Ultra-fine wire diameter lead-free tin-silver-copper solder wire and its manufacturing process

Abstract

This application relates to the field of manufacturing ultra-fine diameter lead-free solder wires. Specifically, it discloses an ultra-fine diameter lead-free silver-copper-tin solder wire and its manufacturing process. The method is as follows: A tin-silver-copper alloy column containing 0.2% - 4.0% silver, 0.2% - 1% copper, 0.01% - 0.2% trace elements, and the balance being tin is extruded into a metal wire with a diameter of 10 mm - 12 mm at a temperature of 110°C - 135°C, a pressure of 30 bar - 50 bar, and an extrusion speed of 16 mm / s - 21 mm / s. During the extrusion process, 3% - 6% of a solid soldering flux is added. The parameters of the extrusion die are as follows: the arc angle β of the feed inlet ranges from 50° to 51.5°, the depth of the feed inlet is 11.5 mm - 12.5 mm, the length a of the reducing zone ranges from 3.5 mm to 4.0 mm, the arc angle α of the discharge outlet ranges from 86° to 87°, and the depth b of the discharge outlet ranges from 1 mm to 3 mm; then the metal wire is stretched to a wire diameter of 0.10 mm - 0.12 mm.

Description

Technical Field

[0001] This application relates to the field of manufacturing ultra-fine diameter lead-free solder wires. More specifically, it relates to ultra-fine diameter lead-free tin-silver-copper-tin wires and their manufacturing processes. Background Art

[0002] Micro-diameter soft soldering lead-free solders play a significant role in the electronic soldering of micro-solder joints. By selecting metal alloys with different melting point ranges and combining resin cores of different active types, different models of solder wire products can be formed, which is beneficial for the soldering of high-tech, high-requirement, and micro-solder joints. As electronic products tend to be lighter, thinner, and smaller, components and solder joints are becoming more and more miniaturized. Therefore, the requirement for the wire diameter of the solder wire as a soldering material is getting higher and higher, and the demand for ultra-fine diameter solder wires with a wire diameter of 0.10 - 0.12 mm is continuously increasing.

[0003] The production of solder wire includes the following steps. First, the solder material is melted. After adjusting the main and auxiliary materials in a certain proportion, they are put into a furnace and melted and stirred at high temperature until completely fused. Then, the melted solder material is poured into a mold to cool into a solder column. Next, the solder column is put into an extruder to be extruded into a wire. After being extruded into a solder wire, the solder wire is stretched to form an ultra-fine diameter solder wire with a wire diameter of 0.10 mm - 0.12 mm. The stretching process is to first stretch the solder wire into a small wire diameter solder wire with a wire diameter of 0.20 mm - 0.30 mm, and then stretch the small wire diameter solder wire to prepare an ultra-fine diameter solder wire. During the process of stretching the small wire diameter solder wire to an ultra-fine diameter solder wire, the small wire diameter solder wire is prone to breakage. Therefore, the production of ultra-fine diameter solder wire is relatively difficult. Summary of the Invention

[0004] In order to reduce the situation where the small wire diameter solder wire with a wire diameter of 0.20 mm - 0.30 mm is prone to breakage during the process of stretching to an ultra-fine diameter solder wire with a wire diameter of 0.10 mm - 0.12 mm, this application provides an ultra-fine diameter lead-free tin-silver-copper-tin wire and its manufacturing process.

[0005] The manufacturing process of the ultra-fine diameter lead-free tin-silver-copper-tin wire provided by this application adopts the following technical solutions:

[0006] Manufacturing process of ultra-fine diameter lead-free tin-silver-copper-tin wire, including the following steps: According to the weight components, a tin-silver-copper alloy column containing 0.2% - 4.0% silver, 0.2% - 1% copper, 0.01% - 0.2% trace elements, and the balance being tin is extruded into a 10mm - 12mm metal wire at a temperature of 110°C - 135°C, a pressure of 30 bar - 50 bar, and an extrusion speed of 16 mm / s - 21 mm / s. During the extrusion process, 3% - 6% of solid soldering flux is added. The parameters of the extrusion die are that the arc of the feed inlet β ranges from 50° to 51.5°, the depth of the feed inlet is 11.5 mm - 12.5 mm, the length of the diameter-changing zone a ranges from 3.5 mm to 4.0 mm, the arc of the discharge outlet α ranges from 86° to 87°, and the depth of the discharge outlet b ranges from 1 mm to 3 mm; then the metal wire is stretched to a wire diameter of 0.10 mm - 0.12 mm.

