A tin-indium alloy solder and a method for producing the same

Abstract

The application relates to the technical field of sputtering target material processing, in particular to a tin-indium alloy solder and a preparation method thereof. The tin-indium alloy solder comprises the following preparation raw materials in parts by mass: 83-88 parts of tin, 6.8-7.3 parts of zinc, 0.2-0.3 parts of silver, 5.0-5.5 parts of indium, 3.0-3.3 parts of bismuth, 0.005-0.008 parts of phosphorus and 0.2-0.3 parts of an antioxidant improver, wherein the antioxidant improver comprises aluminum, germanium and strontium. The tin-indium alloy solder has the advantages of good wettability, high conductivity, high thermal conductivity and excellent oxidation resistance, is suitable for sputtering target binding, can improve the welding quality and efficiency, and is widely used in welding processes in the related field.

Description

Technical Field

[0001] This application relates to the field of sputtering target processing technology, and in particular to a tin-indium alloy solder and its preparation method. Background Technology

[0002] With the rapid development of the electronics and information industry, the application of thin films is becoming increasingly widespread. Sputtering is one of the main technologies for preparing thin films, and the raw material for sputtering deposition is the target material. The preparation of magnetron sputtering targets mostly employs a bonding method to bind the target material to the substrate. Currently, this bonding technology is divided into two types: one uses conductive adhesive, but due to the relatively low conductivity and bonding strength of conductive adhesive, the bonding effect is poor; the other uses low-temperature solder. The main function of the solder is to connect the components being soldered, forming a channel for the circuit. Therefore, the solder is required to have good conductivity. Simultaneously, because the higher the soldering temperature, the lower the surface tension of the liquid metal, and the better the solder's fluidity, the solder is required to have good thermal conductivity. Currently, low-temperature solders developed include pure indium and pure tin solders. Among them, pure indium solder has good performance, but indium is a rare metal and expensive, which limits its use; pure tin solder has a melting point of 232℃, and the casting temperature needs to be raised to about 350℃, which leads to excessive overheating and easy cracking of the target material. Therefore, the bonding efficiency is reduced and the production cost is increased. In addition, pure tin solder has poor wettability with stainless steel or nickel substrates. Therefore, it is necessary to develop a low-cost tin-indium alloy solder with good wettability, high electrical conductivity, high thermal conductivity and excellent oxidation resistance for bonding sputtering targets. Summary of the Invention

[0003] The purpose of this application is to address the shortcomings of current technologies by providing a tin-indium alloy solder and its preparation method. The tin-indium alloy solder of this application is a low-cost solder with good wettability, high electrical conductivity, high thermal conductivity, and excellent oxidation resistance, specifically designed for sputtering target bonding. Adding silver to the tin-indium alloy solder can improve its mechanical properties, creep resistance, electrical conductivity, and thermal conductivity; adding bismuth can lower the solder's melting point, but excessive bismuth content can lead to a wider solidification temperature range and component segregation. Therefore, the amount of bismuth in the alloy is... The amount added needs to be precisely controlled. Adding indium improves the solder's wettability, electrical conductivity, and thermal conductivity. Adding phosphorus enhances the thermal fatigue resistance of the welded area to heat deformation and stress, preventing coarsening of crystal grains and reducing the possibility of cracks caused by poor welding, ensuring reliable welding. Antioxidant modifiers include aluminum, germanium, and strontium. Aluminum readily forms a dense oxide film on the alloy surface, preventing zinc in the solder from contacting air, thus improving the solder's oxidation resistance and wettability. Germanium enhances the alloy's oxidation resistance through surface segregation, stabilizing tin's performance at high temperatures. Strontium, together with germanium, alters the liquidus temperature of tin, reducing the formation of tin oxide slag. The synergistic effect of aluminum, germanium, and strontium in the antioxidant modifiers gives tin-indium alloy solder excellent oxidation resistance, wettability, and thermal conductivity.

[0004] In a first aspect, this application provides a tin-indium alloy solder, which adopts the following technical solution: A tin-indium alloy solder, by weight, comprises the following raw materials: 83-88 parts tin, 6.8-7.3 parts zinc, 0.2-0.3 parts silver, 5.0-5.5 parts indium, 3.0-3.3 parts bismuth, 0.005-0.008 parts phosphorus, and 0.2-0.3 parts antioxidant, wherein the antioxidant comprises aluminum, germanium, and strontium.

