Method for improving heat transfer performance of interface between cold plate and flexible metal and application

Abstract

The present application belongs to the technical field of material heat dissipation, and particularly relates to a method for improving the heat transfer performance of the interface between a cold plate and a flexible metal and application thereof, which comprises the following steps: polishing and polishing the cold plate made of metal or metal matrix composite material; placing the surface of the cold plate in an acid reduction composite medium solution to perform chemical modification treatment, so as to form a transition layer on the surface of the cold plate, wherein the acid reduction composite medium solution contains a flexible metal, an acid and a reducing agent; and performing surface washing on the cold plate with the transition layer, so as to remove the residual acid reduction composite medium solution and fill the flexible metal on the washed cold plate. Through the chemical modification treatment on the surface of the cold plate, the present application solves the problem of poor wettability between the cold plate and the flexible metal, reduces the interface thermal resistance, and improves the heat dissipation performance of the cold plate.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation technology, specifically to a method and application for improving the heat transfer performance at the interface between a cold plate and a flexible metal. Background Technology

[0002] With the rapid development of 5G mobile communication, artificial intelligence (AI), high-performance computing (HPC), and third-generation semiconductor technology, the power density of electronic devices is increasing exponentially. Their heat flux density has exceeded the limits of traditional air-cooling technology, making efficient heat dissipation a technological bottleneck. Flexible metals possess extremely high thermal conductivity, far exceeding that of traditional thermal grease, thus becoming promising advanced thermal interface materials. However, there is a problem of poor wettability between flexible metals and common cold metal plates (such as copper and aluminum). This is due to the high surface tension of flexible metals, which easily form an oxide layer or undergo interfacial reactions on the surface of the cold plate, resulting in a small actual contact area and high interfacial thermal resistance. Therefore, there is an urgent need to develop a simple method that can effectively and stably improve the wettability between flexible metals and cold metal plates, thereby significantly reducing interfacial thermal resistance.

[0003] In existing technologies, methods such as mechanical polishing, applying high mounting pressure, or electroplating are commonly used to improve contact on the surface of cold-plate metal. The first approach involves surface mechanical treatment of the cold-plate metal, i.e., high-precision polishing or grinding, to reduce macroscopic roughness or improve throughput. However, this method only reduces macroscopic voids and is ineffective against nanoscale oxide layers. Furthermore, an overly smooth surface is detrimental to flexible metal anchoring, making it prone to interfacial separation under thermal cycling or vibration. In addition, this approach is costly and has limited effectiveness.

[0004] The second approach involves applying immense pressure using high-strength mechanical clamps to force the flexible metal to deform and fill the gaps. This method significantly increases structural complexity and stress, posing a risk of damaging the chip or metal cold plate, and is unsuitable for stress-sensitive advanced packaging. Furthermore, pressure does not improve intrinsic wettability; once the pressure is released, the thermal resistance may rise again.

[0005] The third approach involves electroplating an inert layer such as nickel, gold, or nickel-phosphorus onto the metal cold plate to increase interfacial wettability. However, the plating itself introduces additional interfacial thermal resistance, and the improvement in wettability between some plating layers and flexible metal is limited, with diffusion still possible under long-term high temperatures. Therefore, a key technical bottleneck has long existed in this field: how to fundamentally and effectively improve the wettability between flexible metal and metal cold plate without introducing additional interfacial thermal resistance, while simultaneously enhancing heat dissipation of the metal cold plate at a low cost, suitable for industrialization. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a method and application for improving the interfacial heat transfer performance between a cold plate and a flexible metal. This method enhances the interfacial heat transfer performance between a metal and metal-based composite cold plate and a flexible metal thermal interface material. By chemically modifying the surface of the metal cold plate, the problem of poor wettability between the metal cold plate and the flexible metal is solved, achieving the goal of producing a long-term stable and effective heat dissipation product.