[0007] By adopting the above technical solution, adding trace elements to the tin-silver-copper alloy column can improve the problem of coarse lattice of the molecular structure in the tin-silver-copper alloy, making the metal grains in the tin-silver-copper alloy finer and capable of maintaining the stability between the components of the alloy and preventing excessive accumulation of copper content. By improving the extrusion die. The original parameters of the extrusion die are that the arc of the feed inlet β is 60°, the depth is 8.5 mm, the length of the diameter-changing zone a is 2.5 mm, the arc of the discharge outlet α is 20°, and the depth b is 7 mm. For the improved extrusion die, the arc of the feed inlet β ranges from 50° to 51.5° and the depth is 11.5 - 12.5 mm, which can improve the metal flexibility of the tin-silver-copper alloy, making the tin-silver-copper alloy better enter the diameter-changing zone. If the feed inlet is further narrowed, the pressure in the diameter-changing zone increases, which will cause the tin wire to be unable to be extruded, and will also cause the diameter-changing zone to not withstand the pressure and crack, even the entire extrusion die to crack. If the depth of the feed inlet continues to deepen, a high content of soldering flux cannot be obtained.

[0008] The length of the diameter-changing zone a is 3.5 - 4.0 mm. The longer time of the tin-silver-copper alloy in the diameter-changing zone improves the compactness of the tin-silver-copper alloy, thereby improving the toughness of the extruded metal wire and reducing the situation of metal wire breakage during stretching. The arc of the discharge outlet α ranges from 86° to 87° and the depth b ranges from 1 mm to 3 mm. The discharge outlet under these parameters enables the extruded metal wire to quickly break away from the die and be cooled, and the structure between the tin-silver alloys solidifies and stabilizes quickly, improving the toughness of the tin-silver alloy and further reducing the situation of metal wire breakage during stretching.

[0009] Optionally, the trace elements include nickel and antimony, and the proportion of antimony accounts for 15% - 40% of the total weight of the trace elements.

[0010] By adopting the above technical solutions, nickel can improve the problem of coarse lattice in the molecular structure of the tin-silver-copper alloy system, making the metal grains in the tin-silver-copper alloy system finer and capable of maintaining the stability between the components of the alloy and preventing excessive accumulation of copper content. The addition of antimony can increase the hardness of the tin-silver-copper alloy system and enhance the strength.

[0011] Optionally, the preparation of the tin-silver-copper-tin alloy column includes the following steps: melting and stirring silver and tin evenly at a temperature of 800°C to 1000°C, and obtaining a first master alloy after cooling, wherein the proportion of silver accounts for 20% to 30% of the total weight of the first master alloy;

[0012] Melting and stirring copper and tin evenly at a temperature of 600°C to 800°C, and obtaining a second master alloy after cooling, wherein the proportion of copper accounts for 10% to 20% of the total weight of the second master alloy;

[0013] Melting and stirring nickel and tin evenly at a temperature of 800°C to 1000°C, and obtaining a third master alloy after cooling, wherein the proportion of nickel accounts for 2% to 5% of the total weight of the third master alloy;

[0014] Melting and stirring antimony and tin evenly at a temperature of 500°C to 600°C, and obtaining a fourth master alloy after cooling, wherein the proportion of antimony accounts for 2% to 5% of the total weight of the fourth master alloy;

[0015] Melting the remaining tin at 350°C to 450°C, and adding the first master alloy and the second master alloy while mixing at a temperature of 350°C to 400°C after the temperature stabilizes, and continuing to stir for a period of time to obtain a mixed master alloy, wherein the mixing includes shear mixing and stirring mixing;

[0016] Mixing the third master alloy and the fourth master alloy with the mixed master alloy, and continuing to stir for a period of time to obtain an alloy liquid, and pouring the alloy liquid into a mold to cool to obtain a tin-silver-copper alloy column, wherein the mixing includes shear mixing and stirring mixing.

