WO2022227220A1

WO2022227220A1 - Heat dissipation device having flat heat pipe and cooling liquid plate composite structure and manufacturing method for heat dissipation device

Info

Publication number: WO2022227220A1
Application number: PCT/CN2021/097438
Authority: WO
Inventors: 秦贯丰; 刘治猛; 崔立峰; 尹辉斌; 彭可文; 翁万良
Original assignee: 东莞理工学院
Priority date: 2021-04-30
Filing date: 2021-05-31
Publication date: 2022-11-03
Also published as: CN113075987A

Abstract

The present invention relates to the technical field of heat dissipation devices, and in particular to a heat dissipation device having a flat heat pipe and cooling liquid plate composite structure and a manufacturing method for the heat dissipation device. The heat dissipation device comprises a substrate, the substrate comprises a cooling liquid plate layer and flat heat pipe layers provided on the upper end face and/or the lower end face of the cooling liquid plate layer, and cooling liquid flow channels are formed in the cooling liquid plate layer. The heat dissipation device can achieve integration of the flat heat pipes and the cooling liquid plate, the flat heat pipe is in contact with a heating element and heat is transferred by means of conduction, and the heat is taken away by a cooling liquid in the cooling liquid plate, so that the heat dissipation device is good in heat dissipation performance and is suitable for heat dissipation of electronic heating elements, especially electronic elements which are ultrahigh in power density and are densely arranged. The heat dissipation device has simple operations in the manufacturing method, is convenient in control, is high in production efficiency, and is capable of being used for large-scale production; moreover, the produced heat dissipation devices are stable in quality, long in service life and good in heat dissipation performance.

Description

Radiator with composite structure of flat heat pipe and cooling liquid plate and method of making the same

technical field

The invention relates to the technical field of radiators, in particular to a radiator with a composite structure of a flat plate heat pipe and a cooling liquid plate.

Background technique

Due to the continuous improvement of the integration level, packaging density and operating clock frequency of modern electronic chips represented by CPU, the calorific value per unit area increases rapidly. Research literature shows that, in some sensitive temperature sections, the system reliability is reduced by 50% for every 10℃ increase in the temperature of a single semiconductor element. According to the characteristics of large computer server CPU heat dissipation, optimizing the heat transfer structure of the radiator and improving the heat transfer coefficient of the surface of the heat sink can effectively improve the heat dissipation effect. based on improving efficiency. The principle is that the heat generated by the high heat flux density device is conducted to the heat pipe, so that the working fluid in the heat pipe undergoes a phase change to transfer the heat to the bottom plate, and then the heat is dissipated through the forced convection between the fins and the air. The heat pipe inlaid on the bottom surface of the radiator can be arranged in various ways. However, the power density of a single central processing unit (CPU) of today's supercomputers is as high as 20W/cm ² , and a huge amount of heat must be removed from the CPU and the cabinet in time to ensure the normal operation of the supercomputing center. Using a finned heat exchanger to dissipate the heat from the CPU into the air can no longer solve this problem. This poses a serious challenge to heat dissipation and temperature control technology. At present, the cooling method for supercomputing CPUs and large data centers mainly adopts liquid cooling method, that is, the cooling liquid is used to transport heat to the outdoor, including cold liquid plate cooling and immersion cooling. Both methods have their own advantages and disadvantages. The said cooling liquid plate is in contact with the surface of the CPU, and the cooling liquid is carried inside and the heat is carried away. Cooling plate heat dissipation is convenient for system debugging and maintenance (after all, a lot of debugging and maintenance is unavoidable for supercomputing), but the cooling effect of cold liquid plate is inferior to that of immersion heat dissipation. Although the latter has a good heat dissipation and temperature control effect, the entire motherboard is immersed in the coolant, which puts forward high requirements for the coolant. At present, high-performance fluorinated liquid is mainly used, which is not only expensive, but also inconvenient for system debugging and maintenance.

