An ultra-thin reinforced boiling capillary wick based on vacuum filtration and a preparation method thereof

Abstract

The present application relates to a kind of ultra-thin reinforced boiling capillary wick based on vacuum filtration and preparation method, preparation method includes the following steps, using anhydrous ethanol to configure micro-nano metal powder suspension liquid;Filter core and metal template with uniform arrangement of micro-nano through-hole are placed on filter bottle from bottom to top in sequence;Micro-nano metal powder suspension liquid is loaded into filter cup, filter cup is inverted on metal template, vacuum is extracted on filter bottle to extract micro-nano metal powder suspension liquid in filter cup, so that micro-nano metal powder in micro-nano metal powder suspension liquid is deposited in the micro-nano through-hole of metal template, metal template is sintered at high temperature, and micro-nano metal powder deposited on metal template is formed on metal template;The metal template used is removed, and the capillary wick formed by micro-nano metal powder is obtained.By controlling filter core gap, the aperture of micro-nano through-hole of metal template and the particle size of micro-nano metal powder and other parameters, ensure that micro-nano metal powder is effectively deposited on metal template, and the thickness of sub-micron to micron level can be achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of design and manufacture of heat plates, and particularly relates to an ultrathin reinforced boiling capillary wick based on vacuum filtration and a preparation method. BACKGROUND

[0002] In recent years, electronic technology has developed rapidly. On the one hand, mobile electronic products are becoming more and more popular, and the types are also more and more diverse. On the other hand, the development of these electronic products has two characteristics, namely, higher and higher performance and smaller and smaller size. Mobile phones, tablet computers, notebook computers and other products indispensable to life and work are becoming lighter and thinner, and their performance is also continuously improving. The pursuit of high performance makes the power of electronic devices continuously increase, and a large amount of heat is generated during use. However, the limited space limits the heat dissipation performance. The current conventional heat dissipation mode is increasingly difficult to meet the heat transfer demand of high heat flux density of high-end electronic devices. Especially with the advent and popularization of 5G products, mobile electronic products have further improved the requirement for high heat flux density heat dissipation scene. The heat dissipation problem has become one of the core problems restricting the development of high-end electronic devices.

[0003] Today, traditional high-thermal-conductivity materials such as copper, aluminum, graphite sheets and the like have been unable to meet the high heat flux density of electronic devices, and phase change heat transfer is the most efficient heat transfer mode. The heat plate is one of the most suitable heat dissipation elements applied to the ultra-thin high heat flux density working condition. It relies on the vaporization and condensation process of the internal working medium for heat dissipation, so its thermal conductivity is much higher than that of traditional heat dissipation devices, and can even reach tens of times that of copper. It is widely used in the fields of mobile phones, notebook computers and the like. The structure of the heat plate includes upper and lower bottom plates, a capillary wick and an air duct. The performance and size of the capillary wick greatly affect the overall heat dissipation performance and size of the heat plate. The most common wick today includes sintered metal powder and silk screen woven belt, and there is a certain limitation in thickness, which is difficult to break through the micron-thickness manufacturing bottleneck. SUMMARY

[0004] In view of the technical problems existing in the prior art, one of the purposes of the present application is to provide a preparation method of an ultrathin reinforced boiling capillary wick based on vacuum filtration, which can prepare a capillary wick with a thickness of sub-micron to micron.

[0005] In view of the technical problems existing in the prior art, the second purpose of the present application is to provide an ultrathin reinforced boiling capillary wick based on vacuum filtration.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] A preparation method of an ultrathin reinforced boiling capillary wick based on vacuum filtration, comprising the following steps,

[0008] The micro-nano metal powder suspension liquid is prepared by using anhydrous ethanol;

[0009] The filter core and the metal template with the uniformly arranged micro-nano through holes are sequentially placed on the filter bottle from bottom to top;

[0010] The micro-nano metal powder suspension liquid is filled into the filter cup, the filter cup is inverted on the metal template, and the filter cup is vacuumized to perform suction filtration on the micro-nano metal powder suspension liquid in the filter cup, so that the micro-nano metal powder in the micro-nano metal powder suspension liquid is deposited in the micro-nano through holes of the metal template, and the anhydrous ethanol in the micro-nano metal powder suspension liquid flows into the filter bottle through the metal template and the filter core;

[0011] The metal template after the suction filtration is high-temperature sintered, so that the micro-nano metal powder deposited on the metal template is formed on the metal template;

[0012] The used metal template is removed, and the capillary liquid absorption core formed by the micro-nano metal powder is obtained.

