Intermetallic compound inhibition type multicomponent alloy brazing filler metal as well as preparation method and application of intermetallic compound inhibition type multicomponent alloy brazing filler metal

Abstract

The invention discloses intermetallic compound inhibition type multicomponent alloy brazing filler metal and a preparation method and application thereof, and belongs to the technical field of welding materials. The multi-element alloy brazing filler metal comprises main brazing filler metal and additive elements, the main brazing filler metal is tin, the tin content is 60-90 wt%, one or more of indium, bismuth and antimony are added as the additive elements, and the total content is 5-20 wt%. The preparation method comprises the steps of raw material weighing, vacuum smelting furnace treatment, stirring and cooling forming. When the solder is welded with a copper base material, under specific welding conditions, the thickness growth rate of an intermetallic compound layer is reduced by 30%-80% compared with that of traditional tin-lead solder. 0.5 wt%-3wt% of rare earth element lanthanum or cerium is added when an aluminum base material is welded, so that formation of intermetallic compounds can be further inhibited, and the thickness growth rate of an intermetallic compound layer is reduced by 20%-50% compared with that of the same brazing filler metal alloy without the rare earth element. The problem that traditional brazing filler metal is difficult to control formation of intermetallic compounds is effectively solved, and the mechanical property and reliability of a welded joint are improved.

Description

Technical Field

[0001] This invention relates to the field of welding materials technology, and in particular to an intermetallic compound-inhibiting multi-element alloy brazing filler metal, its preparation method, and its application. Background Technology

[0002] Welding is a widely used joining technology in many fields such as machinery manufacturing and electronic equipment assembly. When the solder and base material come into contact and are heated during the welding process, intermetallic compounds easily form at the interface between the solder and the base material due to atomic diffusion. Traditional tin-lead solders are widely used in many welding scenarios, but they have significant shortcomings in controlling the formation of intermetallic compounds. With the increasing demands for weld joint quality and reliability in industrial production, excessive intermetallic compounds can lead to a significant decrease in the mechanical properties of the weld joint, such as reduced strength and increased brittleness, seriously affecting the safety and stability of the welded structure during use. Moreover, in the welding of some high-precision electronic equipment, the unevenness or excessive growth of the intermetallic compound layer may cause changes in electrical performance, such as increased resistance and signal transmission interference. Therefore, the development of an intermetallic compound-suppressing multi-element alloy solder is urgently needed to meet the increasingly complex and stringent industrial welding requirements. Summary of the Invention

[0003] The purpose of this invention is to provide an intermetallic compound-inhibiting multi-element alloy brazing filler metal, its preparation method, and its application. This invention addresses the problem in the prior art that traditional tin-lead brazing filler metals easily form intermetallic compounds at the interface with the base material, leading to a significant decrease in the mechanical properties and deterioration of the electrical properties of the welded joint. By inhibiting the growth of intermetallic compounds, the invention improves the safety, stability, and electrical reliability of the welded structure during use.

[0004] To achieve the above objectives, the present invention provides an intermetallic compound-suppressing multi-element alloy solder, comprising a main solder and additive elements. The main solder is tin, with a tin content of 60wt%-90wt%. The additive elements are one or more of indium, bismuth, and antimony, with a total content of 5wt%-20wt%, and the balance being unavoidable impurities. When the additive element includes indium, the indium content is 2wt%-8wt%; when the additive element includes bismuth, the bismuth content is 1wt%-6wt%; and when the additive element includes antimony, the antimony content is 2wt%-10wt%.

[0005] Preferably, the added elements also include rare earth elements.

[0006] Preferably, the rare earth element is lanthanum or cerium, and when the added element includes a rare earth element, the content of the rare earth element is 0.5wt%-3wt%.

[0007] This invention also provides a method for preparing the above-mentioned intermetallic compound-suppressing multi-element alloy solder, specifically including the following steps: S1. Take tin, indium, bismuth, antimony and rare earth elements according to the composition ratio; S2. Place the raw materials in a vacuum furnace, evacuate the vacuum, heat up and melt them, and keep them at the temperature after they are completely melted. S3. Stir thoroughly to ensure that all raw materials are evenly mixed; S4. After stirring, pour the alloy melt into a mold, cool and solidify to obtain the target product.

[0008] Preferably, in step S2, a vacuum is drawn until the pressure is 5 × 10⁻⁶. -3 Pa-1×10 -5 Pa; heat to 300℃-400℃ and hold for 10min-30min.