[0007] This invention is achieved through the following technical solution: a method for improving the heat transfer performance at the interface between a cold plate and a flexible metal, comprising: Grinding and polishing of cold-rolled steel sheets made of metal and metal-based composite materials; The surface of the cold plate is placed in an acidic reducing composite medium solution for chemical modification treatment, forming a transition layer on the surface of the cold plate; the acidic reducing composite medium solution contains a flexible metal, an acid, and a reducing agent; The surface of the cold plate that has formed the transition layer is washed to remove the residual acidic reducing composite medium solution, and then flexible metal is filled into the washed cold plate.

[0008] The present invention is based on the grinding and polishing of metal cold plates, a step designed to reduce the impact of oxide layers on wettability. Most metal oxides have high chemical stability and extremely high melting points, making them difficult to decompose or melt at temperatures between 10℃ and 80℃. This severely hinders the diffusion, reaction, and metallurgical bonding between metal atoms. Furthermore, if oxides are present during chemical modification, fragile, easily peeled oxide interlayers will exist at the bonding interface, becoming crack sources and causing a sharp decrease in bonding strength or even failure, creating potential problems for subsequent processes. The subsequent surface chemical modification process involves constant contact with the acidic reducing composite medium solution. The reducing agent and acidic components in the solution provide strong reducing properties, preventing the formation of new oxides during the process. This ensures that the flexible metal spreads on a clean metal surface, effectively filling gaps and forming a dense, defect-free transition layer. The core of this invention lies in a chemical reaction occurring in an acidic reducing composite medium solution containing 2%-50% by mass of one or more of the following acids: phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, oxalic acid, hydrobromic acid, or acetic acid. Simultaneously, one or more reducing agents, such as potassium iodide, sodium sulfite, sodium sulfide, ascorbic acid, stannous chloride, or sodium borohydride, are added to the acidic reducing composite medium solution at 0.1%-20% by mass. The essence of this process is to chemically activate the surface of the metal cold plate using the acidic reducing composite medium, and through interfacial competitive reaction and solid-state diffusion, achieve a gradient bonding between the metal cold plate and the flexible metal. This process is based on multiphase electron transfer and chemical potential balance between the metal, the reducing agent components in the acidic reducing composite medium, and the active atoms such as indium, gallium, and tin in the flexible metal, ultimately forming an intermetallic compound micro / nanocrystalline transition layer at the interface with a gradient in chemical composition and a continuous transition in crystal structure. The acid component and the reducing agent synergistically regulate the electronic energy levels and chemical potentials on the surface of the metal cold plate. The reducing agent, by providing electrons, lowers the ionization barrier of the cold plate metal atoms, exposing clean crystal faces with high surface energy and unsaturated coordination bonds, and inhibiting their excessive dissolution. Indium, gallium, tin, and other atoms in the flexible metal exist as ions or in an active state in this environment, competing with the cold plate metal atoms for redox reactions at the interface. Due to the differences in electronegativity, atomic radius, and d-electron energy levels among the metal elements, their electron-capturing and atomic binding abilities differ, leading to the coexistence of multiple component reaction pathways. Under thermal drive, the cold plate metal atoms preferentially and controllably dissolve along grain boundaries or defects, forming transient ions; simultaneously, the active atoms of the flexible metal gain electrons at the interface, are reduced in situ, and cross-diffusion with the cold plate metal atoms or ions. This process is driven by the chemical potential gradient. Due to the differences in diffusion coefficients and affinities between different atoms, a series of non-equilibrium binary or multi-metallic compound phases are formed near the interface, which significantly reduces the solid-liquid interface energy, causing the wetting angle to drop below 10°.

[0009] Preferably, the flexible metal element is one or more of indium, tin, gallium, aluminum, zinc, bismuth, mercury, and silver.

[0010] Preferably, the acidic medium in the acidic reducing composite medium solution is a mixture of one or more acids selected from phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, oxalic acid, hydrobromic acid, or acetic acid, with a mass fraction of 2%-50%.

[0011] Preferably, the reducing agent in the acidic reducing composite medium solution is one or more of the following reducing agents: potassium iodide, sodium sulfite, sodium sulfide, ascorbic acid, stannous chloride, sodium borohydride, etc., with a mass fraction of 0.1%-20%.

[0012] Preferably, the temperature of the acidic reducing composite medium solution is between 10°C and 80°C.

