Low-cost high-strength tin-based alloy and processing method thereof

Abstract

The invention discloses a low-cost high-strength tin-based alloy and a processing method thereof. The tin-based alloy comprises the following components in percentage by weight: 4.5%-5.5% of Sb, 0.5%-1.5% of Bi, 0.7%-2.1% of Cu, 0.005%-0.015% of Ge and the balance of Sn. The processing method comprises the following steps: melting Sn, adding Sn-10Cu, then adding Sb, then adding Bi and Sn-1Ge, keeping the temperature, and casting to obtain a casting blank; after the casting blank is subjected to vacuum heat treatment, rough rolling, intermediate rolling, trimming and finish rolling are conducted, and the welding strip is obtained; and slitting or stamping the solder strip, and then carrying out ultrasonic cleaning and vacuum drying to obtain the tin-based alloy. According to the invention, the unification of high strength, low cost and excellent machinability of the alloy is realized by optimizing the cooperation of a silver-free component system and a precision machining process, the prepared welding strip is high in dimensional precision and clean in surface, and the comprehensive performance meets the strict requirements of modern electronic welding.

Description

Technical Field

[0001] This invention relates to the field of tin-based alloy solder and processing technology, specifically to a low-cost, high-strength tin-based alloy and its processing method. Background Technology

[0002] In the field of electronic soldering, tin-based alloys are the primary connecting materials, and their performance directly determines the mechanical strength, electrical reliability, and long-term service stability of electronic component connections. As electronic products evolve towards miniaturization, high-density integration, and high power, more stringent requirements are placed on the comprehensive performance of solder alloys: they not only need excellent wettability, conductivity, and corrosion resistance, but also must possess higher mechanical strength in miniaturized solder joints to resist thermal and mechanical stresses. Simultaneously, for cost control in large-scale production, alloy formulations must also consider economic efficiency.

[0003] However, existing lead-free tin-based alloy systems all have significant limitations in addressing this multi-dimensional challenge, falling into a dilemma of balancing performance, cost, and processability. Currently widely used technical solutions mainly fall into three categories: First, high-silver systems, represented by SAC305 and its high-performance derivative alloy Innolot (Sn-Ag-Cu-Bi-Sb-Ni). While these alloys achieve excellent mechanical properties and reliability through silver (Ag) and multi-element microalloying, their high cost and complex composition increase the difficulty of melting and process control, making them difficult to popularize in cost-sensitive applications. Second, low-cost systems, represented by SnCu0.7, although lacking the precious metal silver, suffer from insufficient inherent strength and fatigue resistance, making it difficult to meet the strength requirements of high-reliability welding. Third, high-antimony-strength systems, represented by Sn-10Sb, can achieve high strength, but excessive antimony content severely impairs the alloy's plasticity and rolling properties, leading to high processing brittleness and difficulty in forming, which also limits its widespread application.

[0004] More critically, existing technologies largely focus on compositional adjustments, but generally lack precise manufacturing processes that are deeply coupled with these adjustments and can ensure stable performance reproduction. Improper melting and casting processes can easily lead to compositional segregation in the cast billet, obvious casting defects, and coarse microstructure. Excessive rolling processes can introduce internal stress and dimensional defects, while inadequate surface treatment can impair welding reliability. This disconnect between "emphasis on composition and neglect of process" prevents many alloys from achieving their designed properties in mass production.

[0005] Therefore, the key technological bottleneck that urgently needs to be overcome in this field is to develop a novel lead-free tin-based alloy system and its supporting preparation method, fundamentally solve the contradiction between "high strength" and "low cost" through innovative composition design, and rely on a set of precise, stable and reproducible proprietary processing technology to ensure that the alloy simultaneously possesses excellent mechanical properties, good processability and formability and stable welding reliability, thereby systematically meeting the urgent needs of modern electronic manufacturing for high-performance and low-cost solders. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide a low-cost, high-strength tin-based alloy and its processing method.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A low-cost, high-strength tin-based alloy, comprising, by mass percentage: 4.5% to 5.5% Sb, 0.5% to 1.5% Bi, 0.7% to 2.1% Cu, 0.005% to 0.015% Ge, with the balance being Sn.

[0008] Furthermore, the tin-based alloy also contains one or more of Co, Ni, and Cr in a total mass content of 0.01% to 0.05%.