[0005] By adopting the above technical solution, tin, as the main component, provides basic welding performance and has good wettability and conductivity. Zinc plays a role in lowering the melting point of the alloy and improving wettability. Silver improves the mechanical and electrical properties of the solder. Indium enhances the wettability, conductivity, and thermal conductivity of the solder. Bismuth lowers the melting point of the solder, but the amount added needs to be precisely controlled to avoid segregation. Phosphorus improves the thermal fatigue characteristics of the welded part under heat deformation and stress, preventing cracks caused by poor welding. Antioxidant improvers (aluminum, germanium, strontium): aluminum forms an oxide film to prevent oxygen contact and improves oxidation resistance; germanium improves oxidation resistance through surface segregation; strontium, together with germanium, changes the liquidus temperature of tin, reducing the formation of oxide slag. All these components interact in the alloy to form a synergistic effect, making the tin-indium alloy solder low-cost, with good wettability, high conductivity, high thermal conductivity, and excellent oxidation resistance.

[0006] Preferably, the mass ratio of aluminum, germanium and strontium is 3:2:1.

[0007] By adopting the above technical solutions, aluminum readily forms a dense oxide film, effectively preventing zinc in the solder from contacting air, thus improving the solder's oxidation resistance and wetting properties. Germanium, through surface segregation, enhances the alloy's oxidation resistance and stabilizes tin's performance at high temperatures. Strontium, acting synergistically with germanium, can alter the liquidus temperature of tin, reducing the formation of tin oxide slag. These three antioxidants work synergistically in the alloy, giving the tin-indium alloy solder superior oxidation resistance, wettability, and thermal conductivity. Together, they improve the solder material's oxidation resistance during the welding process, preventing oxidation-induced welding defects, while simultaneously improving wettability, resulting in smoother and more reliable welding, thereby ensuring welding quality and efficiency.

[0008] Preferably, the melting point of the tin-indium alloy solder is below 210°C.

[0009] Secondly, this application provides a method for preparing a tin-indium alloy solder, which adopts the following technical solution: As a general technical concept, this application also provides a method for preparing the above-mentioned tin-indium alloy solder, including the following steps: S41, according to the mass fraction, tin and covering agent are heated and melted, zinc, bismuth, indium and silver are added, stirred for 5 minutes, cooled to 400-420℃, phosphorus and antioxidant are added, ultrasonically treated at 20KHz for 5-10 minutes, and then held at the temperature for 50-60 minutes to obtain a molten liquid; S42. The molten liquid is poured into a steel mold cooled by cooling water, and the molten liquid is cooled and solidified to obtain a tin-indium alloy block sample. S43. Place the cast tin-indium alloy block sample into a furnace, perform heat treatment under an inert atmosphere, and cool to obtain tin-indium alloy solder.

[0010] By adopting the above technical solution, in step S41, after tin and the covering agent are heated and melted, zinc, bismuth, indium, and silver are gradually added, stirred for 5 minutes, and phosphorus and antioxidants are added. Then, ultrasonic treatment and heat-holding melting are performed. The main purpose is to fully mix the various raw materials and form a uniform alloy melt. Ultrasonic treatment can promote the formation and growth of crystal nuclei in the molten metal, resulting in a more uniform grain structure and improving the mechanical properties and compositional uniformity of the alloy. In step S42, the melt is poured into a steel mold in cooling water, thereby achieving rapid cooling and solidification. The purpose of this step is to rapidly solidify the solder, refine the alloy grains, reduce the generation of defects, and improve production efficiency. In step S43, the tin-indium alloy block sample obtained by casting is heat-treated under an inert atmosphere and then cooled to obtain tin-indium alloy solder. Homogenizing heat treatment of the tin-indium alloy block sample can effectively improve the distribution of raw material elements in the alloy block sample, enhance the subsequent plastic deformation capacity of the alloy ingot, and ultimately improve the compositional uniformity of the alloy solder. The process is carried out under an inert atmosphere, which prevents the formation of oxides and ensures solder quality. By rationally controlling each step, the entire preparation method results in a tin-indium alloy solder with low cost and excellent performance characteristics, making it suitable for sputtering target bonding and improving welding quality and efficiency.

