A composite wick vapor chamber and method of manufacture

Abstract

The present application relates to a kind of composite wick heat plate and preparation method, composite wick heat plate includes the heat plate body being equipped with sealed cavity;Sealed cavity is equipped with braided belt wick;Metal powder sintered wick is flowed into and sintered in braided belt wick by metal powder suspension liquid casting method, metal powder sintered wick and braided belt wick are compounded to form composite wick;Composite wick at least one side wall is sintered in the inner side wall of sealed cavity, composite wick at least has another side wall and the gas passage between the inner side wall of sealed cavity;Sealed cavity is filled with working substance.The present application is flowed into and sintered in braided belt wick by metal powder suspension liquid casting method, and braided belt wick is compounded to form composite wick, can reduce contact thermal resistance, and has the advantages of braided belt wick good permeability and metal powder sintered wick strong capillary performance, improve the capillary performance of wick, effectively improve the heat transfer performance of heat plate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat pipe, in particular to a composite wick vapor chamber and a preparation method. BACKGROUND

[0002] With the rapid development of electronic technology towards miniaturization, high power consumption and light weight, the heat flux density of electronic components is continuously increasing, and the heat generated is also increasing, so the heat management of electronic equipment, i.e. the field of heat dissipation and heat transfer, is facing a major technical problem.

[0003] The vapor chamber is a passive heat exchange device for liquid phase change, which has excellent heat dissipation capacity and strong temperature uniformity, and does not need external power driving, so it can effectively improve the heat management problem of electronic equipment. The shell of the common phase change vapor chamber is mainly made of metal materials such as copper, aluminum and stainless steel. Due to the characteristics of small density and high thermal conductivity, the aluminum-based vapor chamber has become the research focus of solving the lightweight problem of high heat flux density heat dissipation devices.

[0004] The performance of the wick plays a decisive role in the heat transfer performance of the vapor chamber. The wick is a channel for the condensation and reflux of the working medium in the vapor chamber, and relies on the capillary pressure to provide circulation power. The common wick structure can be roughly divided into groove type wick, metal powder sintered wick, metal fiber sintered wick and woven belt wick. Single wick structure has different advantages and disadvantages, for example, the woven belt wick has good permeability but poor capillary performance, the metal powder sintered wick has strong capillary performance but poor permeability, and the contact thermal resistance is large, which leads to poor heat transfer performance of the vapor chamber.

[0005] Therefore, it is urgent to design a vapor chamber with high permeability and capillary performance. SUMMARY

[0006] In view of the problems in the prior art, one of the purposes of the present application is to provide a composite wick vapor chamber with high permeability and capillary performance, small contact thermal resistance and good heat transfer performance.

[0007] The second purpose of the present application is to provide a preparation method of the composite wick vapor chamber.

[0008] In order to achieve the above purposes, the present application adopts the following technical solutions:

[0009] A composite wick vapor chamber, comprising a vapor chamber body provided with a sealed cavity;

[0010] A woven belt wick is arranged in the sealed cavity.

[0011] The braided belt liquid absorbing core is covered with a metal powder sintered liquid absorbing core, which is flowed into and sintered on the braided belt liquid absorbing core by a metal powder suspension casting method, and the metal powder sintered liquid absorbing core and the braided belt liquid absorbing core are combined to form a composite liquid absorbing core.

[0012] The composite liquid absorbing core has at least one side wall sintered to the inner side wall of the sealed cavity, and at least one other side wall of the composite liquid absorbing core has a gas passage left between the inner side wall of the sealed cavity.

[0013] The sealed cavity is filled with a working medium.

[0014] Further, the sealed cavity is provided with a cross-shaped through hole, the composite liquid absorbing core is clamped in the cross-shaped through hole, and the front and rear sides of the composite liquid absorbing core are sintered to the front and rear sides of the cross-shaped through hole, respectively, and the gas passages are formed by the left and right sides of the composite liquid absorbing core and the left and right sides of the cross-shaped through hole, respectively.

[0015] Further, the working medium is acetone, ammonia, freon-21, freon-11 or n-hexane.

[0016] Further, the working medium filling rate is 20%-50%.

[0017] A preparation method of a composite liquid absorbing core heat plate, comprising the following steps,

[0018] The braided belt liquid absorbing core is arranged in the sealed cavity of the heat plate body.

