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CN-122012984-A - Low-cost high-strength tin-base alloy and processing method thereof

CN122012984ACN 122012984 ACN122012984 ACN 122012984ACN-122012984-A

Abstract

A low-cost high-strength tin-base alloy and a processing method thereof. The tin-based alloy comprises 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 steps of melting Sn, adding Sn-10Cu, adding Sb, adding Bi and Sn-1Ge, preserving heat, casting to obtain a casting blank, carrying out vacuum heat treatment on the casting blank, carrying out rough rolling, middle rolling, trimming and finish rolling to obtain a welding strip, cutting or punching the welding strip, carrying out ultrasonic cleaning, and carrying out vacuum drying to obtain the tin-based alloy. The invention realizes the unification of high strength, low cost and excellent processability of the alloy by optimizing the cooperation of the silver-free component system and the precise processing technology, and the prepared welding strip has high dimensional accuracy and clean surface and the comprehensive performance meets the severe requirements of modern electronic welding.

Inventors

  • JIA YUANWEI
  • WAN WEICHAO
  • ZHAO LINGYAN
  • WU JIANXUN
  • LU HONGBO
  • LUO XIAOBIN
  • KONG YANPING
  • WANG QIN
  • MIN ZHAOYOU
  • GUO SHAOXIONG
  • WANG JIAJUN

Assignees

  • 云南锡业新材料有限公司

Dates

Publication Date
20260512
Application Date
20260209

Claims (8)

  1. 1. The low-cost high-strength tin-base alloy is characterized by comprising, by mass, 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.
  2. 2. The low-cost high-strength tin-based alloy according to claim 1, further comprising 0.01% -0.05% by mass of one or more of Co, ni and Cr.
  3. 3.A method of processing a low cost, high strength tin base alloy according to claim 1, comprising the steps of: S1, weighing Sn, sb, bi and Sn-10Cu and Sn-1Ge intermediate alloy according to mass fraction proportion; s2, melting Sn, adding Sn-10Cu at 400-450 ℃, adding Sb after melting and immersing, preserving heat for 30-50min, cooling to 300-350 ℃, adding Bi and Sn-1Ge, preserving heat for 20-50min, and casting to obtain a casting blank; s3, carrying out vacuum heat treatment on the casting blank at 100-150 ℃ for 60-120min; s4, sequentially performing rough rolling, intermediate rolling, trimming and finish rolling on the heat-treated casting blank to obtain a welding strip with uniform thickness; And S5, cutting or stamping the welding belt, and then ultrasonically cleaning and vacuum drying to obtain the low-cost high-strength tin-based alloy.
  4. 4. A method of processing a low cost, high strength tin base alloy according to claim 2, comprising the steps of: s1, weighing Sn, sb, bi and Sn-10Cu, sn-5Ni, sn-2Co, sn-1Cr and Sn-1Ge intermediate alloy according to mass fraction proportion; S2, melting Sn, adding Sn-10Cu and one or more of Sn-5Ni, sn-2Co and Sn-1Cr at 400-450 ℃, adding Sb after melting and immersing, cooling to 300-350 ℃ after heat preservation for 30-50min, adding Bi and Sn-1Ge, and casting after heat preservation for 20-50min to obtain a casting blank; s3, carrying out vacuum heat treatment on the casting blank at 100-150 ℃ for 60-120min; s4, sequentially performing rough rolling, intermediate rolling, trimming and finish rolling on the heat-treated casting blank to obtain a welding strip with uniform thickness; And S5, cutting or stamping the welding belt, and then ultrasonically cleaning and vacuum drying to obtain the low-cost high-strength tin-based alloy.
  5. 5. The method for processing a low-cost high-strength tin-base alloy according to claim 3 or 4, wherein in the step S4, a two-roll reversible hot rolling mill is adopted for rough rolling, the roll temperature is 85-125 ℃, the pressing amount per pass is 0.5-1.5mm, and the thickness is 0.8-1mm.
  6. 6. The method for manufacturing a low-cost high-strength tin-base alloy according to claim 3 or 4, wherein in the step S4, a two-roll reversible cold rolling mill is used for the middle rolling, the rolling reduction per pass is 0.1-0.15mm, and the rolling thickness is 0.35-0.45mm.
  7. 7. The method for manufacturing a low-cost high-strength tin-base alloy according to claim 3 or 4, wherein in the step S4, a reversible four-high mill is used for finish rolling, the rolling reduction per pass is 0.02-0.05mm, the rolling is performed until the final thickness is 0.15-0.2mm, and the tolerance is controlled to be + -0.020 mm.
  8. 8. The method for manufacturing a low-cost high-strength tin-base alloy according to claim 3 or 4, wherein in step S5, ultrasonic cleaning is performed by using a hydrochloric acid-alcohol solution with a volume fraction of 0.25-0.5%, the cleaning temperature is 25-35 ℃, the cleaning time is 10-15min, the cleaning time is rinsed with deionized water, and the vacuum drying is performed at 90-120 ℃ for 60-120min.