[0011] Preferably, in step S41, the temperature rise is to heat the temperature to 460-470°C.

[0012] Preferably, in step S41, the covering agent is a LiCl-KCl covering agent; the mass of the covering agent is 10-15% of the mass of tin.

[0013] By employing the above technical solution, the LiCl-KCl covering agent forms a covering liquid during the heating and melting process, effectively isolating the solder from oxygen and thus preventing oxidation from affecting the solder's quality. The LiCl-KCl covering agent reduces the oxygen concentration on the solder surface, decreasing the likelihood of oxidation reactions and helping to maintain the original properties of the metallic elements in the solder. The LiCl-KCl covering agent also helps improve the solder's fluidity and melting uniformity, making it easier to mix various raw materials and form a homogeneous alloy melt. In summary, the LiCl-KCl covering agent plays a role in the preparation of tin-indium alloy solders by providing protection, reducing oxidation, improving wettability, and enhancing metal melt properties.

[0014] Preferably, the mass ratio of LiCl to KCl in the LiCl-KCl covering agent is 3:7.

[0015] Preferably, in step S42, the temperature of the cooling water is between -10°C and 3°C.

[0016] By employing the above-mentioned technical solution and using low-temperature cooling water, the molten tin-indium alloy material can be rapidly cooled to a solid state, promoting rapid solidification of the alloy. This effectively controls the crystallization behavior of the alloy during solidification, which is beneficial for forming a fine and uniform grain structure, improving the mechanical properties and wear resistance of the alloy. In the preparation of tin-indium alloy solder, rapid cooling of the molten liquid with cooling water can effectively avoid the generation of thermal stress. Thermal stress may cause cracks or deformation inside the solder sample, affecting the performance and quality of the solder material. Cooling with low-temperature cooling water can rapidly solidify the tin-indium alloy material, thereby improving production efficiency. Rapid solidification can shorten the production cycle, save production costs, and increase the efficiency of solder preparation. In summary, by controlling the temperature of the cooling water, rapid solidification of the molten tin-indium alloy can be achieved in step S42, avoiding the generation of thermal stress, improving production efficiency, and ultimately affecting the grain structure and performance of the solder.

[0017] Preferably, in step S43, the inert atmosphere is either nitrogen or argon.

[0018] Preferably, in step S43, the heat treatment process conditions are: the heat treatment temperature is 90-110℃, and the heat treatment time is 16-24 hours.

[0019] By employing the above-mentioned technical solution, prolonged heat treatment of tin-indium alloy block samples at 90-110℃ can promote grain recrystallization. Grain recrystallization eliminates residual stress generated during casting and rapid cooling, improves the grain density and uniformity of the solder, thereby enhancing the alloy's mechanical properties and corrosion resistance. Controlling the temperature and time parameters during heat treatment allows for a more uniform distribution of various elements in the alloy, improving the compositional uniformity and consistency of the solder, and enhancing its weldability and oxidation resistance. Appropriate heat treatment temperature and time can promote grain refinement and homogenization in the alloy, reduce grain boundaries and phase boundaries, optimize the microstructure, increase the material's toughness and strength, and improve the alloy's overall performance. Heat treatment at 90-110℃ effectively eliminates residual stress in the solder, reduces deformation and cracking during welding, and ensures stable and reliable welding quality. Therefore, setting the heat treatment process conditions to 90-110℃ for 16-24 hours will help improve the physical, chemical, and process properties of tin-indium alloy solder, ensuring the quality and stability of the welding process.

[0020] In summary, the beneficial technical effects of this application are as follows: 1. Low cost: Due to the reasonable selection of raw materials in the solder formula and the mature production process, low-cost production is achieved.

[0021] 2. Good wettability: Indium in the solder helps improve the wettability of the solder, making the soldering process smoother and effectively coating the soldering area.

[0022] 3. High conductivity: The addition of silver helps to improve the conductivity of the solder, thereby ensuring unobstructed transmission of electrical signals at the soldering point.

