Solid vapor chamber and manufacturing method thereof

Abstract

The invention provides a solid vapor chamber and a manufacturing method thereof. The solid vapor chamber comprises an aluminum alloy shell and a graphite plate, the aluminum alloy shell comprises an aluminum alloy base and an aluminum alloy cover plate, a groove for containing the graphite plate is machined in the aluminum alloy base, and the aluminum alloy cover plate is located above the graphite plate and compresses the graphite plate. The surfaces of the aluminum alloy base and the aluminum alloy cover plate are plated with nickel layers; an AgCuTi metal layer is formed on the outer surface of the graphite plate; the aluminum alloy shell and the graphite plate are in interface bonding through SnAgCu brazing filler metal. The metal layer is brazed on the surface of the graphite plate in an active brazing filler metal brazing mode, reliable metallurgical connection is formed between the metal layer and the graphite plate, heat transfer is effectively guaranteed, the graphite plate with the metalized surface and the aluminum alloy are welded in a soft brazing mode, it is guaranteed that the metalized layer on the graphite surface is not damaged in the connecting process of the metalized layer and the aluminum alloy, and the service life of the metalized layer is prolonged. The problems that a graphite plate and an aluminum alloy are large in physicochemical property difference and difficult to weld, and a solid vapor chamber is poor in heat conductivity are solved.

Description

Technical Field

[0001] This invention belongs to the field of high thermal conductivity structure manufacturing technology, and specifically relates to a solid heat spreader and its manufacturing method. Background Technology

[0002] With the rapid development of electronic technology, the integration of electronic devices is becoming increasingly sophisticated, and electronic chips are constantly evolving towards higher efficiency, greater integration, and miniaturization. The continuous trend towards lightweight integration in electronic products has also brought about problems such as limited space for electronic components and high heat flux density. Because the performance of electronic devices is highly sensitive to temperature, elevated temperatures can severely impact their reliability, performance, and lifespan. Therefore, heat dissipation has become a bottleneck technology restricting the development of electronic equipment. Traditional heat dissipation methods are no longer sufficient to meet the future heat dissipation needs of electronic devices.

[0003] A vapor chamber is a novel, highly efficient heat dissipation device with a high surface thermal conductivity. By attaching a heat-generating chip to the vapor chamber, heat can be rapidly dissipated, reducing the chip's temperature. Traditional vapor chambers have an internal cavity filled with a liquid working fluid. When heated, the working fluid undergoes a gas-liquid phase change, thus transferring heat. However, in airborne applications, the performance of vapor chambers is extremely unstable due to the instability of the liquid wicking mechanism and the effects of acceleration during flight. Under different power levels and operating conditions, the heat transfer performance of vapor chambers varies greatly, causing performance instability in electronic products and significantly limiting their use in airborne applications. Therefore, developing new types of vapor chambers is of great practical significance. Solid-state vapor chambers are products made from high thermal conductivity materials. Because they are solid-state, there is no gas-liquid phase change process, resulting in high reliability of heat transfer performance, unaffected by acceleration, and thus showing broad application prospects in airborne products.

[0004] Solid-state vapor chambers primarily utilize materials with high thermal conductivity as their main body, leveraging this high conductivity to achieve heat dissipation. High-thermal-conductivity graphite is a prime example, with existing high-thermal-conductivity graphite exhibiting a thermal conductivity of up to 1500 W / (m·K) across its ab surface, making it an excellent material for solid-state vapor chambers. However, graphite itself has relatively low mechanical properties, making it unsuitable as a structural material. Therefore, it is necessary to encapsulate graphite within an aluminum alloy casing to form a composite structure. The encapsulation process of the graphite determines the overall thermal conductivity of this composite structure. Thus, overcoming the limitations of graphite encapsulation technology and achieving the manufacturing of graphite / aluminum alloy composite vapor chambers is of significant importance in the field of heat dissipation for next-generation airborne electronic products. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the inventors have conducted intensive research and provided a method for manufacturing a solid heat spreader, which solves the problems of large differences in the physical and chemical properties of graphite plates and aluminum alloys, making them difficult to weld, and the problem of poor thermal conductivity of solid heat spreaders.

[0006] The technical solution provided by this invention is as follows:

[0007] In a first aspect, a solid heat spreader includes an aluminum alloy shell and a graphite plate; the aluminum alloy shell includes an aluminum alloy base and an aluminum alloy cover plate, the aluminum alloy base is machined with a groove for placing the graphite plate, and the aluminum alloy cover plate is located above the graphite plate to press the graphite plate; the surfaces of the aluminum alloy base and the aluminum alloy cover plate are plated with a nickel layer.

