A high-strength solder alloy for heat-conducting semiconductor packaging and a method for preparing the same

Abstract

The application relates to the technical field of soldering materials, in particular to a high-strength heat-conducting solder alloy for semiconductor packaging and a preparation method thereof. The high-strength heat-conducting solder alloy for semiconductor packaging comprises the following preparation raw materials in parts by mass: 97-98 parts of tin, 0.4-0.6 parts of copper, 0.6-0.8 parts of silver, 0.008-0.011 parts of germanium, 0.01-0.018 parts of phosphorus and 0.8-1.2 parts of copper-nickel-graphene intermediate alloy. The high-strength heat-conducting solder alloy for semiconductor packaging and the preparation method thereof not only have excellent oxidation resistance and low slag production rate, but also have excellent mechanical properties and heat conduction properties, and are particularly suitable for the packaging requirements of high-performance electronic equipment.

Description

Technical Field

[0001] The present application relates to the technical field of solder materials, and in particular to a high-strength thermally conductive solder alloy for semiconductor packaging and a preparation method thereof. Background Art

[0002] Currently, the solder alloys widely used in the semiconductor packaging field primarily include Sn-Pb and Sn-Ag-Cu systems. However, with increasingly stringent environmental protection requirements, lead-free solders are gradually becoming mainstream. However, lead-free solders generally suffer from issues such as high melting points, poor wettability, and poor mechanical properties. This is particularly true for high-frequency, high-speed signal transmission and heat dissipation in high-power devices. Existing lead-free solder materials often struggle to meet the dual requirements of high strength and good thermal conductivity.

[0003] Existing lead-free solder materials are prone to microcracks in high-temperature working environments, resulting in reduced reliability of the connection parts; at the same time, the thermal conductivity coefficient is generally low, which cannot effectively dissipate the heat generated by high-power consumption components, thus restricting the further improvement of the performance of electronic products. Summary of the Invention

[0004] The purpose of this application is to address the deficiencies in current technology and provide a high-strength thermal conductive solder alloy for semiconductor packaging and a preparation method thereof. The high-strength thermal conductive solder alloy for semiconductor packaging of the present application has high oxidation resistance, low slag production rate, mechanical properties and thermal conductivity. By adding copper-nickel-graphene intermediate alloy, not only the overall hardness and wear resistance of the material are improved, but also the thermal conductivity is significantly enhanced. It is particularly suitable for use in the packaging of high-density integrated circuits in high-performance electronic devices, solving the problems of low stability and heat dissipation efficiency of traditional solder materials at high temperatures. The addition of trace amounts of phosphorus and germanium has no significant effect on the melting temperature of the solder alloy, but reduces the slag production and improves the oxidation resistance of the solder alloy. In addition, the preparation method of the present application is simple, with high production efficiency and low cost.

[0005] In the first aspect, the present application provides a solder alloy for high-strength thermal conductive semiconductor packaging, adopting the following technical solution: a solder alloy for high-strength thermal conductive semiconductor packaging, comprising the following raw materials, calculated by mass: 97-98 parts of tin, 0.4-0.6 parts of copper, 0.6-0.8 parts of silver, 0.008-0.011 parts of germanium, 0.01-0.018 parts of phosphorus, and 0.8-1.2 parts of copper-nickel-graphene intermediate alloy.

[0006] By adopting the above technical solution, this high-strength and thermally conductive solder alloy for semiconductor packaging contains multiple elements, each of which plays a unique role in the alloy: Tin: As the main component, tin provides good electrical conductivity and a low melting point, making it easy to melt and form a strong connection after cooling. Copper: A small amount of copper increases the alloy's hardness and wear resistance, while also improving its thermal conductivity. Silver: The addition of silver further enhances the alloy's electrical and thermal conductivity, while also improving its corrosion resistance. Germanium: Although the amount of germanium is extremely small, it helps lower the melting temperature of the solder alloy and improves its oxidation resistance. Phosphorus: Trace amounts of phosphorus also help improve oxidation resistance and reduce slag production during the soldering process. Copper-nickel-graphene master alloy: This composite master alloy significantly improves the overall hardness, wear resistance, and thermal conductivity of the solder alloy, making it particularly suitable for high-density integrated circuit packaging. It solves the problems of traditional solder materials' insufficient stability and heat dissipation efficiency at high temperatures. High oxidation resistance: The addition of germanium and phosphorus effectively improves the alloy's oxidation resistance. Low slag production: Trace amounts of germanium and phosphorus reduce slag production during the soldering process. Mechanical Properties and Thermal Conductivity: Copper, silver, and the copper-nickel-graphene master alloy collectively enhance the alloy's hardness, wear resistance, and thermal conductivity. Uniform Dispersion: The copper-nickel-graphene master alloy's preparation process ensures uniform dispersion of graphene, further optimizing the alloy's microstructure and improving its overall performance. Overall, this solder alloy, through its carefully designed composition ratios and preparation process, achieves excellent mechanical properties, thermal conductivity, and oxidation resistance, making it ideal for high-density integrated circuit packaging in high-performance electronic devices.