[0017] By adopting the above technical solutions, due to the characteristics of metals, tin can dissolve other high-melting-point metals at high temperatures. The addition amount of trace elements is small, and it is difficult to mix them evenly in the main metal materials. The melting points of each metal component are different. By the method of step-by-step melting and mixing, each metal can be mixed evenly, and the distribution of trace elements in the tin-silver-copper alloy system is more uniform, making the functions of nickel and antimony play the maximum role. The step-by-step melting method can also reduce the excessive accumulation of copper. Further improve the tensile resistance of the tin-silver-copper alloy system, reduce the situation of metal wire breakage during the stretching process, and further improve the productivity of the ultra-fine wire diameter lead-free tin-silver-copper-tin wire.

[0018] Optionally, during the process of shear mixing the first master alloy and the second master alloy with tin, and mixing the third master alloy and the fourth master alloy with the mixed master alloy, the rotational speed of shear mixing is 1000 rpm to 1300 rpm, and the rotational speed of stirring and mixing is 600 rpm to 800 rpm.

[0019] Applying mechanical stirring during the solidification process of the metal can achieve the purpose of improving the mechanical strength of the metal and its composites. By adopting the above technical solution, under such rotational speed conditions, the shear force can make the trace elements nickel and antimony evenly distributed, without causing splashing of the liquid and inhalation of gas, which is not conducive to the solidification of the metal, and can effectively increase the mechanical strength of the tin-silver-copper-tin alloy, thereby reducing the situation of fracture of the metal wire during the stretching process.

[0020] Optionally, the alloy liquid is rapidly cooled by the cooling water in the mold.

[0021] By adopting the above technical solution, the heat capacity of the cooling water is large, which can achieve rapid cooling, thereby realizing the rapid cooling of the tin-silver-copper-tin alloy. Rapid cooling is beneficial to the refinement of grains during subsequent extrusion, improving the tightness between crystals in the tin-silver-copper alloy, and thus reducing the occurrence of the situation of fracture of the metal wire during stretching.

[0022] Optionally, the mixing temperature of the third master alloy and the fourth master alloy with the mixed master alloy is 360 °C to 400 °C.

[0023] By adopting the above technical solution, the third master alloy and the fourth master alloy can be evenly mixed with the mixed master alloy under such temperature conditions, and at this temperature, it can ensure that the main material pure tin with a relatively large proportion is completely melted.

[0024] Optionally, during the stretching process of the metal wire, when the wire diameter of the metal wire is stretched from 10 mm to 12 mm to 0.8 mm to 0.2 mm, a reduction ratio of 4.50% to 6.00% is adopted, and when the wire diameter of the metal wire is stretched from 0.8 mm to 0.2 mm to 0.2 mm to 0.1 mm, a reduction ratio of 3.00% to 4.00% is adopted.

[0025] By adopting the above technical solution, the reduction ratio is the absolute value of the reduction in cross-sectional area after stretching divided by the cross-sectional area before stretching. Controlling the reduction ratio during stretching within this range can avoid the situation of fracture of the metal wire during stretching.

[0026] The ultra-fine wire diameter lead-free tin-silver-copper-tin wire provided by this application is prepared by the above manufacturing process.

[0027] By adopting the above technical solution, an ultra-fine wire diameter lead-free tin-silver-copper wire with a wire diameter of 0.10 mm to 0.12 mm can be manufactured by this manufacturing process, and the production efficiency is high.

[0028] In summary, the present application has the following beneficial effects:

[0029] 1. By adding trace elements nickel and antimony to the alloy material, the metal toughness of the tin-silver-copper alloy can be improved, thereby reducing the tin-silver-copper alloy. Combined with the extrusion die structure of specific specifications, the density of the crystal lattice in the metal wire can be enhanced, and the possibility of fracture during the stretching process can be reduced.

[0030] 2. During the melting process of the alloy, the first master alloy and the second master alloy are mixed by shear mixing and stirring mixing to improve the increase in the hardness and strength of the tin-silver-copper alloy caused by the addition of antimony, which may lead to excessive brittleness of the tin-silver-copper-tin alloy and easy fracture during stretching. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 are the parameters of the improved extrusion die used in the embodiments of the present application.

[0032] Figure 2 are the parameters of the extrusion die before improvement. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The following further elaborates on the present application.

[0034] Introduction of Raw Materials

[0035] The soldering flux used is a rosin-based solid soldering flux.

