A high-strength, high-thermal-conductivity thin and light vapor chamber

Abstract

The present invention discloses a high-strength, high-thermal-conductivity, thin and light heat spreader, whose structure includes upper and lower cover plates, a liquid wick, and support columns. The upper and lower cover plates are sealed to form an inner cavity. The upper and lower inner surfaces of the inner cavity are provided with a liquid wick. A certain number of support columns are used to abut the upper and lower inner surfaces of the inner cavity. The gaps between the support columns serve as evaporation chambers or capillary chambers. At least one of the upper and lower cover plates is made of a composite copper material formed by copper alloy / pure copper; wherein, in the composite copper material formed by copper alloy / pure copper, the copper alloy is located on the outside of the cover plate, and the pure copper is located on the inside of the cover plate; when the upper and lower cover plates are sealed to form the inner cavity, the inner layer material of the composite copper material, pure copper, is directly welded to pure copper. The high-strength, high-thermal-conductivity, thin and light heat spreader of the present invention meets the current development requirements of heat spreaders for high efficiency, heat resistance, reliability, and thinness, and solves the current problems of low strength, large thickness and mass, and copper paste welding defects of heat spreaders.

Description

Technical Field

[0001] The invention belongs to the technical field of heat dissipation of electronic devices and relates to a thin and light heat spreader with high strength and high thermal conductivity. Background Art

[0002] With the rapid development of electronic technology, the degree of integration of various mobile electronic products and computing components such as data centers, servers and electric vehicles has increased rapidly, and the size has become smaller and smaller. Especially with the in-depth development of 5G products, the operating power of various mobile electronic products and computing components has increased rapidly, and the product terminals will generate ultra-high heat, which requires the assistance of heat dissipation devices with good heat dissipation functions. Heat spreaders are a good way to solve the heat dissipation problem of electronic products, but conventional heat spreaders cannot meet the heat dissipation requirements of miniaturized products such as chips. Heat spreaders are required to develop towards lighter and thinner, but as the heat spreader becomes lighter and thinner, the strength and reliability of the heat spreader are reduced. At the same time, as the thickness of the heat spreader is reduced to a certain thickness, the thermal resistance of the vapor chamber increases sharply, resulting in a sharp drop in the heat dissipation effect, an increase in the defective rate, and a decrease in reliability. This shows that the lightness and thinness of the heat spreader are complicated and the preparation process is difficult, which is an important influencing factor restricting the miniaturization of electronic products.

[0003] The heat spreader is composed of an upper and lower cover plate forming an inner cavity, which is used to support the wick and the supporting structure. The upper and lower cover plates of existing heat spreader products are all made of a single material, such as pure copper or copper alloy strips. The main reason is that the raw materials are mature and the production process is simple. Since pure copper is the cheap metal with the best thermal conductivity, the upper and lower cover plates of conventional heat spreaders are usually made of pure copper, but the strength and hardness of pure copper are low (tensile strength is 120MPa~150MPa, and hardness is 50HV~60HV). In order to ensure that the heat spreader reaches a certain structural strength, the total thickness of the conventional heat spreader is usually greater than 2mm. In addition, the grains of pure copper are easy to coarse after high-temperature welding at the punching and bending parts, which can easily lead to uneven appearance. There is also a technology that uses C19000 copper alloy to prepare the upper and lower cover plates of the heat spreader, but due to the poor diffusion welding performance of copper alloy, only copper paste can be used for welding at the splicing. However, due to the uniformity of copper paste application, copper paste quality and welding process, the splicing interface is very likely to have problems such as Figure 1 Defects such as the absence of copper paste, excessively thick copper paste, and holes in the vapor chamber exacerbate the leakage rate of the ultra-thin vapor chamber, reducing product reliability. Furthermore, at high service temperatures (approximately 200°C), its strength is low, making it prone to deformation and poor bending strength. This demonstrates the importance of material selection for the upper and lower covers of the vapor chamber. Providing lightweight, high-strength, and highly thermally conductive vapor chambers is crucial and has far-reaching implications for the miniaturization of electronic products such as chips.

[0004] Composite materials can address the low strength, thickness, and weight of single-material vapor chambers, but they are rarely used. This is primarily due to the inherent complex manufacturing process, high cost, low thermal conductivity, and poor interface properties of composite materials. The high hardness of the blanking process during vapor chamber production can lead to defects such as difficulty in deformation, severe mold wear, and prone to cracking of the cover. Copper, with its excellent thermal conductivity, remains a good choice for vapor chamber cover materials, but its relatively thick thickness and susceptibility to deformation need to be addressed. Constructing copper composite materials as vapor chamber cover materials can combine the advantages of multiple materials while simultaneously improving the cover's strength, providing new research ideas for the development of ideal materials for high-strength, high-thermal-conductivity, and lightweight vapor chambers.