[0013] If the processing temperature or the concentration of the acidic reducing composite medium solution is below this range, the driving force of the reaction is insufficient, the displacement reaction rate is too slow, and it is difficult to form a continuous and dense transition layer. If the temperature or concentration exceeds this range, the overall corrosion of the metal matrix will be aggravated, the reaction will be too violent, and it may lead to a rough and porous transition layer, or even damage the integrity of the metal matrix.

[0014] Preferably, the amount of flexible metal in the acidic reducing composite medium solution needs to cover the surface of the metal cold plate.

[0015] The nanoscale rough surface formed by the metal substrate after treatment in the acidic reducing composite medium solution increases the actual reaction area. The amount of flexible metal in the acidic reducing composite medium solution needs to cover the surface of the cold plate to ensure that the solid-liquid interface is always completely covered by the reaction medium during the dynamic reaction process, fully wetted and filled with the micro-uneven structure, avoiding the interruption of the reaction due to the depletion of local flexible metal, and ensuring the uniformity and integrity of the surface chemical modification process.

[0016] Preferably, the surface chemical modification time is 5s-15min, thereby obtaining a transition layer with a thickness of 10µm-100µm.

[0017] The duration of surface chemical modification directly determines the amount of atoms dissolved from the metal matrix into the flexible metal and the thickness of the transition layer. If the time is too short, the interfacial reaction will be insufficient, resulting in a discontinuous intermetallic compound layer, leading to insufficient bonding strength and high interfacial thermal resistance. If the time is too long, an excessively thick intermetallic compound layer will be formed. Due to its inherently low thermal conductivity and the potential for microcracks, this layer will affect heat transfer and significantly increase the overall thermal resistance.

[0018] Preferably, the surface chemical modification process involves rinsing off the residual flexible metal and acidic reducing composite medium solution with deionized water and then vacuum drying at low temperature.

[0019] The residual flexible metal and acidic reducing composite medium solution are rinsed with deionized water to physically remove excess unreacted flexible metal medium and terminate the interfacial reaction.

[0020] Preferably, the thickness of the flexible filler metal is 50µm-300µm, and it is packaged with the chip to obtain the final product.

[0021] The product manufactured by the method proposed in this invention for improving the heat transfer performance of the interface between the cold plate and the flexible metal is used for heat dissipation in electronic devices.

[0022] Compared with the prior art, the present invention has the following advantages: This invention constructs a nanoscale anchoring transition layer on the surface of a metal cold plate through surface chemical reaction. This layer possesses intrinsic nanoscale grain and phase boundaries, providing excellent mechanical interlocking sites for subsequent flexible metal fabrication and significantly enhancing interfacial bonding. This bonding exhibits outstanding stability under thermal cycling or mechanical vibration, completely avoiding the risk of interfacial separation.

[0023] The transition layer interface formed by this invention has its strength determined by chemical bonding forces and the diffusion layer structure, eliminating the need for continuous external mechanical pressure to maintain contact. This not only eliminates the risk of damaging the chip or cold plate due to excessive pressure, making the solution suitable for scenarios extremely sensitive to stress, such as ultra-thin chips and 3D packaging, but also simplifies the packaging structure and reduces system complexity and cost. The interface thermal conductivity is guaranteed by the intrinsic properties of the material, and there is no performance degradation due to stress relaxation.

[0024] The transition layer generated by this invention is a thermodynamically stable phase formed by interdiffusion between metal and flexible metal atoms. The transition layer and the cold plate substrate are atomically diffusely bonded, exhibiting excellent crystallographic compatibility with the flexible metal. This process route resolves the inherent contradictions of traditional methods regarding mechanical anchoring, stress control, and multilayer interface thermal resistance. The resulting interface possesses both extremely low contact thermal resistance and extremely high bonding strength, providing a superior solution for thermal management of high-power-density electronic devices. Attached Figure Description

[0025] Figure 1 This is a photograph of the cold plate after processing in Example 1; Figure 2 This is a SEM cross-sectional view of the cold plate after processing in Example 1; Detailed Implementation