[0019] The metal powder suspension liquid is flowed into the braided belt liquid absorbing core by a casting method and sintered to form a metal powder sintered liquid absorbing core, so that the metal powder sintered liquid absorbing core and the braided belt liquid absorbing core are combined to form a composite liquid absorbing core, wherein the composite liquid absorbing core has at least one side wall sintered to the inner side wall of the sealed cavity, and at least one other side wall of the composite liquid absorbing core has a gas passage left between the inner side wall of the sealed cavity.

[0020] The sealed cavity is filled with a working medium.

[0021] Further, the metal powder suspension liquid is an aluminum powder suspension liquid formed by ultrasonic dispersion of micro-nano aluminum powder and ethanol.

[0022] Further, the composite liquid absorbing core is formed by a sintering process, the sintering adopts a vacuum sintering atmosphere, the sintering temperature is 590-600℃, and the holding time is 30 minutes.

[0023] Further, the heat plate body includes an upper end cover, a shell and a lower end cover welded together, the welding temperature is 585-595℃, and the holding time is 30 minutes.

[0024] Further, the upper end cover and the lower end cover are formed by CNC cutting, and the upper end cover, the shell and the lower end cover are formed by vacuum diffusion welding.

[0025] Further, the vacuum degree inside the sealed cavity is ≤10 Pa.

[0026] In general, the present application has the following advantages:

[0027] The present application flows and sinters the metal powder suspension into the woven belt wick by the metal powder suspension flow casting method, the metal powder sintered wick and the woven belt wick are combined to form a composite wick, which ensures the adhesion of the woven belt wick and the sealed cavity, can reduce the contact thermal resistance, and has the advantages of good permeability of the woven belt wick and strong capillary performance of the metal powder sintered wick, improves the capillary performance of the wick, and effectively improves the heat transfer performance of the vapor chamber. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a three-dimensional structure exploded schematic view of the aluminum-based composite wick vapor chamber.

[0029] Figure 2 It is a cross-sectional view of the upper end cap structure.

[0030] Figure 3 It is a cross-sectional view of the shell structure.

[0031] Figure 4 It is a cross-sectional view of the shell structure.

[0032] Figure 5 It is a cross-sectional view of the shell structure.

[0033] Figure 6 It is a cross-sectional view of the shell structure.

[0034] Figure 7 It is a cross-sectional view of the shell structure.

[0035] Figure 8 It is a cross-sectional view of the lower end cap structure.

[0036] Figure 9 It is a process flow chart of the aluminum-based composite wick vapor chamber.

[0037] In the figure:

[0038] 1-upper end cap, 11-liquid injection pipe, 2-aluminum-based composite wick, 21-aluminum woven belt, 22-aluminum powder, 3-working medium, 4-shell, 41-supporting strip, 42-gas passage, 5-lower end cap. DETAILED DESCRIPTION

[0039] The present application will be further described in detail below.

[0040] For example, Figure 1As shown, a composite wick uniform heat plate includes a uniform heat plate body provided with a sealed cavity, the uniform heat plate body including an upper end cover 1, a shell 4 and a lower end cover 5.

[0041] The sealed cavity is provided with a composite wick 2 and filled with a working medium 3.

[0042] The composite wick can be made of various metals, and the embodiment uses an aluminum-based composite wick 2 made by mixing and sintering aluminum woven belts 21 and aluminum powder 22 by flow casting method. The aluminum woven belt 21 is formed by interlacing a plurality of aluminum-magnesium alloy fiber traction lines, winding the aluminum into a bobbin, and inserting it into the fixed tooth seat of the weaving machine along the ∞-shaped track to form a weft tube.

[0043] As shown in Figure 2 , the upper end cover 1 has a reserved liquid injection pipe 11 hole position, and the liquid injection pipe 11 and the lower end cover 5 are sealed and formed by vacuum diffusion welding, and finally filled with a working medium 3 acetone, and the aluminum-based composite wick 2 uniform heat plate is achieved by internal vacuumization.

