Aluminum-based phase change heat spreader and method of making same

Abstract

The application relates to an aluminum-based phase-change radiator and a preparation method thereof. The aluminum-based phase-change radiator comprises, from bottom to top, an aluminum base plate, an adhesion isolation layer, a combination layer and a copper porous layer. Nano-titanium is used as the adhesion isolation layer, and nano-copper is used as the combination layer of the copper-based porous structure. The aluminum-water incompatibility problem is overcome, the high-efficiency phase-change radiator of the aluminum-water system is formed, and the performance of the aluminum-based phase-change radiator is improved.

Description

Technical Field

[0001] This invention relates to the field of heat pipe technology, specifically to an aluminum-based phase change heat sink and its preparation method. Background Technology

[0002] Phase change heat dissipation devices (such as heat pipes, thermosiphons, and vapor chambers) are mainly made of copper with high thermal conductivity as the base material and water as the working fluid. Although they have excellent heat transfer performance, they are heavy and the raw materials are expensive. Aluminum, as the most abundant metallic element in the earth's crust, is an inexpensive and lightweight metal. Although its thermal conductivity is only about 60% of that of copper, its mass for the same volume is only 3 / 10 of that of copper, and its price for the same mass is only 1 / 10 of that of copper. It is expected to replace copper as the raw material for passive phase change heat dissipation devices.

[0003] However, since aluminum is incompatible with water, aluminum-based phase change heat sinks cannot use water as a working medium. Instead, they have to choose ammonia, ethanol, acetone, and refrigerants, which have poor evaporation / boiling heat transfer performance, as working mediums, which greatly reduces the performance of aluminum-based phase change heat sinks. Summary of the Invention

[0004] Therefore, it is necessary to provide an aluminum-based phase change heat sink and its preparation method that can overcome the problem of aluminum-water incompatibility.

[0005] To achieve the above objectives, the present invention provides a technical solution:

[0006] An aluminum-based phase change heat sink, comprising, from bottom to top, an aluminum substrate, an adhesive isolation layer, a bonding layer, and a copper porous layer.

[0007] Furthermore, the copper porous layer comprises a high capillary copper porous layer and a high porosity copper porous layer arranged sequentially, wherein the high capillary copper porous layer is disposed on the bonding layer.

[0008] Furthermore, the thickness of the high capillary force copper porous layer is 50 nm to 500 nm;

[0009] The thickness of the high-porosity copper porous layer is 50 μm to 500 μm.

[0010] Furthermore, the adhesive isolation layer is nano-titanium.

[0011] Furthermore, the thickness of the adhesive isolation layer is 50–500 nm.

[0012] Furthermore, the bonding layer is made of nano-copper.

[0013] Furthermore, the thickness of the bonding layer is 50–500 nm.

[0014] This invention also provides a method for preparing an aluminum-based phase change heat sink, the method comprising the following steps:

[0015] Clean the aluminum substrate thoroughly.

[0016] An adhesive isolation layer and a bonding layer are sequentially deposited on the aluminum substrate using a thin-film process.

[0017] A porous layer is deposited on the surface of the bonding layer using a sintering or electrodeposition process.

[0018] Furthermore, the thin film process includes magnetron sputtering, vapor deposition, or electrodeposition.

[0019] Furthermore, the specific steps for cleaning the aluminum substrate include:

[0020] The surface of the aluminum substrate was cleaned and dried sequentially using anhydrous ethanol, acetone, and deionized water to keep the surface smooth.

[0021] The beneficial effects of this invention are:

[0022] The aluminum-based phase change heat sink of the present invention comprises, from bottom to top, an aluminum substrate, an adhesive isolation layer, a bonding layer, and a copper porous layer. When the aluminum-based phase change heat sink uses water as the working medium, the nano-titanium of the adhesive isolation layer can isolate the water, overcoming the problem of aluminum-water incompatibility, forming an aluminum-water system with high-efficiency phase change, and improving the performance of the aluminum-based phase change heat sink.

