Production process of ultrathin VC

Abstract

This application relates to the field of heat spreader processing, and more specifically, to a production process for ultra-thin heat spreaders (VCs). The process includes the following steps: a copper powder mixture is 3D printed to form a capillary preform structure on the inner surface of a first thin-film cover; then, after degreasing and sintering, a capillary structure is formed on the inner surface of the first thin-film cover; a second cover is then joined to the first thin-film cover and diffusion welded; post-processing is performed to obtain the ultra-thin VC. The copper powder mixture includes copper powder, flux, and a binder. This process results in a final ultra-thin VC with a thin thickness (as low as 1 mm; for example, a thickness of 0.8 mm has a thermal conductivity of over 15 W / (m·K)) and good structural stability (an integrity rate of over 92% after drop testing).

Description

Technical Field

[0001] This application relates to the field of heat exchanger processing, and more specifically, it relates to a production process for an ultra-thin VC. Background Technology

[0002] With the rapid iteration towards miniaturization, integration, and high performance in consumer electronics, new energy vehicle electronics, aerospace, and other fields, the power density of electronic components inside devices continues to increase, making heat dissipation requirements increasingly stringent. As a highly efficient phase-change heat dissipation element, vapor chambers have become a core component for solving the problem of high-density heat accumulation due to their excellent temperature uniformity and heat dissipation efficiency. In particular, ultra-thin vapor chambers (VCs) can adapt to irregularly shaped installation spaces and meet the requirements of lightweight device designs, and are widely used in smartphones, foldable screen devices, laptops, microservers, and automotive precision electronic modules. Their structural design and manufacturing process directly affect the heat dissipation performance and operational stability of the terminal devices.

[0003] The basic structure of existing ultrathin vapor chambers (VCs) typically consists of a sealed cavity formed by welding or bonding an upper and lower cover that interlocks with each other. This cavity is filled with working fluids such as pure water or ethanol, and a capillary structure is incorporated to provide the reflux force for the working fluid, ensuring the continuous operation of the phase change heat dissipation cycle. As a core functional component of the vapor chamber, the quality of its fabrication significantly impacts the performance of the vapor chamber. Currently, the mainstream methods for fabricating capillary structures in the industry are printing and etching. Printing typically involves printing a paste of ceramic powder or metal powder onto the surface of the cover, followed by sintering and curing. Etching (including chemical etching and laser etching) involves etching grooves or grid-like capillary channels onto the surface of the metal cover.

[0004] Ultra-thin vapor chambers (VCs) present a core technological contradiction between "thinness" and "heat dissipation performance." The irregular shape of 3D vapor chambers inherently requires reserved cavity space to accommodate working fluid flow and phase change diffusion. However, when the thickness is reduced to below 1mm, the effective internal volume of the cavity is significantly compressed, resulting in reduced working fluid filling, shortened vapor diffusion paths, and increased resistance. Due to these shortcomings, existing capillary structure fabrication processes cannot simultaneously achieve sufficient capillary force, unobstructed working fluid channels, and stable structural support within a limited cavity space. Consequently, after achieving the desired thinness, the heat dissipation performance of ultra-thin VCs significantly declines, failing to meet the high-power heat dissipation requirements of high-end electronic devices.

[0005] Currently, although the industry has attempted to improve heat dissipation performance by optimizing the working fluid composition and adjusting the cover material, none of these methods have fundamentally solved the compatibility problem between capillary structure fabrication processes and ultra-thin 3D structures, failing to overcome the mutual constraints between thinness and heat dissipation efficiency. Therefore, developing a capillary structure production process that can balance structural stability and heat dissipation performance and is compatible with ultra-thin VCs (less than 1mm) has become an urgent technical challenge in the current heat spreader processing field. Summary of the Invention

[0006] The purpose of this application is to provide a manufacturing process for ultra-thin vapor chambers (VCs) while obtaining thinner 3D vapor chambers, achieving better heat dissipation performance and structural stability, and improving their durability.

[0007] A manufacturing process for ultra-thin VC includes the following steps: The copper powder mixture is 3D printed to form a capillary preform structure on the inner surface of the first thin sheet cover. After degreasing and sintering, the capillary structure is formed on the inner surface of the first thin sheet cover. The second cover is then joined with the first thin sheet cover and diffusion welded. After post-processing, an ultra-thin VC is obtained. The copper powder mixture includes copper powder, flux and binder.