[0009] The processing method for the low-cost, high-strength tin-based alloy described in this invention includes the following steps: S1: Weigh Sn, Sb, Bi and Sn-10Cu, Sn-1Ge master alloys according to the mass fraction ratio; S2: Melt Sn, add Sn-10Cu at 400-450℃, add Sb after melting and let it immerse, keep it at the temperature for 30-50min, then cool it down to 300-350℃, add Bi and Sn-1Ge, keep it at the temperature for 20-50min and then cast to obtain a billet. S3: Vacuum heat treat the billet at 100-150℃ for 60-120 min; S4: The heat-treated billet is subjected to rough rolling, intermediate rolling, trimming, and finish rolling in sequence to obtain a weld strip with uniform thickness; S5: The solder strip is cut or stamped, then ultrasonically cleaned and vacuum dried to obtain the low-cost, high-strength tin-based alloy.

[0010] The processing method for the low-cost, high-strength tin-based alloy described in this invention may further include the following steps: S1: Weigh Sn, Sb, Bi and Sn-10Cu, Sn-5Ni, Sn-2Co, Sn-1Cr, Sn-1Ge master alloys according to the mass fraction ratio; S2: Melt Sn, add Sn-10Cu and one or more of Sn-5Ni, Sn-2Co and Sn-1Cr at 400-450℃, add Sb after melting and immerse it, keep it at the temperature for 30-50min, then cool it to 300-350℃, add Bi and Sn-1Ge, keep it at the temperature for 20-50min and then cast it to obtain a billet; S3: Vacuum heat treat the billet at 100-150℃ for 60-120 min; S4: The heat-treated billet is subjected to rough rolling, intermediate rolling, trimming, and finish rolling in sequence to obtain a weld strip with uniform thickness; S5: The solder strip is cut or stamped, then ultrasonically cleaned and vacuum dried to obtain the low-cost, high-strength tin-based alloy.

[0011] Furthermore, in step S4, the roughing is performed using a two-roll reversible hot rolling mill with a roll temperature of 85-125℃, a reduction of 0.5-1.5mm per pass, and a thickness of 0.8-1mm.

[0012] Furthermore, in step S4, the intermediate rolling mill adopts a two-roll reversible cold rolling mill, with a reduction of 0.1-0.15 mm per pass, rolling to a thickness of 0.35-0.45 mm.

[0013] Furthermore, in step S4, the finishing rolling adopts a reversible four-high rolling mill, with a reduction of 0.02-0.05 mm per pass, rolling to a final thickness of 0.15-0.2 mm, and the tolerance is controlled within ±0.020 mm.

[0014] Further, in step S5, ultrasonic cleaning is performed using a hydrochloric acid-alcohol solution with a volume fraction of 0.25-0.5%, at a cleaning temperature of 25-35℃ for 10-15 minutes; after cleaning, it is rinsed with deionized water and then vacuum dried at 90-120℃ for 60-120 minutes.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The alloy system described in this invention does not contain silver (Ag). By optimizing the principal component ratio of Sb, Bi, and Cu and their synergistic strengthening effect, a high-strength alloy is obtained, and the raw material cost is significantly lower than that of the SAC305 series alloy, fundamentally solving the industry problem of "high performance inevitably means high cost".

[0016] 2. The Bi content in the alloy of the present invention does not exceed 1.5% by mass. At this point, the Bi element is completely dissolved in the alloy matrix and will not precipitate Bi phase in the alloy, thus avoiding segregation of alloy components and reduction of toughness, so that the alloy can obtain high strength while maintaining excellent plasticity.

[0017] 3. The alloy of this invention is strengthened by Ni, Co, and Cr multi-element solid solution, which further improves the mechanical properties of the alloy and meets the strength requirements of high-reliability welded joints. The addition of Ge element enhances the alloy's oxidation resistance, reduces alloy oxidation, and improves the quality of the cast billet.

[0018] 4. The processing method of the present invention ensures the stability of the alloy ingot composition by melting at different temperatures and adding different alloying elements. The rolling process can effectively ensure that the alloy microstructure is uniform, the internal stress is low, the dimensional accuracy is high (tolerance ±0.020mm) and the surface is clean, thereby ensuring a high degree of consistency and stability of the performance from the ingot to the final weld strip product, and the yield is high.