[0023] The copper porous layer is bonded to the aluminum base plate through an adhesive isolation layer and a bonding layer. The copper porous layer has the characteristic of high equivalent thermal conductivity, which further improves the performance of the aluminum-based phase change heat sink.

[0024] The nano-copper in the bonding layer has high surface energy and can be co-fired with the porous copper layer with high thermal conductivity. This overcomes the problem that the copper and aluminum cannot be co-fired due to the severe mismatch in melting points, and improves the evaporation / boiling heat transfer efficiency and the overall performance of the aluminum-based phase change heat sink.

[0025] The aluminum-based phase change heat sink of the present invention has similar performance to the copper-based phase change heat sink on the market, but reduces the weight of the heat sink and lowers the material cost. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of an aluminum-based phase change heat sink according to an embodiment;

[0027] Figure 2 This is a flowchart illustrating the preparation of an aluminum-based copper-plated composite porous structure in one embodiment;

[0028] Figure 3 This is a flowchart illustrating the fabrication of an aluminum-based phase change heat sink according to one embodiment;

[0029] Figure 4 This is an example of an electrodeposition preparation apparatus.

[0030] Among them, 100 is an aluminum substrate; 200 is an adhesive isolation layer; 300 is a bonding layer; 400 is a copper porous layer; 410 is a high capillary copper porous layer; and 420 is a porosity copper porous layer. Detailed Implementation

[0031] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0032] In the embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0033] like Figure 1 As shown, an aluminum-based phase change heat sink includes, from bottom to top, an aluminum substrate 100, an adhesive isolation layer 200, a bonding layer 300, and a copper porous layer 400.

[0034] The copper porous layer 400 includes a high capillary copper porous layer 410 and a high porosity copper porous layer 420 arranged sequentially, with the high capillary copper porous layer 410 disposed on the bonding layer 300.

[0035] Specifically, aluminum-based phase change radiators and copper-based phase change radiators have the same structure. Both are closed cavities consisting of an evaporation end, a vapor diffusion chamber, and a condensation end. The interior is filled with liquid to undergo endothermic phase change. The generated vapor enters the condensation end through the diffusion chamber to dissipate heat, and the formed liquid returns to the evaporation end under the action of gravity or capillary force, and so on.

[0036] The aluminum-based phase change heat sink of the present invention replaces the shell material of the copper-based phase change heat sink with aluminum, and uses a coating technology to prepare an adhesion isolation layer 200 (nano titanium) and a bonding layer 300 (nano copper) on the surface of the aluminum substrate 100, and then prepares a copper porous layer 400. This allows the aluminum-based heat sink to use water with excellent heat dissipation performance as the working medium, which can not only improve the ultimate heat dissipation power of the aluminum-based phase change heat sink, but also significantly reduce the weight compared to the copper-based phase change heat sink, with its weight being only 3 / 10 of that of the copper-based phase change heat sink.

[0037] The thickness of the high capillary force copper porous layer 410 is 50 nm to 500 nm; the thickness of the high porosity copper porous layer 420 is 50 μm to 500 μm.

[0038] In one embodiment, the adhesive isolation layer 200 is nano-titanium, and the thickness of the adhesive isolation layer 200 is 50-500 nm.

[0039] Specifically, nano-titanium has the following advantages:

[0040] (1) Nano-titanium has a large work function, which can form good ohmic contact with many materials and has excellent adhesion.

[0041] (2) A dense oxide film can be formed on the surface of nano-titanium, which gives nano-titanium stable chemical properties and excellent corrosion resistance, thus preventing water from contacting aluminum.

[0042] In one embodiment, the bonding layer 300 is nano-copper, and the thickness of the bonding layer 300 is 50-500 nm.

