A cascade multi-core 3D heating plate and a preparation method and application thereof

Abstract

The application relates to the technical field of data center high-power-density server heat dissipation, and particularly discloses a cascaded multi-core 3D heat plate and a preparation method and application thereof. The cascaded multi-core 3D heat plate comprises a heat plate body and a plurality of heat pipes installed on the heat plate body, the heat plate body is internally provided with at least two independent heat dissipation cavities, the heat dissipation cavities comprise a first evaporation cavity and a second evaporation cavity, the first evaporation cavity and the second evaporation cavity are filled with working fluid, the heat pipe penetrates through the second evaporation cavity, the first evaporation cavity is internally provided with a first capillary core, the second evaporation cavity is internally provided with a second capillary core, and the inner wall of the heat pipe is covered with a third capillary core. The cascaded multi-core 3D heat plate has the advantages that the heat dissipation effect of the heat plate is good, and the total power and hot point resistance can be considered.

Description

Technical Field

[0001] This application relates to the technical field of heat dissipation for high power density servers in data centers, and in particular to a cascaded multi-core 3D heat sink, its preparation method, and its application. Background Technology

[0002] As the power consumption of data center server CPUs / GPUs exceeds 500W, existing methods of using heat spreaders for cooling have the following drawbacks: 1. The contradiction between thickness and heat dissipation capacity: 1U / 2U server thickness ≤ 10mm, traditional planar heat dissipation plates (VC) are limited by two-dimensional structure, resulting in insufficient total heat dissipation area and thermal resistance ≥ 1.8K / W under total power of 300W or more; 2. Conflict between hot spot and total power: Traditional single-cavity planar heat spreaders use a single capillary structure, which makes it difficult to balance the total power carrying capacity and reduce the hot spot resistance.

[0003] 3. Insufficient rack-level coordination: Traditional heat dissipation devices and rack air ducts lack a three-dimensional heat transfer link, making it easy for heat to circulate within the server and exacerbating the rack heat island effect. Summary of the Invention

[0004] To address the issues of poor heat dissipation performance of vapor chambers and the difficulty in balancing total power and hotspot resistance, this application provides a cascaded multi-core 3D vapor chamber, its preparation method, and its application.

[0005] In a first aspect, this application provides a cascaded multi-core 3D heat sink, employing the following technical solution: A cascaded multi-core 3D vapor chamber includes a vapor chamber body and multiple heat pipes mounted on the vapor chamber body. The vapor chamber body has at least two independent heat dissipation cavities, each including a first evaporation cavity and a second evaporation cavity. Both the first and second evaporation cavities are filled with working fluid. The heat pipes communicate with the second evaporation cavity. The first evaporation cavity has a first capillary wick, the second evaporation cavity has a second capillary wick, and the inner wall of the heat pipe is covered with a third capillary wick.

[0006] By adopting the above technical solution, the vapor chamber body is an oxygen-free copper 3D structure. Through differentiated capillary design, it balances the effects of "hotspot resistance" and "total power carrying capacity". Addressing the heat dissipation bottleneck of high power density and limited space in data center servers, it employs a "dual-stage division of labor + hydraulic independence + 3D structure" design: the first evaporation chamber features a multi-core, multi-cavity array structure, rapidly suppressing localized high heat flow in the CPU / GPU through an ultra-thin capillary core; the top heat-conducting layer is a 3D extended single cavity, carrying 300-500W of total power through a thick capillary core, while integrating a 3D columnar heat pipe array for three-dimensional heat transfer. The two-stage cavities are hydraulically independent and thermally coupled continuously. The vapor chamber size is suitable for 1U / 2U servers (200 mm x 100 mm x 5 mm), with a gravity-resistant thermal resistance ≤0.16K / W. The hotspot temperature is reduced by more than 25℃ compared to traditional vapor chambers, forming a highly efficient heat transfer link of "chip-vapor chamber-3D heat pipe-rack airflow".

