High-entropy copper core ball and preparation method thereof

Abstract

The application provides a high-entropy copper core ball and a preparation method thereof. The preparation method of the high-entropy copper core ball comprises the following steps: S10, electroplating nickel metal on the outer surface of the copper core ball to obtain a first intermediate; S20, performing vacuum hot-dip roll plating treatment on the high-entropy alloy and the first intermediate, and performing inductive uniform heating at a temperature lower than the melting point of the first intermediate to obtain a second intermediate; S30, screening the second intermediate through a screen to obtain high-entropy copper core balls that have been plated, and cooling to obtain a third intermediate; S40, performing fine grinding treatment on the third intermediate to obtain a fourth intermediate; S50, performing screening treatment on the fourth intermediate to obtain the high-entropy copper core ball; and the high-entropy copper core ball is at least coated with the high-entropy alloy. The preparation method of the high-entropy copper core ball realizes the preparation of a high-entropy alloy precise coating, improves the interconnection reliability of the copper core ball product, and reduces the defects of the interconnection welding points of the copper core ball product.

Description

Technical Field

[0001] This invention relates to the field of electronic component manufacturing technology, and more specifically, to a high-entropy copper core sphere and its preparation method. Background Technology

[0002] In recent years, with the increasing miniaturization of electronic devices, the size of interconnect solder joints has been continuously decreasing in order to meet the market requirements of miniaturization, narrow pitch, and multi-pin design in electronic packaging. This has led to the emergence of printed circuit board (PCB) technology, represented by 3D stacked packaging. 3D stacked packaging requires multiple thermal processes. Traditionally, solder balls are used for solder joint interconnection. However, after multiple thermal processes, the solder balls melt, and the weight of the multi-layered electronic components can easily cause the solder balls to disintegrate, resulting in insufficient space between the PCBs. Summary of the Invention

[0003] The high-entropy copper core ball structure of this invention consists of a copper core and a high-entropy alloy plated on the surface as a shell. Its biggest feature is that it can ensure the space required between PKGs after reflow soldering while performing encapsulation interconnection, avoiding the problem of poor solder joint connection reliability, which leads to bridging between solder joints or between solder joints and components and causes pin short circuits.

[0004] The problem solved by this invention is to ensure the space required between PKGs after reflow soldering, improve the interconnect reliability of copper core ball products, and reduce interconnect solder joint defects.

[0005] Therefore, the primary objective of this invention is to provide a method for preparing high-entropy copper core spheres.

[0006] The second objective of this invention is to provide a high-entropy copper core sphere.

[0007] To achieve the first objective of this invention, a method for preparing a high-entropy copper core sphere is provided, comprising: S10: electroplating nickel metal on the outer surface of the copper core sphere to obtain a first intermediate; S20: performing vacuum hot-dip barrel plating on the high-entropy alloy and the first intermediate, followed by uniform induction heating at a temperature lower than the melting point of the first intermediate to obtain a second intermediate; S30: sieving the second intermediate through a sieve to obtain the plated high-entropy copper core sphere, and cooling to obtain a third intermediate; S40: refining the third intermediate to obtain a fourth intermediate; S50: screening the fourth intermediate to obtain a high-entropy copper core sphere; wherein the high-entropy copper core sphere is a copper core sphere coated with a high-entropy alloy.

[0008] The surface coating of copper core spheres is a key material for solder joint interconnection. Therefore, to achieve the preparation of a precise high-entropy alloy coating, this invention provides a high-entropy copper core sphere and its preparation method. First, nickel metal is electroplated on the outer surface of the copper core sphere to prevent diffusion between the copper core sphere and other metals in the high-entropy alloy coating. Second, high-entropy copper core spheres are prepared using vacuum hot roller dipping technology. To prevent metal segregation, induction uniform heating is used, with the heating temperature lower than the melting point of the first intermediate, i.e., the nickel-plated copper core sphere, so that the high-entropy alloy is in a molten state, facilitating the immersion of the workpiece, i.e., the nickel-plated copper core sphere, to form a high-entropy alloy coating on its surface. Third, the high-entropy copper core spheres are sieved out and cooled to obtain a crude copper core sphere with at least a high-entropy alloy coating, i.e., the third intermediate. Fourth, the third intermediate is refined by grinding to ensure uniform size and improve sphericity. Finally, high-entropy copper core spheres with uniform size and sphericity are obtained by screening.

