Copper-nickel-chromium heat sink and chemical electroplating preparation method and application thereof

Abstract

This invention provides a copper-nickel-chromium heat sink, its chemical electroplating preparation method, and its application, relating to the field of heat sink technology. The preparation method includes: degreasing, removing impurities, and drying copper foil to obtain a copper substrate; depositing a nickel layer on the surface of the copper substrate to obtain a copper-nickel substrate; subjecting the copper-nickel substrate to vacuum heat treatment to obtain a copper-nickel composite sheet; chromium plating the copper-nickel composite sheet in a chromium plating solution to obtain a copper-nickel-chromium substrate; and surface reduction of the copper-nickel-chromium substrate in a reducing atmosphere to obtain a copper-nickel-chromium heat sink. This invention, by depositing a nickel layer on the surface of a copper substrate and then performing vacuum heat treatment, helps to improve the density of the nickel layer and the interfacial bonding force between the nickel layer and the copper substrate. Subsequently, chromium plating is performed on the surface of the nickel layer to form a chromium layer. Surface reduction in a reducing atmosphere can reduce high-valence toxic chromium to low-valence chromium, while also improving the uniformity and stability of the coating on the surface of the copper-nickel-chromium heat sink, thus contributing to an increased service life of the heat sink.

Description

Technical Field

[0001] This invention relates to the field of heat sink technology, and in particular to a copper-nickel-chromium heat sink and its chemical electroplating preparation method and application. Background Technology

[0002] Ball Grid Array (BGA) is a high-density surface-mount packaging technology that uses solder balls arranged in an array on the bottom surface of the package to achieve electrical and mechanical interconnection between the chip and the substrate. Compared with the traditional four-sided flat package, BGA packaging can provide more input / output terminals in the same area, shorten the interconnect path and reduce parasitic inductance and resistance. Therefore, BGA packaging is widely used in high-speed, high-power integrated circuits such as high-performance logic devices and memory devices. However, with the continuous shrinking of semiconductor manufacturing processes and the continuous increase of operating frequencies, the switching power consumption and static leakage power consumption of chips have increased sharply, leading to increasingly serious heat flux accumulation problems inside the BGA package.

[0003] Currently, when performing thermal management on BGA packaged chips, thermally conductive interface materials are typically bonded tightly to the back of the chip to diffuse the heat generated by the chip laterally to the heat exchange area. Copper-based heat sinks, due to their high thermal conductivity and good machinability, are often used in combination with BGA packaged chips. In order to improve the performance of copper-based heat sinks, nickel and chromium plating layers are usually deposited sequentially on the copper substrate to form a copper-nickel-chromium multilayer plating structure. This improves the copper-based heat sink's resistance to chemical corrosion and humidity corrosion, which helps to extend its service life and reduce the interface thermal resistance, thereby improving the heat dissipation capacity of the BGA packaged chip.

[0004] However, when forming nickel and chromium layers on a copper substrate using electroplating, an external electric field is required to drive the metal ions to be reduced and deposited on the cathode surface. When the current density on the cathode surface is not uniformly distributed, it can easily lead to non-uniform deposition during the deposition process. This, in turn, increases the interfacial thermal resistance and concentrates thermal stress in the resulting copper-nickel-chromium heat sink, affecting its service life. Therefore, there is an urgent need to provide a solution to improve these problems. Summary of the Invention

[0005] The purpose of this invention is to provide a copper-nickel-chromium heat sink and its chemical electroplating preparation method and application. By depositing a nickel layer on the surface of a copper substrate and performing vacuum heat treatment, the density of the nickel layer and the interfacial bonding force between the nickel layer and the copper substrate are improved. Then, a chromium layer is formed after chromium plating on the surface of the nickel layer. After surface reduction in a reducing atmosphere, the high-valence toxic chromium can be reduced to low-valence chromium. At the same time, the uniformity and stability of the coating on the surface of the copper-nickel-chromium heat sink can be improved, which helps to improve the service life of the heat sink.