[0005] However, selecting copper composite materials for vapor chamber cover is a complex issue. First, a composite material with a small difference in thermal expansion coefficient from copper must be selected, otherwise deformation will occur more easily during vapor chamber preparation. As shown in Table 1, the thermal expansion coefficients of aluminum, titanium, magnesium, tungsten, chromium, and their alloys differ greatly from that of pure copper and are therefore not suitable for composite materials. Second, a composite material with high thermal conductivity must be selected, otherwise the heat dissipation efficiency of the vapor chamber will be significantly reduced. The thermal conductivity of stainless steel, titanium, magnesium, tungsten, chromium, and their alloys is much lower than that of pure copper (400 W·m -1 ·K -1 ); Third, it is necessary to select a composite material with a crystal structure and lattice constant that is as close as possible to pure copper to facilitate composite processing and forming. The crystal structure of copper is face-centered cubic, which is easy to deform during processing. The crystal structures of tungsten and chromium are body-centered cubic, and the crystal structures of titanium and magnesium are hexagonal close-packed, which are all highly resistant to deformation. Composite processing of materials with different crystal structures is more difficult, and the strength is high when punching into a cover plate, which causes severe mold wear. Fourth, the interface between the composite material and pure copper must be considered. Copper, titanium, chromium, and magnesium will form intermetallic compounds at the composite interface, significantly reducing the interfacial bonding strength of the composite material and seriously reducing the overall strength of the composite material. Fifth, the composite material cannot have too high a density. The density of metals such as tungsten and molybdenum is much higher than that of copper, which has a negative impact on the thinning of the heat sink. Sixth, the composite material must have a sufficiently high melting point. Although aluminum and magnesium have low densities, their melting points are lower than the highest temperature used in heat sink manufacturing and cannot be used to manufacture heat sinks. Seventh, the composite material must have a suitable raw material cost. 316L stainless steel contains 14% expensive nickel, which is not a good choice for composite materials.

[0006] In summary, the material selection for the cover plate of the existing ultra-thin heat spreader still has a lot of room for improvement. In order to meet the current development requirements of heat spreaders with high efficiency, heat resistance, reliability and lightness, a high-strength, high-thermal-conductivity, thin heat spreader needs to be developed to solve the problems of low strength, large thickness and mass, and copper paste welding defects of the heat spreader in the above-mentioned existing technologies. Summary of the Invention

[0007] In order to achieve the above objectives, the present invention provides a high-strength, high-thermal-conductivity, thin and light heat spreader, which meets the current development requirements of heat spreaders for high efficiency, heat resistance, reliability and thinness, and solves the current problems of low strength, large thickness and mass, and copper paste welding defects of heat spreaders.

[0008] The technical solution adopted by the present invention is a high-strength, high-thermal-conductivity, thin and light heat spreader, whose structure includes upper and lower cover plates, a liquid wick, and support columns. The upper and lower cover plates are sealed to form an inner cavity. The upper and lower inner surfaces of the inner cavity are provided with liquid wicks, which are made of copper mesh or copper powder. A certain number of support columns are used to connect the upper and lower inner surfaces of the inner cavity (the number of support columns is determined according to the design requirements of the heat spreader). The inner core of the support column is made of pure copper column or composite copper alloy column of the same type as the upper and lower cover plates, which plays a role in supporting the upper and lower cover plates with high strength. At the same time, when welded with the pure copper plate inside the cover plate, the homogeneous material has an excellent welding interface and strength, and the support The outer core of the support column is made of copper powder sintered copper ring. The advantage is that when the heat sink is sintered, under high temperature and pressure, the inner core of the support column expands slightly, and contacts the copper powder sintered copper ring without gaps and is welded into one, which is very conducive to the backflow of the cooling medium. The gap between each support column is used as an evaporation chamber or capillary chamber for rapid heat conduction. At least one of the upper and lower cover plates is made of a composite copper material formed by copper alloy / pure copper; wherein, in the composite copper material formed by copper alloy / pure copper, the copper alloy is located on the outside of the cover plate, and the pure copper is located on the inside of the cover plate; when the upper and lower cover plates are sealed to form an inner cavity, the inner layer material of the composite copper material, pure copper, is directly welded to pure copper.

[0009] Furthermore, the composition of the copper alloy used in the composite copper material formed by copper alloy / pure copper is: Fe 0.1%-10%, Ni 0.1%-5%, Mg 0-0.5%, Si 0-1.5%, Ti 0.2%-3.5%, V 0-0.3%, the unavoidable impurity content is ≤0.5%, the balance is Cu, and the total content of each component is 100%.

[0010] A preferred copper alloy / pure copper composite material comprises the following components: Fe 0-3%, Ni 0-5%, Si 0-1.5%, unavoidable impurities ≤ 0.5%, and the balance being Cu, with the sum of the contents of the various components being 100%.

[0011] Another preferred copper alloy / pure copper composite material comprises the following components: Fe 0-0.5%, Ni 0-0.5%, Mg 0-0.5%, Ti 0-3.5%, V 0-0.3%, with the unavoidable impurity content being ≤0.5%, the balance being Cu, and the sum of the contents of the various components being 100%.

[0012] Fe and Cu in the copper alloy do not form intermetallic compounds, but form a two-phase pseudo alloy, both of which have good thermal conductivity. The copper alloy containing 0-10% iron is conducive to improving strength; Ni, Mg, and Si can form fine Ni2Si and Mg2Si phases, and the alloy contains Ti elements to form Cu4Ti phases. After heat treatment, these phases are uniformly precipitated in the copper alloy in the form of nano-scale particles, playing a major strengthening role, providing the copper alloy with high strength, hardness and heat resistance; at the same time, Ti and Fe form Fe2Ti phases, which have the effect of refining grains; V in the alloy forms (Fe, V)2Ti, which has higher thermal stability, inhibits grain growth during annealing, and prevents coarse grains on the surface after annealing of the heat spreader punching and forming, and the appearance of poor appearance defects such as orange peel; finally, pure copper and the components of the copper alloy do not form intermetallic compounds at the interface, which does not affect the interface bonding.

