A casting mold and mold system for encapsulating a high heat flux graphite-based heat conduction core material

Abstract

The utility model belongs to the field of heat management device manufacturing provides a kind of encapsulation high heat flux graphite-based heat conduction core material's casting mould and mould system, the casting mould includes first mould, recessed cavity of the graphite-based heat conduction core material to be placed in first mould inside is encapsulated;Gap for filling metal liquid is reserved between graphite-based heat conduction core material and recessed cavity;Multiple positioning bosses are provided in recessed cavity, and positioning boss includes coaxial connection large diameter section cylinder and small diameter section cylinder, large diameter section cylinder supports graphite-based heat conduction core material bottom, and small diameter section cylinder is inserted into the through hole on graphite-based heat conduction core material;Pouring opening is equipped on first mould. Heat conduction core material is encapsulated in metal shell using the mould, so that the two can be combined closely, there is no interface gap, through hole is filled with metal column to form mechanical interlocking, significantly improve longitudinal thermal conductivity and structural strength, suitable for the efficient manufacturing of high-power electronic equipment heat dissipation element.

Description

Technical Field

[0001] This utility model belongs to the field of thermal management device manufacturing, and relates to the integrated packaging technology of solid-state heat spreaders in high-power electronic devices, specifically to a casting mold and mold system for packaging high heat flux graphite-based thermally conductive core material. Background Technology

[0002] With the rapid development of 5G communication, artificial intelligence, and new energy vehicles, electronic devices have become an indispensable key component of both civilian and military equipment, directly determining the technological advancement and operational reliability of the entire system. Simultaneously, the increasing demand for high-performance electronic devices has led to a continuous rise in the power density of their internal electronic components, resulting in a sharp increase in heat generation. To ensure the stable operation of equipment under high-load conditions, it is urgent to develop efficient thermal management technologies to quickly dissipate heat generated in hot areas, effectively reduce local temperatures, maintain temperature uniformity on component surfaces, and prevent performance degradation or structural failure caused by thermal stress concentration.

[0003] Against this backdrop, solid-state heat dissipation devices have attracted widespread attention due to their unique advantages. These devices have no internal flow channels and do not rely on phase-change working fluids, fundamentally avoiding problems such as medium degradation failure, flow channel corrosion, flow resistance changes, and start-up delays inherent in traditional heat pipes or vapor chambers. Furthermore, they utilize highly thermally conductive materials as heat conduction paths, exhibiting stable material properties and being unaffected by harsh environments such as external shocks and vibrations, resulting in extremely high reliability and long lifespan. Therefore, solid-state vapor chambers demonstrate enormous application potential in the field of board-level thermal management for high-power electronic devices.

[0004] The core of a solid-state vapor chamber lies in its internal high thermal conductivity functional layer, typically made of graphite-based materials with ultra-high lateral thermal conductivity, such as graphene sheets, pyrolytic graphite, high-purity graphite blocks, or graphite / metal composites. While these materials possess excellent thermal conductivity (lateral thermal conductivity reaching 1000~1500 W / mK or higher), they differ significantly in physical and chemical properties from commonly used metal encapsulation shells (such as aluminum and aluminum alloys). This difference is primarily manifested in a severe mismatch in their coefficients of thermal expansion (graphite approximately 2 × 10⁻⁶ W / mK). -6 / K, aluminum approximately 23×10 -6The graphite-based thermal conductive core material ( / K) is prone to thermal stress cracking; its low surface energy and poor wettability make it difficult to form a good metallurgical bond with metals; its strong chemical inertness makes it difficult to achieve effective connection using conventional welding processes. When using traditional brazing, diffusion welding, or general casting processes for packaging, micro-gaps, pores, or incomplete welds are easily formed between the metal shell and the graphite-based thermal conductive core material, resulting in a significant increase in interfacial contact thermal resistance. Under high-temperature cyclic operating conditions, residual gas expands upon heating, which can further cause "bulging" phenomenon, seriously affecting the heat dissipation efficiency, structural integrity, and long-term stability of the device, resulting in low yield, large performance fluctuations, and extremely difficult subsequent maintenance and replacement.