[0008] This application uses 3D printing technology as its core, combined with a customized copper powder mixture consisting of copper powder, flux, and binder. By precisely adapting it to subsequent debinding and sintering processes, and then combining it with diffusion welding and capping technology, it achieves the following effects: thin final VC thickness (as low as 1mm, such as 0.8mm, with a thermal conductivity of over 15W / (m·K)), good thermal conductivity, good structural stability, and good internal capillary structure stability.

[0009] Specifically, 3D printing, in conjunction with copper powder mixtures and debinding and sintering processes, enables precise shaping and stable solidification of capillary structures. 3D printing allows for the design and direct molding of three-dimensional capillary preforms on the inner surface of the first thin-film cover. The binder provides ample shape support for the preform, ensuring it is less prone to cracking or collapse after 3D printing. Copper powder, as the core thermally conductive substrate, lays the material foundation for subsequent efficient heat conduction channels. The debinding process thoroughly removes the binder, preventing residual impurities from affecting thermal conductivity. In the sintering process, the flux promotes the formation of stable necking bonds between copper powder particles, reducing the sintering temperature to prevent thermal deformation of the ultra-thin cover and enhancing the mechanical strength of the capillary structure, preventing loosening, collapse, or deformation in subsequent processes and during use.

[0010] In this way, the capillary structure has sufficient capillary driving force and smooth working fluid flow channels, ensuring the efficient thermal conductivity of the heat spreader. It also forms a stable integrated structure with the cover, achieving simultaneous improvement in the stability of the capillary structure and the overall structure. This allows the thickness of the finished heat spreader to be stably controlled within the range of 0.3-1mm, precisely adapting to ultra-thin application scenarios, while ensuring excellent thermal conductivity and a reliable overall structure.

[0011] Preferably, the capillary structure includes a capillary mesh, and the first thin sheet cover has a first groove for embedding the capillary mesh.

[0012] 3D printing can form a precise capillary network structure in the first groove of the first thin sheet cover; at the same time, by combining 3D printing with copper powder mixture, debinding sintering, and diffusion welding processes, the capillary structure can be accurately formed and stably cured, ensuring thermal conductivity and structural reliability. The precise adaptation of each component enhances the synergistic effect, which helps to achieve ultra-thinness and high thermal conductivity compatibility, further consolidating the overall structural stability and thermal conductivity, simplifying the process, accurately controlling the ultra-thin thickness, and adapting to the needs of multiple scenarios.

[0013] Preferably, the capillary structure further includes a plurality of capillary copper pillars that abut against the capillary mesh.

[0014] 3D printing enables the creation of precise capillary structures, and the capillary structure formed by the combination of capillary mesh and capillary copper pillars offers superior heat dissipation performance. The capillary copper pillars act as supports, preventing deformation of the internal structure of the ultra-thin vapor chamber after impact, thus avoiding damage or shrinkage of the internal structure and affecting heat dissipation. The capillary mesh and capillary copper pillars work synergistically to construct a composite heat dissipation system of "planar diffusion + columnar conduction," which significantly improves the heat conduction efficiency compared to traditional single capillary structures. This allows for faster diffusion of localized high heat to the entire vapor chamber, significantly optimizing the heat dissipation uniformity and overall heat dissipation power. The capillary copper pillars also serve as supporting components within the cavity, forming a uniformly distributed three-dimensional support system that effectively resists external impact forces, preventing cavity deformation under pressure, capillary mesh collapse, or channel blockage. This ensures that heat dissipation performance is not affected by impacts and extends the lifespan of the vapor chamber.

[0015] Preferably, the specific process of capillary structure forming is as follows: a copper powder mixture is 3D printed to form a capillary mesh on the inner surface of the first thin sheet cover and a capillary column on the inner surface of the second thin sheet cover. After degreasing and sintering, a capillary mesh is formed on the inner surface of the first thin sheet cover and a capillary copper column is formed on the inner surface of the second thin sheet cover. The capillary mesh side of the first thin sheet cover is then joined to the second thin sheet cover, diffused and welded, and post-processed to obtain an ultrathin VC.

[0016] By combining 3D printing technology with a copper powder mixture containing copper powder, flux, and binder, capillary meshes and capillary columns can be precisely formed on the inner surfaces of the first and second thin-film caps, respectively, as needed. The binder provides shape support for the preform, ensuring that the preform is not prone to cracking or collapse after 3D printing. It precisely controls the height, pore size, spacing, and spatial distribution of the capillary structure, adapting to the spatial constraints of ultra-thin cavities of 0.3-1mm. Copper powder serves as the core thermally conductive substrate, laying the foundation for efficient heat conduction channels.

