin cylinder into a Ф12mm tin rod; In step S4, a die cavity with a diameter of φ12mm is used, and the barrel temperature is 85℃-95℃. During the extrusion process, the flux temperature is 150±10℃, and nitrogen is used for injection. In step S4, lubricating oil is added to the die cavity, and the lubricating oil is added at a rate of 20 drops / min-40 drops / min.

[0045] S5: Rolling into a wire: The 12mm tin rod from step S4 is rolled into a 4.4mm tin rod using a rolling mill. In step S5, during the rolling process, cooling water and air cooling are sprayed onto the rollers and tin rod. Part of the cooling water nozzles are positioned above the rollers and tin rod, while the other part is positioned to one side of the air nozzles. With the assistance of the air nozzles, the cooling water is turned into a water mist, thus improving the cooling effect. In step S5, the rolling deformation sequence is: 12mm-11mm-10.5mm-9.2mm-8.3mm-7.8mm-6.9mm-6.1mm-5.3mm-5.0mm-4.8mm-4.6mm-4.4mm. After 13 rolls in the rolling mill, a 4.4mm tin rod is finally formed.

[0046] S6: Finished Wire Drawing: The tin-copper alloy wire from step S5 is placed into a wire drawing machine for drawing. The drawing machine's drawing methods include coarse drawing, medium drawing, fine drawing, and final fine drawing, ultimately forming a Ф0.5mm solder wire. In step S6, the coarse drawing, using a taren wire drawing process, can directly draw the tin rod from a medium 4.4mm diameter to a medium 2.135mm diameter tin-copper alloy. Based on the ductility and wire diameter of the SnCu0.7 alloy rod, the design draw coefficient is 0.832, with 13 drawing passes, and the drawing die arrangement sequence is as follows:

[0047] 4.40mm-4.2mm-4.124mm-3.769mm-3.650mm-3.539mm-3.435mm-3.336mm-3.227mm-2.943mm-2.532mm-2.321mm-2.135mm;

[0048] The rough drawing equipment is a medium-sized water tank wire drawing machine, which uses a high crystal mold for wire drawing and propylene glycol as the wire drawing fluid. The temperature of the wire drawing fluid should be controlled at 70℃-90℃.

[0049] The intermediate drawing process, using Taren wire drawing, allows the tin rod to be drawn directly from a 2.135mm diameter to a 1.86mm diameter tin-copper alloy. Based on the ductility and wire diameter of the SnCu0.7 alloy rod, the draw coefficient is designed to be 0.923, with 6 drawing passes and the drawing die arrangement sequence as follows:

[0050] 2.135mm-1.932mm-1.901mm-1.889mm-1.876mm-1.86mm;

[0051] The medium-sized drawing equipment is a small water tank drawing machine, which uses a high crystal mold drawing die and propylene glycol as the drawing fluid. The temperature of the drawing fluid can be controlled to be maintained at 75℃-85℃.

[0052] Fine drawing, using Talen wire drawing, can directly draw tin rods from a thickness of 1.86mm to a thickness of 0.935mm in tin-copper alloy. Based on the ductility and wire diameter of the SnCu0.7 alloy rod, the draw coefficient is designed to be 0.965, with 12 drawing passes, and the drawing die arrangement sequence is as follows:

[0053] 1.86mm-1.735mm-1.695mm-1.634mm-1.596mm-1.478mm-1.423mm-1.321mm-1.221mm-1.145mm-0.998mm-0.935mm;

[0054] The fine drawing equipment is a small water tank wire drawing machine, which uses a high crystal mold for wire drawing and propylene glycol as the wire drawing fluid. The temperature of the wire drawing fluid should be controlled at 70℃-80℃.

[0055] Fine drawing via Talen wire drawing can directly draw tin rods from 0.935mm to 0.5mm in diameter to form a tin-copper alloy. Based on the ductility and wire diameter of the SnCu0.7 alloy rod, the draw coefficient is designed to be 0.89, with 8 drawing passes and the drawing die arrangement sequence being: 0.935mm-0.895mm-0.835mm-0.795mm-0.736mm-0.585mm-0.525mm-0.5mm.