[0007] Preferably, the mass ratio of the germanium to the phosphorus is 1:1.5.

[0008] By adopting the above technical solution, the mass ratio of germanium to phosphorus is 1:1.5. This ratio is designed to ensure that the solder alloy has high oxidation resistance, low slag production, excellent mechanical properties, and thermal conductivity, while reducing production costs. Germanium is a semiconductor element, and its addition can improve the thermal stability and oxidation resistance of the solder alloy. It also improves the electrical and thermal conductivity of the solder alloy, thereby enhancing its application in high-density integrated circuit packaging. Phosphorus is a non-metallic element, and its addition can lower the melting point of the solder alloy, improve its fluidity and spreadability, thereby reducing slag production. Phosphorus also improves the corrosion resistance and oxidation resistance of the solder alloy. By setting the mass ratio of germanium to phosphorus to 1:1.5, the excellent performance of the solder alloy can be guaranteed while reducing production costs. This ratio also allows germanium and phosphorus to form a stable compound in the solder alloy, further improving the performance of the solder alloy.

[0009] Preferably, the copper-nickel-graphene master alloy comprises the following raw materials, calculated by mass: 15 parts of graphene oxide, 850 parts of ethanol, 15.3 parts of nickel acetate, 60.2 parts of pure copper powder, 4 parts of dopamine and 150 parts of tris(hydroxymethyl)aminomethane hydrochloride solution with a pH of 7.0.

[0010] Preferably, the method for preparing the copper-nickel-graphene master alloy comprises the following steps:

[0011] S41. Mixing graphene oxide, dopamine, and ethanol according to parts by mass to prepare a graphene oxide dispersion;

[0012] S42. Add nickel acetate, pure copper powder and tris(hydroxymethyl)aminomethane hydrochloride) solution with a pH of 7.0 to the graphene oxide dispersion according to their mass fractions, stir evenly, heat to 50-55°C, react for 5-8 hours, concentrate to dryness, and collect the solid phase; S43. Calcine the solid phase at 1170-1190°C in a reducing atmosphere for 3-4 hours, cool to room temperature, and obtain a copper-nickel-graphene intermediate alloy.

[0013] By employing the above technical solution, during the preparation of a copper-nickel-graphene master alloy, the abundant oxygen-containing functional groups on the surface of graphene oxide are utilized. Dopamine is then used to nitrogen-modify the graphene oxide. The nitrogen-containing and oxygen-containing functional groups enable the thorough dispersion of nickel and pure copper powder, resulting in a master alloy with smaller and more uniform particle size distribution. This further improves the dispersibility of these components in the final solder alloy, achieving uniform dispersion of graphene, a more stable structure, and finer grains. The resulting solder alloy exhibits excellent mechanical and heat dissipation properties. The addition of the copper-nickel-graphene master alloy significantly improves the overall hardness and wear resistance of the solder alloy. This is particularly important for the packaging of high-density integrated circuits in high-performance electronic devices, where materials with higher mechanical strength and wear resistance are required. As a highly thermally conductive material, the addition of graphene can significantly enhance the thermal conductivity of the solder alloy. This is crucial for addressing the poor heat dissipation efficiency of traditional solder materials at high temperatures, thereby improving the stability and reliability of electronic devices. The abundant oxygen-containing functional groups on the graphene oxide surface and the nitrogen modification of dopamine enable the thorough dispersion of nickel and pure copper powder, resulting in a master alloy with smaller particle size and more uniform distribution. This helps further improve the dispersion of graphene in the final solder alloy, preventing agglomeration. Due to the uniform dispersion and more stable structure of graphene, the resulting solder alloy exhibits excellent mechanical and heat dissipation properties, which is of great significance for improving the application performance of solder alloys.

[0014] Preferably, in step S43, the reducing gas consists of argon and hydrogen, the volume percentage of argon in the reducing gas is 75-80%, and the balance is hydrogen; the flow rate of the reducing gas is 4.5 L / min.