[0017] The subsequent degreasing process removes the binder, preventing residual impurities from clogging capillary channels or affecting thermal conductivity continuity. During the sintering process, the flux promotes the formation of stable necking bonds between copper powder particles, lowering the sintering temperature to prevent thermal deformation of the ultra-thin cap and significantly improving the mechanical strength of the capillary structure while maintaining its reasonable porosity and connectivity. Subsequent diffusion welding and post-treatment ensure that the finished product thickness is stably controlled within the range of 0.3-1mm, achieving ultra-thin VC. Simultaneously, the capillary structure possesses sufficient capillary driving force and unobstructed working fluid flow channels, guaranteeing the efficient thermal conductivity of the heat spreader. Furthermore, the capillary structure and the cap form a stable integrated structure, achieving a simultaneous improvement in overall structural stability and internal capillary structure stability.

[0018] Preferably, the degreasing process parameters are: under vacuum, the temperature is increased from room temperature by 3-8℃ to 300-350℃ and held at that temperature for 2-4 hours; the sintering process parameters are: under vacuum, the sintering temperature is 800-850℃ and the holding time is 1-2 hours.

[0019] 3D printing and copper powder mixture work synergistically, combined with debinding and sintering processes, to achieve precise capillary structure forming and stable curing, while simultaneously ensuring thermal conductivity and structural reliability. The precise adaptation of each component of the copper powder mixture to the process chain enhances the synergistic efficiency of 3D printing-debinding-sintering, facilitating ultra-thinning and high thermal conductivity compatibility. Diffusion welding is adapted to the pre-process synergy system, further consolidating the overall structural stability and thermal conductivity. The integrated synergistic process simplifies the process, precisely controls the ultra-thin thickness, and adapts to various application scenarios. Specific debinding process parameters ensure debinding stability, resulting in uniform pores.

[0020] Preferably, the copper powder has a particle size of less than 1 micrometer, and the flux is borax.

[0021] Copper powder with a particle size of less than 5 micrometers is mixed with borax flux and a binder to form a copper powder mixture. This mixture is then used in conjunction with 3D printing to form a capillary preform structure on the inner surface of the first thin-film cover. Following debinding and sintering processes, an ultrathin VC (capillary condenser) is ultimately formed. The copper powder with a particle size of less than 5 micrometers facilitates 3D printing, resulting in a compact and stable structure that forms the foundation for efficient heat conduction channels. During the sintering process, the borax flux promotes the formation of stable necking bonds between copper powder particles, lowering the sintering temperature to prevent thermal deformation of the ultrathin cover while preserving the reasonable porosity and connectivity of the capillary structure, significantly improving its mechanical strength. The synergy between 3D printing and the copper powder mixture allows for the design and precise molding of three-dimensional capillary structures, perfectly adapting to the space constraints of ultrathin cavities. The subsequent debinding process removes the binder, preventing impurities from affecting thermal conductivity. The entire process achieves precise preparation of the ultrathin VC, ensuring the finished product thickness is stably controlled within the range of 0.3-1 mm. Furthermore, the heat spreader exhibits excellent thermal conductivity, reliable overall structural stability, and robust internal capillary structure stability.

[0022] Preferably, the adhesive molding agent includes an auxiliary molding agent; the auxiliary molding agent is a combination of one or more of polyethyleneimine, polyethylene glycol, and polybutadiene containing active groups, and at least includes polyethylene glycol or polybutadiene containing active groups; the amount of auxiliary molding agent is 0.5-3 wt%.

[0023] Using 3D printing technology as its core, and combining a copper powder mixture containing copper powder, flux, binder, and specific auxiliary forming agents, a three-dimensional capillary preform structure can be precisely formed on the inner surface of a first thin-film cover as needed through processes such as debinding and sintering. The binder and auxiliary forming agents work synergistically; the binder provides shape support for the preform, while the auxiliary forming agents act specifically on the copper powder. Polyethylene imide ensures tight bonding of copper powder particles, preventing delamination and powder shedding in the printed preform; polyethylene glycol improves material flowability and extrusion uniformity, ensuring the accuracy of the capillary structure; and polybutadiene containing active groups enhances the flexibility and toughness of the preform, preventing cracking and collapse. Subsequent debinding processes remove impurities such as auxiliary forming agents, while the flux in the sintering process promotes the bonding of copper powder particles, lowers the sintering temperature, and improves the mechanical strength of the capillary structure. After diffusion welding and sealing, the thickness of the resulting ultra-thin VC is stable at 0.3-1mm, which is precisely adapted to ultra-thin application scenarios; the capillary structure has sufficient capillary driving force and smooth working fluid flow channels, ensuring the efficient thermal conductivity of the heat spreader; the capillary structure and the cover form a stable integrated structure, realizing the simultaneous improvement of capillary structure stability and overall structural stability.