As shown in Figure 1-2, the heat transfer analysis between the cooling liquid plate in the prior art from the heating device (heat source, such as CPU) to the cooling liquid (cooling source) of the cooling liquid plate is as follows: the heat Q generated by the CPU passes through The thermal conductive adhesive layer, and then from the thermal conductive adhesive layer (silicon grease film) to the cooling liquid plate (including the upper cooling liquid plate and the lower cooling liquid plate), and then from the cooling liquid plate to the cooling liquid, the cooling liquid plate is an aluminum plate.

The overall heat transfer coefficient U can be expressed as:

In the formula, U is the total heat transfer coefficient, δ ₁ is the thickness of the silicone grease (10μm=10×10 ^-6 m), λ ₁ is the thermal conductivity of the silicone grease (5Wm ^-1 K ^-1 ), and δ ₂ is the thickness of the aluminum plate ( 2mm=2×10 ^-3 m), and λ ₂ is the thermal conductivity of the aluminum plate (237Wm ^-1 K ^-1 ). h ₃ is the film heat transfer coefficient of the cooling liquid on the inner surface of the flow channel of the aluminum plate. Let the heat transfer area be the area of the CPU A=5×5=25cm ² =25×10 ⁻⁴ m ² . The total heat transfer thermal resistance 1/(UA) is the sum of the thermal resistance R ₁ of the silicone grease film, the thermal resistance R ₂ of the aluminum plate, and the thermal resistance R ₃ of the cooling liquid heat transfer film (heat transfer boundary layer).

(1) Thermal resistance of silicone grease film (R ₁ ), thickness of silicone grease film δ ₁ =10μm=10×10 ^-6 m, thermal conductivity λ ₁ =5W·m ^-1 ·K ^-1

(2) Thermal resistance of aluminum plate (R ₂ ), aluminum plate thickness ₂ = 2mm, thermal conductivity λ ₂ = 237W·m ^-1 ·K ^-1

(3) The liquid film heat transfer resistance of the cooling liquid (R ₃ ),

Assuming that the flow rate of the cooling liquid in the flow channel is 0.5m·s ^-1 , the heat transfer coefficient of the liquid film can be calculated by the following formula. Calculations are omitted.

h ₃ ≈5000W·m ^-2 ·K ^-1

Therefore, the total thermal resistance from the heat source to the cold source is

R=R ₁ +R ₂ +R ₃ =0.0008+0.0034+0.08=0.0842K·W ⁻¹

According to the above calculations, the heat transfer resistance of the cooling liquid film is nearly 24 times that of the aluminum plate (R ₃ /R ₂ ) and 100 times that of the silicone grease film (R ₃ /R ₁ ). The main heat transfer resistance comes from Heat transfer liquid film between coolant and aluminum plate. It can be seen that to strengthen the cooling effect of the cooling liquid plate, the key is to strengthen the heat transfer between the cooling liquid and the cooling liquid plate. Strengthening the turbulent flow between the cooling liquid and the cooling liquid plate can increase the turbulent flow intensity of the cooling liquid. However, increasing the turbulent flow intensity means increasing the flow rate of the cooling liquid, which is extremely unfavorable for large-scale CPU cluster use (such as supercomputing). For example, if one CPU doubles the coolant flow rate, for a supercomputing cabinet, there are hundreds or thousands of CPUs, which means that the coolant flow rate is doubled!

SUMMARY OF THE INVENTION

In order to overcome the shortcomings and deficiencies in the prior art, the purpose of the present invention is to provide a radiator with a composite structure of a flat plate heat pipe and a cooling liquid plate, which can realize the integration of the flat heat pipe and the cooling liquid plate, and the flat heat pipe and the cooling liquid plate. The heating element contacts and transfers heat through conduction, and the heat is taken away by the cooling liquid in the cooling liquid plate.

Another object of the present invention is to provide a method for making a radiator with a composite structure of a flat heat pipe and a cooling liquid plate, which is simple to operate, easy to control, and has high production efficiency, which can be used in large-scale production and the quality of the radiator produced. Stable, long service life and good heat dissipation.