[0009] In any of the above technical solutions, the method for preparing high-entropy copper core spheres involves a high-entropy alloy being an alloy composition of five or more metallic elements, prepared by vacuum melting.

[0010] The high-entropy coating alloy of this invention differs from the "uniform diffusion" of traditional metals. Its essence lies in the presence of five or more metallic elements, rather than a single element. Atomic movement is constrained by multiple factors, resulting in a delayed diffusion effect. The slow diffusion rate during reflow soldering prevents grain coarsening and recrystallization, thus ensuring weld quality. The melting and heating process employs vacuum magnetic levitation melting technology. This technology uses an electromagnetic field to suspend the molten pool during vacuum melting. An alternating electromagnetic field is generated by an electromagnetic coil, inducing a current in the metal within the coil. This induced current causes the atoms within the alloy to move at high speed and randomly. The collisions and friction between atoms generate heat, melting the metal. Simultaneously, the electromagnetic force formed by the interaction between the electromagnetic field and the induced current suspends the molten metal, resulting in a more uniform composition of the high-entropy alloy and better coating stability.

[0011] In any of the above technical solutions, the high-entropy alloy, by mass parts, specifically includes: Sn, 25-45 parts by mass; the high-entropy alloy also includes: Ag, 10-20 parts by mass; Sb, 10-20 parts by mass; Bi, 15-25 parts by mass; In, 15-25 parts by mass.

[0012] In this invention, Sn is the matrix component of the high-entropy alloy and serves as the coating for the high-entropy copper core ball, acting as an interconnect bonding agent during electronic packaging soldering. Furthermore, Sn-Sb phase particles precipitate in the Sn matrix, enhancing the mechanical properties of the coating and improving the strength of the electronic packaging solder joint without affecting its wettability. Bi and In, as metallic components in the high-entropy alloy, significantly reduce the melting point of the high-entropy copper core ball and improve wettability during electronic packaging soldering. Ag enhances the mechanical properties of the high-entropy copper core ball during soldering. Simultaneously, since the high-entropy alloy lacks solvent atoms, all atoms can be considered solute atoms. The difference in atomic size causes lattice distortion, resulting in solid solution strengthening. Therefore, it possesses strong solid solution strengthening properties, making it a preferred material for chip packaging to improve the reliability of solder joint interconnections. Importantly, this invention optimizes the mass fraction of each component in the high-entropy alloy, achieving multi-component, high-ratio control. This ensures good thermal stability of the high-entropy alloy coating during multiple heating processes of the high-entropy copper core ball, guaranteeing soldering quality.

[0013] In any of the above technical solutions, the preparation method of high-entropy copper core spheres, specifically including vacuum hot-dip barrel plating, comprises: a vacuum degree of 4×10⁻⁶. -1 Pa, rotation speed 120rpm-300rpm, time 5min-15min.

[0014] This invention employs vacuum hot-dip barrel plating, with a vacuum level set at 4×10⁻⁶. -1 A negative pressure state is created by pumping out oxygen from the barrel plating chamber and moisture or residual liquid from the surface of the nickel-copper core ball product. The rotation speed and vacuum hot-dip barrel plating time are adjusted to ensure that the active atoms generated by the metal interface reaction during the hot-dip process are absorbed by the metal surface layer and migrate into the depth to form a diffusion layer. After 5-15 minutes, the obtained high-entropy alloy coating, diffusion layer and base metal nickel-copper core ball, i.e., the first intermediate, form a metallurgical bond, thus achieving an unbreakable high-entropy alloy coating.

[0015] In any of the above technical solutions, the preparation method of high-entropy copper core spheres, including vacuum hot-dip barrel plating, specifically includes: the high-entropy alloy being 10%-30% of the mass of the nickel-plated copper spheres.