[0005] Achieving a tight, reliable, and integrated bond between the metal packaging shell and the non-metallic, high-thermal-conductivity core material is a key technological bottleneck restricting the performance improvement and engineering application of solid-state vapor chambers. Current technologies have not yet proposed a highly efficient packaging solution that can guarantee high-precision positioning, achieve low contact thermal resistance, and is suitable for mass production. Therefore, there is an urgent need to develop an innovative packaging mold and process system to overcome these technical obstacles and promote the practical application of high-performance solid-state vapor chambers. Utility Model Content

[0006] To address the technical problems of inaccurate positioning, easy drift, and poor interface bonding of non-metallic core materials during the casting process in the prior art, and to achieve a dense and integrated bond between the thermally conductive core material and the metal encapsulation shell, thereby improving the structural strength and heat dissipation performance of the solid heat spreader, this utility model discloses a casting mold for encapsulating a high heat flux graphite-based thermally conductive core material. The casting mold includes a first mold with a groove cavity inside, in which the graphite-based thermally conductive core material to be encapsulated is placed. The graphite-based thermally conductive core material has multiple through holes, and a gap for filling molten metal is reserved between its outer surface and the groove cavity. The groove cavity is provided with multiple positioning bosses, each of which includes a large-diameter cylindrical section and a small-diameter cylindrical section coaxially connected. The large-diameter cylindrical section supports the bottom of the graphite-based thermal conductive core material, and the small-diameter cylindrical section is inserted into a through hole on the graphite-based thermal conductive core material to perform axial positioning and anti-drift fixation of the graphite-based thermal conductive core material. The first mold is provided with a pouring port. Molten metal is injected into the gap through the pouring port and, after cooling, forms a metal encapsulation shell covering the graphite-based thermally conductive core material.

[0007] Furthermore, the through holes on the graphite-based thermal conductive core material are arranged in an array, and the total cross-sectional area of ​​the through holes accounts for 3% to 30% of the surface area of ​​the graphite-based thermal conductive core material. The length of the small-diameter cylindrical section is less than the length of the through holes.

[0008] Furthermore, on the graphite-based thermally conductive core material, the density of through-holes in the edge region is greater than that in the central region, forming a gradient through-hole distribution structure.

[0009] Furthermore, the positioning bosses are arranged in a non-uniform manner, and their number is 5% to 30% of the total number of through holes. The density of bosses distributed in the edge area of ​​the heat-conducting core material is greater than the density of bosses in the center area of ​​the heat-conducting core material.

[0010] Furthermore, the first mold is provided with an exhaust channel, one end of which is connected to the groove cavity and the other end is connected to a vacuum pumping port.

[0011] Furthermore, the material of the first mold is any one of coated sand, resin sand, paraffin wax, or foam plastic.

[0012] In an improved embodiment of the casting mold described above, the casting mold further includes a second mold, which is formed by two metal modules fastened together, and is used to constrain the shape of the first mold material and heat-cur it to form the first mold.

[0013] Furthermore, the second mold is provided with a heating hole and a forming groove of the first mold. A heating rod is inserted into the heating hole, and the heating rod heats and solidifies the first mold material filled into the forming groove.

[0014] Furthermore, the second mold is provided with positioning holes, which are used for positioning and mold alignment between the two metal modules.

[0015] This utility model embodiment also provides a mold system, which includes a metal mesh frame, a vacuum pumping device, and the casting mold described above. The metal mesh frame encloses the first mold, and the vacuum pumping device is connected to the exhaust channel on the first mold through a vacuum pumping interface.

[0016] Furthermore, the mold system also includes a heating rod and a temperature control system. The heating rod is disposed within a heating hole in the second mold for heating and curing the material of the first mold. The temperature control system is electrically connected to the heating rod for regulating the heating process.

[0017] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least: 1. Mechanical anchoring is achieved through the positioning boss: the small diameter section is inserted into the through hole and the large diameter section supports the bottom, forming a "pin-hole" mating structure, which effectively resists the impact of molten metal and prevents the core material from drifting. The positioning accuracy can reach ±0.1mm.

[0018] 2. Vacuum assistance can eliminate air bubbles: By setting an exhaust channel on the first mold and connecting it with a vacuum extraction interface, casting can be achieved in a negative pressure environment, which significantly reduces gas retention in the cavity, avoids interface air gaps, and reduces contact thermal resistance by more than 40%.

[0019] 3. The through holes on the graphite-based thermally conductive core material are distributed in a gradient manner, resulting in a higher density of through holes in the edge area, which enhances the longitudinal thermal conductivity of the hot spot area, while improving the structural stiffness and alleviating thermal stress concentration.