[0013] The pure copper used in the copper alloy / pure copper composite material is composed of 99.95% Cu, 0.001% O, and the rest are unavoidable impurities. The sum of the contents of each component is 100%. High copper, low oxygen, and low impurities enable pure copper to maintain the highest thermal conductivity and optimal welding performance. Its thermal conductivity is about 400W·m -1 ·K -1 The inner sides of the upper and lower cover plates are both made of pure copper, and high-temperature diffusion welding is directly adopted to have the best welding interface, avoiding various interface defects caused by copper paste welding between conventional heat spreader cover plates.

[0014] Furthermore, the thickness of pure copper in the composite copper material formed by copper alloy / pure copper is 10% to 50%; the proportion of pure copper and copper alloy in the composite copper material can be adjusted arbitrarily. In order to ensure the diffusion weldability of the inner cavity, the proportion of pure copper is preferably 10% to 50%.

[0015] Furthermore, the preparation method of the composite copper material formed of copper alloy / pure copper comprises the following steps:

[0016] S1, pure copper and copper alloy are smelted and cast into slabs respectively, and the slabs are then hot rolled, milled, cold rolled once, annealed, pickled, and cold rolled twice to produce pure copper sheet strips with a thickness of 1.5 mm and copper alloy sheet strips with a thickness of 1.5 mm;

[0017] S2, the pure copper plate and strip and the copper alloy plate and strip obtained in S1 are respectively subjected to solid solution treatment, and the specific process is: keeping warm at 900℃ for 10min~60min, and then rapidly cooling to room temperature~50℃ at a cooling rate of 200℃ / s~300℃ / s, and the cooling method is water cooling or gas atomization cooling. At this time, the hardness of the pure copper plate and strip is not higher than 60HV, and the hardness of the copper alloy plate and strip is not higher than 120HV. At this time, the hardness of pure copper and copper alloy is the lowest, which is convenient for rolling and compounding.

[0018] S3, pickling the surface of the pure copper plate and strip and the copper alloy plate and strip after the treatment in S2, and then cleaning the surface oxide layer with a steel brush;

[0019] S4, directly cold-rolling the pure copper sheet and strip treated in S3 and the copper alloy sheet and strip (still in a softened state) in air in a single pass to form a composite copper material with a thickness of 1.4 mm; the single pass cold rolling reduction ratio is greater than 50%, preferably greater than 60%;

[0020] S5, holding the composite copper material with a thickness of 1.4 mm obtained in S4 at 800° C. to 930° C. for 2 h (or more than 2 h) under vacuum or protective atmosphere to form a composite copper material with metallurgical interface bonding, wherein the plate is in a soft state, and then rapidly cooling it to room temperature at a cooling rate of 200° C. / s to 300° C. / s, using water cooling or gas atomization cooling to facilitate subsequent cold working;

[0021] S6, cold rolling the copper alloy / pure copper composite material obtained in S5 to the required thickness, as small as 0.08 mm, in a single pass according to the thickness requirements of the heat spreader product; then solution-solution-rolling at 880°C for 20 to 60 minutes, and rapidly cooling to room temperature at a cooling rate of 200°C / s to 300°C / s, using water cooling or gas atomization cooling, to obtain a soft copper alloy / pure copper composite material with uniform appearance, no orange peel, and no cracks, which is used to facilitate the punching of the upper and lower cover plates of the heat spreader.

[0022] Furthermore, in S1 , the hot rolling temperature is 750° C. to 900° C., and the annealing temperature is 700° C. to 850° C.

[0023] Furthermore, in S4, the reduction ratio is greater than 60%.

[0024] Furthermore, in S6, when a single pass of cold rolling cannot achieve the required thickness, a cycle of cold rolling, annealing at 800°C for 20 minutes, and cold rolling is used to achieve the required thickness.

[0025] Furthermore, the welding adopts any one of high temperature diffusion welding, laser welding or ultrasonic welding.

[0026] Furthermore, a method for preparing the upper and lower cover plates of a thin and light heat spreader with high strength and high thermal conductivity is specifically as follows: when at least one of the upper and lower cover plates of the thin and light heat spreader with high strength and high thermal conductivity is prepared using a composite copper material formed of a copper alloy / pure copper, the strength, hardness, and thermal conductivity of the composite copper material formed of the copper alloy / pure copper are finally adjusted by heat treatment. The preparation method is specifically as follows: when punching the cover plates, the outer side of at least one cover plate is a copper alloy and the inner side is pure copper, thereby obtaining at least one upper and lower cover plates made of a composite copper material formed of a copper alloy / pure copper after punching; the inner sides of the upper and lower cover plates are pure copper and pure copper are welded together, and after welding, they are rapidly cooled to room temperature to 50°C at a cooling rate of 200°C / s to 300°C / s, and then heat treated at 300°C to 550°C for 1h to 8h to form a thermal conductivity of 250W·m -1 ·K -1 ~300W·m -1 ·K -1 , a cover plate for a thin and light heat spreader with an overall tensile strength of 300MPa to 800MPa, an overall hardness of 150HV to 270HV, and defect-free interface metallurgical bonding, and high strength and high thermal conductivity.