[0008] The outer surface of the graphite plate is formed with an AgCuTi metal layer;

[0009] The aluminum alloy shell and the graphite plate are bonded together using SnAgCu solder to form an interface.

[0010] Secondly, a method for manufacturing a solid vapor chamber includes the following steps:

[0011] Surface processing of graphite plates;

[0012] AgCuTi solder is uniformly coated onto the surface of a graphite plate;

[0013] A graphite plate coated with AgCuTi brazing filler metal is placed in a vacuum brazing furnace for brazing, and then naturally cooled with the furnace after heat preservation.

[0014] The brazed graphite plate is polished to remove the surface oxide layer;

[0015] The aluminum alloy shell is machined, and the machined aluminum alloy shell is then nickel-plated on the surface.

[0016] The surface-brazed graphite plate and the nickel-plated aluminum alloy shell are cleaned, SnAgCu brazing filler metal is placed at the interface between the graphite plate and the aluminum alloy shell, the aluminum alloy shell and the graphite plate are assembled, and then placed in a vacuum brazing furnace for brazing.

[0017] The welded solid vapor chamber is then precision machined to the final required dimensions.

[0018] The solid heat spreader and its manufacturing method provided by the present invention have the following beneficial effects:

[0019] This invention brazes a metal layer onto the surface of a graphite plate using an active brazing filler metal. This metal layer forms a reliable metallurgical connection with the graphite plate, effectively ensuring heat transfer. The surface-metallized graphite plate is then welded to an aluminum alloy using a soft brazing method, ensuring that the metallized graphite surface layer is not damaged during the connection process with the aluminum alloy. This solves the problems of large differences in the physical and chemical properties of graphite plates and aluminum alloys, making them difficult to weld, as well as the problem of poor thermal conductivity of solid heat spreaders. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a graphite heat spreader.

[0021] Figure 2 This is an exploded view of a graphite heat exchanger. Detailed Implementation

[0022] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0023] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0024] This invention provides a solid-state heat spreader, such as... Figure 1 and Figure 2 As shown, it includes an aluminum alloy shell and a graphite plate; the aluminum alloy shell includes an aluminum alloy base and an aluminum alloy cover plate, the aluminum alloy base is machined with a groove for placing the graphite plate, and the aluminum alloy cover plate is located above the graphite plate to press the graphite plate; the surfaces of the aluminum alloy base and the aluminum alloy cover plate are plated with a nickel layer.

[0025] The outer surface of the graphite plate is formed with an AgCuTi metal layer, the thickness of which is 0.1–0.5 mm.

[0026] The aluminum alloy shell and the graphite plate are bonded together using SnAgCu solder to form an interface.

[0027] This invention provides a method for manufacturing a solid vapor chamber, comprising the following steps:

[0028] (1) Surface processing of high thermal conductivity graphite plate.

[0029] In this step, the high thermal conductivity graphite plate uses pyrolytic graphite, and its ab surface thermal conductivity is not less than 1500w / (m·K).

[0030] In this step, the surface flatness of the processed high thermal conductivity graphite plate is better than 0.1, the surface roughness is better than 3.2, and the plate thickness is 1-3 mm.

[0031] (2) AgCuTi solder is uniformly coated on the surface of a high thermal conductivity graphite plate.

[0032] In this step, the AgCuTi solder is in powder form, and the coating thickness is 0.1–0.5 mm.

[0033] In this step, the uniform coating of AgCuTi brazing filler metal onto the surface of the high thermal conductivity graphite plate is carried out as follows: AgCuTi brazing filler metal is uniformly coated onto the surface of the high thermal conductivity graphite plate, and mica sheets are laid on both sides of the high thermal conductivity graphite plate coated with AgCuTi brazing filler metal. A pressure block is placed on the upper mica sheet to form the assembly to be brazed. After brazing is completed in a vacuum brazing furnace, the pressure block and mica sheets are removed.

[0034] (3) Place the graphite plate coated with AgCuTi brazing filler metal into a vacuum brazing furnace for brazing, and let it cool naturally with the furnace after heat preservation.

[0035] In this step, the brazing temperature is 850–870℃, and the temperature is maintained for at least 10 minutes.

[0036] (4) Polish the brazed graphite plate to remove the surface oxide layer.

[0037] (5) The aluminum alloy shell is processed according to the design drawings, including the aluminum alloy base and the aluminum alloy cover plate. When processing the aluminum alloy base, a groove is reserved for placing the graphite plate. The aluminum alloy cover plate is placed on the groove to press the graphite plate. The processed aluminum alloy shell is then subjected to surface nickel plating treatment, and the thickness of the nickel plating layer is 0.5~0.8~0.6μm.