[0026] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. 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. A method for improving the heat transfer performance of the interface between a cold plate and a flexible metal includes the following steps: Grinding and polishing of cold-rolled steel sheets made of metal and metal-based composite materials; The polished cold plate surface is placed in an acidic reducing composite medium solution for surface chemical modification. The acidic reducing composite medium solution contains one or more acids selected from phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, oxalic acid, hydrobromic acid, or acetic acid at a mass fraction of 2%-50%; one or more reducing agents selected from potassium iodide, sodium sulfite, sodium sulfide, ascorbic acid, stannous chloride, sodium borohydride, etc. at a mass fraction of 0.1%-20%; and flexible metal. The treatment is carried out at a temperature of 10℃-80℃ for 1 min-15 min. Then, the treated cold plate is removed from the acidic reducing composite medium solution, excess flexible metal on the surface is wiped off with lint-free paper, and residual acidic reducing composite medium solution is rinsed off with an appropriate amount of deionized water. The plate is then dried in a vacuum oven to obtain a transition layer between the cold plate and the flexible metal with a thickness between 10µm and 100µm. A 50µm-300µm flexible metal is rapidly filled into a cold plate with a transition layer and then packaged with a chip to obtain the final product.

[0027] In some preferred embodiments, the flexible metal element is one or more of indium, tin, gallium, aluminum, zinc, bismuth, mercury, and silver.

[0028] In some preferred embodiments, the acidic reducing composite medium solution contains one or more of phosphoric acid, sulfuric acid, and hydrochloric acid, with a mass fraction of 0.1%-20%.

[0029] In some preferred embodiments, the acidic reducing composite medium solution contains one or more of sodium sulfide, sodium sulfite, and potassium iodide, with a mass fraction of 2%-50%.

[0030] In some preferred embodiments, the temperature of the acidic reducing composite medium solution is between 10°C and 80°C.

[0031] In some preferred embodiments, the surface chemical modification is performed for 1-15 minutes to obtain a transition layer with a thickness of 10µm-100µm.

[0032] In some preferred embodiments, the chemically modified surface treatment involves wiping away excess flexible metal from the surface with lint-free paper, rinsing with deionized water, and then vacuum drying at low temperature.

[0033] In some preferred embodiments, the thickness of the filler flexible metal is 100µm, and it is packaged with the chip to obtain the final product. Example 1

[0034] A method for enhancing the interfacial heat transfer performance between a metal and metal-based composite cold plate and a flexible metal thermal interface material includes the following steps: The cold plate is ground and polished to remove its surface oxide layer; The surface of the cold plate was placed in an acidic reducing composite medium solution containing 2% phosphoric acid and sulfuric acid (in a 2:8 ratio) and 0.1% sodium sulfite at 70°C. An appropriate amount of gallium-indium-tin alloy (GaInT) was added dropwise to the acidic reducing composite medium solution until it completely covered the surface of the cold plate. The GaInT alloy composition was 50% gallium, 32% indium, and 18% tin. After 12 minutes, the cold plate was removed from the acidic reducing composite medium solution, and excess flexible metal and some of the acidic reducing composite medium solution were wiped off with lint-free paper. It was then rinsed with an appropriate amount of deionized water and dried in a vacuum oven set at 40°C to obtain a transition layer with a thickness of 15µm. A suitable elastic rubber ring with a thickness of 200µm is fitted around the cold plate. 100µm of flexible metal is then quickly filled into the surface of the cold plate and packaged with the chip to obtain the final product. Example 2

[0035] A method for enhancing the interfacial heat transfer performance between a metal and metal-based composite cold plate and a flexible metal thermal interface material includes the following steps: The cold plate is ground and polished to remove its surface oxide layer; The surface of the cold plate was placed in an acidic reducing composite medium solution containing 2% phosphoric acid and sulfuric acid (in a 2:8 ratio) and 20% sodium sulfite at 70°C. An appropriate amount of gallium-indium-tin alloy (GaInT) was added dropwise to the acidic reducing composite medium solution until it completely covered the surface of the cold plate. The GaInT alloy composition was 50% gallium, 32% indium, and 18% tin. After 12 minutes, the cold plate was removed from the acidic reducing composite medium solution, and excess flexible metal and some of the acidic reducing composite medium solution were wiped off with lint-free paper. It was then rinsed with an appropriate amount of deionized water and dried in a vacuum oven set at 40°C to obtain a transition layer with a thickness of 70µm. A suitable elastic rubber ring with a thickness of 200µm is fitted around the cold plate. 100µm of flexible metal is then quickly filled into the surface of the cold plate and packaged with the chip to obtain the final product. Example 3