[0023] 4. High thermal conductivity: The addition of indium can improve the thermal conductivity of the solder, which helps to quickly transfer heat to the welding parts and improve welding efficiency.

[0024] 5. Excellent antioxidant capacity: The synergistic effect of aluminum, germanium and strontium in the antioxidant improver gives the solder excellent antioxidant properties, reducing the impact of oxidation on welding quality.

[0025] 6. Improve mechanical properties and welding quality: By adding silver to the alloy design, the mechanical properties and creep resistance of the solder are improved. At the same time, elements such as phosphorus are added to improve the thermal fatigue resistance, ensuring the stability of the welded part under thermal deformation and stress, and reducing the occurrence of problems such as cracks caused by poor welding.

[0026] 7. Refining grains and optimizing microstructure: Through processes such as ultrasonic treatment and heat treatment, the formation of grains and the optimization of microstructure can be effectively controlled, thereby improving the strength, toughness and stability of the alloy. Detailed Implementation

[0027] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments used without specified manufacturers are all commercially available conventional products. The purity of all metals used is 99.9%, and the purity of phosphorus is 99.95%.

[0028] Example 1 A tin-indium alloy solder, by mass parts, comprises the following raw materials: 8.3 kg tin, 0.68 kg zinc, 0.02 kg silver, 0.50 kg indium, 0.30 kg bismuth, 0.0005 kg phosphorus, and 0.02 kg antioxidant, wherein the antioxidant is composed of aluminum, germanium, and strontium in a mass ratio of 3:2:1.

[0029] A method for preparing a tin-indium alloy solder includes the following steps: S41. According to the mass fractions, tin and LiCl-KCl covering agent (the mass of LiCl-KCl covering agent is 10% of the mass of tin; the mass ratio of LiCl to KCl in the LiCl-KCl covering agent is 3:7) are heated and melted, the temperature is raised to 460°C, zinc, bismuth, indium and silver are added, stirred for 5 minutes, the temperature is lowered to 400°C, phosphorus and antioxidant improver are added, ultrasonic treatment is performed at 20KHz for 5 minutes, and then the mixture is kept at the temperature and smelted for 50 minutes to obtain a molten liquid; S42. The molten liquid is poured into a steel mold cooled by cooling water at a temperature of 3°C, and the molten liquid is cooled and solidified to obtain a tin-indium alloy block sample. S43. The tin-indium alloy block sample obtained by casting is placed in a furnace and heat-treated under nitrogen atmosphere protection. The heat treatment process conditions are: the heat treatment temperature is 90°C, the heat treatment time is 24 hours, and the tin-indium alloy solder is obtained by cooling.

[0030] Example 2 A tin-indium alloy solder, by mass parts, comprises the following raw materials: 8.8 kg tin, 0.73 kg zinc, 0.03 kg silver, 0.55 kg indium, 0.33 kg bismuth, 0.0008 kg phosphorus, and 0.03 kg antioxidant, wherein the antioxidant is composed of aluminum, germanium, and strontium in a mass ratio of 3:2:1.

[0031] A method for preparing a tin-indium alloy solder includes the following steps: S41. According to the mass fractions, tin and LiCl-KCl covering agent (the mass of LiCl-KCl covering agent is 15% of the mass of tin; the mass ratio of LiCl to KCl in the LiCl-KCl covering agent is 3:7) are heated and melted, the temperature is raised to 470°C, zinc, bismuth, indium and silver are added, stirred for 5 minutes, the temperature is lowered to 420°C, phosphorus and antioxidant improver are added, ultrasonic treatment is performed at 20KHz for 10 minutes, and then the mixture is kept at the temperature and smelted for 60 minutes to obtain a molten liquid; S42. The molten liquid is poured into a steel mold cooled by cooling water at a temperature of -10°C, and the tin-indium alloy block sample is obtained by cooling and solidification. S43. The tin-indium alloy block sample obtained by casting is placed in a furnace and heat-treated under an argon atmosphere. The heat treatment process conditions are: the heat treatment temperature is 110°C and the heat treatment time is 16 hours. After cooling, tin-indium alloy solder is obtained.