[0038] (6) Clean the surface-brazed graphite plate and the nickel-plated aluminum alloy shell to remove surface oil stains. Place SnAgCu brazing filler metal at the interface between the graphite plate and the aluminum alloy shell. Assemble the aluminum alloy shell and the graphite plate. After assembly, place them in a vacuum brazing furnace for brazing.

[0039] In this step, the brazing temperature is 200-230°C to 210°C, and the temperature is maintained for at least 20 minutes.

[0040] (7) The welded high thermal conductivity graphite heat spreader is precision machined according to the final required size.

[0041] Example

[0042] Example 1

[0043] A method for manufacturing a solid vapor chamber includes the following steps:

[0044] (1) The surface of the high thermal conductivity graphite plate is processed. The surface flatness is better than 0.1, the surface roughness is better than 3.2, and the plate thickness is 2mm. The high thermal conductivity graphite plate is pyrolytic graphite, and its ab surface thermal conductivity is not less than 1500w / (m·K).

[0045] (2) AgCuTi solder powder is uniformly coated on the surface of a high thermal conductivity graphite plate, with a coating thickness of 0.5 mm;

[0046] AgCuTi brazing filler metal is uniformly coated on the surface of a high thermal conductivity graphite plate, and mica sheets are laid on both sides of the high thermal conductivity graphite plate coated with AgCuTi brazing filler metal. A pressure block is placed on the upper mica sheet to form an assembly to be brazed.

[0047] (3) Place the graphite plate-mica sheet-pressed block coated with AgCuTi brazing powder into a vacuum brazing furnace, adjust the brazing process parameters to 850℃, hold for 10 minutes, and let it cool naturally with the furnace after holding. Remove the press and mica sheet.

[0048] (4) Polish the brazed graphite plate to remove the surface oxide layer;

[0049] (5) The aluminum alloy shell is processed according to the design drawings, including the aluminum alloy base and the aluminum alloy cover plate. When processing the aluminum alloy base, a groove is reserved for placing the graphite plate. The aluminum alloy cover plate is placed on the groove to press the graphite plate. The processed aluminum alloy shell is then nickel-plated, and the thickness of the nickel plating layer is 0.6μm.

[0050] (6) Clean the surface-brazed graphite plate and nickel-plated aluminum alloy shell to remove surface oil stains. Place SnAgCu brazing filler metal at the interface between the graphite plate and the aluminum alloy shell. Assemble the aluminum alloy shell and graphite plate. After assembly, place them in the furnace and set the heating temperature to 210℃. Hold for 20 minutes.

[0051] (7) The welded high thermal conductivity graphite heat spreader is precision machined according to the final required size.

[0052] Example 2

[0053] A method for manufacturing a solid vapor chamber includes the following steps:

[0054] (1) The surface of the high thermal conductivity graphite is processed, and the surface flatness is required to be better than 0.1, the surface roughness is better than 3.2, and the plate thickness is 3mm; the high thermal conductivity graphite plate is pyrolytic graphite, and its ab surface thermal conductivity is not less than 1500w / (m·K);

[0055] (2) AgCuTi solder powder is uniformly coated on the surface of a high thermal conductivity graphite plate, with a coating thickness of 0.3 mm;

[0056] AgCuTi brazing filler metal is uniformly coated on the surface of a high thermal conductivity graphite plate, and mica sheets are laid on both sides of the high thermal conductivity graphite plate coated with AgCuTi brazing filler metal. A pressure block is placed on the upper mica sheet to form an assembly to be brazed.

[0057] (3) Place the graphite plate-mica sheet-pressed block coated with AgCuTi brazing powder into a vacuum brazing furnace, adjust the brazing process parameters to 870℃, hold for 10 minutes, and let it cool naturally with the furnace after holding. Remove the press and mica sheet.

[0058] (4) Polish the brazed graphite plate to remove the surface oxide layer;

[0059] (5) The aluminum alloy shell is processed according to the design drawings, including the aluminum alloy base and the aluminum alloy cover plate. When processing the aluminum alloy base, a groove is reserved for placing the graphite plate. The aluminum alloy cover plate is placed on the groove to press the graphite plate. The processed aluminum alloy shell is then nickel-plated, and the thickness of the nickel plating layer is 0.7μm.

[0060] (6) Clean the surface-brazed graphite plate and nickel-plated aluminum alloy shell to remove surface oil stains. Place SnAgCu brazing filler metal at the interface between the graphite plate and the aluminum alloy shell. Assemble the aluminum alloy shell and graphite plate. After assembly, place them in the furnace and set the heating temperature to 230℃. Hold for 20 minutes.