[0015] Preferably, the graphene oxide has a sheet diameter of 0.5 μm-2 μm and a thickness of 0.8 nm-1.5 nm, and the pure copper powder has a purity of 99.99% and a particle size of 1-2 microns.

[0016] In a second aspect, the present application provides a method for preparing a high-strength thermally conductive solder alloy for semiconductor packaging, which adopts the following technical solution:

[0017] As a general technical concept, the present application also provides a method for preparing the above-mentioned high-strength thermally conductive solder alloy for semiconductor packaging, comprising the following steps:

[0018] S71. Evenly mix tin, copper, silver, and germanium raw materials in proportion according to their weight, preheat to 150-200° C., remove the surface oxide layer, and obtain a mixture;

[0019] S72. Under an argon atmosphere, the mixture is fed into an induction furnace, and the temperature is increased to fully melt the mixture into a liquid state, thereby obtaining a molten alloy A. S73. Phosphorus and a copper-nickel-graphene master alloy are sequentially added to the molten alloy A, and the temperature is increased and stirred to fully melt the mixture into a liquid state, thereby obtaining a molten alloy B.

[0020] S74. Casting the alloy melt B into a mold preheated to 100° C. and cooling it into shape, then performing a first vacuum annealing heat treatment and a second vacuum annealing heat treatment, and finally rapidly cooling it to room temperature to obtain a high-strength thermally conductive solder alloy for semiconductor packaging.

[0021] Preferably, in step S72, the heating is performed by heating to 360-400°C.

[0022] Preferably, in step S73, the heating is heating to 440-450° C.; the stirring is stirring at a speed of 400-500 rpm for 15-20 minutes.

[0023] Preferably, in step S74, the temperature of the first vacuum annealing heat treatment is 250°C-280°C, the time is 1h-2h, and the vacuum degree is 1kPa; the temperature of the second vacuum annealing heat treatment is 220°C-240°C, the time is 1h-2h, and the vacuum degree is 1kPa.

[0024] By adopting the above technical solution, the first and second vacuum annealing heat treatments play a vital role in the preparation process of solder alloys for high-strength thermal conductivity semiconductor packaging, which is specifically reflected in the following aspects: 1. Promote grain recrystallization: The temperature of the first vacuum annealing heat treatment is relatively high, which helps to eliminate the residual stress generated by the alloy during the casting process and rapid cooling, and promotes grain recrystallization. Through grain recrystallization, the grain density and uniformity of the solder can be improved, thereby improving the mechanical properties and corrosion resistance of the solder alloy. The temperature of the second vacuum annealing heat treatment is relatively low, which helps to further optimize the microstructure of the alloy and make the various elements more evenly distributed. This uniform element distribution can improve the composition uniformity and consistency of the solder alloy, thereby improving its welding performance, antioxidant properties and heat dissipation performance. 3. Improve mechanical properties and corrosion resistance: Through two vacuum annealing heat treatments at different temperatures, the microstructure and composition distribution of the solder alloy can be gradually adjusted and optimized, thereby improving its overall mechanical properties and corrosion resistance. This is particularly important for the packaging of high-density integrated circuits in high-performance electronic devices, because in this environment, the material needs to have higher mechanical strength and corrosion resistance. 4. Improve welding performance and oxidation resistance: Controlling the temperature and time parameters during the vacuum annealing heat treatment process can make the various elements in the alloy more evenly distributed, thereby improving the welding performance and oxidation resistance of the solder alloy. This is of great significance for improving the application performance of the solder alloy. 5. Improve production efficiency and reduce costs: Through a reasonable vacuum annealing process, while ensuring the performance of the solder alloy, production costs can be reduced and production efficiency can be improved. In summary, the first and second vacuum annealing heat treatments in step S74 play a vital role in the preparation process of the solder alloy for high-strength thermal conductive semiconductor packaging. They work together to improve the mechanical properties, corrosion resistance, welding performance and oxidation resistance of the solder alloy, thereby meeting the needs of high-density integrated circuit packaging in high-performance electronic devices.

[0025] In summary, the beneficial technical effects of this application are:

[0026] 1. High oxidation resistance: The oxidation resistance of the solder alloy is significantly improved by adding trace amounts of phosphorus and germanium. Although these trace elements do not significantly change the melting temperature, they effectively reduce the formation of oxides during the soldering process, thereby reducing the slag rate.

[0027] 2. Low slag production rate: Due to the addition of phosphorus and germanium, the amount of slag produced by the solder alloy during melting and welding is significantly reduced, which not only improves welding quality and efficiency, but also reduces the complexity of subsequent cleaning work.