[0016] This invention reduces uneven coating during the coating process by setting the feeding quality of high-entropy alloy and nickel-plated copper balls.

[0017] In any of the above technical solutions, the preparation method of the high-entropy copper core sphere specifically includes: a first intermediate with a nickel plating layer thickness of 2μm-5μm.

[0018] This invention uses nickel electroplating on the surface of copper balls as an isolation layer to prevent diffusion between the copper core ball and other metals in the high-entropy alloy plating layer, thus preventing the formation of intermetallic compounds between the copper ball and the high-entropy alloy during hot rolling impregnation of the high-entropy alloy.

[0019] In any of the above technical solutions, the preparation method of the high-entropy copper core sphere specifically includes: a third intermediate with a coating thickness of 5μm-50μm.

[0020] The present invention achieves overall plating of the second intermediate by means of a sufficient plating thickness, thereby producing a third intermediate with the desired properties of higher reliability of interconnect solder joints and stronger mechanical properties.

[0021] In any of the above technical solutions, the preparation method of the high-entropy copper core sphere specifically includes: a fourth intermediate with a sphericity ≤10μm.

[0022] This invention achieves a high-entropy copper core sphere sphericity of less than 10μm through fine grinding, resulting in a smooth surface with good surface roughness and color difference.

[0023] In any of the above technical solutions, the preparation method of high-entropy copper core spheres specifically includes: screening the fourth intermediate with a size deviation ≤10μm.

[0024] This invention removes non-compliant particles and impurities through size screening, ensuring the consistency of high-entropy copper core sphere products.

[0025] The high-entropy copper core sphere material of this application can be prepared by any of the above technical solutions.

[0026] The high-entropy alloy coating of the high-entropy copper core spheres of this invention possesses excellent performance. Strengthening the surface quality of the material extends the service life of metal components and improves efficiency. Thermodynamically, it exhibits a "high-entropy effect," promoting the formation of high-entropy solid solutions; kinetically, it exhibits a "hysteresis diffusion effect," with a diffusion coefficient significantly lower than that of traditional alloys; and microstructurally, it exhibits a "lattice distortion effect," inducing solid solution strengthening and increasing strength. With the copper core sphere as the core and the high-entropy alloy coating on the surface as the shell, it ensures the necessary space between PKGs after reflow soldering while providing stable and reliable encapsulation and interconnection. Attached Figure Description

[0027] Figure 1 This is a comparison chart of the performance of the solder balls and copper core balls of this invention. Detailed Implementation

[0028] The 3D stacking and packaging process of electronic devices requires multiple thermal processes, and the reliability of the connections directly determines the quality of the electronic packaging. Currently, there is some research on the preparation methods of copper core balls both domestically and internationally. Traditional copper core ball plating consists of mono-, binary, or ternary alloys, mainly prepared by electroplating. However, this low- to medium-entropy plating material has poor connection reliability, easily leading to connection defects such as cold solder joints and delamination during reflow soldering. Currently, multiple processes such as X-ray and SPI equipment are used for inspection to address this, resulting in low yield. Research on copper core balls with high-entropy plating is rarely reported. Electroplating high-entropy alloys requires multiple chemical solutions, leading to problems such as chemical pollution, difficulty in preparing the plating solution, and difficulty in process control. Electroplating makes it difficult to accurately achieve high-entropy alloy composition ratios. Evaporation plating, spray plating, and brushing processes involve repetitive plating and cannot plate the entire ball, failing to meet the precision requirements of copper core balls. Therefore, it is urgent to plate copper core balls with multi-element high-entropy alloys to improve the interconnect reliability of copper core ball products and reduce interconnect solder joint defects.

[0029] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0030] The following reference Figure 1 The technical solutions of some embodiments of the present invention are described below.