[0056] The fine drawing equipment is a miniature water tank wire drawing machine, which uses a high crystal mold for wire drawing and propylene glycol as the wire drawing fluid. The temperature of the wire drawing fluid is controlled to be maintained at 70℃-80℃.

[0057] S7: Winding, Packaging and Warehousing: The solder wire from step S6 is wound into a coil using a winding machine and then packaged and stored.

[0058] The solder wire with a diameter of 0.5mm is finally obtained according to the above implementation method.

[0059] Example 1:

[0060] In step S2, during the stirring of the molten tin furnace by the motor, the stirring shaft on the motor is divided into an upper stirring shaft and a lower stirring shaft. The rotation direction of the upper stirring shaft is the same as the rotation direction of the motor drive shaft. A transmission unit is provided between the upper and lower stirring shafts, which enables the upper and lower stirring shafts to rotate in opposite directions. The motor speed for both forward and reverse stirring is 1500 rpm. During the stirring of the molten tin furnace by the motor, the motor should be adjusted to stir in the reverse direction every 15-25 minutes. After stirring for about 30 minutes, stirring is stopped, the temperature inside the furnace is maintained, and the alloy inside the furnace is allowed to stand. After standing for 15 minutes, stirring is restarted, each time for about 10 minutes, once in the forward direction and once in the reverse direction.

[0061] Example 2:

[0062] In step S2, during the stirring of the molten tin furnace by the motor, the stirring shaft on the motor is divided into an upper stirring shaft and a lower stirring shaft. The rotation direction of the upper stirring shaft is the same as the rotation direction of the motor drive shaft. A transmission unit is provided between the upper and lower stirring shafts, which enables the upper and lower stirring shafts to rotate in opposite directions. The motor speed for both forward and reverse stirring is 1800 rpm. During the stirring of the molten tin furnace by the motor, the motor should be adjusted to stir in the reverse direction every 15-25 minutes. After stirring for about 30 minutes, stirring is stopped, the temperature inside the furnace is maintained, and the alloy inside the furnace is allowed to stand. After standing for 15 minutes, stirring is restarted, each time for about 10 minutes, once in the forward direction and once in the reverse direction.

[0063] Example 3:

[0064] In step S2, during the stirring of the molten tin furnace by the motor, the stirring shaft on the motor is divided into an upper stirring shaft and a lower stirring shaft. The rotation direction of the upper stirring shaft is the same as the rotation direction of the motor drive shaft. A transmission unit is provided between the upper and lower stirring shafts, which enables the upper and lower stirring shafts to rotate in opposite directions. The motor speed for both forward and reverse stirring is 2600 rpm. During the stirring of the molten tin furnace by the motor, the motor should be adjusted to stir in the reverse direction every 15-25 minutes. After stirring for about 30 minutes, stirring is stopped, the temperature inside the furnace is maintained, and the alloy inside the furnace is allowed to stand. After standing for 15 minutes, stirring is restarted, each time for about 10 minutes, once in the forward direction and once in the reverse direction.

[0065] Example 4:

[0066] In step S2, during the stirring of the molten tin furnace by the motor, the stirring shaft on the motor is divided into an upper stirring shaft and a lower stirring shaft. The rotation direction of the upper stirring shaft is the same as the rotation direction of the motor drive shaft. A transmission unit is provided between the upper and lower stirring shafts, which enables the upper and lower stirring shafts to rotate in opposite directions. The motor speed for both forward and reverse stirring is 3000 rpm. During the stirring of the molten tin furnace by the motor, the motor should be adjusted to stir in the reverse direction every 15-25 minutes. After stirring for about 30 minutes, stirring is stopped, the temperature inside the furnace is maintained, and the alloy inside the furnace is allowed to stand. After standing for 15 minutes, stirring is restarted, each time for about 10 minutes, once in the forward direction and once in the reverse direction.