[0007] In the heat pipe system, the first, second, and third capillary wicks together form a composite heat transfer network characterized by "high capillary density + large capacity + low thermal resistance." The first capillary wick is made of fine copper powder (10-50 μm). Its purpose is to provide extremely high capillary suction force using extremely small pore sizes, ensuring rapid return of the working fluid under extremely high local heat flux density and preventing the hot spot area from drying out. The second capillary wick is made of coarse copper powder (50-100 μm). Its purpose is to provide high liquid storage capacity and high permeability using larger porosity and a thicker structure, carrying a total power of 300-500 W with extremely low flow resistance. The third capillary wick is integrally sintered with the second capillary wick, covering the inner wall of the heat pipe. Its purpose is to eliminate the interfacial thermal resistance between the heat pipe and the 3D heat pipe, guiding the condensate to flow smoothly back to the bottom layer on a three-dimensional scale.

[0008] The bottom of the heat spreader directly contacts the heat source, corresponding to the multiple hot spots of the server chip. The first evaporation chamber is divided into multiple small chambers by the supporting copper pillars, thus forming a "multi-core heat spreader network". Through the action of the small chambers and the first capillary wick, the local high heat flux (≤10W / mm²) can be quickly homogenized. 2 The hotspot temperature gradient is ≤3℃. The second evaporation chamber, located above the first evaporation chamber, and the second capillary wick can handle a total power of 300-500W. The heat pipes are uniformly arrayed on the upper surface of the heat-conducting top layer, forming a three-dimensional heat transfer path after welding with metal fins. The first capillary wick has higher capillary force than the second capillary wick, ensuring rapid return of the working fluid under the thin core, with a hotspot thermal resistance ≤0.2K / W. The second capillary wick has a high liquid storage capacity, enabling it to handle higher total power, with a total power thermal resistance ≤0.4K / W. The third capillary wick is integrally sintered with the second capillary wick and covers the inner wall of the heat pipe, eliminating interfacial thermal resistance (≤0.01K / W). The condensing end of the 3D heat pipe is parallel to the airflow of the frame, increasing the heat exchange area by 3.5 times compared to a planar heat exchange plate.

[0009] The first evaporation chamber and the second evaporation chamber together form an irregularly shaped connected cavity with a specific necking / flow guiding structure. The return flow of the working fluid in the multi-core small cavity in the first evaporation chamber is not affected by the total power of the heat-conducting top layer, thus avoiding the drying out of the hot spot area.

[0010] Optionally, the heat spreader body includes an evaporator end cover and a condenser end cover. The first evaporator cavity is located on one side near the center of the evaporator end cover, and the second evaporator cavity is located on one side near the condenser end cover. The first capillary wick is located inside the first evaporator cavity. The first evaporator cavity is also provided with a plurality of spaced-apart supporting copper pillars. The axis of each supporting copper pillar is perpendicular to the evaporator end cover. The supporting copper pillars are covered with capillary powder pillars. The second capillary wick is located on the upper side of the supporting copper pillars. The condenser end cover is internally connected to the heat pipe.

[0011] Optionally, the thickness of the capillary powder column is 0.3mm - 0.8mm. Specifically, the thickness of the capillary powder column can be 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, etc.

[0012] By adopting the above technical solution, to further improve the boiling limit under high power density, this application innovatively introduces a gas-liquid separation channel between the first and second evaporation chambers. Specifically, the macroscopic space between adjacent supporting copper pillars (with capillary powder pillars) is configured as an independent steam guiding channel. High-speed steam generated by local high heat flux at the bottom preferentially enters the second evaporation chamber directly upward through this low-resistance guiding channel, while the returning condensate is firmly bound inside the capillary powder pillars for reverse transport. This structure avoids the gas-liquid entrainment phenomenon caused by high-speed steam forcibly penetrating the capillary wick, achieves physical isolation of the gas-liquid two-phase flow paths, significantly reduces the internal pressure drop, and effectively prevents the capillary wick from drying out and failing when dealing with extreme heat flux densities.