[0009] Preferably, in step S2, the heating rate is 5℃ / min-15℃ / min.

[0010] Preferably, in step S3, the stirring speed is 100rpm-500rpm and the stirring time is 5min-20min.

[0011] Preferably, in step S4, the cooling rate is 20℃ / min-80℃ / min.

[0012] The present invention also provides the application of the above-mentioned intermetallic compound-inhibiting multi-element alloy brazing filler metal in the welding of copper base metal, wherein the welding temperature is 180℃-240℃ and the welding time is 10s-90s.

[0013] This invention also provides the application of the above-mentioned intermetallic compound-inhibiting multi-element alloy brazing filler metal in aluminum base metal welding, with a welding temperature of 180℃-240℃ and a welding time of 10s-90s.

[0014] Therefore, the intermetallic compound-suppressing multi-element alloy solder, its preparation method, and its application provided by this invention have the following beneficial effects: (1) Improve the quality of welded joints This multi-element alloy brazing filler metal effectively inhibits the formation of intermetallic compounds, solving the problem of traditional brazing filler metals' difficulty in controlling intermetallic compound formation. During welding, compared to traditional filler metals, it reduces the decline in the mechanical properties of the weld joint caused by excessive intermetallic compound formation, better ensuring key performance indicators such as strength and toughness. For example, tensile strength, impact resistance, and elongation are all improved to varying degrees, significantly enhancing the overall quality and stability of the weld joint, extending the service life of the welded structure, and strengthening its reliability under various working conditions.

[0015] (2) Optimize the adaptability of welding process Its unique alloy composition design endows the brazing filler metal with excellent process adaptability. It exhibits outstanding welding performance whether welding with copper or aluminum base metals. When welding with copper base metals, under specific welding conditions, the growth rate of the intermetallic compound layer is reduced by 30%-80% compared to traditional tin-lead brazing filler metals. Adding rare earth elements such as lanthanum or cerium when welding aluminum base metals further inhibits the formation of intermetallic compounds, reducing the growth rate of the intermetallic compound layer by 20%-50% compared to the same brazing filler metal alloy without rare earth elements. By rationally adding elements such as indium, bismuth, and antimony, and introducing rare earth elements when welding aluminum base metals, the growth of intermetallic compounds can be effectively controlled under different welding temperatures and times. This results in a wider welding process window, reduces the stringent requirements for precise control of welding equipment and process parameters, improves the flexibility and efficiency of the welding production process, and facilitates its application and promotion in various industrial manufacturing scenarios.

[0016] (3) Optimize the electrical performance of welded joints This invention's solder significantly improves the electrical performance of welded joints by suppressing uneven growth and excessive thickening of intermetallic compounds. Test results show that, compared to traditional tin-lead solders, the solder of this invention exhibits lower contact resistance, greater stability, and superior conductivity, effectively reducing signal transmission loss and resistance heating. It perfectly solves the electrical performance problems associated with traditional solders in high-precision electronic device soldering, meeting the stringent requirements of electronic devices for signal transmission stability and electrical reliability, and broadening the application scenarios of solders in high-precision manufacturing fields such as electronics and electrical appliances.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a structural diagram of the multi-element alloy brazing metal base material prepared according to the present invention; Figure Labels 1-First metal base material; 2-Multi-element alloy brazing filler metal; 3-Second metal base material. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims and are all within the protection scope of the present invention.

[0020] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0021] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0022] Unless otherwise specified, the reagents, instruments, and equipment used in this invention are all commonly used by those skilled in the art.

[0023] Example 1 This embodiment provides a method for preparing an intermetallic compound-suppressed multi-element alloy solder. The specific preparation steps are as follows: First, accurately weigh each raw material, which contains 90 wt% tin, 5 wt% indium, and 3 wt% bismuth, with the remainder being impurities. Place the raw materials into a vacuum furnace and evacuate to a vacuum level of 1×10⁻⁶. -4 After Pa, the raw material is heated to 350℃ at 10℃ / min to melt it. After it is completely melted, it is kept at the temperature for 20 minutes, then stirred at 300 rpm for 10 minutes. Finally, it is poured into a mold and cooled and shaped at 50℃ / min.

[0024] The multi-element alloy brazing filler metal prepared in this embodiment was applied to the welding of copper base material, resulting in the following: Figure 1The multi-element alloy brazing filler metal structure shown includes a first metal base 1, a multi-element alloy brazing filler metal 2, and a second metal base 3. In the welding test with copper base metal, the welding temperature was set to 240℃ and the welding time to 30s. The resulting material thickness was 24nm. It was found that the growth rate of the intermetallic compound layer thickness was reduced by about 60% compared with traditional tin-lead brazing filler metal.