[0028] 3. Excellent mechanical properties: By adding a copper-nickel-graphene master alloy, the overall hardness and wear resistance of the solder alloy are significantly enhanced. This master alloy achieves a uniform dispersion of nickel and pure copper powder through nitrogen-modified graphene oxide, thereby improving the mechanical properties of the solder alloy.

[0029] 4. Excellent thermal conductivity: The introduction of graphene significantly improves the thermal conductivity of solder alloys, making them particularly suitable for the packaging of high-density integrated circuits in high-performance electronic devices, solving the problem of low heat dissipation efficiency of traditional solder materials in high-temperature environments.

[0030] 5. Efficient Preparation Process: The preparation method of this application is simple and efficient, including preheating to remove the oxide layer, smelting, adding trace elements, casting, and two vacuum annealing heat treatment steps. The entire process is easy to operate, highly efficient, and low-cost.

[0031] 6. Uniform microstructure: Through strict vacuum annealing heat treatment, the residual stress in the alloy is eliminated, the grains are refined and evenly distributed, thereby further improving the mechanical properties and corrosion resistance of the solder alloy. DETAILED DESCRIPTION

[0032] The embodiments of the present application will be described in detail below with reference to the examples. However, those skilled in the art will appreciate that the following examples are intended to illustrate the present application only and should not be construed as limiting the scope of the present application. Where specific conditions are not specified in the examples, conventional conditions or those recommended by the manufacturer were followed. Reagents and instruments used, where the manufacturer is not specified, are commercially available conventional products. The purity of all metals used was 99.9%, and the purity of phosphorus was 99.95%.

[0033] In the following examples and preparation examples, 1 part means 100 g.

[0034] Preparation Example 1 Preparation of copper-nickel-graphene master alloy

[0035] A copper-nickel-graphene master alloy comprises the following raw materials, calculated by mass: 15 parts of graphene oxide, 850 parts of ethanol, 15.3 parts of nickel acetate, 60.2 parts of pure copper powder, 4 parts of dopamine, and 150 parts of tris(hydroxymethyl)aminomethane hydrochloride solution with a pH of 7.0; the graphene oxide has a flake diameter of 0.5 μm to 2 μm and a thickness of 0.8 nm to 1.5 nm; the pure copper powder has a purity of 99.99% and a particle size of 1 to 2 microns;

[0036] The preparation method of the copper-nickel-graphene master alloy comprises the following steps:

[0037] S41. Mixing graphene oxide, dopamine, and ethanol according to parts by mass to prepare a graphene oxide dispersion;

[0038] S42. Add nickel acetate, pure copper powder, and tris(hydroxymethyl)aminomethane hydrochloride) solution with a pH of 7.0 to the graphene oxide dispersion according to their weight parts, stir them evenly, heat them to 50° C., react for 8 hours, concentrate them to dryness, and collect the solid phase;

[0039] S43. Calcine the solid phase at 1170° C. for 4 hours in a reducing atmosphere, and cool to room temperature to obtain a copper-nickel-graphene master alloy; wherein the reducing gas is composed of argon and hydrogen, the volume percentage of argon in the reducing gas is 75%, and the balance is hydrogen; and the flow rate of the reducing gas is 4.5 L / min.

[0040] Preparation Example 2 Preparation of Copper-Nickel-Graphene Master Alloy

[0041] A copper-nickel-graphene master alloy comprises the following raw materials, calculated by mass: 15 parts of graphene oxide, 850 parts of ethanol, 15.3 parts of nickel acetate, 60.2 parts of pure copper powder, 4 parts of dopamine, and 150 parts of tris(hydroxymethyl)aminomethane hydrochloride solution with a pH of 7.0; the graphene oxide has a flake diameter of 0.5 μm to 2 μm and a thickness of 0.8 nm to 1.5 nm; the pure copper powder has a purity of 99.99% and a particle size of 1 to 2 microns;

[0042] The preparation method of the copper-nickel-graphene master alloy comprises the following steps:

[0043] S41. Mixing graphene oxide, dopamine, and ethanol according to parts by mass to prepare a graphene oxide dispersion;

[0044] S42. Add nickel acetate, pure copper powder, and tris(hydroxymethylaminomethane) hydrochloride solution (pH 7.0) to the graphene oxide dispersion according to their weight fractions, stir evenly, heat to 55° C., react for 5 hours, concentrate to dryness, and collect the solid phase;

[0045] S43. Calcine the solid phase at 1190° C. for 3 hours in a reducing atmosphere, and cool to room temperature to obtain a copper-nickel-graphene master alloy; wherein the reducing gas is composed of argon and hydrogen, the volume percentage of argon in the reducing gas is 80%, and the balance is hydrogen; and the flow rate of the reducing gas is 4.5 L / min.