[0006] In a first aspect, the present invention provides a chemical electroplating preparation method for a copper-nickel-chromium heat sink, comprising: degreasing, removing impurities, and drying a copper foil to obtain a copper substrate; depositing a nickel layer on the surface of the copper substrate to obtain a copper-nickel substrate; subjecting the copper-nickel substrate to vacuum heat treatment to obtain a copper-nickel composite sheet; chromium plating the copper-nickel composite sheet in a chromium plating solution to obtain a copper-nickel-chromium substrate; and performing surface reduction on the copper-nickel-chromium substrate in a reducing atmosphere to obtain a copper-nickel-chromium heat sink.

[0007] Optionally, the copper foil is surface degreased in a degreasing solution.

[0008] Optionally, the degreasing solution contains 10 g / L-15 g / L of sodium hydroxide, 20 g / L-30 g / L of sodium carbonate, 20 g / L-30 g / L of sodium phosphate, and 2 g / L-5 g / L of surfactant.

[0009] Optionally, degreasing can be performed in a degreasing solution at 55°C-65°C.

[0010] Optionally, defatting can be performed under ultrasound.

[0011] Optionally, the defatting process can be performed for 3-10 minutes.

[0012] Optionally, a nickel target can be used as a sputtering source to perform sputtering deposition on a copper substrate.

[0013] Optionally, the purity of the nickel target is greater than or equal to 99.95%.

[0014] Optionally, the deposition is carried out by sputtering at a working pressure of 0.5 Pa to 1.0 Pa.

[0015] Optionally, magnetron sputtering can be performed.

[0016] Optionally, the sputtering power density is 3 W / cm². 2 -5W / cm 2 .

[0017] Optionally, the thickness of the nickel layer on the surface of the copper-nickel substrate is 3μm-8μm.

[0018] Optionally, the copper-nickel substrate can be subjected to vacuum heat treatment at 200℃-300℃.

[0019] Optionally, in 1×10 -3 Pa-5×10 -3 Vacuum heat treatment of copper-nickel substrates at Pa.

[0020] Optionally, heat treatment for 30-120 minutes.

[0021] Optionally, the copper-nickel substrate can be heated at a rate of 2℃ / min to 5℃ / min.

[0022] Optionally, after vacuum heat treatment, the vacuum heat treatment is followed by cooling at a rate of 2°C / min to 5°C / min.

[0023] Optionally, the chromium plating solution contains 200g / L-250g / L chromic anhydride, 1.8g / L-2.5g / L sulfuric acid, 10g / L-20g / L buffer, and 1g / L-3g / L chromium plating additives.

[0024] Optionally, chrome plating can be performed at 45°C-55°C.

[0025] Optionally, at 5A / dm 2 -30A / dm 2 Chromium plating at current density.

[0026] Optionally, a copper-nickel composite sheet can be used as the cathode and a lead-tin alloy as the anode for electroplating.

[0027] Optionally, the chromium plating additive includes at least one of 3-sulfonic acid propionic acid and glutamic acid.

[0028] Optionally, the buffer includes one of boric acid, sodium citrate, and sodium acetate.

[0029] Optionally, the chromium plating additive further includes a composite product, the preparation method of which includes: 3-sulfonic acid propionic acid and glutamic acid undergo an amidation reaction under the action of a condensing agent, and then the composite product is separated.

[0030] Optionally, in preparing the composite product: the condensing agent includes 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride.

[0031] Optionally, in preparing the composite product, the molar ratio of 3-sulfonopropionic acid to glutamic acid is 1:(1-1.2).

[0032] Optionally, in preparing the composite product, the reaction is carried out at 2°C-8°C.

[0033] Optionally, the reaction is carried out for 4-8 hours during the preparation of the composite product.

[0034] Optionally, in preparing the composite product, the reaction is carried out in N,N-dimethylformamide and N-methylpyrrolidone.

[0035] Optionally, in preparing the composite product: the composite product is obtained by rotary evaporation and desolvation after the reaction.

[0036] Optionally, during the preparation of the composite product, an amidation reaction occurs in an alkaline environment.

[0037] Optionally, the reducing gas in the reducing atmosphere includes hydrogen.

[0038] Optionally, the pressure of the reducing atmosphere is 0.1 MPa-0.3 MPa.

[0039] Optionally, surface reduction can be performed at 300℃-350℃.

[0040] Optionally, the surface is reduced for 1-2 hours.