[0031] This invention provides a method for preparing high-entropy copper core spheres, comprising: S10: electroplating nickel metal on the outer surface of the copper core spheres to obtain a first intermediate; S20: performing vacuum hot-dip barrel plating on the high-entropy alloy and the first intermediate, followed by uniform induction heating at a temperature lower than the melting point of the first intermediate to obtain a second intermediate; S30: sieving the second intermediate through a sieve to obtain the plated high-entropy copper core spheres, and cooling to obtain a third intermediate; S40: performing fine grinding on the third intermediate to obtain a fourth intermediate; S50: performing screening on the fourth intermediate to obtain high-entropy copper core spheres; wherein, the high-entropy copper core spheres are copper core spheres coated with a high-entropy alloy.

[0032] The copper core sphere surface coating of this invention is a key material for solder joint interconnection. Therefore, to achieve precise preparation of the high-entropy alloy coating, this application provides a method for preparing a high-entropy copper core sphere. First, nickel metal is electroplated on the outer surface of the copper core sphere to prevent diffusion between the copper core sphere and other metals in the high-entropy alloy coating. Second, the high-entropy copper core sphere is prepared using vacuum hot roller dipping technology. To prevent metal segregation, induction uniform heating is used, with the heating temperature lower than the melting point of the first intermediate, i.e., the nickel-plated copper core sphere, so that the high-entropy alloy is in a molten state, facilitating the immersion of the workpiece to be plated, i.e., the nickel-plated copper core sphere, to form a high-entropy alloy coating on its surface. Third, the high-entropy copper core spheres are sieved out and cooled to obtain a crude copper core sphere with at least a high-entropy alloy coating, i.e., a third intermediate. Next, the third intermediate is refined through a fine grinding process to ensure uniform size and improve sphericity. Finally, through sieving, high-entropy copper core spheres with uniform size and sphericity are obtained. For example, the molten high-entropy alloy liquid can be recycled and reused.

[0033] Specifically, in some embodiments of this application, the preparation method of the high-entropy copper core ball involves a high-entropy alloy being an alloy composition of five or more metallic elements, prepared through vacuum melting. The high-entropy coating alloy of this invention differs from the "uniform diffusion" of traditional metals in that it contains five or more metallic elements, rather than a single element. The movement of atoms is constrained by multiple factors, resulting in a delayed diffusion effect. The slow diffusion rate during reflow soldering makes the alloy material less prone to grain coarsening and recrystallization, thus ensuring welding quality. The melting and heating process employs vacuum magnetic levitation melting technology, which utilizes an electromagnetic field to suspend the molten pool during vacuum melting. An alternating electromagnetic field is generated using an electromagnetic coil. This field induces a current in the metal within the coil, causing the atoms inside the alloy to move at high speed and randomly. The collisions and friction between these atoms generate heat, melting the metal. Simultaneously, the electromagnetic force formed by the interaction between the electromagnetic field and the induced current suspends the molten metal, resulting in a more uniform composition and better stability of the high-entropy alloy coating. For example, a high-entropy alloy can be an alloy composition of zinc, gold, nickel, aluminum, and tin.

[0034] Specifically, in some embodiments of this application, the preparation method of the high-entropy copper core ball includes, by mass, the following high-entropy alloy: Sn, 25-45 parts by mass; the high-entropy alloy also includes: Ag, 10-20 parts by mass; Sb, 10-20 parts by mass; Bi, 15-25 parts by mass; and In, 15-25 parts by mass. In this embodiment, Sn is the matrix component of the high-entropy alloy and serves as the plating layer for the high-entropy copper core ball, playing an interconnect welding role in the electronic packaging welding process. Furthermore, Sn-Sb phase particles precipitate in the Sn matrix, enhancing the mechanical properties of the plating layer and improving the strength of the electronic packaging weld joint without affecting its wettability. Bi and In, as metallic components in the high-entropy alloy, can significantly reduce the melting point of the high-entropy copper core ball and improve wettability during electronic packaging welding. Ag can improve the mechanical properties of the high-entropy copper core ball during welding. Meanwhile, since high-entropy alloys lack solvent atoms, all atoms can be considered solute atoms. The difference in atomic size causes lattice distortion, resulting in solid solution strengthening. Therefore, they exhibit strong solid solution strengthening properties, making them the preferred material for chip packaging to improve the reliability of solder joint interconnects. Importantly, this invention optimizes the mass fraction of each component in the high-entropy alloy, achieving multi-component, high-ratio control. This ensures good thermal stability of the high-entropy alloy coating during multiple heating processes of the high-entropy copper core sphere, guaranteeing welding quality.