[0024] Furthermore, the amount of auxiliary molding agent used is 0.5-3wt%.

[0025] Preferably, the auxiliary molding agent is composed of polyethyleneimine, polyethylene glycol and its derivatives, and polybutadiene containing active groups.

[0026] The compounding of three raw materials—polyethylene imide, polyethylene glycol and its derivatives, and polybutadiene containing active groups—achieves a synergistic effect. Polyethylene glycol and its derivatives, as the main component, effectively reduce the molding viscosity of the copper powder mixture, providing a carrier for the uniform dispersion of the other two components and improving the flowability and extrusion uniformity of the printed material. Polyethylene imide, with its highly polar groups, precisely adsorbs onto the surface of copper powder particles, preventing agglomeration and enhancing interparticle bonding. Polybutadiene containing active groups enhances the flexibility and structural toughness of the preform, preventing cracking and collapse after printing. Its active groups also undergo a cross-linking reaction in the early stages of sintering to stabilize the preform morphology. These three components work synergistically as a binding agent, giving the copper powder mixture excellent shaping, shape retention, and uniform dispersion capabilities, enabling precise molding of dual-capillary preforms. Subsequent degreasing processes ensure no residual impurities block the channels, and during the sintering process, flux and auxiliary molding agent residues work together to cool the material, preventing thermal deformation of the cap and ensuring the mechanical strength and morphological stability of the dual structure. Ultimately, this resulted in a thinner ultrathin VC with better thermal conductivity, and improved overall structural stability and internal capillary structure stability.

[0027] Furthermore, the composition is made up of polyethyleneimine, polyethylene glycol, and polybutadiene containing active groups in a ratio of (0.1-0.5):10:(0.5-2).

[0028] Preferably, the polybutadiene containing active groups is hydroxyl-terminated polybutadiene (HTPB) and / or maleic anhydride-grafted polybutadiene.

[0029] Hydroxyl-terminated polybutadiene (HTPB) and / or maleic anhydride-grafted polybutadiene, along with polyethyleneimine, polyethylene glycol, and their derivatives, form auxiliary molding agents used in binder molding agents. These agents can play multiple roles in copper powder and further improve its performance. Polyethyleneimine, in a low-proportion blend, precisely adsorbs onto the surface of copper powder particles due to its strong polar groups, forming uniform molecular-level bonding bridges that prevent copper powder agglomeration and enhance interparticle bonding. Polyethylene glycol and its derivatives, as the main component, possess excellent plasticizing, lubricating, and dispersing media properties, reducing the molding viscosity of the copper powder mixture and improving material flowability and extrusion uniformity during printing. Hydroxyl-terminated polybutadiene (HTPB) and / or maleic anhydride-grafted polybutadiene are mixed in a specific ratio. The terminal hydroxyl groups of HTPB can form hydrogen bonds with the hydroxyl groups on the surface of copper powder, and its flexible segments encapsulate the copper powder particles, weakening the tendency of particle agglomeration and improving dispersion stability. The maleic anhydride groups of maleic anhydride-grafted polybutadiene form a weak coordination effect with the metal sites on the surface of copper powder, strengthening the interfacial bonding force between copper powder and auxiliary forming agents and binder forming agents. The synergistic effect of these three components gives the copper powder mixture excellent plasticity, shape retention, and uniform dispersion, enabling precise molding of double capillary preforms. In the subsequent debinding process, they can be completely decomposed and volatilized, leaving no residual impurities to block the channels. In the sintering process, they work together with the flux to cool down, preventing thermal deformation of the cap. The uniformly dispersed and tightly bonded copper powder forms a stable necking bond, significantly improving the mechanical strength of the double structure and ensuring morphological stability. Meanwhile, by optimizing the accumulation and bonding state of copper powder, the foundation for heat dissipation is strengthened. The heat conduction efficiency of the "area diffusion + columnar conduction" system formed by the capillary mesh and capillary copper pillars is significantly improved, which can quickly dissipate local high heat, optimize temperature uniformity and heat dissipation power. Combined with the high thermal conductivity of copper powder, the pain point of "heat dissipation attenuation after thinning" of ultra-thin heat spreaders is completely solved, and heat dissipation performance is maximized.