[0019] Compared to high-silver alloys such as SAC305, the low-cost, high-strength tin-based alloy of this invention achieves high strength without the presence of silver (Ag); compared to SnCu0.7 alloy, its mechanical properties are significantly improved; and compared to high-antimony alloys such as Sn-10Sb, its processing plasticity is fundamentally improved. Furthermore, the accompanying preparation method provided by this invention ensures stable and reproducible alloy properties, resulting in solder strip products with high dimensional accuracy and good surface cleanliness, meeting the high reliability requirements of modern electronic soldering. Attached Figure Description

[0020] Figure 1 The welded interface of the tin-based alloy prepared in Example 1 of this invention; Figure 2 The elemental distribution of the tin-based alloy prepared in Example 1 of this invention; Figure 3 The morphology and elemental content of the tin-based alloy after welding prepared in Example 4 of this invention; Figure 4 The DSC curve of the tin-based alloy prepared in Example 4 of this invention; Figure 5 This refers to the tin-based alloy solder strip product prepared by the method of the present invention. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The described embodiments are only some embodiments of the present invention, and not all embodiments, and therefore do not constitute a limitation on the scope of protection of the present invention. Example 1

[0022] This embodiment provides a low-cost, high-strength tin-based alloy with the following mass percentage composition: Sb 5%, Bi 1.5%, Cu 0.7%, Ge 0.01%, and the balance being Sn. The raw materials used are Sn ingots, Sb granules, Bi granules with a purity of 99.9%, and Sn-10Cu and Sn-1Ge master alloys.

[0023] Sn ingots were placed in a tin-melting furnace and heated to 420°C until completely melted. Sn-10Cu master alloy was added to the molten Sn and mechanically stirred until completely melted. Sb granules were then added and completely pressed into the melt, and the furnace was held at 420°C for 30 minutes. The furnace temperature was then lowered to 320°C, Bi granules and Sn-1Ge master alloy were added, stirred, and held at this temperature for 30 minutes. The mixture was then poured into a water-cooled mold, and after cooling, an alloy ingot was obtained.

[0024] The billet is placed in a vacuum drying oven and kept at 120°C for 90 minutes, then cooled to 100°C in the furnace to eliminate casting stress.

[0025] The heat-treated billet is hot-rolled at 100°C to a thickness of 1.0 mm (1.0 mm reduction per pass). Then it is rolled to 0.40 mm (0.12 mm reduction per pass), trimmed, and then finished rolled to a final thickness of 0.15 mm (0.04 mm reduction per pass).

[0026] The rolled strip was immersed in a 0.4% (v / v) hydrochloric acid-alcohol solution and ultrasonically cleaned at 30°C for 10 minutes. After removal, it was rinsed three times with deionized water and placed in a vacuum drying oven to dry at 90°C for 90 minutes to obtain the tin-based alloy product.

[0027] Figure 1 The image shows the welded interface of the tin-based alloy prepared in this embodiment. As can be seen, a smooth IMC layer is formed at the welded interface. Figure 2 The images show the elemental distribution of the tin-based alloy prepared in this embodiment. Image 2-1 shows the alloy morphology, image 2-2 shows the Sn elemental distribution, image 2-3 shows the Sb elemental distribution, image 2-4 shows the Bi elemental distribution, and image 2-5 shows the Cu elemental distribution. It can be seen that Bi is completely dissolved in the matrix, and no Bi phase precipitates. Figure 5 The tin-based alloy solder strip product prepared.

[0028] The alloy has a tensile strength of 73.7 MPa, an elongation after fracture of 31%, a microhardness of 22 HV0.1, and a melting point of 236.54℃. The prepared product has a smooth and defect-free surface. Example 2

[0029] This embodiment provides a low-cost, high-strength tin-based alloy with the following mass percentage composition: Sb 5%, Bi 1.5%, Cu 0.7%, Ni 0.02%, Co 0.02%, Ge 0.005%, and the balance being Sn. The raw materials used are Sn ingots, Sb granules, Bi granules with a purity of 99.9%, and Sn-10Cu, Sn-5Ni, Sn-2Co, and Sn-1Ge master alloys.