[0025] Example 2 This embodiment provides a method for preparing an intermetallic compound-suppressed multi-element alloy solder. The specific preparation steps are as follows: First, accurately weigh each raw material, which contains 90 wt% tin, 5 wt% indium, 3 wt% bismuth, and 1.5 wt% lanthanum, with the remainder being impurities. Place the raw materials into a vacuum furnace and evacuate to a vacuum level of 1×10⁻⁶. -4 After Pa, the raw material is heated to 350℃ at 10℃ / min to melt it. After it is completely melted, it is kept at the temperature for 20 minutes, then stirred at 300 rpm for 10 minutes. Finally, it is poured into a mold and cooled and shaped at 50℃ / min.

[0026] The multi-element alloy brazing filler metal prepared in this embodiment was applied to the welding of aluminum base material. In the welding test with aluminum base material, the welding temperature was set to 200°C and the welding time was 60s. The thickness of the obtained material was 39nm. It was found that the growth rate of the intermetallic compound layer thickness was reduced by about 35% compared with the same brazing filler metal alloy without rare earth elements.

[0027] Example 3 This embodiment provides a method for preparing an intermetallic compound-suppressed multi-element alloy solder. The specific preparation steps are as follows: First, accurately weigh each raw material, with tin content at 85 wt%, indium content at 5 wt%, bismuth content at 5 wt%, and antimony content at 5 wt%. Place the raw materials into a vacuum furnace and evacuate to a vacuum level of 1 × 10⁻⁶. -4 After Pa, the raw material is heated to 350℃ at 10℃ / min to melt it. After it is completely melted, it is kept at the temperature for 20 minutes, then stirred at 300 rpm for 10 minutes. Finally, it is poured into a mold and cooled and shaped at 50℃ / min.

[0028] The multi-element alloy brazing filler metal prepared in this embodiment was applied to the welding of copper base material. In the welding test with copper base material, the welding temperature was set to 240℃, the welding time was 30s, and the thickness of the resulting material was 30nm. It was found that the growth rate of the intermetallic compound layer thickness was reduced by about 50% compared with the traditional tin-lead brazing filler metal. This indicates that the new brazing filler metal has better anti-diffusion properties and can maintain good connection stability at high temperatures for a long time.

[0029] Example 4 This embodiment provides a method for preparing an intermetallic compound-suppressed multi-element alloy solder. The specific preparation steps are as follows: First, accurately weigh each raw material, with the following content: 90 wt% tin, 3 wt% indium, 3 wt% bismuth, 2.5 wt% antimony, and 1.5 wt% lanthanum. Place the raw materials into a vacuum furnace and evacuate to a vacuum level of 1 × 10⁻⁶. -4 After Pa, the raw material is heated to 350℃ at 10℃ / min to melt it. After it is completely melted, it is kept at the temperature for 20 minutes, then stirred at 300 rpm for 10 minutes. Finally, it is poured into a mold and cooled and shaped at 50℃ / min.

[0030] The multi-element alloy brazing filler metal prepared in this embodiment was applied to the welding of aluminum base material. In the welding test with aluminum base material, under the conditions of welding temperature of 200°C and welding time of 60s, the thickness of the material was 45nm. The growth rate of the intermetallic compound layer thickness was reduced by about 25% compared with the same brazing filler metal alloy without rare earth elements.

[0031] Example 5 This embodiment provides a method for preparing an intermetallic compound-suppressed multi-element alloy solder. The specific preparation steps are as follows: First, accurately weigh each raw material, which contains 90 wt% tin, 3 wt% bismuth, and 5 wt% antimony, with the remainder being impurities. Place the raw materials into a vacuum furnace and evacuate to a vacuum level of 1×10⁻⁶. -4 After Pa, the raw material is heated to 350℃ at 10℃ / min to melt it. After it is completely melted, it is kept at the temperature for 20 minutes, then stirred at 300 rpm for 10 minutes. Finally, it is poured into a mold and cooled and shaped at 50℃ / min.

[0032] The multi-element alloy brazing filler metal prepared in this embodiment was applied to the welding of copper base material. In the welding test with copper base material, the welding temperature was set to 240°C and the welding time was 30s. The thickness of the material was 27nm. It was found that the growth rate of the intermetallic compound layer thickness was reduced by about 55% compared with the traditional tin-lead brazing filler metal.