The object of the present invention is achieved by the following technical solutions: a radiator with a composite structure of a flat plate heat pipe and a cooling liquid plate, comprising a base plate, the base plate comprising a cooling liquid plate layer and an upper end surface and/or an upper end surface and/or a cooling liquid plate layer disposed on the cooling liquid plate layer. The flat heat pipe layer on the lower end surface, the cooling liquid flow channel is arranged in the cooling liquid plate layer;

Further, cooling fins are arranged in the cooling liquid flow channel.

Further, a plurality of row holes arranged in parallel are arranged in the flat plate heat pipe layer.

Further, the inner wall of the row of holes is provided with a porous medium layer.

Further, both ends of the hole row channel are provided with sealing plugs, and the sealing plug is used to seal both ends of the hole row channel.

Further, a plurality of cooling liquid flow passages arranged in parallel are arranged in the cooling liquid plate layer, and the row holes are arranged in parallel with the cooling liquid flow passages.

Further, both ends of the cooling liquid plate layer are provided with end caps, and the end caps are provided with a cooling liquid inlet and a cooling liquid outlet.

Further, the substrate is an aluminum substrate, and the cold liquid plate layer and the flat-plate heat pipe layer are integrally formed.

Further, the base plate includes a cold liquid plate layer and a flat plate heat pipe layer disposed on the lower end surface of the cold liquid plate layer.

Further, the upper and lower end surfaces of the cold liquid plate layer are provided with flat plate heat pipe layers.

Another object of the present invention is achieved through the following technical solutions: the above-mentioned manufacturing method of a radiator with a flat plate heat pipe and a cooling liquid plate composite structure comprises the following steps:

S1. Use pure aluminum or aluminum alloy as a material to make an aluminum substrate, and the aluminum substrate includes a cold liquid plate production layer and a flat heat pipe production layer;

S2. A plurality of rows of holes are arranged in the production layer of the flat-plate heat pipe;

S3. A porous medium layer is arranged on the inner wall surface of the row holes of the production layer of the flat heat pipe;

S4. Block one end of the exhaust hole to make it airtight; inject a low-boiling-point working medium into the exhaust hole;

S5, under negative pressure, seal the other end of the row of holes, and seal the low-boiling point working medium in the row of holes to obtain a flat-plate heat pipe layer including a plurality of flat-plate heat pipes;

S6, a porous medium layer is arranged on the inner wall surface of the row holes of the flat-plate heat pipe fabrication layer;

S7. End caps are respectively provided at both ends of the cooling liquid plate manufacturing layer with built-in cooling fins, and the end caps are provided with a cooling liquid inlet and a cooling liquid outlet.

In the step S4, the manufacturing method of the porous medium layer includes the following steps:

A1. Insert a pin in the center of each row of holes along the axial direction, and the cross-sectional area of the pin is set to leave a gap of 0.5-1mm with the inner wall of the row of holes after insertion; The aluminum substrate is placed vertically, and aluminum powder or aluminum alloy powder is filled in the remaining gaps of each row of holes;

A2. Put the aluminum substrate workpiece with inserted pins and filled with aluminum powder or aluminum alloy powder into the powder metallurgy sintering furnace, continue to vacuumize, and remove oxygen for 50-70min;

A3. Fill the sintering furnace with nitrogen, and the partial pressure of moisture in the nitrogen atmosphere is 0.001-0.02kPa; heat the sintering furnace at a heating rate of 5-8°C/min until 560-600°C; maintain it in a nitrogen protective atmosphere at least 1h;

A4. After the sintering is completed, it is naturally cooled to normal temperature, and then the pin is pulled out to obtain a porous medium layer.

Further, in the step A3, the partial pressure of moisture in the nitrogen atmosphere is 0.001-0.02kPa; the sintering furnace is heated at a heating rate of 5-8°C/min until 560-600°C; maintained in a nitrogen protective atmosphere for at least 1 hour .