Description

Low-cost high-strength tin-base alloy and processing method thereof Technical Field The invention relates to the technical field of tin-base alloy solder and processing, in particular to a low-cost high-strength tin-base alloy and a processing method thereof. Background In the field of electronic welding, tin-based alloys are used as main connecting materials, and the performance of the tin-based alloys directly determines the mechanical strength, the conductive reliability and the long-term service stability of the connection of electronic components. With the development of miniaturization, high density integration and high power of electronic products, more stringent requirements are put on the comprehensive performance of the solder alloy, namely, excellent wettability, conductivity and corrosion resistance are required, higher mechanical strength is required to resist thermal stress and mechanical stress in miniaturized welding spots, and meanwhile, the formulation of the alloy is required to be economical in consideration of cost control of mass production. However, the existing common lead-free tin-based alloy system has remarkable limitation in coping with the multi-dimensional challenge, and has the dilemma of 'performance, cost and manufacturability' which are difficult to be combined. The current widely used technical solutions are mainly classified into one of three types, namely a high silver system represented by SAC305 and a high performance derivative alloy Innolot (Sn-Ag-Cu-Bi-Sb-Ni). Although the alloy realizes excellent mechanical property and reliability through silver (Ag) and multi-element microalloying, the cost is high, and complex components increase the difficulty of smelting and process control, so that the alloy is difficult to popularize in cost-sensitive application. Secondly, although the low-cost system represented by SnCu0.7 does not contain noble metal silver, the system has short plates with insufficient inherent strength and fatigue resistance, and the strength requirement of high-reliability welding is difficult to meet. Thirdly, although high strength can be achieved in high antimony strengthening systems represented by Sn-10Sb, too high antimony content can seriously impair the plasticity and rolling processability of the alloy, resulting in high processing brittleness and difficult molding, and also limiting its wide application. More importantly, the prior art focuses on component adjustment, but generally lacks a precise preparation process which is deeply coupled with the component adjustment and can ensure stable and reproducible performance of the component adjustment. Improper smelting and casting processes are prone to segregation of casting blank components, obvious casting defects, coarse structures and the like, rough rolling processes can introduce internal stress and size defects, and insufficient surface treatment can damage welding reliability. This "heavy-component, light-process" disjoint makes the design properties of many alloys impractical in mass production. Therefore, the technical bottleneck to be broken through in the art is to develop a brand new lead-free tin-based alloy system and a matched preparation method thereof, fundamentally break the contradiction between high strength and low cost through innovative component design, and ensure that the alloy has excellent mechanical property, good processing formability and stable welding reliability by means of a set of precise, stable and reproducible special processing technology, thereby systematically meeting the urgent requirements of modern electronic manufacturing on high-performance and low-cost solders. Disclosure of Invention Aiming at the problems existing in the prior art, the invention aims to provide a low-cost high-strength tin-based alloy and a processing method thereof. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: the tin-based alloy comprises, by mass, 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. Further, the tin-based alloy also contains one or more of Co, ni and Cr with the mass content of 0.01-0.05% in total. The processing method of the low-cost high-strength tin-base alloy comprises the following steps of: S1, weighing Sn, sb, bi and Sn-10Cu and Sn-1Ge intermediate alloy according to mass fraction proportion; s2, melting Sn, adding Sn-10Cu at 400-450 ℃, adding Sb after melting and immersing, preserving heat for 30-50min, cooling to 300-350 ℃, adding Bi and Sn-1Ge, preserving heat for 20-50min, and casting to obtain a casting blank; s3, carrying out vacuum heat treatment on the casting blank at 100-150 ℃ for 60-120min; s4, sequentially performing rough rolling, intermediate rolling, trimming and finish rolling on the heat-treated casting blank to obtain a welding strip with uniform thickness; And S5, cutting or stamping the welding belt, and then ultrasonically cle