[0043] Specifically, nano-copper has high surface energy and can be co-fired with copper porous layer 400 with high thermal conductivity, overcoming the problem that copper and aluminum cannot be co-fired due to severe mismatch in melting points, thus improving the evaporation / boiling heat transfer efficiency and the overall performance of aluminum-based phase change heat sinks.

[0044] Preferably, the thickness of the adhesive isolation layer 200 is 100 nm, and the thickness of the bonding layer 300 is 100 mm.

[0045] Specifically, the high capillary copper porous layer 410 is used as an adhesion layer with a thickness on the order of 100 nanometers. It is relatively dense, and the high capillary copper porous layer 410 is relatively thin, so it can be integrally sintered with the nano-copper of the bonding layer 300.

[0046] The high-porosity copper porous layer 420 has a thickness on the order of 100 micrometers and a relatively large pore size. The high-porosity copper porous layer 420 is relatively thick and is the main site for phase transition.

[0047] This invention also provides a method for preparing an aluminum-based phase change heat sink, the method comprising the following steps:

[0048] S100. The surface of the aluminum substrate 100 is cleaned and dried sequentially using anhydrous ethanol, acetone and deionized water to keep the surface smooth.

[0049] S200: Using a thin film process, an adhesion isolation layer 200 and a bonding layer 300 are successively deposited on an aluminum substrate 100.

[0050] Furthermore, thin film processes include magnetron sputtering, vapor deposition, or electrodeposition.

[0051] S300: A porous copper layer 400 is deposited on the surface of the bonding layer 300 using a sintering or electrodeposition process.

[0052] Example 1

[0053] S100. The surface of the aluminum substrate 100 is cleaned and dried sequentially using anhydrous ethanol, acetone and deionized water, and the surface is kept smooth.

[0054] S200. Using magnetron sputtering, an adhesion isolation layer 200 and a bonding layer 300 are successively deposited on an aluminum substrate 100 to obtain an aluminum copper-plated plate:

[0055] The cleaned aluminum substrate 100 is placed in the sputtering chamber of the magnetron sputtering equipment, and the sputtering chamber is evacuated. When the internal pressure inside the sputtering chamber reaches 8.0 × 10⁻⁶, the pressure is increased to 1000 kJ / m². -3 ~8.0×10 -4 After Pa, a rare gas is introduced, with a volumetric flow rate of 30 sccm.

[0056] The rare gas is Ar2, and the volumetric flow rate of Ar2 is 10–30 sccm; the purpose of introducing the rare gas is:

[0057] (1) Prevent oxidation;

[0058] (2) Stable discharge;

[0059] (3) By controlling the flow rate, the film thickness can be precisely controlled.

[0060] The target material of the magnetron sputtering equipment is a nano-titanium target material. The nano-titanium target material is sputtered onto an aluminum substrate 100 to obtain an aluminum-based titanium-plated plate. The pre-sputtering time is 5s, the sputtering power is 30-100W, and the sputtering time is 100-150s.

[0061] The target material of the magnetron sputtering equipment was replaced with a nano-copper target material, and the nano-copper target material was sputtered onto an aluminum-based titanium-plated plate to obtain an aluminum-copper-plated plate. The pre-sputtering time was 5s, the sputtering power was 60-100W, and the sputtering time was 300-450s.

[0062] S300. Using a sintering process, a high capillary copper porous layer 410 and a high porosity copper porous layer 420 are successively deposited on the surface of the bonding layer 300:

[0063] S310. High capillary copper porous layer 410:

[0064] like Figure 2 As shown, small-particle copper powder with a particle size of 1-50 μm is used, shaped by a graphite mold, and filled onto the surface of an aluminum substrate 100 aluminum-coated copper plate coated with an adhesion isolation layer 200 and a bonding layer 300. Then, it is placed in a nitrogen-hydrogen atmosphere sintering furnace for medium-low temperature co-sintering to obtain an aluminum-based copper-plated composite porous structure. The peak sintering temperature is 350-450℃, the sintering time is 10-30 min, and the furnace is cooled after sintering.