[0030] Sn ingots were placed in a tin-melting furnace and heated to 450°C until completely melted. A calculated master alloy of Sn-10Cu, Sn-5Ni, and Sn-2Co was added to the molten Sn, and mechanically stirred until completely melted. Sb particles were then added and completely pressed into the melt, and the furnace was held at 450°C for 30 minutes. The furnace temperature was then lowered to 320°C, Bi particles and Sn-1Ge master alloy were added, stirred, and held at this temperature for 35 minutes. The mixture was then poured into a water-cooled mold, and after cooling, an alloy casting was obtained.

[0031] The billet is placed in a vacuum drying oven and kept at 150°C for 60 minutes, then cooled to 125°C in the furnace to eliminate casting stress.

[0032] The heat-treated billet is hot-rolled at 125°C to a thickness of 0.8 mm (1.5 mm reduction per pass). Then it is rolled in intermediate rolling to a thickness of 0.35 mm (0.1 mm reduction per pass). After trimming, it is finished rolled to a final thickness of 0.2 mm (0.02 mm reduction per pass).

[0033] The rolled strip was immersed in a 0.25% (v / v) hydrochloric acid-alcohol solution and ultrasonically cleaned at 35°C for 10 minutes. After removal, it was rinsed three times with deionized water and placed in a vacuum drying oven at 120°C for 60 minutes to obtain the tin-based alloy product.

[0034] The alloy has a tensile strength of 73.59 MPa, an elongation after fracture of 32.5%, a microhardness of 23.2 HV0.1, and a melting point of 238.02℃. The prepared product has a smooth and defect-free surface. Example 3

[0035] This embodiment provides a low-cost, high-strength tin-based alloy with the following mass percentage composition: Sb 5.5%, Bi 0.5%, Cu 0.7%, Co 0.05%, Ge 0.01%, and the balance being Sn. The raw materials used are Sn ingots, Sb granules, Bi granules with a purity of 99.9%, and Sn-10Cu, Sn-2Co, and Sn-1Ge master alloys.

[0036] Sn ingots were placed in a tin-melting furnace and heated to 420°C until completely melted. Calculated Sn-10Cu and Sn-2Co master alloys were added to the molten Sn, and the mixture was mechanically stirred until completely melted. Sb particles were then added and completely pressed into the melt, and the furnace was held at 400°C for 50 minutes. The furnace temperature was then lowered to 300°C, Bi particles and Sn-1Ge master alloy were added, and the mixture was stirred and held at this temperature for 40 minutes. The mixture was then poured into a water-cooled mold, and after cooling, an alloy casting was obtained.

[0037] The billet is placed in a vacuum drying oven and kept at 120°C for 120 minutes, and then cooled to 85°C with the furnace to eliminate casting stress.

[0038] The heat-treated billet is hot-rolled at 85°C to a thickness of 1.0 mm (with a reduction of 0.5 mm per pass). Then it is rolled in intermediate rolling to a thickness of 0.45 mm (with a reduction of 0.1 mm per pass). After trimming, it is finished rolled to a final thickness of 0.2 mm (with a reduction of 0.05 mm per pass).

[0039] The rolled strip was immersed in a 0.5% (v / v) hydrochloric acid-alcohol solution and ultrasonically cleaned at 25°C for 10 minutes. After removal, it was rinsed three times with deionized water and placed in a vacuum drying oven at 110°C for 80 minutes to obtain the tin-based alloy product.

[0040] The alloy has a tensile strength of 67.3 MPa, an elongation after fracture of 38.5%, a microhardness of 21.3 HV0.1, and a melting point of 240.85℃. The prepared product has a smooth and defect-free surface. Example 4

[0041] This embodiment provides a low-cost, high-strength tin-based alloy with the following mass percentage composition: Sb 5.5%, Bi 1%, Cu 0.9%, Cr 0.01%, Ni 0.01%, Co 0.03%, Ge 0.01%, and the balance being Sn. The raw materials used are 99.9% pure Sn ingots, Sb granules, Bi granules, and Sn-10Cu, Sn-1Cr, Sn-5Ni, Sn-2Co, and S-1Ge master alloys.

[0042] Sn ingots were placed in a tin-melting furnace and heated to 420°C until completely melted. A calculated master alloy of Sn-10Cu, Sn-1Cr, Sn-5Ni, and Sn-2Co was added to the molten Sn, and mechanically stirred until completely melted. Sb particles were then added and completely pressed into the melt, and the furnace was held at 420°C for 50 minutes. The furnace temperature was then lowered to 320°C, Bi particles and Sn-1Ge master alloy were added, stirred, and held at this temperature for 50 minutes. The mixture was then poured into a water-cooled mold, and after cooling, an alloy casting was obtained.