[0036] Embodiments

[0037] Embodiment 1

[0038] Put 0.2% silver and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 1000 °C, and obtain the first master alloy after cooling, where the proportion of silver accounts for 30% of the total weight of the first master alloy;

[0039] Put 1% copper and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 600 °C, and obtain the second master alloy after cooling, where the proportion of copper accounts for 10% of the total weight of the second master alloy;

[0040] Put 0.085% nickel and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 1000 °C, and obtain the third master alloy after cooling, where the proportion of nickel accounts for 5% of the total weight of the third master alloy;

[0041] Put 0.08% antimony and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 500 °C, and obtain the fourth master alloy after cooling, where the proportion of antimony accounts for 2% of the total weight of the fourth master alloy;

[0042] Put the remaining tin into a high-temperature intermediate-frequency furnace and melt it at 350 °C. After the temperature stabilizes, put in the shearing wheel and stirring wheel. The stirring wheel rotates at 800 revolutions per minute, and the shearing wheel rotates at 1000 revolutions per minute. While stirring at a temperature of 350 °C, add the first master alloy and the second master alloy, and stir for 35 minutes to obtain a mixed master alloy. Mix the third master alloy and the fourth master alloy with the mixed master alloy, and stir for 25 minutes at a temperature of 360 °C to obtain an alloy liquid. Pour the alloy liquid into a mold and cool it to obtain a tin-silver-copper alloy column.

[0043] Extrude the tin-silver-copper alloy column into a 10-mm metal wire at a temperature of 110 °C, a pressure of 50 bar, and an extrusion speed of 16 mm / s. During the extrusion process, add 6% solid flux. The parameters of the extrusion die are as follows: the arc β of the feed inlet is 50°, the depth of the feed inlet is 11.5 mm, the length a of the reduced-diameter zone is 4.0 mm, the arc α of the discharge outlet is 86°, and the depth b of the discharge outlet is 1 mm. Then, under the condition of controlling the area reduction rate at 6.00%, stretch the metal wire from a wire diameter of 10 mm to 0.2 mm, and under the condition of controlling the area reduction rate at 3.00%, stretch the metal wire with a wire diameter of 0.2 mm to a wire diameter of 0.10 mm to prepare an ultra-fine wire diameter lead-free tin-silver-copper wire.

[0044] Example 2

[0045] Put 4.0% silver and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 800 °C, and cool to obtain the first master alloy, where the proportion of silver accounts for 20% of the total weight of the first master alloy;

[0046] Put 0.2% copper and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 800 °C, and cool to obtain the second master alloy, where the proportion of copper accounts for 20% of the total weight of the second master alloy;

[0047] Put 0.1985% nickel and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 800 °C, and cool to obtain the third master alloy, where the proportion of nickel accounts for 2% of the total weight of the third master alloy;

[0048] Put 0.0015% antimony and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 500 °C, and cool to obtain the fourth master alloy, where the proportion of antimony accounts for 2% of the total weight of the fourth master alloy;

[0049] Put the remaining tin into a high-temperature intermediate-frequency furnace and melt it at 450 °C. After the temperature stabilizes, put in the shearing wheel and the stirring wheel. The stirring wheel rotates at 600 revolutions per minute, and the shearing wheel rotates at 1300 revolutions per minute. While stirring at a temperature of 400 °C, add the first master alloy and the second master alloy, and stir for 25 minutes to obtain a mixed master alloy. Mix the third master alloy and the fourth master alloy with the mixed master alloy, and stir at a temperature of 400 °C for 35 minutes to obtain an alloy liquid. Pour the alloy liquid into a mold and cool it to obtain a tin-silver-copper alloy column.

[0050] Extrude the tin-silver-copper alloy column into a 12-mm metal wire at a temperature of 135 °C, a pressure of 30 bar, and an extrusion speed of 16 mm / s. During the extrusion process, add 3% solid flux. The parameters of the extrusion die are as follows: the arc β of the feed inlet is 51.5°, the depth of the feed inlet is 12.5 mm, the length a of the reducing diameter zone is 3.5, the arc α of the discharge outlet is 87°, and the depth b of the discharge outlet is 3 mm. Then, under the condition of controlling the area reduction rate at 4.50%, stretch the metal wire from a wire diameter of 12 mm to 0.8 mm, and under the condition of controlling the area reduction rate at 4.00%, stretch the metal wire with a wire diameter of 0.8 mm to a wire diameter of 0.12 mm to prepare an ultra-fine wire diameter lead-free tin-silver-copper wire.