[0067] Example 5:

[0068] In step S2, during the stirring of the molten tin furnace by the motor, the stirring shaft on the motor is divided into an upper stirring shaft and a lower stirring shaft. The rotation direction of the upper stirring shaft is the same as the rotation direction of the motor drive shaft. A transmission unit is provided between the upper and lower stirring shafts, which enables the upper and lower stirring shafts to rotate in opposite directions. The motor speed for both forward and reverse stirring is 3400 rpm. During the stirring of the molten tin furnace by the motor, the motor should be adjusted to stir in the reverse direction every 15-25 minutes. After stirring for about 30 minutes, stirring is stopped, the temperature inside the furnace is maintained, and the alloy inside the furnace is allowed to stand. After standing for 15 minutes, stirring is restarted, each time for about 10 minutes, once in the forward direction and once in the reverse direction.

[0069] In summary, the results are shown in Table 1:

[0070] While keeping other stirring factors unchanged, the motor speed was altered to understand its impact on the alloy solution. Furthermore, uneven composition of the alloy solution can easily lead to numerous inclusions and pores in the ingots, resulting in a rough surface during subsequent product casting.

[0071]

[0072] From the above, we can conclude that the faster the motor speed, the more thoroughly the alloy solution is mixed. However, when the motor speed exceeds a certain limit, the alloy solution begins to deteriorate, leading to subsequent product defects. Therefore, a speed of 3000 rpm allows for more uniform mixing of the alloy solution, ensuring that the product quality meets the required standards.

[0073] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lead-free solder wire processing method characterized by; The method comprises the following steps: S1: selecting ingredients: the first material comprises 20 kg of cathode copper, 180 kg of tin ingot and 1 kg of zinc chloride, and the second material comprises 1000 kg of tin ingot and 160 kg of tin copper intermediate alloy; S2: alloying: the first material in step S1 is put into a medium frequency furnace for stirring and melting, and the product after the first material is melted and cooled is tin copper intermediate alloy, and then the second material is put into a tin melting furnace for stirring and melting; In step S2, the medium frequency furnace and the tin melting furnace are filled with helium, and the flow rate of the helium entering the medium frequency furnace and the tin melting furnace is 1000-2000 ml / min; in step S2, the stirring temperature in the medium frequency furnace is 550-600 DEG C, and then electromagnetic stirring is performed; in step S2, the stirring temperature in the tin melting furnace is 360-380 DEG C, and then motor forward and reverse stirring is adopted for alloying; In step S2, the rotating speed of the electromagnetic stirring is 2000 r / min; in step S2, during the motor stirring of the tin melting furnace, the stirring shaft on the motor is divided into an upper stirring shaft and a lower stirring shaft, the rotating direction of the upper stirring shaft is consistent with the rotating direction of the motor driving shaft, a transmission unit is arranged between the upper stirring shaft and the lower stirring shaft, the transmission unit can make the rotating directions of the upper stirring shaft and the lower stirring shaft opposite, the rotating speed of the motor forward and reverse stirring is 3000 r / min, and during the motor stirring of the tin melting furnace, the motor should be adjusted to stir in the reverse direction every 15-25 minutes; after about 30 minutes of stirring, the stirring is stopped, the temperature in the melting furnace is kept, the alloy in the melting furnace is statically placed, and after 15 minutes of static placement, the alloy is stirred again for about 10 minutes each time, once in the forward direction and once in the reverse direction; S3: alloy pouring: the alloy solution in the tin melting furnace in step S2 is led out to a horizontal continuous casting machine, and after sufficient cooling, the alloy solution forms a Ф100 mm tin cylinder; In step S3, the pouring temperature of the horizontal continuous casting machine is 320-340 DEG C, and after the tin cylinder is completely cooled, the oxides on the tin cylinder are cleaned by scraping and blowing, the scraper is in the form of a circular ring, the scraper is made of an alloy material, and the gas for blowing the oxides is nitrogen; S4: extrusion molding: the tin cylinder in step S3 is placed in an extruder, and then the extruder works to make the tin cylinder become a Ф12 mm tin rod; In step S4, a wire outlet mold cavity with a diameter of φ12 mm is adopted, the barrel temperature is 85-95 DEG C, the temperature of the flux during the extrusion process is 150±10 DEG C, and nitrogen gas pressurization is adopted for filling; S5: rolling into wire: the tin rod in step S4 is rolled into a Ф4.4 mm tin rod by a rolling mill; In step S5, when the tin rod is rolled, the roller and the tin rod are sprayed by cooling water and air cooling, part of the cooling water nozzles is above the roller and the tin rod, and the other part is on one side of the air jet head, under the assistance of the air jet head, the cooling water can become water mist, so that the cooling effect is better; S6: wire drawing finished product: tin copper alloy wire in step S5 is placed into a wire drawing machine for wire drawing, and the wire drawing mode of the wire drawing machine is divided into rough drawing, medium drawing, fine drawing and fine drawing, and finally a soldering tin wire with a diameter of 0.5 mm is formed; S7: winding, packaging and warehousing: the soldering tin wire in step S6 is wound into a roll by using a winding machine, and then packaged and warehoused.