[0046] Preparation Example 3 Preparation of Copper-Nickel-Graphene Master Alloy

[0047] A copper-nickel-graphene master alloy comprises the following raw materials, calculated by mass: 15 parts of graphene oxide, 850 parts of ethanol, 15.3 parts of nickel acetate, 60.2 parts of pure copper powder, 4 parts of dopamine, and 150 parts of tris(hydroxymethyl)aminomethane hydrochloride solution with a pH of 7.0; the graphene oxide has a flake diameter of 0.5 μm to 2 μm and a thickness of 0.8 nm to 1.5 nm; the pure copper powder has a purity of 99.99% and a particle size of 1 to 2 microns;

[0048] The preparation method of the copper-nickel-graphene master alloy comprises the following steps:

[0049] S41. Mixing graphene oxide, dopamine, and ethanol according to parts by mass to prepare a graphene oxide dispersion;

[0050] S42. Add nickel acetate, pure copper powder, and tris(hydroxymethylaminomethane) hydrochloride solution (pH 7.0) to the graphene oxide dispersion according to their weight fractions, stir evenly, heat to 53° C., react for 7 hours, concentrate to dryness, and collect the solid phase;

[0051] S43. Calcine the solid phase at 1180° C. for 3.4 hours in a reducing atmosphere, and cool to room temperature to obtain a copper-nickel-graphene master alloy; wherein the reducing gas is composed of argon and hydrogen, the volume percentage of argon in the reducing gas is 78%, and the balance is hydrogen; and the flow rate of the reducing gas is 4.5 L / min.

[0052] Example 1

[0053] A high-strength thermally conductive solder alloy for semiconductor packaging, comprising the following raw materials, calculated by mass: 97 parts of tin, 0.4 parts of copper, 0.6 parts of silver, 0.008 parts of germanium, 0.01 parts of phosphorus, and 0.8 parts of a copper-nickel-graphene master alloy; the copper-nickel-graphene master alloy is prepared according to Preparation Example 1;

[0054] The method for preparing the above-mentioned high-strength thermally conductive solder alloy for semiconductor packaging comprises the following steps:

[0055] S71. Evenly mix tin, copper, silver, and germanium raw materials in proportion according to their weight, preheat to 150° C., remove the surface oxide layer, and obtain a mixture;

[0056] S72. Under an argon atmosphere, the mixed material is placed in an induction furnace and heated to 360° C. to fully melt the mixed material into a liquid state, thereby obtaining alloy melt A.

[0057] S73, adding phosphorus and copper-nickel-graphene master alloy to alloy melt A in sequence, raising the temperature to 440° C., stirring at a stirring speed of 400 rpm, and stirring for 20 minutes to fully melt the alloy into a liquid state, thereby obtaining alloy melt B;

[0058] S74. Cast the alloy melt B into a mold preheated to 100°C and cool it into shape, then perform a first vacuum annealing heat treatment and a second vacuum annealing heat treatment, and finally quickly cool it to room temperature to obtain a high-strength thermal conductive solder alloy for semiconductor packaging; the temperature of the first vacuum annealing heat treatment is 250°C, the time is 2h, and the vacuum degree is 1kPa; the temperature of the second vacuum annealing heat treatment is 220°C, the time is 2h, and the vacuum degree is 1kPa.

[0059] Example 2

[0060] A high-strength thermally conductive solder alloy for semiconductor packaging, comprising the following raw materials, calculated by mass: 98 parts of tin, 0.6 parts of copper, 0.8 parts of silver, 0.011 parts of germanium, 0.018 parts of phosphorus, and 1.2 parts of a copper-nickel-graphene master alloy; the copper-nickel-graphene master alloy is prepared according to Preparation Example 2;

[0061] The method for preparing the above-mentioned high-strength thermally conductive solder alloy for semiconductor packaging comprises the following steps:

[0062] S71. Evenly mix tin, copper, silver, and germanium raw materials in proportion according to their weight, preheat to 200° C., remove the surface oxide layer, and obtain a mixture;

[0063] S72. Under an argon atmosphere, the mixed material is placed in an induction furnace and heated to 400° C. to fully melt the mixed material into a liquid state, thereby obtaining alloy melt A.