[0051] Example 3

[0052] Put 2.0% silver and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 900 °C, and obtain the first master alloy after cooling, where the proportion of silver accounts for 25% of the total weight of the first master alloy;

[0053] Put 0.6% copper and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 700 °C, and obtain the second master alloy after cooling, where the proportion of copper accounts for 15% of the total weight of the second master alloy;

[0054] Put 0.06% nickel and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 900 °C, and obtain the third master alloy after cooling, where the proportion of nickel accounts for 3.5% of the total weight of the third master alloy;

[0055] Put 0.05% antimony and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 550 °C, and obtain the fourth master alloy after cooling, where the proportion of antimony accounts for 3.5% of the total weight of the fourth master alloy;

[0056] Put the remaining tin into a high-temperature intermediate-frequency furnace and melt it at 400 °C. After the temperature stabilizes, put in the shearing wheel and stirring wheel. The stirring wheel rotates at 700 revolutions per minute, and the shearing wheel rotates at 1200 revolutions per minute. Add the first master alloy and the second master alloy while stirring at a temperature of 375 °C, and stir for 30 minutes to obtain a mixed master alloy. Mix the third master alloy and the fourth master alloy with the mixed master alloy, and stir for 30 minutes at a temperature of 380 °C to obtain an alloy liquid. Pour the alloy liquid into a mold and cool it to obtain a tin-silver-copper alloy column.

[0057] Extrude the tin-silver-copper alloy column into a 11-mm metal wire at a temperature of 120 °C, a pressure of 40 bar, and an extrusion speed of 19 mm / s. During the extrusion process, add 5% of a solid soldering flux. The parameters of the extrusion die are as follows: the arc β of the feed inlet is 50.1 °, the depth of the feed inlet is 12 mm, the length a of the reducing zone is 4.0 mm, the arc α of the discharge outlet is 86.8 °, and the depth b of the discharge outlet is 2 mm. Then, under the condition of controlling the area reduction rate at 5.00%, stretch the metal wire from a wire diameter of 11 mm to 0.5 mm, and under the condition of controlling the area reduction rate at 3.50%, stretch the metal wire with a wire diameter of 0.5 mm to a wire diameter of 0.10 mm to prepare an ultra-fine wire diameter lead-free tin-silver-copper wire.

[0058] Comparative example

[0059] Comparative example 1

[0060] The difference from Example 3 is that nickel is replaced with antimony in equal amounts. The preparation steps of the third master alloy are as follows: Put 0.06% of antimony and tin into a high-temperature furnace, melt and stir evenly at a temperature of 550 °C, where the proportion of antimony accounts for 3.5% of the total weight of the third master alloy. The other components remain unchanged, and the tin-silver-copper wire is prepared according to the same steps.

[0061] Low ratio 2

[0062] The difference from Example 3 is that antimony is replaced with nickel in equal amounts. The preparation steps of the fourth master alloy are as follows: Put 0.05% of nickel and tin into a high-temperature intermediate-frequency furnace, melt and stir evenly at a temperature of 900 °C, where the proportion of nickel accounts for 3.5% of the total weight of the fourth master alloy. The other components remain unchanged, and the tin-silver-copper wire is prepared according to the same steps.

[0063] Comparative example 3

[0064] The difference from Example 3 is that during the process of extruding the tin-silver-copper alloy column into a metal wire, the extrusion die before improvement is used, and the other components remain unchanged. The tin-silver-copper wire is prepared according to the same steps. The relevant parameters of the extrusion die are as follows: the arc β of the feed inlet is 60 °, the depth is 8.5 mm, the length a of the reducing zone is 2.5 mm, the arc α of the discharge outlet is 20 °, and the depth b of the discharge outlet is 7 mm.

[0065] Comparative Example 4

[0066] The difference from Example 3 is that during the process of extruding the tin-silver-copper alloy column into a metal wire, the extrusion die used has the following relevant parameters: the arc of the feed port β is 48°, the depth is 14.5 mm, the length a of the variable diameter zone is 5 mm, the arc of the discharge port α is 88°, and the depth of the discharge port b is 1 mm. The other components remain unchanged, and the tin-silver-copper-tin wire is prepared according to the same steps.

[0067] Performance testing

[0068] Processing fracture situation test

[0069] During the actual production and manufacturing process, the situation of the tin-silver-copper-tin wire breaking during drawing.