[0013] Optionally, the diameter of the supporting copper pillar is 2-3mm, the spacing between adjacent supporting copper pillars is 3-8mm, and the supporting copper pillars are arranged in an array.

[0014] The array arrangement in this application can be either uniform or non-uniform, and its arrangement can be directly adapted to the "core heat point (Die)" topology of next-generation high-performance GPUs (such as the Chiplet architecture) to achieve precise targeted heat dissipation.

[0015] Optionally, the diameter of the independent small cavity can be 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, etc.; the spacing between multiple independent small cavities can be 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, etc.

[0016] Optionally, the heat pipes are arranged in a circular array at intervals on the surface of the condenser end cover plate.

[0017] Optionally, the hot spot thermal resistance of the first capillary core is ≤0.2K / W, the first capillary core is sintered from copper powder with a particle size of 10-50μm, and the thickness of the first capillary core is 0.1mm-0.3mm.

[0018] Optionally, the copper powder particle size of the first capillary core can be 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, etc.

[0019] Optionally, the thickness of the first capillary core can be 0.1mm, 0.13mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, etc.

[0020] Optionally, the total power thermal resistance of the second capillary core is ≤0.4K / W, the second capillary core is sintered from copper powder with a particle size of 50-100μm, and the thickness of the second capillary core is 0.5mm-2.0mm.

[0021] Optionally, the copper powder particle size of the second capillary core can be 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, etc.

[0022] Optionally, the thickness of the second capillary core can be 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, etc.

[0023] Optionally, the third capillary core is sintered from copper powder with a particle size of 50-100μm, and the thickness of the third capillary core is 0.3mm-0.8mm.

[0024] Optionally, the copper powder particle size of the third capillary core can be 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, etc., and the thickness of the third capillary core can be 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, etc.

[0025] Optionally, the heat spreader body is made of oxygen-free copper.

[0026] Optionally, the working fluid is deionized water, and the filling ratio of the deionized water is 55%-65%.

[0027] Optionally, the volume percentage of the deionized water can be 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, etc.

[0028] Secondly, this application provides a method for preparing a cascaded multi-core 3D vapor chamber, employing the following technical solution: A method for preparing a cascaded multi-core 3D vapor chamber includes the following steps: (1) Preparation of the first capillary core: Surface pretreatment of the evaporator end cover plate; Copper powder with a particle size of 10-50 μm and an organic binder are uniformly coated on a designated area of ​​the evaporation end cover plate, the designated area being opposite to the position of the first evaporation chamber; The first capillary core is formed by vacuum sintering at a temperature of 750-950℃ for 0.5-3h, and the first capillary core is integrally formed with the evaporation end cover plate. (2) Preparation of the second capillary core: A metal mold is filled with copper powder with a particle size of 50-100μm, and the metal mold has holes that are adapted to the mounting holes of the supporting copper pillars. The sintering inside the mold was completed by vacuum sintering at a temperature of 750-950℃ for 0.5-3h to obtain the formed second capillary core; The sintered second capillary core is positioned and assembled with a supporting copper column containing capillary powder columns, and then fixed above the first capillary core by laser spot welding. (3) Preparation of the third capillary core: The inner wall of the heat pipe is pretreated with chemical nickel plating; Then, copper powder with a particle size of 50-100μm is uniformly coated on the inner wall of the heat pipe, and the third capillary core inside the heat pipe is sintered under vacuum at a temperature of 750-950℃ for a time of 0.5-3h. The heat pipe with the sintered third capillary core is positioned and assembled with the condenser end cover plate, and a liquid injection pipe is reserved at the designated position. Then, the heat pipe-condenser end cover plate-second capillary core are integrated and sintered under vacuum at a temperature of 750-950℃ for 0.5-3h to form an integrated structure. (4) Degassing and liquid injection sealing High vacuum evacuation is performed through the injection pipe pre-installed on the heat spreader body. After the vacuum reaches 0.05 Torr, deionized water with a filling ratio of 55%-65% is injected. Finally, the injection pipe is mechanically flattened and welded to complete the overall sealing.