[0064] S73, adding phosphorus and copper-nickel-graphene master alloy to alloy melt A in sequence, raising the temperature to 450° C., stirring at a stirring speed of 500 rpm, and stirring for 15 minutes to fully melt the alloy into a liquid state, thereby obtaining alloy melt B;

[0065] S74. Cast the alloy melt B into a mold preheated to 100°C and cool it into shape, then perform a first vacuum annealing heat treatment and a second vacuum annealing heat treatment, and finally quickly cool it to room temperature to obtain a high-strength thermal conductive solder alloy for semiconductor packaging; the first vacuum annealing heat treatment is performed at a temperature of 280°C, a time of 1 hour, and a vacuum degree of 1 kPa; the second vacuum annealing heat treatment is performed at a temperature of 240°C, a time of 1 hour, and a vacuum degree of 1 kPa.

[0066] Example 3

[0067] A high-strength thermally conductive solder alloy for semiconductor packaging, comprising the following raw materials, calculated by mass: 97.5 parts of tin, 0.5 parts of copper, 0.7 parts of silver, 0.009 parts of germanium, 0.012 parts of phosphorus, and 1 part of a copper-nickel-graphene master alloy; the copper-nickel-graphene master alloy is prepared according to Preparation Example 3;

[0068] The method for preparing the above-mentioned high-strength thermally conductive solder alloy for semiconductor packaging comprises the following steps:

[0069] S71. Evenly mix tin, copper, silver, and germanium raw materials in proportion according to their weight, preheat to 180° C., remove the surface oxide layer, and obtain a mixture;

[0070] S72. Under an argon atmosphere, the mixed material is placed in an induction furnace and heated to 390° C. to fully melt the mixed material into a liquid state, thereby obtaining alloy melt A.

[0071] S73, adding phosphorus and copper-nickel-graphene master alloy to alloy melt A in sequence, raising the temperature to 445° C., stirring at a stirring speed of 450 rpm, and stirring for 17 minutes to fully melt the mixture into a liquid state, thereby obtaining alloy melt B;

[0072] S74. Cast the alloy melt B into a mold preheated to 100°C and cool it into shape, then perform a first vacuum annealing heat treatment and a second vacuum annealing heat treatment, and finally quickly cool it to room temperature to obtain a high-strength thermal conductive solder alloy for semiconductor packaging; the temperature of the first vacuum annealing heat treatment is 270°C, the time is 1.4h, and the vacuum degree is 1kPa; the temperature of the second vacuum annealing heat treatment is 230°C, the time is 1.4h, and the vacuum degree is 1kPa.

[0073] Example 4

[0074] The same as Example 3, except that 0.010 parts of germanium and 0.015 parts of phosphorus are used.

[0075] Comparative Example 1

[0076] The same as Example 4, except that 0 parts of germanium and 0 parts of phosphorus are used.

[0077] Comparative Example 2

[0078] The same as Example 4, except that an equal amount of a mixed material (graphene oxide, pure nickel powder with a particle size of 2 microns and pure copper powder with a particle size of 1-2 microns mixed in a mass ratio of 15:3.7:60.2) is used instead of the copper-nickel-graphene master alloy.

[0079] Comparative Example 3

[0080] The same as embodiment 4, except that, in step S74, there is only the first vacuum annealing heat treatment and no second vacuum annealing heat treatment.

[0081] Comparative Example 4

[0082] The same as embodiment 4, except that, in step S74, there is no first vacuum annealing heat treatment, but only a second vacuum annealing heat treatment.

[0083] Performance Testing

[0084] The high-strength thermally conductive solder alloys for semiconductor packaging prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were sampled and made into welding rods for performance testing.

[0085] Melting point: The melting temperature of the solder alloy was measured using a Diamondosc differential scanning calorimeter. The sample mass was approximately 10 mg, the test temperature range was 50-450°C, and the heating rate was 10°C / min.

[0086] Wetting angle: measured using IPC-TM-6502.4.45 test method;

[0087] Thermal conductivity: The thermal conductivity of the solder alloy was measured using a DynaCool thermal conductivity meter in a test temperature range of 37-97°C and a sample size of 2 mm × 2 mm × 8 mm.

[0088] Elongation test: The test is conducted according to GB / 11364-89 "Test method for solder spreadability and filleting performance". The greater the elongation, the better the solderability of the solder alloy for high-strength thermal conductive semiconductor packaging.

[0089] Oxidation resistance: The oxidation resistance was tested by static oxidation method. The furnace temperature was 270℃, the mass was 500g, the slag was scraped every 60s, and the slag was taken every 5min. Each group of tests was repeated 3 times, and the average value of the 3 times was taken.

