A copper plate strip material production process of a vc uniform temperature plate

Abstract

This invention relates to a production process for copper strip material of VC heat exchange plate, belonging to the field of metal materials technology, and includes the following steps: The components are weighed according to the following mass fractions: Ag: 0.05-0.25%; Zr: 0.05-0.15%; Cr: 0.05-0.20%, with the balance being Cu and unavoidable impurities; the aforementioned components are melted, and the melt is introduced into a twin-roll thin strip casting mill for rapid solidification and casting to obtain a cast strip billet; subsequently, online solution treatment and high-pressure gas-water mist composite quenching are performed; then, the strip billet is subjected to single-pass high-deformation warm rolling; finally, graded aging and controlled annealing are performed. The copper strip material obtained by this invention has high tensile strength and yield strength, high thermal conductivity and high thermal diffusion efficiency, achieving an excellent synergy between high strength and ultra-high thermal conductivity. The obtained copper alloy strip also has excellent etching and brazing properties, which can meet the needs of precision manufacturing.

Description

Technical Field

[0001] This invention belongs to the field of metal materials technology, specifically, it relates to a production process of copper strip material for VC heat exchange plates. Background Technology

[0002] With the rapid increase in power density of 5G / 6G communication and high-performance computing chips, higher requirements are placed on the heat dissipation efficiency of VC vapor chambers. The core components of VC (cover plate and capillary core substrate) require materials that possess: 1) high thermal conductivity to quickly dissipate heat; 2) sufficient strength to support the ultra-thin cavity structure; and 3) good reprocessability for subsequent processes such as etching and welding.

[0003] Existing technologies, such as reference document CN111394610B, focus on using tin-phosphorus bronze (C5191) and optimizing its phosphorus content to address warping issues caused by etching blackening and residual stress. However, this approach has the following limitations: Material limitations: Tin-phosphor bronze itself is a medium-to-low thermal conductivity material. Its thermal conductivity is typically below 80 W / (m·K), far lower than that of pure copper (approximately 400 W / (m·K)). Sacrificing thermal conductivity for strength and etching performance becomes a bottleneck in extreme heat dissipation scenarios.

[0004] The problem is limited in its focus: it mainly addresses the "etching process compatibility" (blackening, warping) rather than improving the "core heat dissipation performance" (thermal conductivity) and "mechanical reliability" (strength, creep resistance) of VC from the material's fundamental source.

[0005] Therefore, the industry urgently needs a new material and process that can fundamentally break through the contradiction between "high thermal conductivity" and "high strength" and is suitable for VC manufacturing. Summary of the Invention

[0006] In order to overcome the problems existing in the background art, the present invention provides a copper strip material production process for VC heat exchange plate.

[0007] To achieve the above objectives, the first aspect of the present invention provides a copper strip material manufacturing process for a VC heat exchanger, comprising the following steps: S1, weigh the components according to the following mass fractions: Ag: 0.05 - 0.25%; Zr: 0.05 - 0.15%; Cr: 0.05 - 0.20%; The balance is Cu and unavoidable impurities; S2 involves melting the components from step S1 in a vacuum melting furnace, then introducing the molten alloy liquid into a twin-roll thin strip casting and rolling mill. Under conditions of a cooling roll speed of 20-40 m / min and a rolling force of 100-200 kN, the casting, solidification, and preliminary deformation are completed in one go, resulting in a cast and rolled strip billet with a thickness of 3-6 mm and a rapidly solidified microcrystalline structure. S3. After the cast and rolled strip exits the roll, it immediately enters the adjacent online induction heating solution furnace. Under a protective atmosphere, the temperature is controlled at 950±10℃ and held for 30-90 seconds. Then, high-pressure nitrogen-water mist composite quenching is performed to rapidly cool the strip to below 150℃ within 3 seconds to obtain a supersaturated solid solution. S4: After quenching, the strip is preheated to 300-450℃, and then subjected to single-pass large deformation rolling, with the deformation controlled at 60%-75%. S5, the rolled strip is subjected to graded aging treatment: first stage aging: holding at 450-480℃ for 1-2 hours; second stage aging: holding at 380-420℃ for 2-4 hours; third stage: annealing at 550-600℃ in a hydrogen atmosphere for 5-15 minutes. S6 involves micro-tension straightening and electrochemical polishing of the aged strip to obtain the finished strip.