[0029] Optionally, the sintering temperature can be 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃, 880℃, 890℃, 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, etc., and the sintering time can be 0.5h, 0.7h, 1h, 1.2h, 1.5h, 1.8h, 2h, 2.2h, 2.5h, 2.8h, 3h, etc.

[0030] By employing the above technical solution, during the preparation of the first, second, and third capillary cores, the sintering temperature is controlled within the range of 750℃-950℃, and the sintering time is controlled within the range of 0.5h-3h, thus forming capillary cores of a specific thickness and ensuring uniform heating. When the temperature is too high, excessive melting of the copper powder leads to significant densification, resulting in a substantial decrease in the porosity of the capillary core, or even pore closure, completely losing its capillary suction and liquid storage capabilities. When the temperature is too low, effective metallurgical bonding cannot be formed between the copper powder particles (resulting in a smaller sintering neck), leading to extremely poor capillary mechanical strength, easy powder shedding during use, and a significant increase in interparticle thermal resistance.

[0031] Optionally, the copper support column with capillary powder column is prepared by in-situ sintering, which includes the following steps: In a metal mold with a specific array of apertures, a solid copper support column is pre-placed at the center of the mold aperture, and then copper powder is filled into the annular gap between the copper column and the aperture wall. Through vacuum sintering, the copper powder is directly metallurgically bonded to the outer wall of the support column, forming an integrated support column with capillary powder columns.

[0032] Optional organic binders include polyvinyl alcohol (PVA), polyethylene glycol (PEG), methylcellulose, or terpineol.

[0033] By adopting the above technical solution, the binder will completely volatilize or decompose during the heating stage of vacuum sintering (such as 300℃-500℃), and no carbonized substances will remain in the capillary core, thereby ensuring the purity and capillary performance of oxygen-free copper.

[0034] Thirdly, this application provides an application of a cascaded multi-core 3D heat sink, employing the following technical solution: An application of a cascaded multi-core 3D vapor chamber for heat dissipation of 1U / 2U servers in data centers.

[0035] By adopting the above technical solution, the heat dissipation plate body is integrated with the CPU / GPU heat dissipation module in the 1U / 2U server to form a four-level heat transfer link: "chip → bottom multi-core heat dissipation → top 3D heat conduction → 3D heat pipe array (welded heat dissipation fins) → rack air duct". The heat from multiple servers in a single rack is collected to the main air duct of the rack through the 3D heat pipes of the cascaded heat dissipation plate, which improves the heat dissipation efficiency by 40% and alleviates the rack-level heat island effect.

[0036] In summary, this application has the following beneficial effects: 1. Addressing the heat dissipation bottlenecks of high power density and space constraints in data center servers, a "dual-stage division of labor + hydraulic independence + 3D three-dimensional structure" design is adopted: The first evaporation chamber features a multi-core, multi-cavity array structure, rapidly suppressing localized high heat flow in the CPU / GPU through an ultra-thin capillary wick; the top heat-conducting layer is a 3D extended single cavity, supporting 300-500W of total power through a thick capillary wick, while integrating a 3D columnar heat pipe array for three-dimensional heat transfer. The two-stage cavities are hydraulically independent and thermally coupled continuously. The vapor chamber's dimensions are compatible with 1U / 2U servers (200 mm x 100 mm x 5 mm), with a gravity-resistant thermal resistance ≤0.16K / W. The hotspot temperature is reduced by more than 25℃ compared to traditional vapor chambers, forming a highly efficient heat transfer link of "chip-vapor chamber-3D heat pipe-rack airflow".