[0030] Preferably, the adhesive molding agent is one of UV-curable adhesive, thermoplastic adhesive, water-soluble adhesive, and wax-based adhesive.

[0031] A variety of binders are available to suit different production needs and process conditions. UV-curable binders offer fast curing speeds, improving production efficiency; thermoplastic binders provide excellent plasticity and processing performance, facilitating the molding of complex capillary structures; water-soluble binders are environmentally friendly and easy to clean, reducing pollution during production; wax-based binders offer good adhesion and release properties, aiding in the precise molding of capillary structures. This variety of binders enhances process flexibility and adaptability, better meeting the needs of different production scenarios for ultra-thin VCs, ensuring the molding quality and stability of capillary structures, and thus guaranteeing the overall performance of the heat spreader. Furthermore, UV-curable and thermoplastic binders are preferred, as these are solvent-free, resulting in stable preforms that are easy to degrease. This facilitates more efficient removal of impurities in subsequent degreasing and sintering processes, ensuring unobstructed capillary channels and continuous thermal conductivity, thereby improving the overall performance of ultra-thin VCs.

[0032] In summary, this application includes at least one of the following beneficial technical effects: This technology focuses on adapting 3D printing technology to a copper powder mixture containing copper powder, flux, and binder. Combined with debinding and sintering processes, it achieves precise shaping and stable curing of capillary structures, ensuring thermal conductivity and structural reliability. 3D printing can design and shape three-dimensional capillary preforms as needed. The binder ensures preform stability, copper powder provides the foundation for thermal conductivity, debinding removes impurities, and sintering enhances the mechanical strength of the capillary structure. This solves the problem of existing processes being unable to balance capillary structure performance and stability in ultra-thin applications, enabling stable control of ultra-thin VC thickness within 0.3-1mm, balancing ultra-thin thickness with excellent thermal conductivity. The capillary mesh and capillary copper pillars work synergistically to construct a composite heat dissipation system of "planar diffusion + columnar conduction," improving heat transfer efficiency and optimizing the heat dissipation uniformity and overall heat dissipation power of the vapor chamber. The capillary mesh provides phase change contact points for the working fluid, while the capillary copper pillars form longitudinal heat conduction pathways. Combined with copper powder mixtures and sintering processes, this addresses the pain point of "heat dissipation performance degradation after thinning" in traditional ultra-thin vapor chambers. The capillary copper pillars also serve a supporting function, enhancing the overall structure's impact resistance and ensuring long-term reliable heat dissipation stability. After 3D printing and debinding sintering, the capillary copper pillars and capillary mesh form a three-dimensional support system, preventing the internal structure of the ultra-thin VC from collapsing or the cavity from deforming, thus avoiding any impact on heat dissipation. The auxiliary molding agent is a multi-component composition of polyethyleneimine, polyethylene glycol, and polybutadiene containing active groups. It works synergistically with the binder molding agent, adapting to the characteristics of 3D printing and copper powder to achieve precise molding and stable curing of the dual capillary structure. Each component of the auxiliary molding agent plays a different role in the printing, debinding, and sintering processes, enhancing shaping ability and shape retention, ensuring continuous thermal conductivity, improving the mechanical strength of the dual structure, and further improving the overall performance of ultra-thin VC. The specific selection and formulation of the auxiliary forming agent optimizes the capillary structure performance and enhances the heat dissipation efficiency of the dual-structure system. It enables the copper powder to be evenly dispersed, eliminates thermal conductivity blind zones, and forms a capillary structure with high density and uniform pore distribution. Combined with the dual-structure heat dissipation system and the high thermal conductivity of copper powder, it maximizes heat dissipation performance. Attached Figure Description

[0033] Appendix Figure 1 This is a schematic diagram of the capillary network structure formed on the inner surface of the first thin sheet cover of this application.

[0034] Appendix Figure 2 This is a schematic diagram of the structure of capillary copper pillars formed on the inner surface of the second thin sheet cover of this application.