[0065] S320. High-porosity copper porous layer plated 420:

[0066] like Figure 3As shown, large-particle copper powder with a particle size of 50-300 μm is used. It is shaped by a graphite mold and sintered at a high temperature of 850-950℃ to form a large-particle copper capillary core. This core is then filled onto the surface of an aluminum substrate 100, which is coated with an adhesion isolation layer 200, a bonding layer 300, and a high capillary force copper porous layer 410. The core is then placed in a nitrogen-hydrogen atmosphere sintering furnace for low-temperature co-firing to obtain an aluminum-based phase change heat sink. The peak sintering temperature is 350-450℃, the sintering time is 10-30 min, and the core is cooled with the furnace after sintering.

[0067] Example 2

[0068] The other steps are the same as in Example 1, and will not be repeated in this example.

[0069] S300. Employs electrodeposition technology, such as Figure 4 As shown, a high capillary force copper porous layer 410 and a high porosity copper porous layer 420 are successively deposited on the surface of the bonding layer 300:

[0070] S310. High capillary copper porous layer 410:

[0071] Cathode: An aluminum substrate 100 coated with an adhesive isolation layer 200 and a bonding layer 300;

[0072] Anode: Copper sheet;

[0073] Electrolyte: Copper sulfate solution with a concentration of 0.2–0.6 mol / L, and an appropriate amount of dilute sulfuric acid with a concentration of 0.1–1 mol / L is added to the electrolyte to provide hydrogen ions;

[0074] Input DC current, with a current magnitude of 30–150 mA / cm 2 ;

[0075] The deposition time is 1200–3600 s;

[0076] The electrodeposited sample was placed in a nitrogen-hydrogen atmosphere sintering furnace for sintering. The peak sintering temperature was 350–450℃, and the sintering time was 10–30 min. The sample was then cooled with the furnace after sintering.

[0077] S320. Porous copper plating layer 420:

[0078] Repeat step S310 above to control the thickness of the copper porous layer 420 with high porosity by controlling the deposition time, deposition time and copper sulfate concentration.

[0079] It should be noted that the specific parameters or reagents in the above embodiments are specific or preferred embodiments under the concept of the present invention, and not limitations thereof; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present invention.

Claims

1. An aluminum-based phase change heat sink, characterized in that... The aluminum-based phase change heat sink comprises, from bottom to top, an aluminum substrate, an adhesive isolation layer, a bonding layer, and a copper porous layer. The copper porous layer includes a high capillary copper porous layer and a high porosity copper porous layer arranged sequentially, wherein the high capillary copper porous layer is disposed on the bonding layer; The adhesive isolation layer is nano-titanium; The bonding layer is made of nano-copper.

2. The aluminum-based phase change heat sink according to claim 1, characterized in that, The thickness of the high capillary force copper porous layer is 50nm~500nm; The thickness of the high-porosity copper porous layer is 50μm~500μm.

3. The aluminum-based phase change heat sink according to claim 1, characterized in that, The thickness of the adhesive isolation layer is 50~500 nm.

4. The aluminum-based phase change heat sink according to claim 1, characterized in that, The thickness of the bonding layer is 50~500nm.

5. A method for preparing an aluminum-based phase change heat sink as described in any one of claims 1 to 4, characterized in that, The preparation method includes the following steps: Clean the aluminum substrate thoroughly. An adhesive isolation layer and a bonding layer are sequentially deposited on the aluminum substrate using a thin-film process. A porous copper layer is deposited on the surface of the bonding layer using a sintering or electrodeposition process.

6. The preparation method according to claim 5, characterized in that, The thin film process includes magnetron sputtering, vapor deposition, or electrodeposition.

7. The preparation method according to claim 5, characterized in that, The specific steps for cleaning the aluminum substrate include: The surface of the aluminum substrate was cleaned and dried sequentially using anhydrous ethanol, acetone, and deionized water to keep the surface smooth.

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