[0037] 2. The bottom of the heat spreader directly contacts the heat source, corresponding to the multiple hot spots of the server chip. The first evaporation chamber is divided into multiple independent small chambers by the supporting copper pillars, thus forming a "multi-core heat spreader network". Through the action of the small chambers and the first capillary wick, the local high heat flux (≤10W / mm) can be quickly homogenized. 2The hotspot temperature gradient is ≤3℃. The second evaporation chamber, located above the first evaporation chamber, and the second capillary wick can handle a total power of 300-500W. The heat pipes are uniformly arrayed on the upper surface of the heat-conducting top layer, forming a three-dimensional heat transfer path after welding with metal fins. The first capillary wick has higher capillary force than the second capillary wick, ensuring rapid return of the working fluid under the thin core, with a hotspot thermal resistance ≤0.2K / W. The second capillary wick has a high liquid storage capacity, enabling it to handle higher total power, with a total power thermal resistance ≤0.4K / W. The third capillary wick is integrally sintered with the second capillary wick and covers the inner wall of the heat pipe, eliminating interfacial thermal resistance (≤0.01K / W). The condensing end of the 3D heat pipe is parallel to the airflow of the frame, increasing the heat exchange area by 3.5 times compared to a planar heat exchange plate.

[0038] 3. After integrating the heat spreader body with the CPU / GPU heat dissipation modules in the 1U / 2U server, a four-level heat transfer chain is formed: "chip → bottom multi-core heat spreader → top 3D heat conduction → 3D heat pipe array (welded heat dissipation fins) → rack air duct". The heat from multiple servers in a single rack is collected to the main air duct of the rack through the 3D heat pipes of the cascaded heat spreader, improving the heat dissipation efficiency by 40% and alleviating the rack-level heat island effect. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of the heat spreader and heat pipes.

[0040] Figure 2 This is a schematic diagram of the structure of the evaporator end cap and heat pipe.

[0041] Figure 3 This is an exploded schematic diagram of the heat spreader body and heat pipes.

[0042] Figure 4 This is a cross-sectional view of the heat spreader body and heat pipes.

[0043] Figure 5 This is a schematic diagram showing the heat flow direction of the heat spreader body under working conditions.

[0044] Explanation of reference numerals in the attached drawings: 1. Heat spreader body; 11. Evaporator end cover plate; 12. Condenser end cover plate; 13. First evaporation chamber; 14. Second evaporation chamber; 15. Supporting copper column; 16. Capillary powder column; 17. First capillary wick; 18. Second capillary wick; 2. Heat pipe; 21. Third capillary wick. Detailed Implementation

[0045] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail.

[0046] This embodiment provides a cascaded multi-core 3D vapor chamber.

[0047] Reference Figure 1 and Figure 2 A cascaded multi-core 3D vapor chamber includes a vapor chamber body 1 and multiple heat pipes 2, made of oxygen-free copper, and has an overall 3D structure. The vapor chamber body 1 has dimensions of 200mm x 100mm x 5mm, which can be adapted to 1U or 2U servers. In this embodiment, there are 9 heat pipes 2, with an inner diameter of 6mm and a length of 180mm.

[0048] Reference Figure 3 and Figure 4 The heat spreader body 1 includes an evaporator end cover 11 located near the heat source and a condenser end cover 12 located away from the heat source. Both the evaporator end cover 11 and the condenser end cover 12 are horizontally arranged and integrally formed at their edges. The evaporator end cover 11 is located below the condenser end cover 12. The bottom evaporator end cover 11 and the top condenser end cover 12 are integrally formed at their four edges, directly forming thermal contact with each other. The thermal resistance is ≤0.02K / W, achieving lossless heat transfer. Multiple heat pipes 2 are vertically fixed on the condenser end cover 12 and are evenly distributed in a circular array. The condenser end cover 12 has openings that penetrate the heat pipes 2, allowing the interior of the heat pipes 2 to communicate with the interior of the second evaporation chamber 14. The length direction of the heat pipes 2 is parallel to the airflow direction.

[0049] A heat dissipation cavity is provided between the evaporator end cover plate 11 and the condenser end cover plate 12. The heat dissipation cavity includes a first evaporation cavity 13 and a second evaporation cavity 14. The first evaporation cavity 13 is located below the second evaporation cavity 14. Both the first evaporation cavity 13 and the second evaporation cavity 14 are filled with a working fluid, which is deionized water, with a filling ratio of 60% and a vacuum degree of 0.05 Torr.