[0061] (7) The welded high thermal conductivity graphite heat spreader is precision machined according to the final required size.

[0062] Comparative Example

[0063] Comparative Example 1

[0064] Comparative Example 1 is the same as Example 1, except that the surface of the high thermal conductivity graphite plate is not coated with AgCuTi solder powder, and a bare graphite plate is used.

[0065] Comparative Example 2

[0066] Comparative Example 2 is the same as Example 1, except that the aluminum alloy casing is not nickel-plated.

[0067] The heat spreaders obtained in Examples 1-2 and Comparative Examples 1-2 were tested, and the test results are shown in Table 1 below:

[0068] Table 1. Test Results of High Thermal Conductivity Graphite Heat Spreader

[0069]

[0070]

[0071] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0072] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A solid-state heat spreader, characterized in that, It includes an aluminum alloy housing and a graphite plate; the aluminum alloy housing includes an aluminum alloy base and an aluminum alloy cover plate, the aluminum alloy base is machined with a groove for placing the graphite plate, and the aluminum alloy cover plate is located above the graphite plate to press the graphite plate; the surfaces of the aluminum alloy base and the aluminum alloy cover plate are plated with a nickel layer. An AgCuTi metal layer is formed on the outer surface of the graphite plate; The aluminum alloy shell and the graphite plate are bonded together using SnAgCu solder to form an interface.

2. The solid-state heat spreader according to claim 1, characterized in that, The thickness of the AgCuTi metal layer on the outer surface of the graphite plate is 0.1 to 0.5 mm.

3. The solid-state heat spreader according to claim 1, characterized in that, The nickel layer thickness on the surface of the aluminum alloy base and aluminum alloy cover plate is 0.5 to 0.8 mm.

4. The solid-state heat spreader according to claim 1, characterized in that, The graphite plate is made of pyrolytic graphite, and its thermal conductivity on the ab surface is not less than 1500 W / (m·K).

5. A method for manufacturing a solid heat spreader according to any one of claims 1 to 4, characterized in that, Includes the following steps: Surface processing of graphite plates; AgCuTi solder is uniformly coated onto the surface of a graphite plate; A graphite plate coated with AgCuTi brazing filler metal is placed in a vacuum brazing furnace for brazing, and then naturally cooled with the furnace after heat preservation. The brazed graphite plate is polished to remove the surface oxide layer; The aluminum alloy shell is machined, and the machined aluminum alloy shell is then nickel-plated on the surface. The surface-brazed graphite plate and the nickel-plated aluminum alloy shell are cleaned, SnAgCu brazing filler metal is placed at the interface between the graphite plate and the aluminum alloy shell, the aluminum alloy shell and the graphite plate are assembled, and then placed in a vacuum brazing furnace for brazing. The welded solid heat spreader is then precision machined to the final required dimensions.

6. The method for manufacturing a solid vapor chamber according to claim 5, characterized in that, In the step of surface processing of the graphite plate, the surface flatness of the processed graphite plate is better than 0.1 and the surface roughness is better than 3.

2.

7. The method for manufacturing a solid vapor chamber according to claim 5, characterized in that, In the step of uniformly coating the surface of the graphite plate with AgCuTi solder, the AgCuTi solder is in powder form and the coating thickness is 0.1 to 0.5 mm.

8. The method for manufacturing a solid vapor chamber according to claim 5, characterized in that, The step of uniformly coating the surface of the high thermal conductivity graphite plate with AgCuTi brazing filler metal is specifically implemented as follows: AgCuTi brazing filler metal is uniformly coated onto the surface of the high thermal conductivity graphite plate, and mica sheets are laid on both sides of the coated high thermal conductivity graphite plate. A pressure block is placed on the upper mica sheet to form the assembly to be brazed. After brazing is completed in a vacuum brazing furnace, the pressure block and mica sheets are removed.

9. The method for manufacturing a solid vapor chamber according to claim 5, characterized in that, The step of placing the graphite plate coated with AgCuTi brazing filler metal into a vacuum brazing furnace for brazing is described, with a brazing temperature of 850-870°C and a holding time of at least 10 minutes.

10. The method for manufacturing a solid vapor chamber according to claim 5, characterized in that, In the steps of placing SnAgCu brazing filler metal at the interface between the graphite plate and the aluminum alloy shell, assembling the aluminum alloy shell and the graphite plate, and then placing the assembled material in a vacuum brazing furnace for brazing, the brazing temperature is 200-230-210°C, and the temperature is maintained for at least 20 minutes.

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