[0013] Further, the power of the vacuum pump is 3-5.

[0014] Further, the size of the filter core is matched with the used metal template, and the gap of the filter core is smaller than the particle diameter of the used micro-nano metal powder.

[0015] Further, the metal template is an alumina AAO double-through template.

[0016] Further, the ratio of the micro-nano metal powder to the micro-nano through hole diameter of the metal template is 1 / 5-1 / 10.

[0017] Further, the micro-nano through hole diameter of the metal template is 5-10 microns, the hole distance is 10-20 microns, the micro-nano metal powder diameter is 0.2-1 micron.

[0018] Further, the concentration of the micro-nano metal powder suspension liquid is 0.5 mg / 100 ml-2 mg / 100 mg.

[0019] Further, the sintering time is one hour of uniform heating, four hours of heat preservation, and then natural cooling.

[0020] Further, the method further comprises the following steps: preparing a corrosion liquid to perform oxidation treatment on the capillary liquid absorption core to enhance the capillary performance, the corrosion liquid comprises sodium hydroxide and potassium persulfate, the concentration of the sodium hydroxide is 1-2 mol / L, the concentration of the potassium persulfate is 0.2-0.5 mol / L, and the soaking time is 30-60 minutes.

[0021] The application discloses an ultra-thin reinforced boiling capillary liquid absorption core based on vacuum suction filtration.

[0022] Compared with the prior art, the application has the following beneficial effects:

[0023] By controlling the filter core gap, the pore size of the micro-nano through hole of the metal template, and the particle size of the micro-nano metal powder and other parameters, when vacuum filtration is performed, the micro-nano metal powder suspension liquid is ensured to flow through the metal template and the micro-nano metal powder is effectively deposited on the metal template. The present application provides a preparation method of an ultimate ultra-thin reinforced boiling capillary wick based on vacuum filtration. Compared with other conventional capillary wicks, the capillary wick prepared by the present application can achieve a thickness of sub-micron to micron, and the best capillary effect can be obtained. Therefore, the ultra-thin vapor chamber packaged by the present application can also be truly ultra-thin, which has great significance for high-end electronic industry, 5G electronic products and other fields. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The flowchart of the preparation of the ultimate ultra-thin reinforced boiling capillary wick based on the vacuum filtration method.

[0025] Figure 2 The structure diagram of the ultimate ultra-thin reinforced boiling capillary wick prepared based on the vacuum filtration method.

[0026] Figure 3 The structure diagram of the vacuum filtration facility.

[0027] Figure 4 The local diagram of the vacuum filtration process.

[0028] Figure 5 The structure diagram of the double-pass alumina AAO template.

[0029] In the drawings:

[0030] 1-capillary wick, 2-bottom plate, 3-columnar structure, 4-filter cup, 5-micro-nano metal powder suspension liquid, 6-vacuum pump, 7-filter core, 8-filter bottle, 9-anhydrous ethanol, 10-pumping pipe, 11-double-pass alumina AAO template, 12-micro-nano through hole, 13-micro-nano metal powder. DETAILED DESCRIPTION

[0031] The present application will be further described in detail as follows.

[0032] Example 1

[0033] The present embodiment provides a preparation method of an ultra-thin reinforced boiling capillary wick 1 based on vacuum filtration, using a double-pass alumina AAO template 11 as a filtration metal template, as shown in Figure 5 The metal template is uniformly distributed with a plurality of micro-nano through holes 12, the diameter is preferably 5 microns, the hole distance is preferably 10 microns, and the micro-nano metal powder 13 uses micron copper powder to configure the micro-nano metal powder suspension liquid 5, and the micron copper powder has a diameter of 1 micron to obtain the best capillary effect.