2. The method of claim 1, wherein: In step S4, lubricating oil is added in the wire outlet mold cavity, and the adding speed of the lubricating oil is 20-40 drops / min.

3. The method of claim 1, wherein the lead-free solder wire is processed by the steps of: In step S5, the rolling deformation sequence is: ​ 12mm-11mm-10.5mm-9.2mm-8.3mm-7.8mm-6.9mm-6.1mm-5.3mm-5.0mm-4.8mm-4.6mm-4.4mm, after 13 times of roller rolling, 4.4mm tin rod is finally formed.

4. The method of claim 1, wherein the lead-free solder wire is processed by the steps of: In step S6, the rough drawing is drawn by Taren wire drawing, which can directly draw the tin rod from 4.4mm to 2.135mm tin copper alloy. According to the ductility and diameter of SnCu0.7 alloy rod, the drawing coefficient is designed as 0.832, 13 times of drawing, and the arrangement sequence of the drawing die is: ​ 4.40mm-4.2mm-4.124mm-3.769mm-3.650mm-3.539mm-3.435mm-3.336mm-3.227mm-2.943mm-2.532mm-2.321mm-2.135mm; The rough drawing equipment is a medium-sized water tank drawing machine, high crystal drawing dies are used, propylene glycol is used as drawing liquid, and the drawing liquid temperature is controlled to keep at 70-90℃; The medium drawing is drawn by Taren wire drawing, which can directly draw the tin rod from 2.135mm to 1.86mm tin copper alloy. According to the ductility and diameter of SnCu0.7 alloy rod, the drawing coefficient is designed as 0.923, 6 times of drawing, and the arrangement sequence of the drawing die is: 2.135mm-1.932mm-1.901mm-1.889mm-1.876mm-1.86mm; The medium drawing equipment is a small-sized water tank drawing machine, high crystal drawing dies are used, propylene glycol is used as drawing liquid, and the drawing liquid temperature is controlled to keep at 75-85℃; The fine drawing is drawn by Taren wire drawing, which can directly draw the tin rod from 1.86mm to 0.935mm tin copper alloy. According to the ductility and diameter of SnCu0.7 alloy rod, the drawing coefficient is designed as 0.965, 12 times of drawing, and the arrangement sequence of the drawing die is: 1.86mm-1.735mm-1.695mm-1.634mm-1.596mm-1.478mm-1.423mm-1.321mm-1.221mm-1.145mm-0.998mm-0.935mm; The fine drawing equipment is a small-sized water tank drawing machine, high crystal drawing dies are used, propylene glycol is used as drawing liquid, and the drawing liquid temperature is controlled to keep at 70-80℃; Fine drawing through the tower drawing, tin rod from the middle 0.935 mm directly to the middle 0.5 mm tin copper alloy, according to the ductility of SnCu0.7 alloy rod and wire diameter, design drawing coefficient is 0.89, 8 drawing, and the drawing die arrangement order is: 0.935 mm-0.895 mm-0.835 mm-0.795 mm-0.736 mm-0.585 mm-0.525 mm-0.5 mm; Fine drawing equipment for micro water tank drawing machine, using high crystal drawing die, propylene glycol as drawing liquid, control the drawing liquid temperature to keep at 70-80 ℃.

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