[0036] A method for enhancing the interfacial heat transfer performance between a metal and metal-based composite cold plate and a flexible metal thermal interface material includes the following steps: The cold plate is ground and polished to remove its surface oxide layer; The surface of the cold plate was placed in an acidic reducing composite medium solution containing 50% phosphoric acid and sulfuric acid (in a 2:8 ratio) and 0.1% sodium sulfite at 70°C. An appropriate amount of gallium-indium-tin alloy (GaInT) was added dropwise to the acidic reducing composite medium solution until it completely covered the surface of the cold plate. The GaInT alloy composition was 50% gallium, 32% indium, and 18% tin. After 8 minutes, the cold plate was removed from the acidic reducing composite medium solution, and excess flexible metal and some of the acidic reducing composite medium solution were wiped off with lint-free paper. It was then rinsed with an appropriate amount of deionized water and dried in a vacuum oven set at 40°C to obtain a transition layer with a thickness of 85µm. A suitable elastic rubber ring with a thickness of 200µm is fitted around the cold plate. 100µm of flexible metal is then quickly filled into the surface of the cold plate and packaged with the chip to obtain the final product. Example 4

[0037] A method for enhancing the interfacial heat transfer performance between a metal and metal-based composite cold plate and a flexible metal thermal interface material includes the following steps: The cold plate is ground and polished to remove its surface oxide layer; The surface of the cold plate was placed in an acidic reducing composite medium solution containing 50% phosphoric acid and sulfuric acid (in a 2:8 ratio) and 20% sodium sulfite at 70°C. An appropriate amount of gallium-indium-tin alloy (GaInT) was added dropwise to the acidic reducing composite medium solution until it completely covered the surface of the cold plate. The GaInT alloy composition was 50% gallium, 32% indium, and 18% tin. After 5 minutes, the cold plate was removed from the acidic reducing composite medium solution, and excess flexible metal and some of the acidic reducing composite medium solution were wiped off with lint-free paper. It was then rinsed with an appropriate amount of deionized water and dried in a vacuum oven set at 40°C to obtain a transition layer with a thickness of 60µm. A suitable elastic rubber ring with a thickness of 200µm is fitted around the cold plate. 100µm of flexible metal is then quickly filled into the surface of the cold plate and packaged with the chip to obtain the final product.

[0038] Comparative Example 1 The difference from Example 1 is that the method described in this invention for enhancing the interfacial heat transfer performance between metal and metal-based composite cold plates and flexible metal thermal interface materials was not used. The cold plate is ground and polished to remove its surface oxide layer; A suitable elastic rubber ring with a thickness of 200µm is fitted around the cold plate. 100µm of flexible metal is then quickly filled into the surface of the cold plate and packaged with the chip to obtain the final product.

[0039] Comparative Example 2 The only difference from Example 1 is that the mass fraction of the acidic medium in the acidic reducing composite medium solution is 1%. A method for enhancing the interfacial heat transfer performance between a metal and metal-based composite cold plate and a flexible metal thermal interface material includes the following steps: The cold plate is ground and polished to remove its surface oxide layer; The surface of the cold plate was placed in an acidic reducing composite medium solution containing 1% phosphoric acid and sulfuric acid (in a 2:8 ratio) and 0.1% sodium sulfite at 70°C. An appropriate amount of gallium-indium-tin alloy (GaInT) was added dropwise to the acidic reducing composite medium solution until it completely covered the surface of the cold plate. The GaInT alloy composition was 50% gallium, 32% indium, and 18% tin. After 12 minutes, the cold plate was removed from the acidic reducing composite medium solution, and excess flexible metal and some of the acidic reducing composite medium solution were wiped off with lint-free paper. It was then rinsed with an appropriate amount of deionized water and dried in a vacuum oven set at 40°C to obtain a non-uniform transition layer with a thickness of 3µm-10µm. A suitable elastic rubber ring with a thickness of 200µm is fitted around the cold plate. 100µm of flexible metal is then quickly filled into the surface of the cold plate and packaged with the chip to obtain the final product.