[0044] The upper end cover 1, the shell 4 and the lower end cover 5 are all made of aluminum-based materials, the shell 4 is formed by double-die extrusion, the cross-shaped die is placed inside the shell 4, and the die is placed outside, and the shell 4 with cross-shaped through holes is obtained by pre-tightening force extrusion.

[0045] The size of the cross-shaped through hole is designed according to the aluminum woven belt 21, which can limit the aluminum woven belt 21. When the aluminum woven belt 21 is clamped into the cross-shaped through hole, the front and back sides of the aluminum woven belt 21 abut against the front and back sides of the cross-shaped through hole, and the left and right sides of the aluminum woven belt 21 are spaced apart from the left and right sides of the cross-shaped through hole to form a gas-liquid flow channel, realize gas-liquid coplanar, control the phase change cycle of the working medium 3 in the same plane, and can effectively reduce the thickness of the uniform heat plate and improve the heat transfer efficiency.

[0046] The upper end cover 1 and the lower end cover 5 are formed by CNC cutting, and the sealing is realized by vacuum sintering furnace welding process in the welding process.

[0047] As shown in Figure 5 , Figure 6 , after reserving the gas-liquid flow channel in the inner cavity of the shell 4, it is placed into a sintering clamp, first vertically placed at the bottom end for closed fixation, then inserted into the aluminum woven belt 21, and the ethanol and micro-nano aluminum powder 22 are ultrasonically dispersed to form a suspension, the suspension is flowed into the gas-liquid channel in the inner cavity of the shell 4 along the woven belt by flow casting method, and the top end is fixed and pre-tightened. Place it horizontally into the oven and heat it, remove the ethanol by taking advantage of the property of ethanol volatilization, and place it into a vacuum sintering furnace for sintering to obtain an aluminum-based composite wick 2.

[0048] As shown in Figure 3 , Figure 4 , Figure 7As shown, the front and rear sidewalls of the aluminum-based composite wick 2 are sintered to the front and rear sidewalls of the cross-shaped through hole, which can effectively reduce the thermal resistance; the left and right sides of the aluminum-based composite wick 2 form a gas channel 42 between the left and right sides of the cross-shaped through hole, and the thickness is 1.5mm-4mm.

[0049] Finally, the upper end cover 1, the shell 4 and the lower end cover 5 are sealed by a vacuum diffusion welding process. The working medium 3 is acetone, and the liquid filling rate is 30%.

[0050] An aluminum-based composite wick 2 heat plate preparation method, the implementation method is simple, suitable for industrial production, including the following steps:

[0051] S1, shell 4 preparation. Put the shell 4 into the double mold by extrusion molding to obtain a specific shell 4 shape. The shell 4 material is 6061 aluminum, the shell 4 outer size is 100x44x3mm, and the shell 4 internal hole size is 2.8x1.8mm, and 4 cross-shaped through holes are arranged at intervals and parallel to each other, as shown in Figure 3 、 Figure 5 The support bars 41 between adjacent cross-shaped through holes can support the composite wick.

[0052] S2, cleaning. The processed shell 4 is first placed in acetone, isopropyl alcohol to clean the oil and ester impurities of the shell 4, and then placed in ethanol to remove the participating acetone and isopropyl alcohol by the principle of similarity and compatibility, and the shell 4 is washed with deionized water multiple times.

[0053] S3, composite wick preparation. The shell 4 is vertically placed, the bottom end is fixed by a clamp, 4 woven belts with a length of 50mm are cut and placed in the cross-shaped through holes inside the shell 4, the micro-nano aluminum powder 22 is mixed uniformly with the 4 aluminum filler metal and added to ethanol to form a suspension, the suspension is flowed into the inner cavity of the shell 4 and the aluminum woven belt 21 by a flow casting method, and the top end is fixed and pre-tightened. The composite wick is formed by a sintering process, the sintering adopts a vacuum sintering atmosphere, the sintering temperature is 590-600℃, the holding time is 30 minutes, and the formed aluminum-based composite wick 2 is obtained.

[0054] S4, heat plate welding. The shell 4 structure obtained above is used to clamp and pre-tighten the upper end cover 1 and the lower end cover 5, and then the vacuum sintering furnace is used, the welding temperature is 585-595℃, the holding time is 30 minutes, and the vacuum diffusion welding is used to realize the integral sealing of the heat plate.