[0033] Example 6 This embodiment provides a method for preparing an intermetallic compound-suppressed multi-element alloy solder. The specific preparation steps are as follows: First, accurately weigh each raw material, which contains 90 wt% tin, 3 wt% bismuth, 5 wt% antimony, and 1.5 wt% lanthanum, with the remainder being impurities. Place the raw materials into a vacuum furnace and evacuate to a vacuum level of 1×10⁻⁶. -4 After Pa, the raw material is heated to 350℃ at 10℃ / min to melt it. After it is completely melted, it is kept at the temperature for 20 minutes, then stirred at 300 rpm for 10 minutes. Finally, it is poured into a mold and cooled and shaped at 50℃ / min.

[0034] The multi-element alloy brazing filler metal prepared in this embodiment was applied to the welding of aluminum base material. In the welding test with aluminum base material, under the conditions of welding temperature of 200°C and welding time of 60s, the thickness of the material was 42nm. The growth rate of the intermetallic compound layer thickness was reduced by about 30% compared with the same brazing filler metal alloy without rare earth elements.

[0035] Therefore, the multi-element alloy brazing filler metal prepared by this invention can effectively suppress the formation of intermetallic compounds, effectively solving the problem of traditional brazing filler metals' difficulty in controlling intermetallic compound formation. When brazing with copper base metal, under specific welding conditions, the growth rate of intermetallic compound layer thickness is reduced by 30%-80% compared to traditional tin-lead brazing filler metals. When brazing aluminum base metal, adding rare earth elements lanthanum or cerium can further suppress the formation of intermetallic compounds, reducing the growth rate of intermetallic compound layer thickness by 20%-50% compared to the same brazing filler metal alloy without added rare earth elements.

[0036] Using traditional tin-lead solder as a comparative example, the mechanical properties of the above embodiments and traditional tin-lead solder were tested multiple times.

[0037] 1. Test Method Description Tensile strength test: According to GB / T 2651-2008 standard, a universal testing machine was used. The specimen was dumbbell-shaped (gauge length diameter 4mm, length 20mm). The tensile rate was set to 2mm / min. The test was conducted at room temperature (25℃). The average value of 3 parallel specimens was taken.

[0038] Shear strength test: Refer to GB / T 11363-2008 standard, use single lap joint specimens (lap length 5mm, base material thickness 2mm), shear rate 1mm / min, test at room temperature, and each group of valid data shall have no less than 3.

[0039] Elongation test: Performed simultaneously with tensile strength test. The deformation of the gauge length is recorded using the extensometer built into the testing machine. The elongation of the gauge length after fracture is calculated, and the average value of parallel specimens is taken.

[0040] Impact energy test: According to GB / T 229-2020 standard, Charpy V-notch specimens (size 10mm×10mm×55mm, notch depth 2mm) were used for impact testing at room temperature. Each specimen was tested 3 times, and the arithmetic mean of the valid data was taken.

[0041] 2. The test results are shown in Table 1.

[0042] Table 1

[0043] As shown in Table 1, the brazing filler metals prepared in Examples 1-6 exhibit significantly better performance than traditional tin-lead brazing filler metals in all four key mechanical properties: tensile strength, shear strength, elongation, and impact energy. This directly demonstrates the effectiveness of the proposed technical approach of suppressing intermetallic compound (IMC) growth by adding indium, bismuth, antimony, and rare earth elements, successfully achieving the invention's objective of improving the mechanical properties and reliability of welded joints. IMC layers are typically hard and brittle; excessive thickness can increase the overall brittleness of the joint, making it a weak point. The significantly improved tensile and shear strength in the embodiments of this invention indicate that the interfacial IMC layer formed by the brazing filler metal is thinner, more uniform, and less prone to brittle fracture, thereby enhancing the load-bearing capacity of the joint. The substantial increase in elongation and impact energy indicates enhanced plasticity and impact resistance of the welded joint, confirming that suppressing excessive growth of brittle IMC can effectively alleviate the tendency for joint embrittlement, making it more tolerant of deformation under stress or thermal cycling and less prone to brittle fracture, thus improving safety and lifespan. Comparing Examples 2, 4, and 6 (containing rare earth elements) used for aluminum base materials with Examples 1, 3, and 5 (containing no rare earth elements or the same matrix composition) used for copper base materials, it can be seen that the technical solution of the present invention has good process adaptability and base material compatibility. Therefore, the brazing filler metal prepared by the present invention through specific alloying design (addition of In, Bi, Sb, and rare earth elements) can significantly improve the comprehensive mechanical properties of the welded joint, with both its strength and toughness being enhanced. This fundamentally addresses the problem of joint embrittlement and decreased reliability caused by excessive IMC growth.