[0070] Uniformity test of tin-silver-copper-tin wire

[0071] Take several 5-cm-long ultra-fine tin-silver-copper wire segments cut from the drawn ultra-fine tin-silver-copper wire. Select three segments from several ultra-fine tin-silver-copper wire segments, measure the diameter sizes at the top, middle, and bottom, and make a judgment on the uniformity of the ultra-fine tin-silver-copper wire according to the difference values of these three diameters. The smaller the difference value, the more uniform the ultra-fine tin-silver-copper wire, and the smaller the error value, the more uniform the ultra-fine tin-silver-copper wire.

[0072] Table 1 Related test data

[0073]

[0074] It can be seen from Example 3 and Comparative Examples 1-4 in Table 1 that adding trace elements nickel and antimony to the tin-silver-copper alloy column and improving the extrusion die can effectively reduce the easy fracture situation of small-diameter tin wires with a wire diameter of 0.20 mm - 0.30 mm during the process of stretching to ultra-fine wire diameter tin wires with a wire diameter of 0.10 mm - 0.12 mm.

[0075] It can be seen from Example 3 and Comparative Examples 1 and 2 that for trace elements nickel and antimony, nickel can improve the problem of coarse molecular structure lattice in the tin-silver-copper alloy, making the metal grains in the tin-silver-copper alloy molecules finer and able to maintain the stability between the components of the alloy and prevent the excessive accumulation of copper content. The addition of antimony can increase the hardness and strength of the tin-silver-copper alloy. Only when the antimony element and the nickel element cooperate with each other can the hardness and ductility of the tin-silver-copper alloy be effectively improved. Without the addition of trace elements and only with process improvement, the small-diameter tin wires with a wire diameter of 0.20 mm - 0.30 mm are still prone to fracture during the process of stretching to ultra-fine wire diameter tin wires with a wire diameter of 0.10 mm - 0.12 mm.

[0076] From Example 3 and Comparative Example 3, it can be seen that for the original extrusion die parameters, the arc β of the feed inlet is 60°, the depth is 8.5 mm, the length a of the reducing zone is 2.5 mm, the arc α of the discharge outlet is 20°, and the depth b is 7 mm. For the improved extrusion die, when the arc β of the feed inlet is 50° - 51.5° and the depth is 11.5 - 12.5 mm, the metal flexibility of the tin-silver-copper alloy system can be improved, enabling the tin-silver-copper alloy system to better enter the reducing zone. The length a of the reducing zone is 3.5 - 4.0 mm. The longer residence time of the tin-silver-copper alloy system in the reducing zone improves the compactness of the tin-silver-copper alloy system, thereby enhancing the toughness of the extruded metal wire and reducing the breakage of the metal wire during the stretching process. The arc α of the discharge outlet is 86° - 87°, and the depth b is 1 mm - 3 mm. The discharge outlet with these parameters enables the extruded metal wire to quickly separate from the die for cooling, and the structure between the tin-silver-copper alloys solidifies and stabilizes rapidly. Without modifying the extrusion die parameters, small-diameter tin wires with a wire diameter of 0.20 mm - 0.30 mm are prone to breakage during the stretching process to ultra-fine tin wires with a wire diameter of 0.10 mm - 0.12 mm.

[0077] By comparing Example 3 and Comparative Example 4, it can be seen that further narrowing the feed inlet will impose a greater pressure on the reducing zone, and the tin wire cannot be extruded. During the experiment, the entire extrusion die even cracked brittlely. Moreover, the content of the soldering flux is controlled by adjusting the distance between the die and the soldering flux nozzle. When the distance between the soldering flux nozzle and the die is close, the content of the soldering flux on the tin wire is high; conversely, when the distance is far, the content of the soldering flux on the tin wire is low. If the depth of the feed inlet is further increased, a high content of the soldering flux cannot be obtained. Therefore, only when the die parameters are within the scope of this application can the breakage of small-diameter tin wires with a wire diameter of 0.20 mm - 0.30 mm during the stretching process to ultra-fine tin wires with a wire diameter of 0.10 mm - 0.12 mm be effectively reduced.

[0078] The above specific embodiments are merely explanations of this application and do not limit this application. After reading this specification, those skilled in the art can make modifications to this application that do not involve creative contributions as needed, but all should be covered within the protection scope of this application.