[0035] Figure 3 This is a schematic diagram showing the dimensions of the first thin sheet cover and the capillary mesh of this application.

[0036] Figure 4 This is a schematic diagram showing the dimensions of the capillary copper columns formed on the inner surface of the second thin sheet cover of this application. Detailed Implementation

[0037] The following is in conjunction with the appendix Figure 1-4 The present application will be further described in detail with reference to the embodiments.

[0038] Introduction to some raw materials: Ethoxyethoxyethyl acrylate, CAS No. 7328-17-8; Trimethylolpropane triacrylate, CAS No. 15625-89-5; 1,4-Butanediol diacrylate, CAS No. 1070-70-8; Hydroxyl-terminated polybutadiene (HTPB) POLYVEST® HT series HT 1300; Maleic anhydride-grafted polybutadiene POLYVEST® MA series MA 75; The number average molecular weight of polyethylene is 20,000-50,000. Epoxidized soybean oil CAS No. 8013-07-8.

[0039] Preparation example of adhesive molding agent Preparation Example 1 A bonding agent is obtained by the following method: UV resin (Inoue UV-8901 difunctional polyurethane acrylate), diluent (composed of ethoxyethoxyethyl acrylate, trimethylolpropane triacrylate, and 1,4-butanediol diacrylate in a weight ratio of 2:1:1), and photoinitiator (composed of photoinitiator 184 and photoinitiator 1173 in a weight ratio of 1:1) were weighed in a mixing device at a weight ratio of 50:47:3 and placed into a mixing device. The mixture was stirred at a speed of 100 r / min for 10 min to ensure thorough and uniform mixing, thereby obtaining the adhesive molding agent.

[0040] Preparation Example 2 One type of adhesive is a UV-curable adhesive, which is obtained by the following method: UV resin (Inoue UV-8901 difunctional polyurethane acrylate), diluent (composed of ethoxyethoxyethyl acrylate, trimethylolpropane triacrylate, and 1,4-butanediol diacrylate in a weight ratio of 2:1:1), photoinitiator (composed of photoinitiator 184 and photoinitiator 1173 in a weight ratio of 1:1), and auxiliary molding agent (composed of polyethyleneimine and polyethylene glycol in a weight ratio of 1:4) were weighed in a mixing device and stirred at 100 r / min for 10 min to ensure thorough mixing and uniformity, thus obtaining the adhesive molding agent.

[0041] Preparation Example 3 The difference between Preparation Example 3 and Preparation Example 2 is that the auxiliary molding agent is composed of polyethyleneimine, polyethylene glycol, and polybutadiene with active groups (hydroxyl-terminated polybutadiene) in a weight ratio of 1:3:1.

[0042] Preparation Example 4 The difference between Preparation Example 4 and Preparation Example 2 is that the auxiliary molding agent is composed of polyethyleneimine, polyethylene glycol, and polybutadiene with active groups (maleic anhydride-grafted polybutadiene) in a weight ratio of 1:3:1.

[0043] Preparation Example 5 The difference between Preparation Example 5 and Preparation Example 4 is that the polybutadiene containing active groups is composed of hydroxyl-terminated polybutadiene and maleic anhydride-grafted polybutadiene in a weight ratio of 1:1.

[0044] Example of copper powder mixture preparation Preparation Example 6 A copper powder mixture is prepared by the following method: Copper powder, flux, and the binder / forming agent obtained in Preparation Example 1 were weighed and mixed evenly in a weight ratio of 83:2:15 to obtain a copper powder mixture. The flux was borax, and the average particle size of the copper powder and borax was 200 nm.

[0045] Preparation Example 7 The difference between Preparation Example 7 and Preparation Example 6 is that the adhesive molding agent obtained in Preparation Example 2 was used.

[0046] Preparation Example 8 The difference between Preparation Example 8 and Preparation Example 6 is that the adhesive molding agent obtained in Preparation Example 3 was used.

[0047] Preparation Example 9 The difference between Preparation Example 9 and Preparation Example 6 is that the adhesive molding agent obtained in Preparation Example 4 was used.

[0048] Preparation Example 10 The difference between Preparation Example 10 and Preparation Example 6 is that the adhesive molding agent obtained in Preparation Example 5 was used.