[0041] Optionally, the gas flow rate in the reducing atmosphere is 0.5 L / min to 5 L / min.

[0042] Optionally, the volume concentration of the reducing gas in the reducing atmosphere is 4%-10%.

[0043] Optionally, the reducing atmosphere includes an inert carrier gas, which includes argon.

[0044] Secondly, the present invention also provides a copper-nickel-chromium heat sink prepared by any of the above-described preparation methods.

[0045] Thirdly, the present invention also provides an application of the copper-nickel-chromium heat sink prepared by any of the above preparation methods.

[0046] The method for preparing copper-nickel-chromium heat sinks provided by this invention has at least one of the following beneficial technical effects compared to the prior art: 1. By heat-treating the copper-nickel substrate in a vacuum environment, the nickel atoms in the nickel layer can be thermally diffused on the surface of the copper substrate, thereby forming a dense and uniform copper-nickel diffusion layer. This not only improves the interfacial bonding stability of the nickel layer on the surface of the copper substrate, but also eliminates the internal stress generated during the nickel layer deposition process, avoids cracks in the nickel layer, and thus helps to improve the service life of the heat sink and the surface uniformity of the nickel layer. 2. By reducing the surface of the copper-nickel-chromium substrate in a reducing atmosphere, the high-valence chromium on the surface of the chromium plating layer can be reduced to low-valence chromium (0 valence, +3 valence). This helps to eliminate toxic high-valence chromium, thereby improving the environmental friendliness and safety of the heat sink. At the same time, the reduction process helps to form a dense and uniform chromium plating layer and improves the interfacial bonding between the chromium plating layer and the nickel plating layer. This helps to improve the heat sink's resistance to peeling and significantly extend the service life of the heat sink under thermal shock environments. Attached Figure Description

[0047] Figure 1 This is a schematic flowchart of a chemical electroplating preparation method for a copper-nickel-chromium heat sink provided by the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0049] See Figure 1 This invention provides a chemical electroplating method for preparing copper-nickel-chromium heat sinks, comprising the following steps: S1. Degrease, remove impurities from, and dry the copper foil to obtain a copper-based sheet; S2. A copper-nickel substrate is prepared by depositing a nickel layer on the surface of a copper substrate; S3. Vacuum heat treatment of copper-nickel substrate yields copper-nickel composite sheet; S4. Chromium plating is performed on the copper-nickel composite sheet in the chromium plating solution to obtain a copper-nickel-chromium substrate. S5. Surface reduction of copper-nickel-chromium substrate in a reducing atmosphere to obtain copper-nickel-chromium heat sink.

[0050] In fact, by degreasing and removing impurities from the copper foil in step S1, this invention helps improve the cleanliness of the copper substrate surface, which in turn helps the uniformity and bonding stability of the nickel layer deposition on the copper substrate surface in step S2. Furthermore, by using vacuum heat treatment in step S3, nickel atoms are encouraged to penetrate into the copper substrate, which also improves the density and uniformity of the nickel plating surface. This also helps improve the uniformity of the chromium plating surface after chromium plating in step S4. In addition, the reduction of the chromium plating in step S5 can reduce the valence state of chromium, eliminate the toxicity of the heat sink, and improve the density and anti-peeling ability of the chromium plating.

[0051] In some embodiments, the copper foil is surface degreased in a degreasing solution in step S1. In fact, wetting the copper foil surface with a degreasing solution helps improve the uniformity and efficiency of degreasing. Further, during surface degreasing in the degreasing solution, the copper foil can be immersed in the degreasing solution at 55°C-65°C for 3-10 minutes, then removed and washed with purified water. Further still, to improve degreasing efficiency, degreasing can be performed in an ultrasonic environment, utilizing the ultrasonic cavitation effect to effectively eliminate air bubbles on the copper foil surface and loosen surface dirt.

[0052] In some embodiments, the degreasing solution used in step S1 contains 10 g / L-15 g / L sodium hydroxide, 20 g / L-30 g / L sodium carbonate, 20 g / L-30 g / L sodium phosphate, and 2 g / L-5 g / L surfactant dissolved in it. In fact, during the degreasing process, sodium hydroxide can undergo a saponification reaction with the oils remaining on the copper foil surface, thereby achieving surface degreasing, while the surfactant can reduce the surface tension of the degreasing solution, thus improving the degreasing effect on the copper foil. Furthermore, the surfactants used include anionic surfactants and nonionic surfactants, specifically sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, AEO-9, OP-10, etc.