[0035] Specifically, in some embodiments of this application, the method for preparing high-entropy copper core spheres, including vacuum hot-dip barrel plating, specifically includes: a vacuum degree of 4×10⁻⁶. -1 The pressure is Pa, the rotation speed is 120rpm-300rpm, and the time is 5min-15min. This embodiment of the invention uses vacuum hot-dip barrel plating, with a vacuum degree of 4×10⁻⁶. -1 A negative pressure state is created by pumping out oxygen from the barrel plating chamber and removing moisture or residual liquid from the surface of the nickel-plated copper core ball. The rotation speed and vacuum hot-dip barrel plating time are adjusted to ensure that the active atoms generated by the metal interface reaction during hot-dip plating are absorbed by the metal surface layer and migrate deeper, forming a diffusion layer. After 5-15 minutes, a metallurgical bond is formed between the obtained high-entropy alloy coating, the diffusion layer, and the base metal nickel-plated copper core ball (the first intermediate), thus achieving an unbreakable high-entropy alloy coating. For example, in this embodiment of the invention, a motor can drive a graphite drum to rotate, causing the high-entropy alloy layer to be barrel-plated onto the surface of the copper ball.

[0036] In some embodiments of this application, the method for preparing high-entropy copper core spheres, specifically a vacuum hot-dip barrel plating process, includes: the high-entropy alloy comprising 10%-30% of the mass of the nickel-plated copper spheres. This invention reduces uneven coating during the coating process by setting the mass of the high-entropy alloy and the nickel-plated copper spheres. For example, during the vacuum hot-dip barrel plating process, friction is generated between the nickel-plated copper spheres during rolling, transforming the uneven high-entropy alloy layer coated on the spheres into a more uniform coating through friction and rolling.

[0037] In some embodiments of this application, the preparation method of the high-entropy copper core sphere specifically includes: electroplating nickel metal onto the outer surface of the copper core sphere, with a nickel plating thickness of 2μm-5μm. This invention uses nickel electroplating on the surface of the copper sphere as an isolation layer to prevent diffusion between the copper core sphere and other metals in the high-entropy alloy plating, thus preventing the formation of intermetallic compounds between the copper sphere and the high-entropy alloy during hot-rolling high-entropy alloy immersion.

[0038] In some embodiments of this application, the preparation method of high-entropy copper core balls specifically includes: a crude high-entropy copper core ball, i.e., a third intermediate, with a plating thickness of 5μm-50μm. Generally, thin plating layers are not continuous; depending on the deposition conditions, they can consist of isolated regions connected by parts of the plating material. In this embodiment of the invention, the third intermediate, with a sufficient plating thickness, achieves overall plating of the second intermediate, thereby producing a third intermediate with the desired properties of higher reliability of interconnect solder joints and stronger mechanical properties. For example, if the plating thickness of the third intermediate is less than 5μm, the second intermediate cannot be completely plating, resulting in a poor yield of high-entropy copper core balls, and it cannot be guaranteed that all high-entropy copper core balls have the properties of higher reliability of interconnect solder joints and stronger mechanical properties; if the plating thickness of the third intermediate is greater than 50μm, achieving overall plating of the second intermediate consumes too much high-entropy alloy raw material, the performance improvement of the prepared high-entropy copper core balls is not significant, the production cost is high, and it is difficult to industrialize.