[0027] When the upper and lower covers of the high-strength, high-thermal-conductivity, light-weight heat spreader are both made of a composite copper material formed by copper alloy / pure copper, the specific preparation method is as follows:

[0028] The copper alloy / pure copper composite material was bent 180 degrees to observe the interface bonding. Figure 4 It can be seen from a and 4b that the interfaces after bending on both sides are good and without cracks, indicating that the composite copper material formed by the copper alloy / pure copper obtained has sufficient plastic toughness. During punching, the outer side of the cover plate is copper alloy and the inner side is pure copper, and the upper and lower cover plates prepared by the composite copper material formed by the copper alloy / pure copper after punching are obtained; the inner sides of the upper and lower cover plates are pure copper and pure copper welded together, and the welding method adopts high-temperature diffusion welding, and the temperature of high-temperature diffusion welding is 700℃~920℃, and the insulation time is 1~3h to obtain an ultra-thin heat spreader. Laser welding or ultrasonic welding can also be used, and the welding quality is ideal, and the weld has no defects such as compounds and holes, and the bonding force is strong, avoiding the phenomenon of leakage failure caused by uneven application of copper paste, while reducing the cost of copper paste. The welding interface of copper alloy / pure copper is as follows Figure 3 As shown, the interface transition is good, without defects such as oxides, compounds, and pores, and metallurgical bonding is fully achieved. Various interface defects that exist in traditional copper paste welding do not appear. After welding, it is quickly cooled to room temperature ~ 50°C at a cooling rate of 200°C / s ~ 300°C / s. The cooling method is water cooling or gas atomization cooling, and then placed in a heat treatment at 300°C ~ 550°C for 1h ~ 8h, so that the heat spreader has the best comprehensive performance and forms a thermal conductivity of 250W·m -1 ·K -1 ~300W·m -1 ·K -1The overall tensile strength is 300MPa ~ 800MPa, the overall hardness is 150HV ~ 270HV, and the interface metallurgical bonding is defect-free. The high-strength cover supports the heat sink cavity and effectively prevents deformation.

[0029] The resulting high-strength, high-thermal-conductivity, thin vapor chamber has a tensile strength of 300MPa to 800MPa and a hardness of 150HV to 270HV, which are much higher than the 150MPa and 50HV of pure copper vapor chambers. Its performance remains unchanged in long-term service at 250°C, and its overall thermal conductivity is 250W·m -1 ·K -1 ~300W·m -1 ·K -1 , which is much higher than the thermal conductivity of heat sinks made of composite materials of copper and non-copper metals such as titanium, stainless steel, tungsten, chromium and their alloys.

[0030] When one of the upper and lower cover plates of a high-strength, high-thermal-conductivity thin and light heat spreader is made of a composite copper material formed by copper alloy / pure copper, and the other cover plate is made of pure copper, the specific preparation method is: one cover plate is directly punched out of pure copper, and the other cover plate is punched out of the composite copper cover plate formed by copper alloy / pure copper. The welding and heat treatment process of the pure copper cover plate and the composite copper cover plate formed by copper alloy / pure copper are the same as those of the above-mentioned high-strength, high-thermal-conductivity thin and light heat spreader in which both the upper and lower cover plates are made of the composite copper material formed by copper alloy / pure copper.

[0031] The beneficial effects of the specific embodiments of the present invention are:

[0032] (1) The specific embodiment of the present invention adopts a composite copper material formed by copper alloy / pure copper as the upper and lower cover plates of the heat spreader, and the inner chamber of the heat spreader is prepared by welding pure copper to pure copper, combining the thermal conductivity and welding properties of pure copper with the high strength, hardness and heat resistance of copper alloy. Pure copper has the best thermal conductivity and welding properties. The preparation of the inner chamber of the heat spreader with pure copper ensures the heat dissipation efficiency and welding reliability of the heat spreader; the copper alloy has high strength and hardness after aging treatment, and is made into the outer frame of the heat spreader, which effectively supports and fixes the appearance of the heat spreader. At the same time, the high-temperature strength of the copper alloy is higher than that of pure copper, especially the ultra-thin heat spreader ensures heat dissipation efficiency when serving at high temperatures, has high overall strength, and has good product dimensional stability. The composite copper material used in the upper and lower cover plates of the heat spreader of this application has a good composite interface between copper and non-copper alloy and high thermal conductivity.

[0033] (2) The specific embodiment of the present invention uses copper alloy plates and strips and pure copper plates and strips to cold-roll into composite copper materials. The copper alloy and pure copper have low deformation resistance and do not require vacuum treatment. They are directly cold-rolled and composited in the atmosphere, which can achieve large-scale continuous production of composite materials with simple processes and lower costs. The composite copper material has low hardness after solution softening, and the cold working deformation can be greater than 80%. The thickness of the composite material can be as thin as 0.08mm, meeting the requirements of any heat spreader cover for lightness and thinness. The interface of the composite copper material formed by the copper alloy / pure copper does not produce intermetallic compounds, has excellent interface bonding, and the pure copper and copper alloy can be arbitrarily adjusted. When the heat spreader is made, the pure copper and pure copper are directly diffusion welded, without the need for copper paste, resulting in good weld quality and higher reliability, while reducing the cost of copper paste.