[0053] In some embodiments, after degreasing the copper foil in step S1, it can be immersed in a dilute hydrochloric acid solution to remove copper oxide from the surface of the copper foil. This also roughens the surface of the copper foil, which is beneficial for improving the interfacial adhesion when depositing the nickel layer in step S2. Further, after immersion in the dilute hydrochloric acid solution and washing with pure water to remove residual impurities, the copper substrate is obtained by drying it to constant weight under vacuum at 50℃-100℃. Specifically, the thickness of the copper foil used can be 20μm-100μm.

[0054] In some embodiments, a nickel target can be used as a sputtering source to perform magnetron sputtering deposition on the copper substrate in step S2. In the magnetron sputtering process, high-energy argon ions bombard the nickel target, causing nickel atoms to escape in a single-atom state and deposit uniformly on the surface of the copper substrate. This helps improve the uniformity and density of the nickel plating, while avoiding the introduction of impurity elements, thus contributing to the improvement of the purity of the nickel plating. Specifically, the purity of the nickel target used is greater than or equal to 99.95%.

[0055] In some embodiments, during magnetron sputtering in step S2, the copper substrate is transferred and fixed on the work stand of the magnetron sputtering chamber, and the chamber is evacuated to 5 × 10⁻⁶. -4 After Pa, high-purity argon gas is introduced to maintain the working pressure at 0.5 Pa-1.0 Pa, then at 3 W / cm 2 -5W / cm 2 Sputter deposition was performed on a copper substrate at a power density of 3 μm-8 μm, controlling the thickness of the nickel layer on the copper-nickel substrate surface. Furthermore, the workpiece was rotated at a speed of 5 rpm-20 rpm during sputtering to improve deposition uniformity.

[0056] In some embodiments, step S3 can be performed at 200℃-300℃ and 1×10⁻⁶. -3 Pa-5×10 -3The copper-nickel substrate was heat-treated in an environment of Pa for 30-120 minutes. Specifically, the copper-nickel substrate was transferred into the furnace chamber of a vacuum furnace, and the copper-nickel substrate was heated to 200-300°C at a rate of 2°C / min-5°C / min and held at that temperature for 30-120 minutes. Then, it was cooled to room temperature with the furnace to obtain a copper-nickel composite sheet.

[0057] In some embodiments, in step S4, the copper-nickel composite sheet is electroplated in a chromium plating bath at 45°C-55°C. Further, the current density during chromium plating is 5 A / dm³. 2 -30A / dm 2 Furthermore, a copper-nickel composite sheet is used as the cathode, and a lead-tin alloy is used as the anode for electroplating. In fact, the chromium plating solution contains 200g / L-250g / L of chromic anhydride, 1.8g / L-2.5g / L of sulfuric acid, 10g / L-20g / L of buffer, and 1g / L-3g / L of chromium plating additives.

[0058] In some embodiments, the chromium plating additive includes at least one of 3-sulfonopropionic acid and glutamic acid. In fact, during the chromium plating process, 3-sulfonopropionic acid can react with chromic anhydride to generate a sulfonate chromyl intermediate. The propyl group serves as a donor group to increase the stability of the Cr-OS bond in the intermediate, thereby effectively improving the cathode current efficiency during electroplating. Simultaneously, glutamic acid acts as a buffer and effectively controls the grain size of chromium deposition during electroplating. Specifically, the chromium plating additive includes 3-sulfonopropionic acid and glutamic acid in a molar ratio of 1:(1-1.2).

[0059] In other embodiments, the chromium plating additive also includes a composite product, and the preparation method of the composite product includes: after 3-sulfonopropionic acid and glutamic acid undergo an amidation reaction under the action of a condensing agent, the composite product is separated. In fact, modifying glutamic acid onto 3-sulfonopropionic acid using an amide bond can further improve the stability of the sulfonate chromyl intermediate in the electroplating process, thereby improving the cathode current efficiency. Simultaneously, it can improve the stability of glutamic acid during the electroplating process, preventing the decomposition of glutamic acid in a strongly acidic environment. Further, the buffer used includes one of boric acid, sodium citrate, and sodium acetate.