[0043] The billet is placed in a vacuum drying oven and kept at 100°C for 120 minutes, then cooled to 90°C in the furnace to eliminate casting stress.

[0044] The heat-treated billet is hot-rolled at 90°C to a thickness of 1.0 mm (with a reduction of 0.5 mm per pass). Then it is rolled in intermediate rolling to a thickness of 0.45 mm (with a reduction of 0.1 mm per pass). After trimming, it is finished rolled to a final thickness of 0.2 mm (with a reduction of 0.05 mm per pass).

[0045] The rolled strip was immersed in a 0.5% (v / v) hydrochloric acid-alcohol solution and ultrasonically cleaned at 25°C for 15 minutes. After removal, it was rinsed three times with deionized water and placed in a vacuum drying oven at 110°C for 80 minutes to obtain the final product.

[0046] The alloy has a tensile strength of 67.5 MPa, an elongation after fracture of 41%, a microhardness of 21.6 HV0.1, and a melting point of 237.9℃. The prepared product has a smooth and defect-free surface.

[0047] Figure 3 The morphology and elemental content of the tin-based alloy interface after welding prepared in this embodiment (elemental content of sample taken at point A is shown in the table in the figure) are obtained from... Figure 3 As can be seen, the added Co and Ni elements form a (Cu, Ni, Co)6Sn5 structure at the interface, thereby improving the interface structure. Figure 4 The DSC curve of the tin-based alloy prepared in this embodiment shows that the alloy melting point is 237.99℃. Example 5

[0048] This embodiment provides a low-cost, high-strength tin-based alloy with the following mass percentage composition: Sb 4.5%, Bi 1.5%, Cu 2.1%, Co 0.01%, Ge 0.015%, and the balance being Sn. The raw materials used are Sn ingots, Sb granules, Bi granules with a purity of 99.9%, and Sn-10Cu and Sn-2Co master alloys.

[0049] Sn ingots were placed in a tin-melting furnace and heated to 420°C until completely melted. Calculated Sn-10Cu and Sn-2Co master alloys were added to the molten Sn, and the mixture was mechanically stirred until completely melted. Sb particles were then added and completely pressed into the melt, and the furnace was held at 420°C for 40 minutes. The furnace temperature was then lowered to 350°C, Bi particles and Sn-1Ge master alloy were added, and the mixture was stirred and held at this temperature for 40 minutes. The mixture was then poured into a water-cooled mold, and after cooling, an alloy ingot was obtained.

[0050] The billet is placed in a vacuum drying oven and kept at 120°C for 120 minutes, and then cooled to 90°C with the furnace to eliminate casting stress.

[0051] The heat-treated billet is hot-rolled at 80°C to a thickness of 0.9 mm (with a reduction of 0.5 mm per pass). Then it is rolled in intermediate rolling to a thickness of 0.45 mm (with a reduction of 0.15 mm per pass). After trimming, it is finished rolled to a final thickness of 0.19 mm (with a reduction of 0.05 mm per pass).

[0052] The rolled strip was immersed in a 0.5% (v / v) hydrochloric acid-alcohol solution and ultrasonically cleaned at 25°C for 12 minutes. After removal, it was rinsed three times with deionized water and placed in a vacuum drying oven at 100°C for 120 minutes to obtain the final product.

[0053] The alloy has a tensile strength of 79.8 MPa, an elongation after fracture of 30.3%, a microhardness of 22.7 HV0.1, and a melting point of 239.1℃. The prepared product has a smooth and defect-free surface.

[0054] Comparative Example Comparative Example 1 is SAC305 alloy; Comparative Example 2 is Sn-0.7Cu alloy; Comparative Example 3 is Sn-5Sb alloy; Comparative Example 4 is Sn-10Sb alloy.

[0055] The performance comparison of the alloys in Examples 1-5 and the comparative examples is shown in Table 1.

[0056] Table 1. Performance comparison of alloys in Examples 1-5 and comparative examples

[0057] As can be seen from Table 1, the melting point of the alloy of the present invention is 236.54-240.85℃, which is lower than that of Sn-5Sb and Sn-10Sb alloys; the mechanical properties of the alloy of the present invention are significantly improved compared with the comparative alloy.