Beneficial effects of the present invention: the radiator of the present invention has a composite structure of a flat heat pipe and a cooling liquid plate, the radiator can realize the integration of the flat heat pipe and the cooling liquid plate, the flat heat pipe contacts the heating element and transfers heat through conduction, and the cooling The cooling liquid in the liquid plate takes away heat and has good heat dissipation performance, which can be suitable for heat dissipation of electronic heating elements, especially ultra-high power density and densely arranged electronic elements.

Description of drawings

1 is a cross-sectional side view of a cooling liquid plate in the prior art;

Fig. 2 is a cross-sectional top view along A-A in Fig. 1;

3 is a cross-section of the substrate of Example 1;

Fig. 4 is the schematic diagram that the aluminum powder of embodiment 1 is filled into the row hole of flat heat pipe;

5 is a cross-sectional side view of the heat sink of Embodiment 1;

6 is a top view of the heat sink of Embodiment 1;

7 is a schematic cross-sectional view of Embodiment 1;

8 is a cross-section of the substrate of Example 2;

9 is a partial enlarged view of a section of flat heat pipe layer and a cooling liquid plate of Example 2;

Reference numerals are: 11, upper cooling liquid plate; 12, lower cooling liquid plate; 13, cooling liquid chamber; 14, fixing bolts; 15, heating element; 16, thermal conductive adhesive layer; 17, cooling liquid flow channel; 18, Flat heat pipe layer; 19, end cap; 20, base plate; 21, pin; 22, row hole; 23, cooling fin; 24, condensation area; 25, evaporation area; 26, porous medium layer; 27, steam channel ; 28, sealing plug.

Detailed ways

In order to facilitate the understanding of those skilled in the art, the present invention will be further described below with reference to the embodiments and the accompanying drawings, and the contents mentioned in the embodiments are not intended to limit the present invention.

As shown in FIGS. 3-9 , in a typical embodiment of the present invention, a heat sink with a composite structure of a flat heat pipe and a cooling liquid plate is provided, including a base plate 20 , and the base plate 20 includes a cooling liquid plate layer and a flat-plate heat pipe layer 18 arranged on the upper end face and/or the lower end face of the cooling liquid plate layer, the cooling liquid flow channel 17 is arranged in the cooling liquid plate layer; the cooling liquid flow channel 17 is arranged with radiating fins twenty three.

In one embodiment, the flat-plate heat pipe layer 18 is provided with a plurality of row holes 22 arranged in parallel. The inner wall of the row holes 22 is provided with a porous medium layer 26 .

In one embodiment, sealing plugs 28 are provided at both ends of the channels of the row holes 22 , and the sealing plugs 28 are used to seal the two ends of the channels of the row holes 22 . The row holes 22 are used to install a low-boiling-point working medium, and the low-boiling-point working medium is preferably, but not limited to, acetone and R134a.

In one embodiment, a plurality of cooling liquid flow channels 17 arranged in parallel are arranged in the cooling liquid plate layer, and the row holes 22 are arranged in parallel with the cooling liquid flow channels 17 .

In one embodiment, both ends of the cooling liquid plate layer are provided with end caps 19, and the end caps 19 are provided with a cooling liquid inlet and a cooling liquid outlet.

In one embodiment, the substrate 20 is an aluminum substrate 20 , and the cold liquid plate layer and the flat-plate heat pipe layer 18 are integrally formed.

In one embodiment, the base plate 20 includes a cold liquid plate layer and a flat plate heat pipe layer 18 disposed on the lower end surface of the cold liquid plate layer.

In one embodiment, a flat plate heat pipe layer 18 is provided on both the upper end surface and the lower end surface of the cold liquid plate layer.