[0090] Corrosion resistance test: Determined using IPC-TM-6502.6.15 test method.

[0091] Table 1 Performance test

[0092]

[0093]

[0094] Analyzing the data in Table 1, we can see that:

[0095] 1) The high-strength and thermally conductive solder alloys for semiconductor packaging prepared in Examples 1 to 4 have high oxidation resistance, low slag production rate, mechanical properties, and thermal conductivity.

[0096] 2) A comparative analysis of the performance of the high-strength, thermally conductive solder alloys for semiconductor packaging prepared in Example 4, Example 3, and Comparative Example 1 shows that the mass ratio of germanium to phosphorus is 1:1.5. This ratio is designed to ensure that the solder alloy has high oxidation resistance, low slag production, excellent mechanical properties, and thermal conductivity while reducing production costs. By setting the mass ratio of germanium to phosphorus to 1:1.5, the excellent performance of the solder alloy can be maintained while reducing production costs. This ratio also allows germanium and phosphorus to form a stable compound in the solder alloy, further improving the performance of the solder alloy.

[0097] 3) A comparative analysis of the performance of the high-strength, thermally conductive solder alloy for semiconductor packaging prepared in combination with Example 4 and Comparative Example 2 shows that in the preparation process of the copper-nickel-graphene master alloy, the graphene oxide surface is rich in oxygen-containing functional groups, and dopamine is used to nitrogen-modify the graphene oxide. The nitrogen-containing groups and oxygen-containing functional groups are used to fully disperse the nickel element and pure copper powder, thereby obtaining a master alloy with a smaller particle size and more uniform distribution; thereby further improving the dispersibility of the above components in the final solder alloy, achieving uniform dispersion of graphene, a more stable structure, and more refined grains. The prepared solder alloy exhibits excellent mechanical properties and heat dissipation performance. By adding the copper-nickel-graphene master alloy, the overall hardness and wear resistance of the solder alloy can be significantly improved. This is particularly important for the packaging of high-density integrated circuits in high-performance electronic devices, because in this environment, the material needs to have higher mechanical strength and wear resistance. As a high thermal conductivity material, the addition of graphene can significantly enhance the thermal conductivity of the solder alloy. This is of great significance in addressing the problem of poor heat dissipation efficiency of traditional solder materials at high temperatures, helping to improve the stability and reliability of electronic devices. The abundant oxygen-containing functional groups on the surface of graphene oxide and the nitrogen modification of dopamine enable the full dispersion of nickel and pure copper powder, resulting in an intermediate alloy with smaller particle size and more uniform distribution. This helps further improve the dispersion of graphene in the final solder alloy, preventing agglomeration. Due to the uniform dispersion of graphene and its more stable structure, the resulting solder alloy exhibits excellent mechanical and heat dissipation properties. This is of great significance for improving the application performance of solder alloys.

[0098] 4) The performance comparison analysis of the high-strength thermal conductive semiconductor encapsulation solder alloy prepared in combination with Example 3 and Comparative Examples 3-4 shows that the first and second vacuum annealing heat treatments play a vital role in the preparation process of the high-strength thermal conductive semiconductor encapsulation solder alloy, which is specifically reflected in the following aspects: 1. Promote grain recrystallization: The temperature of the first vacuum annealing heat treatment is relatively high, which helps to eliminate the residual stress generated by the alloy during the casting process and rapid cooling, and promotes grain recrystallization. Through grain recrystallization, the grain density and uniformity of the solder can be improved, thereby improving the mechanical properties and corrosion resistance of the solder alloy. The temperature of the second vacuum annealing heat treatment is relatively low, which helps to further optimize the microstructure of the alloy and make the various elements more evenly distributed. This uniform element distribution can improve the composition uniformity and consistency of the solder alloy, thereby improving its welding performance, oxidation resistance and heat dissipation performance. 3. Improve mechanical properties and corrosion resistance: Through two vacuum annealing heat treatments at different temperatures, the microstructure and composition distribution of the solder alloy can be gradually adjusted and optimized, thereby improving its overall mechanical properties and corrosion resistance. This is particularly important for the packaging of high-density integrated circuits in high-performance electronic devices, because in this environment, the material needs to have higher mechanical strength and corrosion resistance. 4. Improve welding performance and oxidation resistance: The control of temperature and time parameters during the vacuum annealing heat treatment process can make the various elements in the alloy more evenly distributed, thereby improving the welding performance and oxidation resistance of the solder alloy. This is of great significance for improving the application performance of the solder alloy. In summary, the first and second vacuum annealing heat treatments in step S74 play a vital role in the preparation process of the solder alloy for high-strength thermal conductive semiconductor packaging. They work together to improve the mechanical properties, corrosion resistance, welding performance and oxidation resistance of the solder alloy, thereby meeting the needs of high-density integrated circuit packaging in high-performance electronic devices.