[0049] Example

[0050] A process for producing ultra-thin VC is obtained by the following method: The copper powder mixture obtained in Preparation Example 6 was 3D printed to form capillary mesh and capillary columns on the inner surface of the first and second thin-film caps respectively. After degreasing and sintering, capillary mesh was formed on the inner surface of the first and second thin-film caps respectively. The capillary mesh side of the first and second thin-film caps was then joined together and diffusion soldered (890℃, 20 min; cooled at 25℃ for 15 h). Post-processing (including gas reduction, liquid injection, polishing, surface treatment, etc.) yielded an ultrathin VC. The structure of this ultrathin VC is as follows: Figure 1 and Figure 2 As shown, the dimensions are as follows Figure 3 and Figure 4 As shown, the capillary copper column is 0.2 mm high, the total thickness of the capillary mesh is 0.1 mm, the four-layer mesh structure has a mesh size of 1500 mesh, the total thickness of the ultra-thin VC is 0.8 mm, the thickness of the first thin sheet cover and the second thin sheet cover are equal, the capillary copper columns are equidistantly distributed, and the distance between two adjacent ones is 0.3 mm.

[0051] Among them, the degreasing process parameters are: at a vacuum degree of 10... - At ³Pa, the temperature was increased from room temperature (25℃) to 320℃ in increments of 5℃, and held at that temperature for 3 hours; sintering process parameters: at a vacuum degree of 10 - At ³Pa, the sintering temperature was 830℃; the holding time was 1.5h.

[0052] 3D printing parameter settings: Using a 3D printer, the printing parameters are: nozzle 0.1mm, speed 20mm / s, pressure 1MPa, barrel temperature 25℃, printing environment temperature 50℃, ultraviolet light wavelength 365nm, and ultraviolet light power 100mW / cm².

[0053] Example 2 The difference between Example 2 and Example 1 lies in the different process parameters, as detailed below; Degreasing process parameters: at a vacuum degree of 10 - Under ³Pa, the temperature was increased from room temperature (25℃) to 350℃ in increments of 8℃, and held at that temperature for 2 hours; sintering process parameters: under a vacuum degree of 10 - At ³Pa, the sintering temperature was 800℃; the holding time was 2h.

[0054] Example 3 The difference between Example 3 and Example 1 lies in the different process parameters, as detailed below; Degreasing process parameters: at a vacuum degree of 10 - Under ³Pa, the temperature was increased from room temperature (25℃) to 300℃ in increments of 3℃, and held at that temperature for 4 hours; sintering process parameters: under a vacuum degree of 10 - At ³Pa, the sintering temperature was 850℃; the holding time was 1h.

[0055] Example 4 The difference between Example 4 and Example 1 is that the copper powder mixture obtained in Preparation Example 7 was used.

[0056] Example 5 The difference between Example 5 and Example 1 is that the copper powder mixture obtained in Preparation Example 8 was used.

[0057] Example 6 The difference between Example 6 and Example 1 is that the copper powder mixture obtained in Preparation Example 9 was used.

[0058] Example 7 The difference between Example 7 and Example 1 is that the copper powder mixture obtained in Preparation Example 10 was used.

[0059] Example 8 The difference between Example 8 and Example 1 is that there are no capillary copper pillars. The specific process is as follows: The copper powder mixture obtained in Preparation Example 6 was used to form capillary preforms on the inner surface of the first thin sheet cover body by 3D printing. After degreasing and sintering, capillary meshes were formed on the inner surface of the first thin sheet cover body. The capillary mesh side of the first thin sheet cover body was then joined with the inner surface of the second thin sheet cover body by diffusion welding (890℃, 20min; room temperature 25℃, cooling for 15h). Post-processing (including gas reduction, liquid injection, polishing, surface treatment, etc.) was performed to obtain ultrathin VC.

[0060] Experimental Testing and Analysis thermal conductivity The thermal conductivity of the ultrathin VC obtained in Examples 1-8 was tested using the ASTM D5470 standard for testing the thermal transfer performance of thin thermally conductive solid materials. A thermal conductivity of 15 W / (m·K) or higher was considered qualified.

[0061] Structural stability (drop resistance) test Evaluate the structural integrity and performance retention of the temperature riser after an accidental drop impact.

[0062] A dedicated drop test machine is used to ensure high accuracy and controllable release posture.

[0063] In the experiment, the initial thermal conductivity (λ0) of the ultrathin VC obtained in Examples 1-8 was measured before the drop using method 1 described above.

[0064] The ultra-thin VC (with the panel surface perpendicular to the horizontal plane and the second thin cover facing the ground) is dropped freely from a height of 2.0 meters onto a rigid horizontal smooth surface (marble floor).