[0039] In some embodiments of this application, the preparation method of high-entropy copper core balls specifically includes: fine grinding to obtain a fourth intermediate with a sphericity ≤10μm. Sphericity is one of the indicators for measuring the quality of solder balls; the smaller the sphericity, the better the quality of the high-entropy copper core balls. In this embodiment of the invention, through fine grinding, the sphericity of the high-entropy copper core balls is controlled to below 10μm. At this point, the surface is smooth, and the surface roughness and color difference are also in good condition. Preferably, the fine grinding process of this invention uses a vertical ball grinding machine for fine grinding. During the grinding process, a fourth intermediate with good dimensional consistency is obtained through a fixed mold.

[0040] In some embodiments of this application, the method for preparing high-entropy copper core spheres specifically includes: screening a fourth intermediate to ensure a size deviation ≤10μm. This embodiment of the invention removes non-compliant particles and impurities through size screening, ensuring the consistency of the final product. For example, a ball sorter is used to screen the fourth intermediate, i.e., the ground high-entropy copper core sphere crude product, by size.

[0041] In the embodiments of this application, any partial implementation of the above technical solutions can prepare the high-entropy copper core sphere material of this application.

[0042] The high-entropy alloy coating on the high-entropy copper core spheres prepared in this invention exhibits excellent performance. Strengthening the surface quality of the material extends the service life of metal components and improves efficiency. Thermodynamically, it possesses a "high-entropy effect," promoting the formation of high-entropy solid solutions; kinetically, it exhibits a "hysteresis diffusion effect," with a diffusion coefficient significantly lower than that of traditional alloys; and microstructurally, it possesses a "lattice distortion effect," inducing solid solution strengthening and increasing strength. With the copper core sphere as the core and the high-entropy alloy coating on its surface as the shell, the required space between PKGs after reflow soldering is ensured while providing stable and reliable encapsulation and interconnection.

[0043]

Example 1

[0044] (1) Electroplating nickel metal onto the outer surface of the copper core sphere, with a plating thickness of 2μm;

[0045] (2) Prepare a high-entropy alloy with a certain alloy composition by vacuum melting according to the required alloy composition: Sn, 25 parts by mass; Ag, 10 parts by mass; Sb, 10 parts by mass; Bi, 15 parts by mass; In, 15 parts by mass.

[0046] (3) The prepared high-entropy alloy and copper balls are loaded into a graphite drum, wherein the high-entropy alloy accounts for 10% of the mass of the nickel-plated copper balls. A vacuum is then applied to a vacuum level of 4 × 10⁻⁶. -1 Pa, uniform induction heating is used, the melting temperature is lower than the melting point of copper, and a motor drives the graphite drum to rotate at a speed of 120 rpm, stirring for 5 minutes to make the copper ball surface uniformly plated.

[0047] (4) Pour the molten metal into a sieve, screen out the high-entropy copper core balls and cool them to recover the high-entropy alloy;

[0048] (5) Use a ball grinding machine to finely grind the plated high-entropy copper core balls to make them uniform in size, improve the sphericity, and adjust the roundness to ≤10μm;

[0049] (6) Finally, the finished product is screened to obtain high-entropy copper core spheres with a size deviation of ≤10μm.

[0050]

Example 2

[0051] (1) Electroplating nickel metal onto the outer surface of the copper core sphere, with a plating thickness of 5 μm;

[0052] (2) Prepare a high-entropy alloy with a certain alloy composition by vacuum melting according to the required alloy composition: Sn, 45 parts by mass; Ag, 20 parts by mass; Sb, 20 parts by mass; Bi, 15 parts by mass; In, 25 parts by mass.

[0053] (3) The prepared high-entropy alloy and copper balls are loaded into a graphite drum, wherein the high-entropy alloy accounts for 30% of the mass of the nickel-plated copper balls. A vacuum is then applied to a vacuum level of 4 × 10⁻⁶. -1 Pa, uniform induction heating is used, the melting temperature is lower than the melting point of copper, and a motor drives the graphite drum to rotate at a speed of 300 rpm. Stirring for 15 minutes makes the copper ball surface uniformly plated.