[0008] Furthermore, the method for melting the components of step S1 in the vacuum melting furnace in step S2 is as follows: first, add copper and Cr, heat to 1200-1220℃, and fully melt; then cool to 1180-1200℃, add Zr and Ag, turn on strong magnetic stirring to control the temperature not to exceed 1220℃, stir for 3-8 minutes, and then introduce into a twin-roll thin strip casting and rolling mill.

[0009] Furthermore, the protective atmosphere used in step S3 is nitrogen.

[0010] The beneficial effects of this invention are: 1. The obtained copper alloy strip has high tensile strength and yield strength, high thermal conductivity and thermal diffusion efficiency at a thickness of 0.25mm, achieving an excellent synergy between high strength and ultra-high thermal conductivity.

[0011] 2. The resulting copper alloy strip has excellent etching and brazing properties, which can meet the requirements of precision manufacturing. Detailed Implementation

[0012] To make the objectives, technical solutions, and beneficial effects of the present invention clearer, the preferred embodiments of the present invention will be described in detail below to facilitate understanding by those skilled in the art.

[0013] Example 1 A manufacturing process for copper strip material in a VC heat exchanger includes the following steps: S1, weigh the components according to the following mass fractions: Ag: 0.05%; Zr: 0.05%; Cr: 0.05%; The balance is Cu and unavoidable impurities; S2 involves melting the components from step S1 in a vacuum melting furnace, then introducing the molten alloy liquid into a twin-roll thin strip casting mill. Under the conditions of a cooling roll speed of 20 m / min and a rolling force of 100 kN, the casting, solidification, and preliminary deformation are completed in one go, resulting in a cast-rolled strip billet with a thickness of 3 mm and a rapidly solidified microcrystalline structure. S3. After the cast and rolled strip exits the roll, it immediately enters the adjacent online induction heating solution furnace. Under the protection of nitrogen, the temperature is controlled at 950±10℃ and held for 30 seconds. Then, high-pressure nitrogen-water mist composite quenching is performed to rapidly cool the strip to below 150℃ within 3 seconds to obtain a supersaturated solid solution. S4: The quenched strip is preheated to 300℃, and then subjected to single-pass large deformation rolling, with the deformation controlled at 60%; S5, the rolled strip is subjected to graded aging treatment: first stage aging: holding at 450℃ for 1 hour; second stage aging: holding at 380℃ for 2 hours; third stage: annealing at 550℃ in a hydrogen atmosphere for 5 minutes. S6 involves micro-tension straightening and electrochemical polishing of the aged strip to obtain the finished strip.

[0014] The method for melting the components of step S1 in step S2 using a vacuum melting furnace is as follows: first, add copper and Cr, heat to 1200℃ and melt fully; then cool to 1180℃, add Zr and Ag, turn on strong magnetic stirring and control the temperature not to exceed 1220℃, stir for 3 minutes and then introduce into a twin-roll thin strip casting and rolling mill.

[0015] Example 2 A manufacturing process for copper strip material in a VC heat exchanger includes the following steps: S1, weigh the components according to the following mass fractions: Ag: 0.15; Zr: 0.10%; Cr: 0.13%; The balance is Cu and unavoidable impurities; S2 involves melting the components from step S1 in a vacuum melting furnace, then introducing the molten alloy liquid into a twin-roll thin strip casting and rolling mill. Under the conditions of a cooling roll speed of 30 m / min and a rolling force of 150 kN, the casting, solidification, and preliminary deformation are completed in one go, resulting in a cast and rolled strip billet with a thickness of 4 mm and a rapidly solidified microcrystalline structure. S3. After the cast and rolled strip exits the roll, it immediately enters the adjacent online induction heating solution furnace. Under the protection of nitrogen, the temperature is controlled at 950±10℃ and held for 60 seconds. Then, high-pressure nitrogen-water mist composite quenching is performed to rapidly cool the strip to below 150℃ within 3 seconds to obtain a supersaturated solid solution. S4: The quenched strip is preheated to 400℃ and then subjected to single-pass large deformation rolling, with the deformation controlled at 65%. S5, the rolled strip is subjected to graded aging treatment: first stage aging: holding at 465℃ for 1.5 hours; second stage aging: holding at 400℃ for 3 hours; third stage: annealing at 575℃ in a hydrogen atmosphere for 10 minutes. S6 involves micro-tension straightening and electrochemical polishing of the aged strip to obtain the finished strip.