Claims

1. The manufacturing process of an ultra-fine diameter lead-free tin-silver-copper-tin wire, characterized in that: It includes the following steps: According to the weight components, a tin-silver-copper alloy column containing 0.2% - 4.0% silver, 0.2% - 1% copper, 0.01% - 0.2% trace elements, and the balance being tin is extruded into a metal wire with a diameter of 10 mm - 12 mm at a temperature of 110°C - 135°C, a pressure of 30 bar - 50 bar, and an extrusion speed of 16 mm / s - 21 mm / s. During the extrusion process, 3% - 6% of a solid soldering flux is added. The parameters of the extrusion die are that the arc angle β of the feed inlet ranges from 50° to 51.5°, the depth of the feed inlet is 11.5 mm - 12.5 mm, the length a of the reduced diameter zone ranges from 3.5 mm to 4.0 mm, the arc angle α of the discharge outlet ranges from 86° to 87°, and the depth b of the discharge outlet ranges from 1 mm to 3 mm; then the metal wire is stretched to a wire diameter of 0.10 mm - 0.12 mm; The trace elements include nickel and antimony, and the proportion of antimony accounts for 15% - 40% of the total weight of the trace elements; The preparation of the tin-silver-copper alloy column includes the following steps: Silver and tin are melted and stirred evenly at a temperature of 800°C - 1000°C, and after cooling, the first master alloy is obtained, where the proportion of silver accounts for 20% - 30% of the total weight of the first master alloy; Copper and tin are melted and stirred evenly at a temperature of 600°C - 800°C, and after cooling, the second master alloy is obtained, where the proportion of copper accounts for 10% - 20% of the total weight of the second master alloy; Nickel and tin are melted and stirred evenly at a temperature of 800°C - 1000°C, and after cooling, the third master alloy is obtained, where the proportion of nickel accounts for 2% - 5% of the total weight of the third master alloy; Antimony and tin are melted and stirred evenly at a temperature of 500°C - 600°C, and after cooling, the fourth master alloy is obtained, where the proportion of antimony accounts for 2% - 5% of the total weight of the fourth master alloy; The remaining tin is melted at 350°C - 450°C. After the temperature stabilizes, the first master alloy and the second master alloy are added while mixing at a temperature of 350°C - 400°C, and after continuing to stir for a period of time, a mixed master alloy is obtained, where the mixing includes shear mixing and stirring mixing; The third master alloy and the fourth master alloy are mixed with the mixed master alloy, and after continuing to stir for a period of time, an alloy liquid is obtained. The alloy liquid is poured into a mold and cooled to obtain a tin-silver-copper alloy column, where the mixing includes shear mixing and stirring mixing.

2. The manufacturing process of the ultra-fine wire diameter lead-free tin-silver-copper-tin wire according to claim 1, characterized in that: During the process of mixing the first master alloy and the second master alloy with tin by stirring, and mixing the third master alloy and the fourth master alloy with the mixed master alloy, the rotation speed of shear mixing is 1000 rpm - 1300 rpm, and the rotation speed of stirring mixing is 600 rpm - 800 rpm.

3. The manufacturing process of the ultra-fine wire diameter lead-free tin-silver-copper-tin wire according to claim 1, characterized in that: The alloy liquid is rapidly cooled by cooling water in the mold.

4. The manufacturing process of the ultra-fine wire diameter lead-free tin-silver-copper-tin wire according to claim 1, characterized in that: The mixing temperature of the third master alloy and the fourth master alloy with the mixed master alloy is 360°C - 400°C.

5. The manufacturing process of the ultra-fine wire diameter lead-free tin-silver-copper-tin wire according to claim 1, characterized in that: During the stretching process of the metal wire, when the wire diameter of the metal wire is stretched from 10 mm to 12 mm to 0.8 mm to 0.2 mm, a reduction rate of 4.50% to 6.00% is adopted. When the wire diameter of the metal wire is stretched from 0.8 mm to 0.2 mm to 0.2 mm to 0.1 mm, a reduction rate of 3.00% to 4.00% is adopted.

6. The lead-free tin-silver-copper solder wire with an ultra-fine wire diameter is characterized in that: It is made by the manufacturing process of the ultra-fine wire diameter lead-free tin-silver-copper-tin wire described in any one of claims 1 to 5.

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