[0020] 4. The positioning bosses on the first mold are arranged in a non-uniform manner, with more positioning bosses placed in the edge area to enhance the positioning reliability of the high heat load area and prevent local deformation.

[0021] 5. A dual-mold system consisting of a first mold and a second mold is adopted. The first mold, made of metal, is used to heat, solidify, and shape-constrain the first mold made of soft material (such as coated sand), ensuring the dimensional stability of the first mold and making it suitable for mass production.

[0022] 6. By making the length of the small-diameter cylindrical section on the positioning boss less than the length of the through hole, a "metal column" can be formed by filling the through hole when pouring molten metal. The metal column is integrally formed with the metal shell, forming a mechanical interlocking structure, which significantly improves the longitudinal thermal conductivity (more than 3 times) and tensile strength. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the first mold; Figure 2 This is a schematic diagram of the second mold; Figure 3 A schematic diagram of a high heat flux solid vapor chamber; Among them, 1. First mold; 2. Groove cavity; 3. Graphite-based thermally conductive core material; 4. Positioning boss; 5. Gap; 6. Pour port; 7. Second mold; 8. Metal encapsulation shell; 9. Metal column; 31. Through hole; 71. Heating hole; 72. Forming groove; 73. Positioning hole. Detailed Implementation

[0025] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0026] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features of the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more features. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this disclosure. The drawings only show the components related to this disclosure and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0029] This utility model discloses a casting mold for encapsulating a high heat flux graphite-based thermally conductive core material. See [link to relevant documentation]. Figure 1 As shown, the casting mold includes a first mold 1, and the first mold has a groove cavity 2 inside, in which the graphite-based thermally conductive core material 3 to be packaged is placed.

[0030] The graphite-based thermally conductive core material 3 has multiple through holes 31, and a gap 5 for filling molten metal is reserved between its outer surface and the groove cavity 2. Multiple positioning bosses 4 are provided within the groove cavity 2. Each positioning boss 4 includes a large-diameter cylindrical section and a small-diameter cylindrical section coaxially connected. The large-diameter cylindrical section supports the bottom of the graphite-based thermally conductive core material 3, and the small-diameter cylindrical section is inserted into the through holes 31 on the graphite-based thermally conductive core material 3 to axially position and prevent drifting. The first mold 1 has a pouring port 6, through which molten metal is injected into the gap 5. After cooling, it forms a metal encapsulation shell covering the graphite-based thermally conductive core material 3.

[0031] In one embodiment, the metal encapsulation shell can be any one of aluminum, 6063 aluminum, 6061 aluminum, or cast aluminum 101, with a thickness of 1~3mm. The graphite-based thermally conductive core material 3 can be one of graphene plate, pyrolytic graphite, high-purity graphite block, or graphite metal composite material, and the diameter of the through hole 31 is 2~5mm.

[0032] In one embodiment, the through holes 31 on the graphite-based thermal conductive core material 3 are arranged in an array, and the total cross-sectional area of ​​the through holes accounts for 3% to 30% of the surface area of ​​the graphite-based thermal conductive core material 3. The length of the small-diameter cylindrical section is less than the length of the through hole 31, so that there is a filling space at the top of the through hole, which facilitates the complete filling of the molten metal liquid and the formation of an exhaust channel.

[0033] During implementation, the first mold 1, into which the graphite-based thermally conductive core material 3 is inserted, is evacuated or placed in a vacuum environment. Molten metal flows through the gap 5 between the graphite-based thermally conductive core material 3 and its surface into each through-hole 31, partially filling the through-holes 31. After casting and demolding, the through-holes 31 into which the small-diameter cylindrical section is inserted are filled to form a metal column using stir welding, laser welding, or electron beam welding processes.

[0034] In one embodiment, the positioning bosses 4 are arranged in a non-uniform manner, and their number is 5% to 30% of the total number of through holes 31. The density of bosses distributed in the edge area of ​​the heat-conducting core material is greater than the density of bosses in the center area of ​​the heat-conducting core material.

[0035] In one embodiment, the first mold 1 is provided with an exhaust channel. One end of the exhaust channel is connected to the groove cavity 2, and the other end is connected to a vacuum extraction port. The exhaust channel can remove gas from the cavity during the casting process and prevent air bubbles from accumulating.

[0036] In one embodiment, the density of through holes 31 in the edge region of the graphite-based thermally conductive core material 3 is greater than that in the central region, forming a gradient through hole distribution structure to optimize the heat flow path and structural strength in the hot spot region.