[0034] (3) In a specific embodiment of the present invention, the composite copper material is dissolved at 880°C for 20 minutes to 60 minutes to form a composite copper material with metallurgical interface bonding. The plate is in a soft state. After the composite copper material formed by the copper alloy / pure copper is softened, the hardness of the two is low. When the cover plate is punched, the punching force is small and the mold wear is small. Due to the same crystal structure and the small mechanical internal stress of the punching deformation, and the close thermal expansion coefficients of the two, the thermal stress of the heat treatment process is small. Therefore, the heat spreader is not easily deformed during the preparation process.

[0035] (4) The overall thermal conductivity of the high-strength, high-thermal-conductivity thin heat spreader prepared by the specific embodiment of the present invention is 250 W·m -1 ·K -1 ~300W·m -1 ·K -1 The overall tensile strength is 300MPa~800MPa, and the overall hardness is 150HV~270HV, which is at least 30% higher than the traditional single-layer pure copper or single-layer copper alloy heat spreader cover, and the weight and thickness are reduced by more than 30%. It is a high-strength, high-thermal conductivity, thin and light heat spreader cover material, which will help promote the rapid development of ultra-thin heat spreaders. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 This is a microscopic morphology of the welding interface defects of the copper alloy heat sink when the copper paste coating welding technology is used.

[0038] Figure 2 It is a structural schematic diagram of a high-strength, high-thermal-conductivity, thin and light heat spreader made according to a specific embodiment of the present invention.

[0039] Figure 3 This is a microscopic morphology of the diffusion welding interface of a thin and light heat spreader cover with high strength and high thermal conductivity made according to a specific embodiment of the present invention.

[0040] Figure 4 This is a microscopic morphology of the interface between the copper alloy and pure copper in the composite copper material formed by the copper alloy / pure copper prepared in a specific embodiment of the present invention, which is bent 180 degrees on both sides. Figure 4 Figure a in the middle shows the microscopic morphology of the interface of the composite copper material with inner copper and outer copper alloy at 180 degrees bend on both sides. Figure 4 Figure b in the middle shows the microscopic morphology of the interface of the composite copper material with inner copper alloy and outer copper at 180 degrees on both sides.

[0041] Figure 5 It is a comparison chart of tensile test curves of a composite copper vapor chamber cover formed of copper alloy / pure copper and a pure copper vapor chamber cover made according to a specific embodiment of the present invention.

[0042] Figure 6 It is a cross-sectional view of the tensile fracture of a composite copper material soaking plate cover formed of copper alloy / pure copper prepared according to a specific embodiment of the present invention.

[0043] Figure 7 This is a graph showing the change in thermal conductivity of a high-strength, high-thermal-conductivity, thin vapor chamber before and after heat treatment at different temperatures, produced according to a specific embodiment of the present invention.

[0044] 1-Composite copper material formed by copper alloy / pure copper, 2-Liquid wick, 3-Support column, 4-Interface between copper alloy and pure copper in the composite copper material, 5-Welding interface, 1.1-Copper alloy, 1.2-Pure copper, 3.1-Copper powder. DETAILED DESCRIPTION

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] Example 1

[0047] A high-strength, high-thermal-conductivity, thin and light heat spreader, whose structure includes upper and lower cover plates, a liquid wick 2, and support columns 3. The upper and lower cover plates are sealed to form an inner cavity. The upper and lower inner surfaces of the inner cavity are provided with a liquid wick 2. A certain number of support columns 3 are used to abut between the upper and lower inner surfaces of the inner cavity. The gaps between the support columns serve as evaporation chambers or capillary chambers. The upper and lower cover plates are both made of a composite copper material 1 formed of copper alloy / pure copper; wherein, in the composite copper material 1 formed of copper alloy / pure copper, the copper alloy 1.1 is located on the outer side of the cover plate, and the pure copper 1.2 is located on the inner side of the cover plate; when the upper and lower cover plates are sealed to form the inner cavity, the inner layer material of the composite copper material 1, pure copper 1.2, is directly welded to the pure copper 1.2; the welding is any one of high-temperature diffusion welding, laser welding or ultrasonic welding.

[0048] The composition of the copper alloy 1.1 used in the composite copper material 1 formed of copper alloy / pure copper is: Fe 0.2%, Ni 2.5%, Mg 0.5%, Si 0.5%, Ti 0.2%, the content of unavoidable impurities ≤ 0.5%, the balance being Cu, and the sum of the contents of each component is 100%.

[0049] The thickness of the pure copper 1.2 in the composite copper material 1 formed of the copper alloy / pure copper accounts for 10%.

[0050] The preparation method of the composite copper material 1 formed of copper alloy / pure copper comprises the following steps:

[0051] S1, pure copper and copper alloy are smelted and cast into slabs respectively, and the slabs are then hot rolled, milled, cold rolled once, annealed, pickled, and cold rolled twice to produce pure copper sheet strips with a thickness of 1.5 mm and copper alloy sheet strips with a thickness of 1.5 mm; the hot rolling temperature is 920° C., and the annealing temperature is 900° C.;

[0052] S2, the pure copper sheet and the copper alloy sheet obtained in S1 were solution-treated at 900°C for 30 min and then rapidly cooled to room temperature at a cooling rate of 200°C / s. At this time, the hardness of the pure copper sheet and the copper alloy sheet were 50HV and 90HV, respectively.