[0040] Comparative Example 3 The only difference from Example 1 is that the flexible metal in the acidic reducing composite medium solution does not cover the surface of the cold plate. A method for enhancing the interfacial heat transfer performance between a metal and metal-based composite cold plate and a flexible metal thermal interface material includes the following steps: The cold plate is ground and polished to remove its surface oxide layer; The surface of the cold plate was placed in an acidic reducing composite medium solution containing 2% phosphoric acid and sulfuric acid (in a 2:8 ratio) and 0.1% sodium sulfite at 70°C. A small amount of gallium-indium-tin alloy (GaInTI) was added dropwise to the acidic reducing composite medium solution. The GaInTI alloy had a composition of 50% gallium, 32% indium, and 18% tin. After 12 minutes, the cold plate was removed from the acidic reducing composite medium solution, and excess flexible metal and some of the acidic reducing composite medium solution were wiped off with lint-free paper. It was then rinsed with an appropriate amount of deionized water and dried in a vacuum oven at 40°C to obtain a non-uniform transition layer with a thickness of 0µm-10µm. A suitable elastic rubber ring with a thickness of 200µm is fitted around the cold plate. 100µm of flexible metal is then quickly filled into the surface of the cold plate and packaged with the chip to obtain the final product.

[0041] Comparative Example 4 The only difference from Example 1 is that the acidic reducing composite medium solution does not contain a reducing agent: A method for enhancing the interfacial heat transfer performance between a metal and metal-based composite cold plate and a flexible metal thermal interface material includes the following steps: Grinding and polishing of the cold-rolled steel plate; The surface of the cold plate was placed in an acidic reducing composite medium solution containing 2% (w / w) of a mixture of phosphoric acid and sulfuric acid, with a phosphoric acid to sulfuric acid ratio of 2:8, at a temperature of 70°C. An appropriate amount of gallium-indium-tin alloy (GaInT) was added dropwise to the acidic reducing composite medium solution until it completely covered the surface of the cold plate. The GaInT alloy composition was 50% gallium, 32% indium, and 18% tin. After 12 minutes, the cold plate was removed from the acidic reducing composite medium solution, and excess flexible metal and some of the acidic reducing composite medium solution were wiped off with lint-free paper. It was then rinsed with an appropriate amount of deionized water and dried in a vacuum oven set at 40°C to obtain a non-uniform transition layer with a thickness of 2-5 µm. A suitable elastic rubber ring with a thickness of 200µm is fitted around the cold plate. 100µm of flexible metal is then quickly filled into the surface of the cold plate and packaged with the chip to obtain the final product.

[0042] The sample with surface chemical modification in Example 1 is shown below. Figure 1 and Figure 2 As shown.

[0043] Performance testing: The same model of cold plate was selected for testing. Under the same power (1000W), pressure (400N), and condensate flow rate (2L / min) parameters, the heat dissipation capacity of each embodiment and comparative example was tested.

[0044] The test results are shown in Table 1.

[0045] Table 1. Test results for examples and comparative examples.