[0016] The method for melting the components of step S1 in step S2 using a vacuum melting furnace is as follows: first, add copper and Cr, heat to 1210℃, and melt fully; then cool to 11890℃, add Zr and Ag, turn on strong magnetic stirring to control the temperature not to exceed 1220℃, stir for 6 minutes, and then introduce into a twin-roll thin strip casting and rolling mill.

[0017] Example 3 A manufacturing process for copper strip material in a VC heat exchanger includes the following steps: S1, weigh the components according to the following mass fractions: Ag: 0.25%; Zr: 0.15%; Cr: 0.20%; The balance is Cu and unavoidable impurities; S2 involves melting the components from step S1 in a vacuum melting furnace, then introducing the molten alloy liquid into a twin-roll thin strip casting and rolling mill. Under the conditions of a cooling roll speed of 40 m / min and a rolling force of 200 kN, the casting, solidification, and preliminary deformation are completed in one go, resulting in a cast and rolled strip billet with a thickness of 6 mm and a rapidly solidified microcrystalline structure. S3. After the cast and rolled strip exits the roll, it immediately enters the adjacent online induction heating solution furnace. Under the protection of nitrogen, the temperature is controlled at 950±10℃ and held for 90 seconds. Then, high-pressure nitrogen-water mist composite quenching is performed to rapidly cool the strip to below 150℃ within 3 seconds to obtain a supersaturated solid solution. S4: The quenched strip is preheated to 450°C and then subjected to single-pass large deformation rolling, with the deformation controlled at 75%. S5, the rolled strip is subjected to graded aging treatment: first stage aging: holding at 480℃ for 2 hours; second stage aging: holding at 420℃ for 4 hours; third stage: annealing at 600℃ in a hydrogen atmosphere for 15 minutes. S6 involves micro-tension straightening and electrochemical polishing of the aged strip to obtain the finished strip.

[0018] The method for melting the components of step S1 in step S2 using a vacuum melting furnace is as follows: first, add copper and Cr, heat to 1220℃, and melt them completely; then cool to 1200℃, add Zr and Ag, turn on strong magnetic stirring to control the temperature not to exceed 1220℃, stir for 8 minutes, and then introduce the mixture into a twin-roll thin strip casting and rolling mill.

[0019] Experimental Example I. Thermal conductivity test Standard based on: ASTM E1461-13, "Standard Test Method for Determination of Thermal Diffusivity by Flash Method" Equipment: Laser Blitz (LFA) thermal conductivity meter, Netzsch LFA 467 HyperFlash.

[0020] Sample preparation: A circular sample with a diameter of 12.7 mm was cut from the strip.

[0021] Ensure that both sides of the sample are parallel, flat, and clean, and lightly sandblast the surface to enhance laser absorption and infrared emissivity.

[0022] Measure and record the precise thickness of the sample (average of 5 measurements).

[0023] Test steps: Place the sample in the center of the LFA sample holder.

[0024] The system is filled with an inert gas (argon) to reduce convective heat loss.

[0025] Set test parameters: Select a laser pulse width and data acquisition time that are appropriate for the sample thickness and material.

[0026] Test start: The instrument emits a short laser pulse to uniformly irradiate the lower surface of the sample, while the infrared detector on the upper surface records the temperature rise curve over time (Tt curve).

[0027] The thermal diffusivity (α, unit: mm² / s) of the material at the test temperature was calculated by fitting the Tt curve using a mathematical model (using the Cowan model).

[0028] This experiment was conducted at room temperature (25℃).

[0029] Data processing and recording: The thermal conductivity (λ, W / (m·K)) is calculated using the following formula: λ = α × ρ × Cp where: α: Thermal diffusivity obtained from the test; ρ: Material density; calculated using Archimedes' displacement method (according to GB / T 3850). Cp: ​​Specific heat capacity; measured using DSC (Differential Scanning Calorimeter).