In another typical embodiment of the present application, the above-mentioned manufacturing method of a radiator with a flat plate heat pipe and a cooling liquid plate composite structure includes the following steps:

S1. Using pure aluminum or aluminum alloy as a material, an aluminum substrate 20 is fabricated by extrusion molding, precision casting or 3D printing. The aluminum substrate 20 includes a cold liquid plate fabrication layer and a flat heat pipe fabrication layer; the aluminum substrate 20 can be A schematic diagram of the structure of the two-layer substrate 20 or the structure of the three-layer substrate 20; the plate walls between the channels in the substrate 20 have no trachoma or cracks that can cause leakage.

S2. A plurality of holes 22 are arranged in the production layer of the flat heat pipe; the holes 22 constituting the flat heat pipe can be square holes or round holes; the size is controlled within a certain range, such as 1×1mm ² /piece -5×5mm ² /piece, or circular holes with a diameter of 1-5mm, the number of the row holes 22 is determined by the width of the flat heat pipe layer 18 . The length and width of the flat heat pipe are usually larger than the size of the heating element 15 such as the CPU, so as to increase the effective heat transfer area; the size of the square holes is preferably 1×1mm ² /piece, 2×2mm ² /piece, 3× 3mm ² / and 4×4mm ² /piece, 5×5mm ² /piece; the size of the circular hole is preferably 1mm, 2mm, 3mm, 4mm and 5mm in diameter;

S3. A porous medium layer 26 is provided on the inner wall surface of the row holes 22 of the flat heat pipe fabrication layer; The thickness of the porous medium layer 26 is 0.5-1 mm, and the porous medium layer 26 is preferably 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm and 1 mm.

S4, block one end of the exhaust hole 22 to make it airtight, and use a plug for laser welding sealing or a plug for argon arc welding to form a sealing plug 28; inject a low-boiling point working medium into the exhaust hole 22; the working medium Including but not limited to acetone, R134a.

S5. Under negative pressure, seal the other end of the row hole 22, and use plug laser welding or plug argon arc welding to seal the low-boiling point working medium in the row hole 22 to obtain a plurality of flat heat pipes. The flat plate heat pipe layer 18;

S6, a porous medium layer 26 is provided on the inner wall surface of the row holes 22 of the flat-plate heat pipe fabrication layer;

S7. End caps 19 are respectively provided at both ends of the cold liquid plate fabrication layer with built-in cooling fins 23, and the end caps 19 are provided with a cooling liquid inlet and a cooling liquid outlet.

Further, in the step S4, the manufacturing method of the porous medium layer 26 includes the following steps:

A1. Insert a pin 21 along the axial direction in the center of each row hole 22, the cross-sectional area of the pin 21 is large enough to leave a gap of 0.5-1mm with the inner wall surface of the row hole 22; insert the pin The aluminum substrate 20 of 21 is placed vertically, and aluminum powder or aluminum alloy powder is filled into the remaining gap of each row of holes 22; the width of the gap is preferably 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm ; The aluminum powder or aluminum alloy powder is filled in the way of natural gravity accumulation, and mechanical vibration can be applied to assist filling, but no mechanical external force is applied to compact, so that the thin layer maintains a high porosity, as shown in Figure 4, The granular material in FIG. 4 is aluminum powder or aluminum alloy powder; the pin 21 is a square pin or a cylindrical pin with a circular cross-section;

A2. Put the aluminum substrate 20 workpiece with the pins 21 inserted and filled with aluminum powder or aluminum alloy powder into the powder metallurgy sintering furnace, continue to vacuumize, and remove oxygen for 50-70min;

A4. After the sintering is completed, it is naturally cooled to normal temperature, and then the pin 21 is pulled out to obtain the porous medium layer 26; the porosity of the obtained sintered porous medium layer 26 is 40-50%;

Further, in the step A1, the porous medium layer 26 is made of aluminum powder or aluminum alloy powder through a powder metallurgy sintering process. The aluminum powder or aluminum alloy powder can be, but not limited to, spherical or nearly spherical particles, and the diameter can be in the range of 1-500 μm. It is preferably in the range of 50-100 μm, and a more uniform particle diameter distribution (that is, a narrower particle diameter distribution range) is selected as much as possible to ensure the porosity and permeability of the porous medium layer 26; non-spherical (irregular shape) ) particles are beneficial to increase the porosity and permeability of the sintered thin layer; the raw material aluminum powder or aluminum alloy powder can be evenly mixed with an appropriate amount of sintering aids, such as tin powder and magnesium powder, and the dosage is 0.1 of the aluminum powder. -1wt%, you can also not use it.