[0065] After the drop test, visual inspection and leak detection are performed first: check for any visible deformation, cracks, weld breaks, or working fluid leaks.

[0066] If there is no leakage, after standing for 30 minutes, measure its thermal conductivity (λ1) after the drop again.

[0067] Calculate the rate of change of thermal conductivity: Rate of change = |λ1 - λ0| / λ0 × 100% Acceptance criteria: Change rate ≤ 5%, and no visible structural damage or leakage; Integrity Test: Samples from Examples 1-7 were scanned using micro-CT scanning and the results were recorded. Samples that underwent drop tests were also scanned using micro-CT scanning to quickly identify unqualified samples with obvious copper pillar breakage, collapse, or detachment. The number of capillary copper pillars with these defects was recorded, and the integrity rate was calculated as (number of intact pillars / total number before drop test).

[0068] The experimental data are detailed in Table 1. Table 1 Experimental data of Examples 1-8

[0069] As can be seen from the combination of Comparative Examples 1-10, Examples 1-8 and Table 1: This application uses 3D printing technology as its core, combined with a customized copper powder mixture consisting of copper powder, flux, and binder. By precisely adapting it to subsequent debinding and sintering processes, and combining it with diffusion welding and capping technology, it achieves the following effects: thin final VC thickness (as low as 1mm, such as 0.8mm, with a thermal conductivity of over 15W / (m·K)), good thermal conductivity, good structural stability, and good internal capillary structure stability (the integrity rate reaches over 92% after drop test).

[0070] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A manufacturing process for ultra-thin vitamin C, characterized in that, The following steps are included: Copper powder mixture is 3D printed to form a capillary preform structure on the inner surface of the first thin sheet cover. After degreasing and sintering, a capillary structure is formed on the inner surface of the first thin sheet cover. The second cover is then joined with the first thin sheet cover and diffusion welded. After post-processing, an ultrathin VC is obtained. The copper powder mixture includes: copper powder, flux, and binder.

2. The production process of ultra-thin VC according to claim 1, characterized in that: The capillary structure includes a capillary mesh, and the first thin sheet cover has a first groove for embedding the capillary mesh.

3. The production process for ultra-thin VC according to claim 2, characterized in that: The capillary structure also includes a number of capillary copper pillars that abut against the capillary mesh.

4. The production process for ultra-thin VC according to claim 3, characterized in that, The specific process of capillary structure forming is as follows: Copper powder mixture is 3D printed to form capillary preform mesh on the inner surface of the first thin sheet cover and capillary preform column on the inner surface of the second thin sheet cover. After degreasing and sintering, capillary mesh is formed on the inner surface of the first thin sheet cover and capillary copper column is formed on the inner surface of the second thin sheet cover. The capillary mesh side of the first thin sheet cover is then joined with the second thin sheet cover, diffusion welding is performed, and post-processing is carried out to obtain ultrathin VC.

5. The production process for ultra-thin VC according to claim 1, characterized in that, The degreasing process parameters are as follows: under vacuum, the temperature is increased from room temperature by 3-8℃ to 300-350℃ and held for 2-4 hours; the sintering process parameters are as follows: under vacuum, the sintering temperature is 800-850℃ and the holding time is 1-2 hours.

6. The production process of ultra-thin VC according to claim 1, characterized in that: The copper powder has a particle size of less than 5 micrometers, and the flux is borax.

7. The production process of ultra-thin VC according to claim 1, characterized in that: The adhesive molding agent includes an auxiliary molding agent; the auxiliary molding agent is one or more of polyethyleneimine, polyethylene glycol, and polybutadiene containing active groups, and at least includes polyethylene glycol or polybutadiene containing active groups.

8. The production process of ultra-thin VC according to claim 1, characterized in that: The auxiliary molding agent is composed of polyethyleneimine, polyethylene glycol and its derivatives, and polybutadiene containing active groups.

9. The production process of ultra-thin VC according to claim 4, characterized in that: The polybutadiene containing active groups is hydroxyl-terminated polybutadiene (HTPB) and / or maleic anhydride-grafted polybutadiene.

10. A manufacturing process for ultra-thin VC according to any one of claims 1-9, characterized in that: The adhesive molding agent is one of the following: UV-curable adhesive, thermoplastic adhesive, water-soluble adhesive, and wax-based adhesive.

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