[0046] In the field of electronic heat dissipation, flexible metals, with their significantly higher thermal conductivity and lower viscosity than traditional thermal greases or phase change materials, have become key thermal interface materials for addressing the thermal management challenges of high-power-density chips. Their core function is to efficiently fill the microscopic gaps between the heat-generating chip and the cold plate, establishing a low-thermal-resistance heat transfer path from the chip junction temperature to the external environment, thereby significantly reducing the chip's operating temperature and improving system performance and reliability. In this heat transfer path, the interfacial wettability and interfacial thermal resistance between the flexible metal and the cold plate are the key bottlenecks determining the overall heat dissipation efficiency. However, current technologies typically improve contact by mechanically polishing the cold plate surface, applying enormous mounting pressure, or electroplating, which carries the risk of interface separation and cannot provide long-term, stable heat dissipation, becoming a technological bottleneck in the industry. This invention involves grinding and polishing a metal cold plate to remove its surface oxide layer. The surface of the cold plate is then placed in an acidic reducing composite medium solution containing 2%-50% phosphoric acid and sulfuric acid, and 0.1%-20% sodium sulfite, at a temperature of 70°C. The acidic reducing composite medium solution contains a certain amount of flexible gallium indium tin alloy. After 1-15 minutes, the cold plate is removed from the acidic reducing composite medium solution, excess flexible metal and some of the acidic reducing composite medium solution are removed, and the plate is rinsed with an appropriate amount of deionized water. It is then dried in a vacuum oven at 40°C to obtain a transition layer with a thickness of 10µm-120µm. A 200µm thick, appropriately sized elastic rubber ring is then fitted around the cold plate, and 100µm of flexible metal is quickly filled in. This is then packaged with a chip to obtain the final product. This design solves the problem of poor wettability between the cold plate and the flexible metal while reducing interfacial thermal resistance and enhancing the heat dissipation capacity of the cold plate. Meanwhile, the process is simple, suitable for industrialization, and the resulting transition layer is relatively stable and effective over a long period.

[0047] Compared with the examples, Comparative Example 1 did not use the method, and there was no transition layer on the surface of the cold plate; Comparative Example 2 had insufficient reaction driving force and slow displacement reaction rate due to the low concentration of the medium in the acidic reducing composite medium solution, making it difficult to form a transition layer with a certain thickness and uniformity in a short time; Comparative Example 3 had insufficient flexible metal content, which could not ensure that the solid-liquid interface was always completely covered by the reaction medium during the dynamic reaction, resulting in the depletion of local flexible metal, interruption of the reaction, and thus affecting the uniformity and integrity of the alloy layer; Comparative Example 4 did not add a reducing agent and lacked effective electron transfer control, making it difficult for flexible metal atoms to have a sufficient and uniform interfacial reaction with the cold plate, and thus failing to form a continuous and dense gradient transition layer.

[0048] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for improving the interfacial heat transfer performance between a cold plate and a flexible metal, characterized in that, include: Grinding and polishing of cold-rolled steel sheets made of metal and metal-based composite materials; The polished surface of the cold plate is placed in an acidic reducing composite medium solution for chemical modification treatment, forming a transition layer on the surface of the cold plate; the acidic reducing composite medium solution contains a flexible metal, an acid, and a reducing agent; The surface of the cold plate that has formed the transition layer is washed to remove the residual acidic reducing composite medium solution, and then flexible metal is filled into the washed cold plate.

2. The method as described in claim 1, characterized in that, The acidic reducing composite medium solution contains 2%-50% by mass of one or more acids selected from phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, oxalic acid, hydrobromic acid, or acetic acid.

3. The method as described in claim 1, characterized in that, The acidic reducing composite medium solution contains one or more of the following in a mass fraction of 0.1%-20%: potassium iodide, sodium sulfite, sodium sulfide, ascorbic acid, stannous chloride, and sodium borohydride.

4. The method as described in claim 1, characterized in that, The temperature of the acidic reducing composite medium solution is 10℃-80℃.

5. The method as described in claim 1, characterized in that, The flexible metal is one or more of indium, tin, gallium, aluminum, zinc, bismuth, mercury, and silver.

6. The method as described in claim 1, characterized in that, The amount of flexible metal used in the acidic reducing composite medium solution needs to cover the surface of the cold plate.

7. The method as described in claim 1, characterized in that, The surface chemical modification treatment time is 5 s-15 min.

8. The method as described in claim 1, characterized in that, The residual flexible metal and acidic reducing composite medium solution after surface chemical modification are rinsed with deionized water and dried under low temperature vacuum to obtain a transition layer with a thickness of 10µm-100µm and a smooth and bright surface.

9. The method as described in claim 1, characterized in that, The cold plate filled with flexible metal is then packaged with the chip.

10. The application of the method as described in any one of claims 1-9 in heat dissipation of electronic devices.

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