[0034] As shown in Figure 1 , the preparation includes the following steps:

[0035] Step one, configure the micron copper powder suspension: add an appropriate amount of micron copper powder in a beaker, then add anhydrous ethanol 9 and a dispersing agent, and mix well using a magnetic stirrer to make a micron copper powder suspension. The suspension density is preferably 0.5 mg / 100 ml. Take the non-deposited part for later use.

[0036] Step two, build a filtration platform: as shown in Figure 3 , the ultra-thin liquid absorption core is prepared using a vacuum filtration device. The vacuum filtration device includes a filter cup 4, a filter core 7, a filter bottle 8, an air suction pipe 10, and a vacuum pump 6. The vacuum pump 6 is connected to the filter bottle 8 through the air suction pipe 10. The vacuum pump 6 has a horsepower of three. During preparation, place the double-channel alumina AAO template 11 on the filter core 7, and place the rubber pad with holes on it to prevent the micron copper powder suspension from flowing out from the periphery of the double-channel alumina AAO template 11. The double-channel alumina AAO template 11 is distributed with uniformly arranged micro-nano through holes 12.

[0037] Step three, perform filtration: as shown in Figure 4 , pour the micron copper powder suspension into the filter cup 4, start the vacuum pump 6, and form a pressure difference between the filter bottle 8 and the filter cup 4, forcing the micron copper powder suspension in the filter cup 4 to pass through the micro-nano through holes 12 on the double-channel alumina AAO template 11 into the filter bottle 8 below. The micron copper powder is filtered out in the micro-nano through holes 12 and gradually deposited, while the anhydrous ethanol 9 passes through the filter core 7 into the filter bottle 8 below.

[0038] Step four, high-temperature sintering: remove the double-channel alumina AAO template 11 after filtration, place it in a 950°C sintering furnace for five hours, and introduce 95% nitrogen and 5% hydrogen to protect it from oxidation. After sintering, cool it naturally in a protective gas and remove it.

[0039] Step five, remove the double-channel alumina AAO template 11: add the sintered double-channel alumina AAO template 11 to a strong base, melt it in a high-temperature environment, and then wash it with different concentrations of sodium hydroxide solution to remove the double-channel alumina AAO template 11, leaving the ultra-thin capillary liquid absorption core 1 sintered from micron copper powder.

[0040] Step six, oxidation treatment: soak the obtained ultra-thin capillary liquid absorption core 1 in a solution composed of sodium hydroxide and potassium persulfate, and take it out after a period of time to enhance its capillary performance.

[0041] Step seven, washing: wash the obtained ultra-thin capillary liquid absorption core 1 with anhydrous ethanol 9 and deionized water, and air dry naturally.

[0042] As shown in the figure, the prepared ultra-thin capillary wick 1 includes a bottom plate 2 and a plurality of columnar structures 3 deposited by micron copper powder uniformly distributed on the bottom plate 2. Compared with the capillary wick 1 prepared by the conventional method, the thickness is thinner, and the application range is expanded. Figure 2

[0043] Preferably, the diameter of the micron copper powder in step one corresponds to the micro-nano through hole 12 on the double-pass alumina AAO template 11, and the diameter ratio is 1 / 5, so as to obtain a relatively dense ultra-thin capillary wick 1.

[0044] The sintering time in step four is one hour of uniform heating, four hours of heat preservation, and then natural cooling, and a special mold is used to fix the double-pass alumina AAO template 11 during heating to prevent bending and deformation during heating.

[0045] The strong base mentioned in step five is sodium hydroxide and potassium hydroxide, and a small amount of sodium carbonate is added as a primer in a nickel crucible, and the heating temperature is preferably 600°C. The concentration of the sodium hydroxide solution is gradually reduced from high to low, and the concentrations are 90%-70%-50%-30%.

[0046] The concentration of sodium hydroxide in the alkaline solution mentioned in step six is 1 mol / L, and the concentration of potassium persulfate is 0.2 mol / L, and the soaking time is 30 minutes.