[0053] S3, pickling the surface of the pure copper plate and strip and the copper alloy plate and strip after the treatment in S2, and then cleaning the surface oxide layer with a steel brush;

[0054] S4, directly cold-rolling the pure copper sheet and strip processed in S3 and the copper alloy sheet and strip in air in a single pass to form a composite copper material with a thickness of 1.4 mm; the single-pass cold rolling reduction rate is 50%;

[0055] S5, holding the composite copper material with a thickness of 1.4 mm obtained in S4 at 900° C. for 2 h in vacuum or protective atmosphere to form a composite copper material with metallurgical interface bonding, and then rapidly cooling it to room temperature at a cooling rate of 200° C. / s;

[0056] S6, the copper alloy / pure copper composite material obtained in S5 is cold-rolled to the required thickness in a single pass according to the thickness requirements of the heat spreader product, then solution-treated at 900°C for 20 minutes, and rapidly cooled to room temperature at a cooling rate of 200°C / s to obtain a soft copper alloy / pure copper composite material 1, which is used to facilitate the punching of the upper and lower cover plates of the heat spreader.

[0057] When the upper and lower cover plates of the high-strength, high-thermal-conductivity thin and light heat spreader are both prepared using a composite copper material 1 formed of copper alloy / pure copper, the strength, hardness, and thermal conductivity of the composite copper material formed of the copper alloy / pure copper are finally adjusted by heat treatment. The specific preparation method is: when the cover plate is punched, the outer side of the cover plate is copper alloy 1.1, and the inner side is pure copper 1.2, to obtain the punched upper and lower cover plates prepared using the composite copper material 1 formed of copper alloy / pure copper; the inner sides of the upper and lower cover plates are pure copper 1.2 and welded together with pure copper 1.2, and after welding, they are rapidly cooled to room temperature at a cooling rate of 200°C / s, and then placed at 300°C for heat treatment for 1h to form a cover plate of the high-strength, high-thermal-conductivity thin and light heat spreader.

[0058] Example 2

[0059] A thin and light heat spreader with high strength and high thermal conductivity

[0060] The composition of the copper alloy 1.1 used in the composite copper material 1 formed of copper alloy / pure copper is: Fe 0.2%, Ni 0.1%, Ti 3.2%, inevitable impurity content ≤ 0.5%, and the balance is Cu. The total content of each component is 100%.

[0061] The thickness of the pure copper 1.2 in the composite copper material 1 formed of the copper alloy / pure copper accounts for 50%.

[0062] Preparation method of composite copper material 1 formed by copper alloy / pure copper, except

[0063] S1, hot rolling temperature is 880℃, annealing temperature is 850℃;

[0064] S2, rapidly cooling to 50°C at a cooling rate of 300°C / s, at which time the hardness of the pure copper sheet and strip and the copper alloy sheet and strip are 50HV and 110HV, respectively;

[0065] S4, cold rolling single pass reduction rate is 60%;

[0066] S5, holding at 930 °C for 2 h to form a metallurgical interface-bonded composite copper material, and then rapidly cooling to room temperature at a cooling rate of 300 °C / s;

[0067] S6, the composite copper material formed by the copper alloy / pure copper obtained in S5 is processed to the required thickness according to the thickness requirements of the heat spreader product. A single cold rolling cannot reach the required thickness, so the composite copper material is processed by cold rolling, annealing at 800°C for 20 minutes, and cold rolling cycle to the required thickness, and then solid solution is carried out at 880°C for 60 minutes. It is quickly cooled to room temperature at a cooling rate of 300°C / s to obtain a soft composite copper material 1 formed by the copper alloy / pure copper, which is used to facilitate the punching of the upper and lower cover plates of the heat spreader.

[0068] When the upper and lower cover plates of the high-strength, high-thermal-conductivity thin heat spreader are both made of a composite copper material 1 formed of copper alloy / pure copper, the preparation method is to rapidly cool to 50°C at a cooling rate of 300°C / s after welding, and then place it at 550°C for heat treatment for 8 hours to form a high-strength, high-thermal-conductivity thin heat spreader cover plate.

[0069] The rest are the same as in Example 1.

[0070] Example 3

[0071] A thin and light heat spreader with high strength and high thermal conductivity

[0072] The composition of the copper alloy 1.1 used in the copper alloy / pure copper composite material 1 is as follows: Fe 5%, Ni 0.5%, Ti 0.2%, unavoidable impurities ≤ 0.5%, the balance being Cu, and the sum of the contents of the various components being 100%;

[0073] The thickness of the pure copper 1.2 in the composite copper material 1 formed of the copper alloy / pure copper accounts for 20%.

[0074] In the preparation method of the composite copper material 1 formed of copper alloy / pure copper, S2, the solution time is 10 min;

[0075] The rest are the same as in Example 2.

[0076] Example 4

[0077] A thin and light heat spreader with high strength and high thermal conductivity

[0078] The composition of the copper alloy 1.1 used in the copper alloy / pure copper composite material 1 is as follows: Fe 10%, Ni 0.8%, Ti 0.2%, unavoidable impurities ≤ 0.5%, and the balance is Cu, the sum of the contents of the various components being 100%;

[0079] The thickness of the pure copper 1.2 in the composite copper material 1 formed of the copper alloy / pure copper accounts for 30%.

[0080] In the preparation method of the composite copper material 1 formed of copper alloy / pure copper, S2, the solution time is 60 min;

[0081] The rest are the same as in Example 2.