[0030] The results are shown in Table 1 below: Table 1. Thermal diffusivity and thermal conductivity obtained in each embodiment II. Room temperature tensile test and hardness test (mechanical properties) According to the standard: GB / T 228.1-2021 Metallic materials, tensile testing – Part 1: Test at room temperature GB / T 4340.1-2009 Metallic materials – Vickers hardness test – Part 1: Test methods Part A: Tensile Testing at Room Temperature Equipment: Electronic universal testing machine (equipped with an extensometer with ±0.5 accuracy), Instron 5967.

[0031] Sample preparation: Samples were taken along the rolling direction (longitudinal) and perpendicular to the rolling direction (transverse) to assess anisotropy.

[0032] Rectangular cross-section specimens are used, referring to specimen B.2 (non-proportional specimen) in Appendix B of GB / T 228.1. Dimensions: width within the gauge length 12.5 mm, parallel length ≥ 75 mm, original gauge length G = 50 mm. Thickness is the actual material thickness (e.g., 0.25 mm).

[0033] The specimens are machined using precision slow wire cutting to ensure that the edges are free of burrs and work-hardened layers.

[0034] Test steps: The initial gauge length is marked in the middle of the parallel section of the sample using a non-contact method (such as laser marking).

[0035] The specimen is clamped symmetrically and vertically in the testing machine fixture with moderate clamping force to prevent slippage or damage.

[0036] Install the extensometer and align it precisely with the gauge mark.

[0037] Key setting: Strain rate control mode is adopted.

[0038] During the expected elastic phase, the strain rate was set to 0.00025 / s.

[0039] From the elastic stage to the yield stage, this rate is maintained to accurately determine the yield point.

[0040] After yielding, the strain rate was switched to 0.0067 / s until the specimen fractured.

[0041] Once the test is started, the system automatically and continuously records the load-displacement and stress-strain (based on extensometer) curves.

[0042] After the sample breaks, it is removed and carefully reassembled. The gauge length after the break and the minimum width and thickness of the necking are measured with vernier calipers.

[0043] The experimental results are shown in Table 2 below: Table 2 Tensile test data for each embodiment Part B: Vickers Hardness Test Objective: To rapidly assess the overall strength and uniformity of materials in a micro-area manner.

[0044] Equipment: Micro Vickers hardness tester.

[0045] Test steps: Take a small sample, inlay it, grind it, and polish it to a mirror finish.

[0046] Select an appropriate test force based on the thickness: Use HV0.5 and make 5 indentations evenly on the sample surface along the rolling direction and transverse direction respectively. The spacing between the indentations should be more than 3 times the length of the diagonal of the indentation.

[0047] The diagonal length of each indentation is measured, and the instrument automatically calculates the hardness value.

[0048] The results are shown in Table 3 below: Table 3 Vickers hardness test data for each embodiment III. Etching Performance Test Objective: To simulate the capillary trench etching process in VC manufacturing and evaluate the etching uniformity, surface quality, and deformation of the material.

[0049] Equipment and reagents: etching machine (or constant temperature water bath), FeCl3 etching solution (concentration 38°Bé, i.e., about 40wt%), digital microscope, surface profilometer, laser displacement sensor.

[0050] Sample and Procedure: Sample preparation: The strips from Examples 1 to 3 were cut into 50mm × 50mm cubes. After cleaning and drying, photoresist was coated on one side, and a mask with the same periodic trench pattern was prepared by photolithography.

[0051] Etching process: The sample was vertically immersed in FeCl3 etching solution maintained at a constant temperature of 45°C.

[0052] The etching time is set to 10 minutes.

[0053] Shake the etching tank at a constant speed to ensure uniform etching.

[0054] Post-processing: After the time is reached, immediately remove the sample, rinse it with plenty of deionized water, neutralize it with sodium carbonate solution, and finally remove the photoresist and clean and dry it.

[0055] Evaluation methods and data recording: Macroscopic observation and warpage: Observe whether the etched surface is black and whether the color is uniform.