[0058] Compared to Ag- or high-Sn solder alloys such as SAC305 and SnCu0.7, the raw materials used in this invention do not contain precious metals and have a relatively low tin content, which can effectively reduce costs.

[0059] This invention achieves a balance between high strength, low cost, and excellent machinability in alloys by optimizing the silver-free composition system and precision machining processes. The resulting solder strips have high dimensional accuracy, clean surfaces, and overall performance that meets the stringent requirements of modern electronic welding.

Claims

1. A low-cost, high-strength tin-based alloy, characterized in that, The tin-based alloy comprises, by mass percentage: 4.5% to 5.5% Sb, 0.5% to 1.5% Bi, 0.7% to 2.1% Cu, 0.005% to 0.015% Ge, with the balance being Sn.

2. The low-cost, high-strength tin-based alloy according to claim 1, characterized in that, The tin-based alloy also contains one or more of Co, Ni, and Cr in a total mass content of 0.01% to 0.05%.

3. The processing method for a low-cost, high-strength tin-based alloy as described in claim 1, characterized in that, Includes the following steps: S1: Weigh Sn, Sb, Bi and Sn-10Cu, Sn-1Ge master alloys according to the mass fraction ratio; S2: Melt Sn, add Sn-10Cu at 400-450℃, add Sb after melting and let it immerse, keep it at the temperature for 30-50min, then cool it down to 300-350℃, add Bi and Sn-1Ge, keep it at the temperature for 20-50min and then cast to obtain a billet. S3: Vacuum heat treat the billet at 100-150℃ for 60-120 min; S4: The heat-treated billet is subjected to rough rolling, intermediate rolling, trimming, and finish rolling in sequence to obtain a weld strip with uniform thickness; S5: The solder strip is cut or stamped, then ultrasonically cleaned and vacuum dried to obtain the low-cost, high-strength tin-based alloy.

4. The processing method for a low-cost, high-strength tin-based alloy as described in claim 2, characterized in that, Includes the following steps: S1: Weigh Sn, Sb, Bi and Sn-10Cu, Sn-5Ni, Sn-2Co, Sn-1Cr, Sn-1Ge master alloys according to the mass fraction ratio; S2: Melt Sn, add Sn-10Cu and one or more of Sn-5Ni, Sn-2Co and Sn-1Cr at 400-450℃, add Sb after melting and immerse it, keep it at the temperature for 30-50min, then cool it to 300-350℃, add Bi and Sn-1Ge, keep it at the temperature for 20-50min and then cast it to obtain a billet; S3: Vacuum heat treat the billet at 100-150℃ for 60-120 min; S4: The heat-treated billet is subjected to rough rolling, intermediate rolling, trimming, and finish rolling in sequence to obtain a weld strip with uniform thickness; S5: The solder strip is cut or stamped, then ultrasonically cleaned and vacuum dried to obtain the low-cost, high-strength tin-based alloy.

5. A method for processing a low-cost, high-strength tin-based alloy according to claim 3 or 4, characterized in that, In step S4, the roughing is performed using a two-roll reversible hot rolling mill with a roll temperature of 85-125℃, a reduction of 0.5-1.5mm per pass, and a thickness of 0.8-1mm.

6. A method for processing a low-cost, high-strength tin-based alloy according to claim 3 or 4, characterized in that, In step S4, the intermediate rolling mill uses a two-roll reversible cold rolling mill, with a reduction of 0.1-0.15 mm per pass, rolling to a thickness of 0.35-0.45 mm.

7. A method for processing a low-cost, high-strength tin-based alloy according to claim 3 or 4, characterized in that, In step S4, the finishing rolling is carried out using a reversible four-high mill, with a reduction of 0.02-0.05 mm per pass, rolling to a final thickness of 0.15-0.2 mm, and the tolerance is controlled within ±0.020 mm.

8. A method for processing a low-cost, high-strength tin-based alloy according to claim 3 or 4, characterized in that, In step S5, ultrasonic cleaning is performed using a hydrochloric acid-alcohol solution with a volume fraction of 0.25-0.5%, at a cleaning temperature of 25-35℃ for 10-15 minutes. After cleaning, the solution is rinsed with deionized water and then vacuum dried at 90-120℃ for 60-120 minutes.

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