[0032] Example 3 A tin-indium alloy solder, by mass parts, comprises the following raw materials: 8.5 kg tin, 0.7 kg zinc, 0.025 kg silver, 0.53 kg indium, 0.32 kg bismuth, 0.0007 kg phosphorus, and 0.025 kg antioxidant, wherein the antioxidant is composed of aluminum, germanium, and strontium in a mass ratio of 3:2:1.

[0033] A method for preparing a tin-indium alloy solder includes the following steps: S41. According to the mass fractions, tin and LiCl-KCl covering agent (the mass of LiCl-KCl covering agent is 13% of the mass of tin; the mass ratio of LiCl to KCl in the LiCl-KCl covering agent is 3:7) are heated and melted, the temperature is raised to 465°C, zinc, bismuth, indium and silver are added, stirred for 5 minutes, the temperature is lowered to 410°C, phosphorus and antioxidant improver are added, ultrasonic treatment is performed at 20KHz for 8 minutes, and then the mixture is kept at the temperature and smelted for 55 minutes to obtain a molten liquid; S42. The molten liquid is poured into a steel mold cooled by cooling water at a temperature of -3°C, and the molten liquid is cooled and solidified to obtain a tin-indium alloy block sample. S43. The tin-indium alloy block sample obtained by casting is placed in a furnace and heat-treated under nitrogen atmosphere protection. The heat treatment process conditions are: the heat treatment temperature is 100°C, the heat treatment time is 20 hours, and the tin-indium alloy solder is obtained by cooling.

[0034] Example 4 Same as Example 3, except that germanium is 0.01 kg and cerium is 0.005 kg.

[0035] Comparative Example 1 Similar to Example 3, except that no silver was added to the raw materials.

[0036] Comparative Example 2 Similar to Example 3, except that no phosphorus was added to the raw materials.

[0037] Comparative Example 3 Similar to Example 3, except that the antioxidant improver is aluminum.

[0038] Comparative Example 4 Same as in Example 3, except that the antioxidant improver is germanium.

[0039] Comparative Example 5 Same as in Example 3, except that the antioxidant improver is strontium.

[0040] Comparative Example 6 Similar to Example 3, except that the temperature of the cooling water is 20°C.

[0041] Comparative Example 7 Similar to Example 3, except that step S43 was not performed, i.e., the tin-indium alloy block sample obtained by casting was not subjected to heat treatment.

[0042] Performance testing Samples of the tin-indium alloy solders prepared in Examples 1-3 and Comparative Examples 1-7 were taken and made into tin-indium alloy solders. Pure indium and pure tin were used as control examples for performance testing. Melting point: The melting temperature of the solder alloy was measured using a DiamondOsc differential scanning calorimeter. The mass of the sample was approximately 10 mg, the test temperature range was 50-450℃, and the heating rate was 10℃ / min. Resistivity: The resistivity of the solder alloy was measured using a 44-type double-arm bridge. The sample size was 10mm×10mm×100mm. Wetting angle: The wetting performance of solder alloy and nickel substrate was measured using ZDF-5227 high temperature and high vacuum wettability testing equipment, and the wetting angle was measured using the wettability measuring instrument attached to the equipment. The test temperature was 300℃, the holding time was 30min, and the sample size was 3mm×3mm×3mm. Thermal conductivity: The thermal conductivity of the solder alloy was measured using a DynaCool thermal conductivity meter. The test temperature range was 37-97℃, and the sample size was 2mm×2mm×8mm. Elongation test: The test is conducted according to GB / 11364-89 "Test method for spreadability and filler properties of solder". The greater the elongation, the better the solderability of the tin-indium alloy solder. Antioxidant properties: Antioxidant properties were tested by static oxidation method. The furnace temperature was 270℃, the mass was 500g, the slag was scraped once every 60s, and the slag was taken once every 5min. Each group was tested 3 times, and the average value of the 3 tests was taken.

[0043] Table 1 Performance Tests In the table, “—” indicates that no test was performed.

[0044] Analyzing the data in Table 1, we can see that: 1) The tin-indium alloy solders prepared in Examples 1-3 have advantages such as good wettability, high solderability, high thermal conductivity and excellent oxidation resistance. At the same time, the resistivity is close to that of pure tin, making it suitable for sputtering target bonding. It can improve welding quality and efficiency and is widely used in welding processes in related fields.