[0054] (4) Pour the molten metal into a sieve, screen out the high-entropy copper core balls and cool them to recover the high-entropy alloy;

[0055] (5) Use a ball grinding machine to finely grind the plated high-entropy copper core balls to make them uniform in size, improve the sphericity, and adjust the roundness to ≤10μm;

[0056] (6) Finally, the finished product is screened to obtain high-entropy copper core spheres with a size deviation of ≤10μm.

[0057]

Example 3

[0058] (1) Electroplating nickel metal onto the outer surface of the copper core sphere, with a plating thickness of 4 μm;

[0059] (2) Prepare a high-entropy alloy with a certain alloy composition by vacuum melting according to the required alloy composition: Sn, 35 parts by mass; Ag, 18 parts by mass; Sb, 18 parts by mass; Bi, 15 parts by mass; In, 20 parts by mass.

[0060] (3) The prepared high-entropy alloy and copper balls are loaded into a graphite drum, wherein the high-entropy alloy accounts for 8% of the mass of the nickel-plated copper balls. A vacuum is then applied, with a vacuum degree of 4 × 10⁻⁶. -1 Pa, uniform induction heating is used, the melting temperature is lower than the melting point of copper, and a motor drives the graphite drum to rotate at a speed of 200 rpm. Stirring for 10 minutes makes the copper ball surface uniformly plated.

[0061] (4) Pour the molten metal into a sieve, screen out the high-entropy copper core balls and cool them to recover the high-entropy alloy;

[0062] (5) Use a ball grinding machine to finely grind the plated high-entropy copper core balls to make them uniform in size, improve the sphericity, and adjust the roundness to ≤10μm;

[0063] (6) Finally, the finished product is screened to obtain high-entropy copper core spheres with a size deviation of ≤10μm.

[0064] Reference Figure 1 As shown, the high-entropy alloy of this invention enables the preparation of precise coatings, improves the interconnect reliability of copper core ball products, and reduces interconnect solder joint defects.

[0065] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0066] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for preparing a high-entropy copper core sphere, characterized in that, include: S10: Electroplating nickel metal onto the outer surface of the copper core sphere yields the first intermediate; S20: Vacuum hot-dip barrel plating is performed on the high-entropy alloy and the first intermediate, followed by uniform induction heating at a temperature lower than the melting point of the first intermediate to obtain the second intermediate. S30: The second intermediate is sieved through a screen to remove the high-entropy copper core spheres, cooled, and the third intermediate is obtained; S40: The third intermediate is finely ground to obtain the fourth intermediate; S50: The fourth intermediate is screened to obtain the high-entropy copper core sphere; Wherein, the high-entropy copper core sphere is a copper core sphere coated with the high-entropy alloy; The high-entropy alloy is prepared by vacuum melting and consists of the following components: Sn, 25-45 parts by weight; Ag, 10-20 parts by weight; Sb, 10-20 parts by weight; Bi, 15-25 parts by weight; In, 15 parts by weight - 5 parts by weight; The vacuum hot-dip barrel plating process has a vacuum degree of 4×10⁻⁶. -1 Pa.

2. The method for preparing high-entropy copper core spheres according to claim 1, characterized in that, The vacuum hot-dip barrel plating process is carried out at a speed of 120 rpm to 300 rpm for 5 min to 15 min.

3. The method for preparing high-entropy copper core spheres according to claim 1, characterized in that, The high-entropy alloy constitutes 10-30% of the mass of the first intermediate.

4. The method for preparing high-entropy copper core spheres according to claim 1, characterized in that, The first intermediate has a nickel plating thickness of 2μm-5μm.

5. The method for preparing high-entropy copper core spheres according to claim 1, characterized in that, The third intermediate has a coating thickness of 5μm-50μm.

6. The method for preparing high-entropy copper core spheres according to claim 1, characterized in that, The fourth intermediate has a roundness ≤ 10 μm.

7. The method for preparing high-entropy copper core spheres according to claim 1, characterized in that, The high-entropy copper core sphere has a size deviation of ≤10μm.

8. A high-entropy copper core sphere, characterized in that, The high-entropy copper core spheres are obtained using the preparation method described in any one of claims 1-7.

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