[0060] In some embodiments, when preparing the composite product, 3-sulfonylpropionic acid (CAS: 44826-45-1) can be dissolved in N,N-dimethylformamide and N-methylpyrrolidone to obtain a 3-sulfonylpropionic acid solution. Then, a condensing agent is added to the 3-sulfonylpropionic acid solution under an inert atmosphere and stirred until dissolved. Glutamic acid is added at 2°C-8°C and the reaction is stirred for 4-8 hours. After rotary evaporation to remove the solvent, the product is acidified, washed with water, and recrystallized to obtain the composite product. In practice, the composite product includes at least the reactants of 3-sulfonylpropionic acid and glutamic acid, as well as unreacted 3-sulfonylpropionic acid and glutamic acid.

[0061] In some embodiments, the condensing agent used in preparing the composite product includes 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (CAS: 25952-53-8). Specifically, the condensing agent is mixed with a solution of 3-sulfonylpropionic acid and stirred at 2°C-8°C for 30-45 minutes. Further, the molar ratio of the condensing agent to 3-sulfonylpropionic acid is (1.1-1.2):1.

[0062] In some embodiments, an amidation reaction occurs in an alkaline environment to prepare the composite product. Specifically, an organic base and glutamic acid are added to the system at 2°C-8°C and stirred for 4-8 hours. In fact, an alkaline environment is beneficial for increasing the amino activity of glutamic acid, thereby facilitating the amidation reaction between glutamic acid and 3-sulfonylpropionic acid to generate the composite product. Further, the organic base used includes triethylamine, and the molar ratio of triethylamine to 3-sulfonylpropionic acid is (2-3):1.

[0063] In some embodiments, the reducing gas in the reducing atmosphere used in step S5 includes hydrogen, and the reducing atmosphere also includes an inert carrier gas, with a volume concentration of 4%-10%. In practice, the copper-nickel-chromium substrate can be transferred to the furnace chamber of an atmosphere furnace, and after introducing inert gas to adjust the furnace pressure to 0.1 MPa-0.3 MPa, a reducing gas is introduced to mix within the furnace to obtain a reducing atmosphere. The atmosphere furnace is heated to 300℃-350℃ at a rate of 2℃ / min-10℃ / min and held at that temperature for 1-2 hours. Further, to improve the stability of the reducing gas concentration in the reducing atmosphere, the gas flow rate can be controlled to be 0.5 L / min-5 L / min.

[0064] Example 1: A method for preparing a copper-nickel-chromium heat sink by chemical electroplating, comprising the following steps: S1. A copper foil with a thickness of 50 μm is immersed in a degreasing solution at 60℃ and kept at that temperature for 5 min under ultrasonic treatment. The copper foil is then removed and immersed in dilute hydrochloric acid for ultrasonic treatment for 3 min. After removing the copper foil and rinsing it with pure water, it is dried in a vacuum drying oven at 80℃ to constant weight to obtain a copper matrix. The degreasing solution contains 13 g / L sodium hydroxide, 25 g / L sodium carbonate, 25 g / L sodium phosphate and 3 g / L sodium dodecylbenzenesulfonate. S2. Transfer and fix the copper substrate onto the work stand of the magnetron sputtering cavity, and evacuate the cavity to a vacuum level better than 5×10⁻⁶. -4 After passing through Pa, high-purity argon gas is introduced to maintain the working pressure at 1.0 Pa. A nickel target with a purity greater than or equal to 99.5% is then used as the target material, at a pressure of 3 W / cm². 2A nickel-nickel substrate was prepared by bombarding nickel-palladium with high-energy argon ions at a power density to deposit a nickel layer on the surface of a copper substrate; wherein the thickness of the nickel layer on the surface of the copper-nickel substrate was 5 μm. S3. Transfer the copper-nickel substrate into the furnace chamber of a vacuum furnace, introduce argon gas for gas replacement, and then evacuate to a vacuum level of 1×10⁻⁶. -3 Pa, the temperature was raised to 250°C in a vacuum furnace at a rate of 3°C / min and held for 60 min, and then cooled to room temperature in the furnace to obtain a copper-nickel composite sheet; S4. The copper-nickel composite sheet was used as the cathode and immersed in a chromium plating solution at 50°C. A lead-tin alloy plate was used as a prototype. The plating speed was 15 A / dm. 2 After electroplating at a current density of 5 min, the substrate was removed and rinsed with an 8 g / L sodium bicarbonate aqueous solution, then rinsed with pure water, and dried to constant weight in a vacuum drying oven at 80℃ to obtain a copper-nickel-chromium substrate. The chromium plating solution contained 230 g / L chromic anhydride (CAS: 1333-82-0), 2.0 g / L sulfuric acid, 15 g / L boric acid, and 2 g / L chromium plating additive, which was 3-sulfonic acid propionic acid and glutamic acid in a molar ratio of 1:1.2. S5. After purging the atmosphere furnace with argon, the copper-nickel composite sheet is transferred into the furnace chamber. The gas pressure in the atmosphere furnace is adjusted to 0.2 MPa. Hydrogen is then introduced and the hydrogen gas fraction in the furnace chamber is adjusted to 6%. The atmosphere furnace is heated to 320°C at a rate of 5°C / min and held at that temperature for 1.5 hours. During the heating and holding process, the gas flow rate in the atmosphere furnace is 2 L / min. After holding, the furnace is cooled to room temperature to obtain the copper-nickel-chromium heat sink.