[0045] 2) The performance comparison analysis of the tin-indium alloy solders prepared in Example 3 and Comparative Example 1 shows that adding an appropriate amount of silver can improve its mechanical properties, creep resistance, electrical conductivity, and thermal conductivity.

[0046] 3) The performance comparison analysis of the tin-indium alloy solders prepared in Example 3 and Comparative Example 2 shows that the addition of phosphorus can improve the thermal fatigue characteristics of the welded part under thermal deformation and stress, prevent the coarsening of crystal grains, reduce the possibility of cracks caused by poor welding, and ensure reliable welding.

[0047] 4) A comparative analysis of the performance of the tin-indium alloy solders prepared in Example 3 and Comparative Examples 3-5 shows that the use of an antioxidant (aluminum, germanium, and strontium in a mass ratio of 3:2:1) and the synergistic effects of aluminum, germanium, and strontium in the alloy result in tin-indium alloy solders with superior oxidation resistance, wettability, and thermal conductivity. These components work together during the welding process to improve the oxidation resistance of the solder material, preventing poor welding caused by oxidation, while simultaneously improving the wettability of the solder, making welding smoother and more reliable, thereby ensuring welding quality and efficiency.

[0048] 5) A comparative analysis of the performance of the tin-indium alloy solders prepared in Example 3 and Comparative Example 6 shows that by using low-temperature cooling water, the tin-indium alloy material in the molten liquid can be rapidly cooled to a solid state, promoting rapid solidification of the alloy. This effectively controls the crystallization behavior of the alloy during solidification, which is beneficial for forming a fine and uniform grain structure and improving the mechanical properties of the alloy.

[0049] 6) A comparative analysis of the performance of the tin-indium alloy solders prepared in Example 3 and Comparative Example 7 shows that prolonged heat treatment of the tin-indium alloy block samples at 90-110℃ can promote the recrystallization of the alloy grains. Grain recrystallization can eliminate residual stress generated during the casting process and rapid cooling, improve the grain density and uniformity of the solder, and thus enhance the mechanical properties of the alloy. Controlling the temperature and time parameters during the heat treatment process allows for a more uniform distribution of various elements in the alloy, thereby improving the compositional uniformity and consistency of the solder, and enhancing its welding performance and oxidation resistance.

[0050] The above embodiments are only used to explain the technical solutions of this application and are not intended to limit it. Although the above embodiments have provided specific descriptions of this application, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this invention. Any modifications and equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of this application.

Claims

1. A method for preparing a tin-indium alloy solder, characterized in that, Includes the following steps: S41. According to the mass fraction, heat and melt tin and covering agent, raise the temperature, add zinc, bismuth, indium and silver, stir for 5 minutes, cool to 400-420℃, add phosphorus and antioxidant improver, ultrasonically treat at 20KHz for 5-10 minutes, and then heat and melt for 50-60 minutes to obtain molten liquid; S42. Cast the molten liquid into a steel mold cooled by cooling water, and cool and solidify to obtain tin-indium alloy block sample; S43. Place the cast tin-indium alloy block sample into a furnace, perform heat treatment under inert atmosphere protection, and cool to obtain tin-indium alloy solder; The covering agent is a LiCl-KCl covering agent; the mass of the covering agent is 10-15% of the mass of tin; The mass ratio of LiCl to KCl in the LiCl-KCl covering agent is 3:7; The amounts of each raw material, by weight, are as follows: 83-88 parts tin, 6.8-7.3 parts zinc, 0.2-0.3 parts silver, 5.0-5.5 parts indium, 3.0-3.3 parts bismuth, 0.005-0.008 parts phosphorus, and 0.2-0.3 parts antioxidant improver, wherein the antioxidant improver is aluminum, germanium, and strontium; The mass ratio of aluminum, germanium, and strontium is 3:2:1; The melting point of the tin-indium alloy solder is below 210°C; In step S41, the temperature is raised to 460-470℃; In step S43, the heat treatment process conditions are: the heat treatment temperature is 90-110℃, and the heat treatment time is 16-24 hours.

2. The method for preparing a tin-indium alloy solder according to claim 1, characterized in that, In step S43, the inert atmosphere is either nitrogen or argon.

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