[0082] Example 5

[0083] A thin and light heat spreader with high strength and high thermal conductivity

[0084] The composition of the copper alloy 1.1 used in the composite copper material 1 formed of copper alloy / pure copper is as follows: Fe 0.1%, Ni 3.5%, Si 0.7%, Ti 0.5%, V 0.3%, unavoidable impurities ≤ 0.5%, the balance being Cu, and the sum of the contents of the various components being 100%;

[0085] The thickness of the pure copper 1.2 in the composite copper material 1 formed of the copper alloy / pure copper accounts for 40%.

[0086] The rest are the same as in Example 2.

[0087] Example 6

[0088] A thin and light heat spreader with high strength and high thermal conductivity

[0089] The composition of the copper alloy 1.1 used in the composite copper material 1 formed of copper alloy / pure copper is: Fe 0.2%, Ni 5%, Ti 3.5%, V 0.2%, unavoidable impurity content ≤ 0.5%, and the balance is Cu. The total content of each component is 100%.

[0090] The rest are the same as in Example 2.

[0091] Example 7

[0092] A thin and light heat spreader with high strength and high thermal conductivity

[0093] Except that one of the upper and lower cover plates is made of a composite copper material 1 formed of copper alloy / pure copper, the other is made of pure copper.

[0094] When one of the upper and lower cover plates of a high-strength, high-thermal-conductivity thin and light heat spreader is made of a composite copper material 1 formed of copper alloy / pure copper, and the other cover plate is made of pure copper, the specific preparation method is: one cover plate is directly punched out of pure copper, and another cover plate is punched out of the composite copper material 1 cover plate formed of copper alloy / pure copper. The welding and heat treatment process of the pure copper cover plate and the composite copper material 1 cover plate formed of copper alloy / pure copper is the same as that of the upper and lower cover plates of the high-strength, high-thermal-conductivity thin and light heat spreader in Example 1, in which both the upper and lower cover plates are made of the composite copper material 1 formed of copper alloy / pure copper.

[0095] The rest are the same as in Example 2.

[0096] Example 8

[0097] A thin and light heat spreader with high strength and high thermal conductivity

[0098] The composition of the copper alloy 1.1 used in the composite copper material 1 formed of copper alloy / pure copper is: Fe 0.2%, Ni 1.2%, Si 1.5%, Ti 1.5%, V 0.3%, the content of unavoidable impurities ≤ 0.5%, the balance is Cu, and the total content of each component is 100%.

[0099] The rest are the same as in Example 7.

[0100] Experimental example

[0101] The copper alloy / pure copper composite material 1 of the present invention exhibits minimal mechanical internal stress during deformation due to the small difference in hardness in the soft state during cold working. Furthermore, the thermal stress is minimal during heat treatment due to the similar thermal expansion coefficients of the two materials. Therefore, the vapor chamber is less susceptible to deformation during preparation. The copper alloy / pure copper composite material 1 of the present invention is a homogeneous material, resulting in a better weld interface 5 than heterogeneous materials. When forming an inner cavity, pure copper is diffusely welded to pure copper via high-temperature diffusion welding, resulting in lower cracking and leakage rates.

[0102] Mechanical performance testing was conducted on the upper and lower covers of the resulting high-strength, high-thermal-conductivity, lightweight vapor chamber. Strength, elongation, and hardness were measured, and fracture interfaces were observed. Thermal conductivity was also measured at different temperatures to evaluate the thermal conductivity of the upper and lower covers. The high-strength, high-thermal-conductivity, lightweight vapor chamber covers are at least 30% thinner and lighter than those made of traditional pure copper or copper alloys. With a heat resistance of up to 250°C, they are particularly suitable for use as covers for ultra-thin vapor chambers and those used for high-temperature heat dissipation.

[0103] The mechanical properties of the composite copper material 1 formed by the copper alloy / pure copper of the present application are compared with those of pure copper and C19000 copper alloy. The tensile curves are shown in FIG. Figure 5 The performance results are shown in Table 1. The strength of the composite copper material reaches 333MPa~617MPa, which is much higher than the 136MPa of pure copper. The elongation of the composite copper material is 15%~22%, which meets the blanking requirements. The hardness of the composite copper material of this application is 208HV~249HV, which is much higher than the hardness of pure copper (50HV~60HV). It is about 60HV higher than the hardness of C19000 copper alloy. The thermal conductivity of the composite copper material 1 formed by the copper alloy / pure copper of this application is 265.3W·m -1 ·K -1 , which is higher than the thermal conductivity of the current copper alloy heat sink C19000 material (253W·m -1 ·K -1 ), meeting the thermal conductivity requirements of the heat spreader.

[0104] Table 1 Performance comparison of composite copper materials, pure copper used in current soaking plates, and C19000 copper alloy

[0105]

[0106] The cross section of the composite copper material 1 formed by copper alloy / pure copper after being broken is as follows: Figure 6 As shown, there is no tearing at the interface 4 between the copper alloy and pure copper in the composite copper material, indicating that the interface 4 between the copper alloy and pure copper in the composite copper material 1 formed by the copper alloy / pure copper is still well bonded under large deformation.

[0107] The thermal conductivity of the composite copper material prepared in Example 1 was tested at room temperature, 100 and 200 °C. Figure 7 At room temperature, the overall thermal conductivity of the composite copper material 1 formed by the copper alloy / pure copper before heat treatment is 167W·m -1 ·K -1 , after heat treatment, it increased to 265.3W·m -1 ·K -1 , which is higher than the thermal conductivity of the current copper alloy heat sink C19000 material (253W·m -1 ·K -1 ).