[0050] The first evaporation chamber 13 is fixed with multiple vertically arranged supporting copper pillars 15. The supporting copper pillars 15 are arranged in an array. The array arrangement of the supporting copper pillars 15 can be uniform or non-uniform to adapt to actual usage requirements. In this embodiment, the copper pillars are uniformly distributed. The diameter of the supporting copper pillars 15 is 2mm, and the distance between adjacent supporting copper pillars 15 is 5mm. The supporting copper pillars 15 are arranged in an array. The outer surface of the supporting copper pillars 15 is covered with capillary powder pillars 16. The thickness of the capillary powder pillars 16 is 0.3-0.8mm. Under the projection in the vertical direction, the first evaporation chamber 13 is divided into multiple small cavities under the action of the supporting copper pillars 15. The projection of the small cavities in the vertical direction is arranged in an array to form a multi-core heat dissipation network.

[0051] Reference Figure 4 and Figure 5The macroscopic space between adjacent supporting copper pillars 15 (with capillary powder pillars 16) is configured as an independent steam guiding channel. High-speed steam generated by localized high heat flux at the bottom preferentially enters the second evaporation chamber 14 directly upwards through this low-resistance guiding channel, while the returning condensate is firmly bound inside the capillary powder pillars 16 and transported in reverse. This structure avoids the gas-liquid entrainment phenomenon caused by high-speed steam forcibly penetrating the capillary wick, achieving physical isolation of the vapor-liquid two-phase flow paths, significantly reducing internal pressure drop, and effectively preventing capillary wick drying out and failing when dealing with extreme heat flux densities.

[0052] The first evaporation chamber 13 is equipped with a first capillary wick 17, which is sintered from copper powder with a particle size of 20μm and a thickness of 0.1mm-0.3mm. The structure inside the first evaporation chamber 13 is designed for the multiple hot spots of the server chip. By utilizing the small cavity and the high capillary force of the first capillary wick 17, it ensures that the working fluid can quickly return under extremely high local heat flux density, avoids the hot spot area from drying out, and can quickly homogenize the local high heat flux (≤10W / mm²), so that the hot spot temperature gradient is controlled within 3℃ and the hot spot thermal resistance is ≤0.2K / W.

[0053] The second evaporation chamber 14 occupies the main space of the heat spreader body 1. A second capillary wick 18, with a thickness of 0.5mm-2.0mm, is installed inside the second evaporation chamber 14. The second capillary wick 18 is located above the supporting copper pillar 15 and is sintered from copper powder with a particle size of 65μm. The large porosity and thick structure of the second capillary wick 18 provide high liquid storage capacity and high permeability, enabling it to carry a total power of 300-500W with extremely low flow resistance, and a total power thermal resistance ≤0.4K / W.

[0054] The inner wall of heat pipe 2 is covered with a third capillary wick 21, with a thickness of 0.3mm-0.8mm. Heat pipe 2 is used for welding to the fins, and the third capillary wick 21 inside heat pipe 2 is integrally sintered with the second capillary wick 18, eliminating interfacial thermal resistance (≤0.01K / W) and guiding the condensate to flow smoothly back to the bottom layer in three dimensions. This increases the heat exchange area by 3.5 times compared to traditional planar heat exchange plates, forming a three-dimensional heat transfer path.

[0055] The implementation principle of a cascaded multi-core 3D vapor chamber in this application embodiment is as follows: The vapor chamber body 1 employs a differentiated capillary design to balance low hotspot resistance with total power handling capacity. The multi-core small-cavity structure at the bottom of the vapor chamber, combined with an ultra-thin capillary wick, rapidly suppresses localized high heat flow in the CPU / GPU. The top layer of the vapor chamber uses a thick capillary wick to handle high total power and integrates a 3D columnar heat pipe array for three-dimensional heat transfer. The two-stage cavities are hydraulically independent yet thermally coupled, forming a highly efficient heat transfer link: "chip-vapor chamber-3D heat pipe-rack airflow." Under anti-gravity conditions, the thermal resistance is ≤0.16K / W, and the hotspot temperature is reduced by more than 25℃ compared to traditional vapor chambers.