[0055] S5, leak detection. To verify the air tightness of the welding, the air inlet is covered with a silica gel tube on the liquid filling port of the upper end cover 1, and the shell 4 is placed in a water tank to determine whether bubbles are generated, and if no bubbles are generated, it indicates that the heat plate has good air tightness.

[0056] S6, liquid sealing. The working medium 3 is filled in the cavity through the reserved liquid filling port structure of the upper end cover 1. The working medium 3 is acetone, the liquid filling rate is 30%, the cavity is vacuumized, and when the vacuum degree is 8 Pa, hydraulic sealing is performed under the vacuum state, so that the cavity is kept in a high vacuum state. Finally, the heat spreader is immersed in a 60℃ water tank to detect the finished product, and if no bubbles are generated, it proves to be completely sealed. The complete heat spreader preparation process is as shown in Figure 9

[0057] After the above steps S1-S6, an aluminum-based composite wick 2 heat spreader of the present embodiment is obtained, as shown in Figure 1

[0058] In the aluminum-based composite wick 2 heat spreader of the present embodiment, the composite wick is formed by mixing and sintering the aluminum woven belt 21 and the aluminum powder 22 by the flow casting method, and has the advantages of good permeability of the woven belt wick and strong capillary performance of the metal powder sintered wick, effectively reducing the contact thermal resistance and effectively improving the heat transfer performance of the heat spreader.

[0059] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.​​

Claims

1. A composite wick vapor chamber, characterized by: The heat plate body is provided with a sealed cavity; The sealed cavity is provided with a braided belt liquid absorbing core; The braided belt liquid absorbing core is covered with a metal powder sintered liquid absorbing core, which is formed by flowing and sintering the metal powder suspension into the braided belt liquid absorbing core, and the metal powder sintered liquid absorbing core and the braided belt liquid absorbing core are combined to form a composite liquid absorbing core; At least one side wall of the composite liquid absorbing core is sintered to the inner side wall of the sealed cavity, and at least one other side wall of the composite liquid absorbing core is provided with a gas passage with the inner side wall of the sealed cavity; The sealed cavity is filled with a working medium; The sealed cavity is provided with a cross-shaped through hole, and the composite liquid absorbing core is clamped in the cross-shaped through hole, and the front and rear sides of the composite liquid absorbing core are sintered to the front and rear sides of the cross-shaped through hole, respectively, and the gas passages are formed by the left and right sides of the composite liquid absorbing core and the left and right sides of the cross-shaped through hole, respectively.

2. The composite wick vapor chamber of claim 1, wherein: The working medium is acetone, ammonia, freon-21, freon-11 or n-hexane.

3. The composite wick vapor chamber of claim 1, wherein: The working medium filling rate is 20%-50%.

4. The method of claim 1-3, wherein the method is characterized by: The method comprises the following steps, arranging a braided belt liquid absorbing core in the sealed cavity of the heat plate body; flowing and sintering the metal powder suspension into the braided belt liquid absorbing core by a flow casting method to form a metal powder sintered liquid absorbing core, and combining the metal powder sintered liquid absorbing core and the braided belt liquid absorbing core to form a composite liquid absorbing core, wherein at least one side wall of the composite liquid absorbing core is sintered to the inner side wall of the sealed cavity, and at least one other side wall of the composite liquid absorbing core is provided with a gas passage with the inner side wall of the sealed cavity; filling the sealed cavity with a working medium.

5. The method of claim 4, wherein: The metal powder suspension is an aluminum powder suspension formed by ultrasonic dispersion of micro-nano aluminum powder and ethanol.

6. The method of claim 4, wherein: The composite liquid absorbing core is formed by a sintering process, the sintering adopts a vacuum sintering atmosphere, the sintering temperature is 590-600℃, and the holding time is 30 minutes.

7. The method of claim 4, wherein: The heat plate body comprises an upper end cover, a shell and a lower end cover welded together, the welding temperature is 585-595℃, and the holding time is 30 minutes.

8. The method of claim 7, wherein: The upper end cover and the lower end cover are formed by CNC cutting, and the upper end cover, the shell and the lower end cover are formed by vacuum diffusion welding.

9. The method of claim 4, wherein: The internal vacuum degree of the sealed cavity is ≤10Pa.

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