[0044] Using traditional tin-lead solder as a comparative example, the electrical performance of the above embodiments and traditional tin-lead solder was tested multiple times.

[0045] 1. Test Method Description Contact resistance test: A four-probe tester was used, the test pressure was set to 1N, and the test environment was room temperature (25℃). Three different test points were selected for each sample, and the average value was taken as the final test result. Conductivity test: The test was conducted using an eddy current conductivity meter according to ASTM B193 standard. The test frequency was 60kHz. Each sample was tested 5 times, and the average value was taken as the final test result. The result was expressed as a percentage of the International Standard for Annealed Copper (IACS).

[0046] 2. The test results are shown in Table 2.

[0047] Table 2

[0048] As shown in Table 2, the solders prepared in Examples 1-6 exhibit significantly lower contact resistance (only 40%-55% of traditional tin-lead solders) and significantly higher conductivity (10%-20% higher) than traditional tin-lead solders in terms of electrical performance. This fully demonstrates the superiority of the technical solution of the present invention in optimizing electrical performance. It directly addresses the technical pain point raised in the background art, namely that "uneven thickness or excessive growth of the intermetallic compound layer will cause increased resistance and signal transmission interference," and can meet the stringent requirements of high-precision electronic equipment for the electrical performance of welded joints.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A multi-element alloy solder with intermetallic compound suppression, characterized in that: It includes the main solder and additives. The main solder is tin, with a tin content of 60wt%-90wt%. The additives are one or more of indium, bismuth, and antimony, with a total additive content of 5wt%-20wt%, and the balance being unavoidable impurities. When the additives include indium, the indium content is 2wt%-8wt%; when the additives include bismuth, the bismuth content is 1wt%-6wt%; and when the additives include antimony, the antimony content is 2wt%-10wt%.

2. The intermetallic compound-suppressing multi-element alloy solder according to claim 1, characterized in that: The added elements also include rare earth elements.

3. The intermetallic compound-suppressing multi-element alloy solder according to claim 2, characterized in that: The rare earth element is lanthanum or cerium. When the added element contains a rare earth element, the content of the rare earth element is 0.5wt%-3wt%.

4. The method for preparing an intermetallic compound-suppressing multi-element alloy solder as described in any one of claims 1-3, characterized in that, Specifically, the following steps are included: S1. Take tin, indium, bismuth, antimony and rare earth elements according to the composition ratio; S2. Place the raw materials in a vacuum furnace, evacuate the vacuum, heat up and melt them, and keep them at the temperature after they are completely melted. S3. Stir thoroughly to ensure that all raw materials are evenly mixed; S4. After stirring, pour the alloy melt into a mold, cool and solidify to obtain the target product.

5. The method for preparing an intermetallic compound-suppressing multi-element alloy solder according to claim 4, characterized in that: In step S2, a vacuum is drawn until the pressure is 5 × 10⁻⁶. -3 Pa-1×10 -5 Pa; heat to 300℃-400℃ and hold for 10min-30min.

6. The method for preparing an intermetallic compound-suppressing multi-element alloy solder according to claim 4, characterized in that: In step S2, the heating rate is 5℃ / min-15℃ / min.

7. The method for preparing an intermetallic compound-suppressing multi-element alloy solder according to claim 4, characterized in that: In step S3, the stirring speed is 100rpm-500rpm and the stirring time is 5min-20min.

8. The method for preparing an intermetallic compound-suppressing multi-element alloy solder according to claim 4, characterized in that: In step S4, the cooling rate is 20℃ / min-80℃ / min.

9. The application of the intermetallic compound-suppressing multi-element alloy solder as described in any one of claims 1, characterized in that: The multi-element alloy brazing filler metal is used in the welding of copper base material, with a welding temperature of 180℃-240℃ and a welding time of 10s-90s.

10. The application of the intermetallic compound-suppressing multi-element alloy solder as described in any one of claims 2-3, characterized in that: The multi-element alloy brazing filler metal is used in the welding of aluminum base material, with a welding temperature of 180℃-240℃ and a welding time of 10s-90s.

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