[0065] Example 2: A chemical electroplating preparation method for a copper-nickel-chromium heat sink, differing from Example 1 in that a composite product is dissolved in the chromium plating solution in step S4. The preparation method of the composite product includes: dissolving 3-sulfonylpropionic acid in N,N-dimethylformamide to obtain a 3-sulfonylpropionic acid solution; dissolving 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (molar ratio of 1.1:1 to 3-sulfonylpropionic acid) in the 3-sulfonylpropionic acid solution under an argon atmosphere and at a low temperature of 4°C; stirring and maintaining the temperature for 30 min; adding triethylamine and glutamic acid to the system and stirring and reacting at 4°C for 6 h; removing the solvent by rotary evaporation; acidifying to neutrality with dilute hydrochloric acid; washing with water; and recrystallizing to purify the composite product; wherein the molar ratio of triethylamine, glutamic acid, and 3-sulfonylpropionic acid is 2:1.2:1.

[0066] Comparative Example 1: A chemical electroplating preparation method for a copper-nickel-chromium heat sink, which differs from Example 1 in that step S3 is omitted, and the copper-nickel substrate obtained in step S2 is used as the cathode for direct electroplating deposition in step S4.

[0067] Comparative Example 2: A chemical electroplating preparation method for a copper-nickel-chromium heat sink, which differs from Example 1 in that step S5 is omitted, and the copper-nickel-chromium composite sheet obtained in step S4 is used as the copper-nickel-chromium heat sink.

[0068] Performance Testing: The copper-nickel-chromium heat sinks prepared in Examples 1 and 2, and Comparative Examples 1 to 2, were subjected to the following tests: Heat Dissipation Performance Test: A heat-generating chip was fixed on the back of the heat sink, and a fan with a rotation speed of 2000 rpm was fixed on the front of the heat sink. The highest temperature on the surface of the heat-generating chip was measured, and the highest temperature obtained in Example 1 was used as the benchmark. The rate of change of the highest temperature of the heat-generating chip on the surface of Examples 2, 1, and 2 relative to the benchmark was calculated (rate of change (%) = Example 2 / Example 1 × 100%). Adhesion Strength: Based on the method described in GB / T 5270-2024 "Review of Test Methods for Adhesion Strength of Electrodeposition and Chemical Deposition of Metallic Coatings on Metal Substrates", the heat sink was heated to 300°C in an argon atmosphere and then rapidly transferred to water at 25°C for cooling. The morphology of the surface coating was observed after cooling. The above test results are shown in Table 1 below. Table 1 Performance Testing of Copper-Nickel-Chromium Heat Sinks While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A method for preparing a copper-nickel-chromium heat sink by chemical electroplating, characterized in that, include: Copper foil is degreased, impurities removed, and dried to obtain a copper substrate; a nickel layer is deposited on the surface of the copper substrate to obtain a copper-nickel substrate. A copper-nickel composite sheet is obtained by vacuum heat treatment of a copper-nickel substrate; a copper-nickel composite sheet is obtained by chromium plating in a chromium plating solution; and a copper-nickel-chromium heat sink is obtained by surface reduction of the copper-nickel-chromium substrate in a reducing atmosphere.