[0037] In one embodiment, the material of the first mold 1 is any one of coated sand, resin sand, paraffin wax, or foam plastic. The resulting first mold 1 is breathable and can be removed after casting by vibration, solvent dissolution, or high-temperature baking. The breathable mold made of the above materials, along with vacuum assistance during encapsulation, allows the molten metal to quickly fill the mold cavity, preventing air bubbles from forming at the contact surface due to an excessively large wetting angle between the graphite and metal materials.

[0038] When encapsulating graphite-based thermal conductive core materials in metal, the physical principle of solidification and contraction of molten metal at high temperatures is relied upon to ensure a tight fit between the metal shell and the internal graphite-based thermal conductive core material. This avoids excessively high contact thermal resistance caused by the matching tolerances of welding and other processes, as well as the processing tolerances of the thermal conductive material. At the same time, it reduces various pre-treatment processes such as surface treatment of the thermal conductive material.

[0039] In an improved embodiment of the above-described casting mold, see [reference needed]. Figure 2 As shown, the casting mold also includes a second mold 7, which is formed by two metal modules fastening together, and is used to constrain the shape of the first mold material and heat and solidify it to form the first mold 1.

[0040] In one embodiment, the second mold 7 is made of 06Cr. 19 Ni 10 Gray iron, DC 53 Cr 12 Made of a metallic material such as MoV.

[0041] In one embodiment, see Figure 2 As shown, the second mold 7 is provided with a heating hole 71 and a forming groove 72 of the first mold 1. A heating rod is inserted into the heating hole 71, and the heating rod heats and solidifies the first mold material filled into the forming groove 72.

[0042] In one embodiment, the second mold 7 is provided with a positioning hole 73, which is used for positioning and mold alignment between the two metal modules.

[0043] This embodiment of the invention also provides a mold system, which includes a metal mesh frame, a vacuum extraction device, and the aforementioned casting mold. The metal mesh frame encloses the first mold 1, providing structural support and preventing deformation during the casting process. The vacuum extraction device is connected to the exhaust channel on the first mold 1 via a vacuum extraction interface, and is used to achieve vacuum-assisted casting.

[0044] When the graphite-based thermally conductive core material 3 is encapsulated in the casting process, at a temperature of 650~850℃, a vacuum pumping device is used to assist the molten metal liquid to enter from the pouring port 6 into the gap 5 between the first mold 1 and the surface of the graphite-based thermally conductive core material 3.

[0045] Furthermore, the mold system also includes a heating rod and a temperature control system. The heating rod is disposed within the heating hole 71 of the second mold 7 and is used to heat and solidify the first mold material. The temperature control system is electrically connected to the heating rod and is used to regulate the heating process.

[0046] A high heat flux solid-state vapor chamber is manufactured using an integrated casting process with the aforementioned mold and model system, such as... Figure 3 As shown, the high heat flux solid-state vapor chamber includes a metal encapsulation shell 8 and a graphite-based thermally conductive core material 3 inside it. The two are tightly bonded without interface gaps, and the through hole 31 is filled with a metal pillar 9. This high heat flux solid-state vapor chamber has the advantages of high mechanical strength and excellent heat dissipation performance, and can significantly improve longitudinal thermal conductivity and thermal shock resistance.

[0047] The embodiments of this utility model achieve the following technical effects: 1. Mechanical anchoring is achieved through the positioning boss: the small diameter section is inserted into the through hole and the large diameter section supports the bottom, forming a "pin-hole" mating structure, which effectively resists the impact of molten metal and prevents the core material from drifting. The positioning accuracy can reach ±0.1mm.

[0048] 2. Vacuum assistance can eliminate air bubbles: By setting an exhaust channel on the first mold and connecting it with a vacuum extraction interface, casting can be achieved in a negative pressure environment, which significantly reduces gas retention in the cavity, avoids interface air gaps, and reduces contact thermal resistance by more than 40%.

[0049] 3. The through holes on the graphite-based thermally conductive core material are distributed in a gradient manner, resulting in a higher density of through holes in the edge area, which enhances the longitudinal thermal conductivity of the hot spot area, while improving the structural stiffness and alleviating thermal stress concentration.

[0050] 4. The positioning bosses on the first mold are arranged in a non-uniform manner, with more positioning bosses placed in the edge area to enhance the positioning reliability of the high heat load area and prevent local deformation.