[0047] Example 2

[0048] In this embodiment, the double-pass alumina AAO template 11 is used as the suction filtration metal template, the diameter of the micro-nano through hole 12 is preferably 5 microns, the hole distance is preferably 10 microns, and the micro-nano metal powder 13 uses micron stainless steel powder to configure the micro-nano metal powder suspension 5, and the diameter of the micron stainless steel powder is preferably 1 micron to obtain the best capillary effect.

[0049] The preparation includes the following steps:

[0050] Step one, configure the micron stainless steel powder suspension: add an appropriate amount of micron stainless steel powder in a beaker, then add anhydrous ethanol 9 and a dispersing agent, and mix well using a magnetic stirrer to prepare a micron stainless steel powder suspension. The density of the micron stainless steel powder suspension is preferably 0.6 mg / 100 ml, and the non-sedimented part is taken for use.

[0051] ​Step two, build the filtration platform: ultra-thin liquid absorption core is prepared by vacuum filtration equipment, vacuum filtration equipment includes filter cup 4, filter core 7, filter bottle 8, suction tube 10, vacuum pump 6, the vacuum pump 6 horsepower is four. When preparing, the double-pass alumina AAO template 11 is placed on the filter core 7, and the rubber pad with holes is placed on it to prevent the micron stainless steel powder suspension from flowing out from the periphery of the double-pass alumina AAO template 11. The double-pass alumina AAO template 11 is distributed with uniform micro-nano through holes 12.

[0052] Step three, filtration: pour the micron stainless steel powder suspension into the filter cup 4, start the vacuum pump 6, and form a pressure difference between the filter bottle 8 and the filter cup 4, forcing the micron stainless steel powder suspension in the filter cup 4 to pass through the micro-nano through holes 12 on the double-pass alumina AAO template 11 into the filter bottle 8 below. The micron stainless steel powder is filtered out in the micro-nano through holes 12 and gradually deposited, while the anhydrous ethanol 9 enters the filter bottle 8 below through the filter core 7.

[0053] Step four, high temperature sintering: remove the double-pass alumina AAO template 11 after filtration, put it into a 1200℃ sintering furnace for five hours, and pass in 95% nitrogen and 5% hydrogen for protection to prevent the micron stainless steel powder deposited in the through hole from being oxidized. After sintering, it is naturally cooled in the protection gas and taken out.

[0054] Step five, remove the double-pass alumina AAO template 11: add the sintered double-pass alumina AAO template 11 to strong alkali, melt in a high temperature environment, and then wash with different concentrations of sodium hydroxide solution to remove the double-pass alumina AAO template 11, leaving the ultra-thin capillary absorption core 1 sintered from micron stainless steel powder.

[0055] Step six, oxidation treatment: immerse the obtained ultra-thin capillary absorption core 1 in a solution composed of sodium hydroxide and potassium persulfate, and take it out after a period of time to enhance its capillary performance.

[0056] Step seven, washing: wash the obtained ultra-thin capillary absorption core 1 with anhydrous ethanol 9 and deionized water respectively, and air dry naturally.

[0057] Preferably, the diameter of the micron stainless steel powder in step one corresponds to the micro-nano through holes 12 on the double-pass alumina AAO template 11, with a diameter ratio of 1 / 10 to obtain a relatively dense ultra-thin capillary absorption core 1.

[0058] The sintering time mentioned in step four is one hour of uniform heating, four hours of holding, and then natural cooling, and a special mold is used to fix the double-pass alumina AAO template 11 during heating to prevent it from bending and deforming during heating.

[0059] The strong base mentioned in step five is sodium hydroxide and potassium hydroxide, and a small amount of sodium carbonate is added to the nickel crucible as a primer, and the heating temperature is preferably 700 DEG C. The concentration of the sodium hydroxide solution is washed in sequence from high to low, and the concentrations are 80%-60%-40%-20% respectively.

[0060] The concentration of sodium hydroxide in the alkaline solution mentioned in step six is 1 mol / L, the concentration of potassium persulfate is 0.3 mol / L, and the soaking time is 60 minutes.