[0056] This application also discloses a method for preparing a cascaded multi-core 3D vapor chamber, comprising the following steps: (1) Preparation of the first capillary core: The surface of the evaporation end cover plate is pretreated; copper powder with a particle size of 20μm and polyvinyl alcohol are uniformly coated on a designated area of ​​the evaporation end cover plate as organic binders, the designated area being opposite to the position of the first evaporation chamber; the plate is placed in a vacuum sintering furnace and sintered under process parameters of 850℃ and 1.5h to form the first capillary core, which is integrally formed with the evaporation end cover plate to avoid interface gaps in subsequent assembly.

[0057] (2) Preparation of the second capillary core: Copper powder with a particle size of 65μm is filled into a metal mold, which has holes that match the mounting holes of the supporting copper pillar. Sintering is completed in the mold at 800℃ for 1 hour to obtain the formed second capillary core. The sintered second capillary core is positioned and assembled with the supporting copper pillar with capillary powder on its surface, and fixed above the first capillary core by laser spot welding to ensure that the installation accuracy is ≤0.1mm.

[0058] The copper support column with capillary powder is made from copper powder with a particle size of 65μm through an in-situ sintering method, which includes the following steps: In a metal mold with a specific aperture array, a solid copper support column is pre-placed in the center of the mold hole, and then copper powder is filled into the annular gap between the copper column and the hole wall. Through vacuum sintering, the copper powder is directly metallurgically bonded to the outer wall of the copper support column to form an integrated copper support column with capillary powder.

[0059] The surface performance parameters of the capillary powder column are similar to those of the second capillary core, ensuring smooth backflow under gravity or anti-gravity conditions with low flow resistance, achieving optimal matching of resistance and power. The main function of the capillary powder column is to handle macroscopic liquid delivery along the Z-axis (vertical) direction, guiding condensate from the top second capillary core back to the bottom first capillary core at a high flow rate. It exhibits high permeability in long-distance, high-flow-rate transport.

[0060] (3) Preparation of the third capillary core: The inner wall of the columnar heat pipe is pretreated with chemical nickel plating to enhance the adhesion of copper powder. Then, copper powder with a particle size of 65μm is uniformly coated on the inner wall of the heat pipe, and the third capillary core inside the heat pipe is sintered at 820℃ for 1 hour. The heat pipe with the sintered third capillary core is positioned and assembled with the condenser end cover plate, and then the integration sintering of "heat pipe-condenser end cover plate-second capillary core" is completed at 850℃ for 1 hour to form an integrated structure.

[0061] (4) Degassing and liquid injection sealing High vacuum evacuation is performed through the injection pipe pre-installed on the heat spreader body. After the vacuum reaches 0.05 Torr, deionized water with a filling ratio of 60% is injected. Finally, the injection pipe is mechanically flattened and welded to complete the overall sealing.

[0062] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A cascaded multi-core 3D vapor chamber, characterized in that: The device includes a heat spreader body (1) and multiple heat pipes (2) mounted on the heat spreader body (1). The heat spreader body (1) has a heat dissipation cavity, which includes a first evaporation cavity (13) and a second evaporation cavity (14). Both the first evaporation cavity (13) and the second evaporation cavity (14) are filled with working fluid. The heat pipes (2) are connected to the second evaporation cavity (14). The first evaporation cavity (13) has a first capillary wick (17), and the second evaporation cavity (14) has a second capillary wick (18). The inner wall of the heat pipes (2) is covered with a third capillary wick (21).