[0108] It should be noted that, in this application, relational terms such as first, second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0109] Each embodiment in this specification is described in a related manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0110] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A light and thin heat spreader with high strength and high thermal conductivity, the structure of which includes upper and lower cover plates, a liquid wick (2), and support columns (3), the upper and lower cover plates are sealed to form an inner cavity, the upper and lower inner surfaces of the inner cavity are provided with liquid wicks (2), a certain number of support columns (3) are used to abut the upper and lower inner surfaces of the inner cavity, and the gaps between the support columns (3) serve as evaporation chambers or capillary chambers, characterized in that: At least one of the upper and lower cover plates is made of a composite copper material (1) formed of copper alloy / pure copper; wherein, in the composite copper material (1) formed of copper alloy / pure copper, the copper alloy (1.1) is located on the outer side of the cover plate, and the pure copper (1.2) is located on the inner side of the cover plate; when the upper and lower cover plates are sealed to form an inner cavity, the inner layer material of the composite copper material, pure copper (1.2), is directly welded to the pure copper (1.2); The composition of the copper alloy (1.1) used in the copper alloy / pure copper composite material (1) is as follows: Fe 0.1%-10%, Ni 0.1%-5%, Mg 0-0.5%, Si 0-1.5%, Ti 0.2%-3.5%, V 0-0.3%, the content of unavoidable impurities is ≤0.5%, the balance is Cu, and the sum of the contents of each component is 100%; The thickness of pure copper (1.2) in the composite copper material (1) formed by the copper alloy / pure copper is 10% to 50%; The preparation method of the composite copper material (1) formed of the copper alloy / pure copper comprises the following steps: S1, pure copper and copper alloy are smelted and cast into slabs respectively, and the slabs are then hot rolled, milled, cold rolled once, annealed, pickled, and cold rolled twice to produce pure copper sheet strips with a thickness of 1.5 mm and copper alloy sheet strips with a thickness of 1.5 mm; S2, solutionizing the pure copper sheet and the copper alloy sheet obtained in S1 at 900°C for 10 min to 60 min and then rapidly cooling to room temperature to 50°C at a cooling rate of 200°C / s to 300°C / s, wherein the hardness of the pure copper sheet is not higher than 60 HV, and the hardness of the copper alloy sheet is not higher than 120 HV; S3, pickling the surface of the pure copper plate and strip and the copper alloy plate and strip after the treatment in S2, and then cleaning the surface oxide layer with a steel brush; S4, directly cold-rolling the pure copper sheet and strip treated in S3 and the copper alloy sheet and strip in air in a single pass to form a composite copper material with a thickness of 1.4 mm; the cold rolling single pass reduction rate is greater than 50%; S5, heat-keeping the composite copper material with a thickness of 1.4 mm obtained in S4 at 800° C. to 930° C. for 2 h in vacuum or protective atmosphere to form a composite copper material with metallurgical interface bonding, and then rapidly cooling it to room temperature at a cooling rate of 200° C. / s to 300° C. / s; S6, cold rolling the copper alloy / pure copper composite material obtained in S5 to the required thickness according to the thickness requirement of the heat spreader product, then solution-rolling at 880°C for 20 minutes to 60 minutes, and rapidly cooling to room temperature at a cooling rate of 200°C / s to 300°C / s to obtain a soft copper alloy / pure copper composite material (1), which is used to facilitate the punching of the upper and lower covers of the heat spreader; In S1, the hot rolling temperature is 750°C to 900°C, and the annealing temperature is 700°C to 850°C; In said S4, the reduction ratio is greater than 60%; In S6, when a single pass of cold rolling cannot achieve the desired thickness, a cycle of cold rolling, annealing at 800° C. for 20 minutes, and cold rolling is used to achieve the desired thickness.

2. A high-strength, high-thermal-conductivity, thin vapor chamber according to claim 1, characterized in that: The welding is carried out by any one of high temperature diffusion welding, laser welding or ultrasonic welding.

3. The high-strength, high-thermal-conductivity, thin vapor chamber according to claim 1, characterized in that: When at least one of the upper and lower covers of the high-strength, high-thermal-conductivity thin heat spreader is prepared using a composite copper material (1) formed of copper alloy / pure copper, the strength, hardness, and thermal conductivity of the composite copper material (1) formed of copper alloy / pure copper are finally adjusted by heat treatment. The preparation method is specifically as follows: when punching the cover plates, the outer side of at least one cover plate is copper alloy (1.1) and the inner side is pure copper (1.2), thereby obtaining at least one upper and lower cover plates made of the composite copper material (1) formed of copper alloy / pure copper after punching; the inner sides of the upper and lower cover plates are pure copper (1.2) and welded together with the pure copper (1.2), and after welding, they are rapidly cooled to room temperature to 50°C at a cooling rate of 200°C / s to 300°C / s, and then subjected to heat treatment at 300°C to 550°C for 1h to 8h, thereby forming a thermal conductivity of 250W•m -1 •K -1 ~300W•m -1 •K -1 , an overall tensile strength of 300MPa~800MPa, an overall hardness of 150HV~270HV, and a high-strength, high-thermal-conducting, thin and light heat spreader cover with no metallurgical defects at the interface.

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