[0061] The advantages of the present application relative to the prior art are as follows:

[0062] (1) The present application provides a kind of limit ultra-thin enhanced boiling capillary wick 1 preparation method based on vacuum filtration, proposes a kind of new preparation of uniform heat plate capillary wick 1 method, can obtain more light and thin capillary wick 1, has great potential in the field of enhanced boiling.

[0063] (2) The present application provides a kind of limit ultra-thin enhanced boiling capillary wick 1 preparation method based on vacuum filtration, can further reduce the thickness of ultra-thin uniform heat plate, is applied in high heat flow density occasion to improve the performance of high-end electronic devices, or further reduce its size, make it more portable.

[0064] The above embodiment is the preferred embodiment of the present application, but the embodiment of the present application is not limited by the above embodiment, any change, modification, substitution, combination, simplification made without departing from the spirit and principles of the present application should be equivalent replacement mode, all included in the protection scope of the present application.

Claims

1. A method for preparing an ultra-thin reinforced boiling capillary wick based on vacuum suction filtration, characterized by: The method comprises the following steps of: configuring a micro-nano metal powder suspension with anhydrous ethanol; sequentially placing a filter core and a metal template with uniformly arranged micro-nano through holes on the filter bottle from bottom to top; filling the micro-nano metal powder suspension into the filter cup, inverting the filter cup on the metal template, and using a vacuum pump to perform vacuum suction on the micro-nano metal powder suspension in the filter cup to perform suction filtration, so that the micro-nano metal powder in the micro-nano metal powder suspension is deposited in the micro-nano through holes of the metal template, and the anhydrous ethanol in the micro-nano metal powder suspension flows into the filter bottle through the metal template and the filter core; high-temperature sintering of the metal template after suction filtration to form the micro-nano metal powder deposited on the metal template; removing the used metal template to obtain a capillary liquid absorption core formed by the micro-nano metal powder; the diameter of the micro-nano through holes of the metal template is 5-10 microns, and the hole distance is 10-20 microns; the diameter of the micro-nano metal powder is 0.2-1 micron.

2. The method for preparing an ultra-thin reinforced boiling capillary wick based on vacuum suction filtration according to claim 1, characterized in that: The power of the vacuum pump is 3-5 horsepower.

3. The method for preparing an ultra-thin reinforced boiling capillary wick based on vacuum suction filtration according to claim 1, characterized in that: The size of the filter core matches the used metal template, and the gap of the filter core is smaller than the particle size of the used micro-nano metal powder.

4. The method for preparing an ultra-thin reinforced boiling capillary wick based on vacuum suction filtration according to claim 1, characterized in that: The metal template is an alumina AAO double-through template.

5. The method for preparing an ultra-thin reinforced boiling capillary wick based on vacuum suction filtration according to claim 1, characterized in that: The ratio of the diameter of the micro-nano metal powder to the diameter of the micro-nano through holes of the metal template is 1 / 5-1 / 10.

6. The method for preparing an ultra-thin reinforced boiling capillary wick based on vacuum suction filtration according to claim 1, characterized in that: The concentration of the micro-nano metal powder suspension is 0.5-2 mg / 100 ml.

7. The method for preparing an ultra-thin reinforced boiling capillary wick based on vacuum suction filtration according to claim 1, characterized in that: The sintering time is one hour of uniform heating, four hours of heat preservation, and then natural cooling.

8. The method for preparing an ultra-thin reinforced boiling capillary wick based on vacuum suction filtration according to claim 1, characterized in that: The method further comprises the following steps of: preparing a corrosion liquid to soak the capillary liquid absorption core to enhance the capillary performance of the capillary liquid absorption core, the corrosion liquid comprising sodium hydroxide and potassium persulfate, the concentration of the sodium hydroxide being 1-2 mol / L, the concentration of the potassium persulfate being 0.2-0.5 mol / L, and the soaking time being 30-60 minutes.

9. An ultra-thin reinforced boiling capillary wick based on vacuum suction filtration, characterized by: The method is prepared by using the method for preparing an ultra-thin reinforced boiling capillary liquid absorption core based on vacuum suction filtration according to any one of claims 1-8.

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