2. The cascaded multi-core 3D vapor chamber according to claim 1, characterized in that: The heat spreader body (1) includes an evaporator end cover plate (11) and a condenser end cover plate (12). The first evaporator cavity (13) is located on one side near the center of the evaporator end cover plate (11), and the second evaporator cavity (14) is located on one side near the condenser end cover plate (12). The first capillary wick (17) is located inside the first evaporator cavity (13). The first evaporator cavity (13) is also provided with a plurality of spaced supporting copper pillars (15). The axis of each supporting copper pillar (15) is perpendicular to the evaporator end cover plate (11). The supporting copper pillar (15) is covered with a capillary powder pillar (16). The second capillary wick (18) is located on the upper side of the supporting copper pillar (15). The condenser end cover plate (12) is connected to the heat pipe (2).

3. A cascaded multi-core 3D vapor chamber according to claim 2, characterized in that: The diameter of the supporting copper column (15) is 2-3mm, the spacing between adjacent supporting copper columns (15) is 3-8mm, and the supporting copper columns (15) are arranged in an array.

4. The cascaded multi-core 3D vapor chamber according to claim 1, characterized in that: The hot spot thermal resistance of the first capillary core (17) is ≤0.2K / W. The first capillary core (17) is sintered from copper powder with a particle size of 10-50μm. The thickness of the first capillary core (17) is 0.1mm-0.3mm.

5. A cascaded multi-core 3D vapor chamber according to claim 1, characterized in that: The total power thermal resistance of the second capillary core (18) is ≤0.4K / W. The second capillary core (18) is sintered from copper powder with a particle size of 50-100μm. The thickness of the second capillary core (18) is 0.5mm-2.0mm.

6. A cascaded multi-core 3D vapor chamber according to claim 1, characterized in that: The third capillary core (21) is sintered from copper powder with a particle size of 50-100μm, and the thickness of the third capillary core (21) is 0.3mm-0.8mm.

7. A cascaded multi-core 3D vapor chamber according to claim 1, characterized in that: The heat spreader body (1) is made of oxygen-free copper.

8. A cascaded multi-core 3D vapor chamber according to claim 1, characterized in that: The working fluid is deionized water, and the filling ratio of the deionized water is 55%-65%.

9. A method for preparing a cascaded multi-core 3D vapor chamber as described in any one of claims 1-8, characterized in that: Includes the following steps: (1) Preparation of the first capillary core: Surface pretreatment of the evaporator end cover plate; Copper powder with a particle size of 10-50 μm and an organic binder are uniformly coated on a designated area of ​​the evaporation end cover plate, the designated area being opposite to the position of the first evaporation chamber; The first capillary core is formed by vacuum sintering at a temperature of 750-950℃ for 0.5-3h, and the first capillary core is integrally formed with the evaporation end cover plate. (2) Preparation of the second capillary core: A metal mold is filled with copper powder with a particle size of 50-100μm, and the metal mold has holes that match the mounting holes of the supporting copper pillars. The sintering inside the mold was completed by vacuum sintering at a temperature of 750-950℃ for 0.5-3h to obtain the formed second capillary core; The sintered second capillary core is positioned and assembled with a supporting copper column containing capillary powder columns, and then fixed above the first capillary core by laser spot welding. (3) Preparation of the third capillary core: The inner wall of the heat pipe is pretreated with chemical nickel plating; Then, copper powder with a particle size of 50-100μm is uniformly coated on the inner wall of the heat pipe, and the third capillary core inside the heat pipe is sintered under vacuum at a temperature of 750-950℃ for a time of 0.5-3h. The heat pipe with the sintered third capillary core is positioned and assembled with the condenser end cover plate and a liquid injection pipe is reserved at the designated position. Then, the heat pipe-condenser end cover plate-second capillary core are integrated and sintered under vacuum at a temperature of 750-950℃ for 0.5-3h to form an integrated structure. (4) Degassing and liquid injection sealing High vacuum evacuation is performed through the injection pipe pre-installed on the heat spreader body. After the vacuum reaches 0.05 Torr, deionized water with a filling ratio of 55%-65% is injected. Finally, the injection pipe is mechanically flattened and welded to complete the overall sealing.

10. An application of the cascaded multi-core 3D heat spreader according to any one of claims 1-8, characterized in that, Used to adapt to heat dissipation of 1U / 2U servers in data centers.

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