2. The preparation method according to claim 1, characterized in that: Copper foil is surface degreased in a degreasing solution, wherein: the degreasing solution contains 10 g / L-15 g / L sodium hydroxide, 20 g / L-30 g / L sodium carbonate, 20 g / L-30 g / L sodium phosphate, and 2 g / L-5 g / L surfactant; and / or, degreasing is performed in a degreasing solution at 55℃-65℃; and / or, degreasing is performed under ultrasound; and / or, the degreasing treatment lasts for 3 min-10 min.

3. The preparation method according to claim 1, characterized in that: The copper substrate is sputter-deposited by using a nickel target as a sputtering source; wherein: the purity of the nickel target is greater than or equal to 99.95%; and / or, the sputter-deposition is carried out at a working pressure of 0.5 Pa-1.0 Pa; and / or, the sputter-deposition is carried out by using a magnetron sputtering; and / or, the sputter power density is 3 W / cm 2 -5 W / cm 2 ; and / or, the thickness of the nickel layer on the surface of the copper-nickel substrate is 3 μm-8 μm.

4. The preparation method according to claim 1, characterized in that: Vacuum heat treatment of copper-nickel substrates at 200℃-300℃; and / or, at 1×10 -3 Pa-5×10 -3 Vacuum heat treatment of copper-nickel substrates at Pa; and / or, heat treatment for 30 min to 120 min; and / or, heating of copper-nickel substrates at a rate of 2 °C / min to 5 °C / min; and / or, cooling of copper-nickel substrates at a rate of 2 °C / min to 5 °C / min after vacuum heat treatment.

5. The preparation method according to claim 1, characterized in that: The chromium plating solution contains 200 g / L-250 g / L chromic anhydride, 1.8 g / L-2.5 g / L sulfuric acid, 10 g / L-20 g / L buffer, and 1 g / L-3 g / L chromium plating additive; wherein chromium plating is performed at 45℃-55℃; and / or at 5A / dm 2 -30A / dm 2 Chromium plating at current density; and / or, electroplating using a copper-nickel composite sheet as the cathode and a lead-tin alloy as the anode.

6. The preparation method according to claim 5, characterized in that: The chromium plating additive includes at least one of 3-sulfonylpropionic acid and glutamic acid; and / or, the buffer includes one of boric acid, sodium citrate, and sodium acetate; and / or, the chromium plating additive further includes a composite product, the preparation method of which includes: 3-sulfonylpropionic acid and glutamic acid undergo an amidation reaction under the action of a condensing agent, and then the composite product is separated.

7. The preparation method according to claim 6, characterized in that: In preparing the composite product: the condensing agent includes 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride; and / or, the molar ratio of 3-sulfonic acid propionic acid to glutamic acid is 1:(1-1.2); and / or, the reaction is carried out at 2℃-8℃; and / or, the reaction is carried out for 4h-8h; and / or, the reaction is carried out in N,N-dimethylformamide and N-methylpyrrolidone; and / or, the composite product is obtained by rotary evaporation after the reaction; and / or, an amidation reaction is carried out in an alkaline environment.

8. The preparation method according to claim 1, characterized in that: The reducing gas in the reducing atmosphere includes hydrogen; and / or, the pressure of the reducing atmosphere is 0.1 MPa-0.3 MPa; and / or, surface reduction is carried out at 300℃-350℃; and / or, surface reduction is carried out for 1h-2h; and / or, the gas flow rate in the reducing atmosphere is 0.5L / min-5L / min; and / or, the volume concentration of the reducing gas in the reducing atmosphere is 4%-10%; and / or, the reducing atmosphere includes an inert carrier gas, which includes argon.

9. A copper-nickel-chromium heat sink prepared by the preparation method according to any one of claims 1 to 8.

10. The application of a copper-nickel-chromium heat sink prepared by the preparation method according to any one of claims 1 to 8.

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