[0099] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the above embodiments provide a detailed description of the present application, relevant technical personnel should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modifications and equivalent replacements that do not depart from the spirit and scope of the present application should be included in the scope of protection of the present application.

Claims

1. A high-strength thermally conductive solder alloy for semiconductor packaging, characterized in that: The preparation material comprises the following raw materials by weight: 97-98 parts of tin, 0.4-0.6 parts of copper, 0.6-0.8 parts of silver, 0.008-0.011 parts of germanium, 0.01-0.018 parts of phosphorus, and 0.8-1.2 parts of copper-nickel-graphene master alloy; The copper-nickel-graphene master alloy comprises the following raw materials, calculated by mass: 15 parts of graphene oxide, 850 parts of ethanol, 15.3 parts of nickel acetate, 60.2 parts of pure copper powder, 4 parts of dopamine, and 150 parts of tris(hydroxymethyl)aminomethane hydrochloride solution with a pH of 7.

0.

2. A high-strength thermally conductive solder alloy for semiconductor packaging according to claim 1, characterized in that: The mass ratio of the germanium to the phosphorus is 1:1.

5.

3. The high-strength thermally conductive solder alloy for semiconductor packaging according to claim 1, characterized in that: The preparation method of the copper-nickel-graphene master alloy comprises the following steps: S41. Mixing graphene oxide, dopamine, and ethanol according to parts by mass to prepare a graphene oxide dispersion; S42. Add nickel acetate, pure copper powder, and tris(hydroxymethyl)aminomethane hydrochloride) solution with a pH of 7.0 to the graphene oxide dispersion according to their weight parts, stir evenly, heat to 50-55° C., react for 5-8 hours, concentrate to dryness, and collect the solid phase; S43. calcining the solid phase at 1170-1190° C. for 3-4 hours in a reducing atmosphere, and cooling to room temperature to obtain a copper-nickel-graphene master alloy.

4. The high-strength thermally conductive solder alloy for semiconductor packaging according to claim 3, characterized in that: In step S43, the reducing gas is composed of argon and hydrogen, the volume percentage of argon in the reducing gas is 75-80%, and the balance is hydrogen; the flow rate of the reducing gas is 4.5 L / min.

5. The high-strength thermally conductive solder alloy for semiconductor packaging according to claim 3, characterized in that: The graphene oxide has a sheet diameter of 0.5 μm-2 μm and a thickness of 0.8 nm-1.5 nm. The pure copper powder has a purity of 99.99% and a particle size of 1-2 microns.

6. A method for preparing a high-strength thermally conductive solder alloy for semiconductor packaging according to any one of claims 1 to 5, characterized in that: The following steps are involved: S71. Evenly mix tin, copper, silver, and germanium raw materials in proportion according to their mass fractions, preheat to 150-200° C., and remove the surface oxide layer to obtain a mixture; S72. Under an argon atmosphere, the mixed material is placed in an induction furnace and heated to fully melt into a liquid state to obtain alloy melt A; S73, sequentially adding phosphorus and copper-nickel-graphene master alloy to alloy melt A, heating, stirring, and fully melting the alloy melt into a liquid state to obtain alloy melt B; S74. Casting the alloy melt B into a mold preheated to 100° C. and cooling it into shape, then performing a first vacuum annealing heat treatment and a second vacuum annealing heat treatment, and finally rapidly cooling it to room temperature to obtain a high-strength thermally conductive solder alloy for semiconductor packaging.

7. The method for preparing a high-strength thermally conductive solder alloy for semiconductor packaging according to claim 6, characterized in that: In step S72, the temperature is raised to 360-400°C.

8. The method for preparing a high-strength thermally conductive solder alloy for semiconductor packaging according to claim 6, characterized in that: In step S73, the heating is performed by heating to 440-450°C; and the stirring is performed at a speed of 400-500 rpm for 15-20 minutes.

9. The method for preparing a high-strength thermally conductive solder alloy for semiconductor packaging according to claim 6, wherein: In step S74, the first vacuum annealing heat treatment is performed at a temperature of 250°C-280°C, for 1 hour-2 hours, and at a vacuum degree of 1 kPa; the second vacuum annealing heat treatment is performed at a temperature of 220°C-240°C, for 1 hour-2 hours, and at a vacuum degree of 1 kPa.

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