[0056] The etched sample is placed on an optical platform, and a laser displacement sensor is used to scan along the diagonal of the sample to determine its maximum warpage.

[0057] Microstructure and dimensional accuracy: The roughness (Ra) of the trench sidewalls was measured using a surface profilometer.

[0058] The results are shown in Table 4 below: Table 4 Etching performance data for each embodiment IV. Brazing performance test Standards: Refer to GB / T 11363-2008 "Test Method for Strength of Brazed Joints" and industry-standard methods.

[0059] Objective: To evaluate the interfacial bonding quality and reliability of the material when used as a VC cover plate and vacuum brazed with the frame.

[0060] Equipment and materials: vacuum brazing furnace, BNi-2 nickel-based brazing foil (50μm thick), oxygen-free copper frame (same material), electronic universal testing machine.

[0061] Sample preparation and procedures: Preparation of the lap joint: The strips from Examples 1 to 3 (as cover plates) are lapped with oxygen-free copper sheets of the same size (as frames). The lap area is 10mm × 10mm. A BNi-2 solder foil is placed in the middle of the lap interface.

[0062] Vacuum brazing: The assembled sample is placed in a vacuum furnace.

[0063] Evacuate to a level better than 5×10⁻³Pa.

[0064] Heat according to the standard BNi-2 brazing process curve: increase to 1050℃ at 10℃ / min and hold for 10 minutes.

[0065] Cool in the furnace to below 200°C before being removed from the furnace.

[0066] Shear strength test: The brazed sample is fixed in a special shearing fixture to ensure that the shearing force is applied to the brazed joint interface.

[0067] Perform a shear test on a universal testing machine at a speed of 0.5 mm / min until the joint fails.

[0068] Record the maximum shear load (F_max).

[0069] Data processing and recording: Joint shear strength (τ) = F_max / A; Where A is the overlap area (100 mm²).

[0070] The experimental results are shown in Table 5 below: Table 5. Brazing performance data for each embodiment Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A manufacturing process for copper strip material of a VC heat spreader, characterized in that: It includes the following steps: S1, weigh the components according to the following mass fractions: Ag: 0.05 - 0.25%; Zr: 0.05 - 0.15%; Cr: 0.05 - 0.20%; The balance is Cu and unavoidable impurities; S2 involves melting the components from step S1 in a vacuum melting furnace, then introducing the molten alloy liquid into a twin-roll thin strip casting and rolling mill. Under conditions of a cooling roll speed of 20-40 m / min and a rolling force of 100-200 kN, the casting, solidification, and preliminary deformation are completed in one go, resulting in a cast and rolled strip billet with a thickness of 3-6 mm and a rapidly solidified microcrystalline structure. S3. After the cast and rolled strip exits the roll, it immediately enters the adjacent online induction heating solution furnace. Under a protective atmosphere, the temperature is controlled at 950±10℃ and held for 30-90 seconds. Then, high-pressure nitrogen-water mist composite quenching is performed to rapidly cool the strip to below 150℃ within 3 seconds to obtain a supersaturated solid solution. S4: After quenching, the strip is preheated to 300-450℃, and then subjected to single-pass large deformation rolling, with the deformation controlled at 60%-75%. S5, the rolled strip is subjected to graded aging treatment: first stage aging: holding at 450-480℃ for 1-2 hours; second stage aging: holding at 380-420℃ for 2-4 hours; third stage: annealing at 550-600℃ in a hydrogen atmosphere for 5-15 minutes. S6 involves micro-tension straightening and electrochemical polishing of the aged strip to obtain the finished strip.

2. The copper strip material production process for a VC heat spreader according to claim 1, characterized in that: The method for melting the components of step S1 in the vacuum melting furnace in step S2 is as follows: first add copper and Cr, heat to 1200-1220℃ and melt fully; cool to 1180-1200℃, add Zr and Ag, turn on strong magnetic stirring and control the temperature not to exceed 1220℃, stir for 3-8 minutes and then introduce into a twin-roll thin strip casting and rolling mill.

3. The copper strip material production process for a VC heat spreader according to claim 1, characterized in that: The protective atmosphere used in step S3 is nitrogen.

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