[0051] 5. A dual-mold system consisting of a first mold and a second mold is adopted. The first mold, made of metal, is used to heat, solidify, and shape-constrain the first mold made of soft material (such as coated sand), ensuring the dimensional stability of the first mold and making it suitable for mass production.

[0052] 6. By making the length of the small-diameter cylindrical section on the positioning boss less than the length of the through hole, a "metal column" can be formed by filling the through hole when pouring molten metal. The metal column is integrally formed with the metal shell, forming a mechanical interlocking structure, which significantly improves the longitudinal thermal conductivity (more than 3 times) and tensile strength.

[0053] Obviously, those skilled in the art should understand that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. For those skilled in the art, the embodiments of the present utility model can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

[0054] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A casting mold for encapsulating a high-heat-flux graphite-based thermally conductive core material, characterized in that, Includes a first mold (1), the first mold has a groove cavity (2) inside, and the graphite-based thermal conductive core material (3) to be packaged is placed in the groove cavity (2); The graphite-based thermally conductive core material (3) has multiple through holes (31), and a gap (5) for filling molten metal is reserved between its outer surface and the groove cavity (2). The groove cavity (2) is provided with multiple positioning bosses (4). The positioning bosses (4) include a large-diameter cylindrical section and a small-diameter cylindrical section connected coaxially. The large-diameter cylindrical section supports the bottom of the graphite-based thermal conductive core material (3). The small-diameter cylindrical section is inserted into the through hole (31) on the graphite-based thermal conductive core material (3) to perform axial positioning and anti-drift fixation of the graphite-based thermal conductive core material (3). The first mold (1) is provided with a pouring port (6). Molten metal liquid is injected into the gap (5) through the pouring port (6) and after cooling, a metal encapsulation shell covering the graphite-based thermally conductive core material (3) is formed.

2. The casting mold for encapsulating high heat flux graphite-based thermally conductive core material according to claim 1, characterized in that, The through holes (31) on the graphite-based thermal conductive core material (3) are arranged in an array. The total cross-sectional area of ​​the through holes accounts for 3% to 30% of the surface area of ​​the graphite-based thermal conductive core material (3). The length of the small-diameter cylindrical section is less than the length of the through holes (31).

3. The casting mold for encapsulating high heat flux graphite-based thermally conductive core material according to claim 1, characterized in that, The positioning bosses (4) are arranged in a non-uniform manner, and their number is 5% to 30% of the total number of through holes (31). The density of bosses distributed in the edge area of ​​the heat-conducting core material is greater than the density of bosses in the center area of ​​the heat-conducting core material.

4. The casting mold for encapsulating high heat flux graphite-based thermally conductive core material according to claim 3, characterized in that, On the graphite-based thermally conductive core material (3), the density of the through holes (31) in the edge region is greater than that in the center region, forming a gradient through hole distribution structure.

5. The casting mold for encapsulating high heat flux graphite-based thermally conductive core material according to claim 1, characterized in that, The first mold (1) is provided with an exhaust channel, one end of which is connected to the groove cavity (2), and the other end is connected to the vacuum pumping interface.

6. The casting mold for encapsulating high heat flux graphite-based thermally conductive core material according to claim 1, characterized in that, The material of the first mold (1) is any one of coated sand, resin sand, paraffin wax or foam plastic.

7. The casting mold for encapsulating high heat flux graphite-based thermally conductive core material according to any one of claims 1 to 6, characterized in that, It also includes a second mold (7), which is formed by two metal modules fastening together and is used to constrain the shape of the first mold material and heat and solidify it to form the first mold (1).

8. The casting mold for encapsulating high heat flux graphite-based thermally conductive core material according to claim 7, characterized in that, The second mold (7) is provided with a heating hole (71) and a molding groove (72) of the first mold (1). A heating rod is inserted into the heating hole (71) and the heating rod heats and solidifies the first mold material filled into the molding groove (72).

9. The casting mold for encapsulating high heat flux graphite-based thermally conductive core material according to claim 7, characterized in that, The second mold (7) is provided with positioning holes (73), which are used for positioning and mold alignment between the two metal modules.

10. A mold system, characterized in that, The device includes a metal mesh frame, a vacuum pumping device, and a casting mold according to any one of claims 1 to 9. The metal mesh frame encloses the first mold (1), and the vacuum pumping device is connected to the exhaust channel on the first mold (1) through a vacuum pumping interface.

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