Example 1

As shown in Figures 3-7, a radiator with a composite structure of a flat plate heat pipe and a cooling liquid plate includes a base plate 20, the base plate 20 includes a cooling liquid plate layer and a heat sink disposed on the upper end surface and the lower end surface of the cooling liquid plate layer Two flat heat pipe layers 18 are provided with cooling liquid flow channels 17 in the cooling liquid plate layers. The flat heat pipe layer 18 is used for contacting with electronic components, so as to dissipate heat from the electronic components, and the electronic components are CPU or other electronic components.

Further, the substrate 20 is an aluminum substrate 20 , and the cold liquid plate layer and the flat heat pipe layer 18 are integrally formed. The radiator is a composite radiator having a composite structure of a flat heat pipe and a cooling liquid plate. The cooling liquid plate layer provided with the cooling liquid plate and the flat heat pipe layer 18 provided with the flat heat pipe are integrally arranged.

Further, the flat-plate heat pipe layer 18 is provided with a plurality of row holes 22 arranged in parallel. The inner wall of the row holes 22 is provided with a porous medium layer 26 . Due to the arrangement of the above structure, a plurality of flat plate heat pipes distributed in parallel are formed in the flat plate heat pipe layer 18 .

Further, sealing plugs 28 are provided at both ends of the passage of the row holes 22 , and the sealing plugs 28 are used to seal both ends of the passage of the row holes 22 . The cooling liquid channel 17 is provided with heat dissipation fins 23 to enhance the heat dissipation effect.

The cooling liquid plate in the prior art is shown in Figures 1-2. The cooling liquid plate includes an upper cooling liquid plate 11 and a lower cooling liquid plate 12. The upper cooling liquid plate 11 and the lower cooling liquid plate 12 are fixed by fixing bolts 14. , a cooling liquid cavity 13 and a cooling liquid flow channel 17 are formed between the upper cooling liquid plate 11 and the lower cooling liquid. The heat conduction analysis of the cooling liquid plate in use is as follows: the heat Q generated by the heating element 15 such as (CPU) passes through the thermal conductive adhesive layer 16, and then from the thermal conductive adhesive layer 16 (silicone film) to the cooling liquid plate (including the upper cooling liquid plate 11). and the lower cooling liquid plate 12), and then from the cooling liquid plate to the cooling liquid, the cooling liquid plate is an aluminum plate, and the thermally conductive adhesive layer 16 is a silicone grease film. The heat dissipation effect of the above cooling liquid plate needs to be improved.

The present invention is an integrated radiator combining a flat heat pipe and a cooling liquid plate, and is used for ultra-high power density and densely arranged electronic components, such as CPU and circuit board temperature control in a supercomputing center cabinet. By increasing the effective heat transfer area between the cooling liquid and the cooling liquid plate, the heat transfer and heat dissipation effect of the cooling liquid plate is improved. A solution for the integration of the flat heat pipe and the cooling liquid plate is proposed. Theoretical estimation shows that the heat transfer resistance can still be reduced to around 0.01K·W ^-1 under the condition of greatly reducing the coolant flow rate. The heat transfer density can be guaranteed up to 70W·cm ^-2 .

Calculation of the mass flow rate of water: The heat generated by a CPU is 500W (ie 500J/s), which must be equal to the heat taken away by the flowing water, in order to stabilize the temperature of the CPU from rising.

where Q is the heating power of the CPU,

is the mass flow rate of water, c _p is the specific heat capacity of water (=4.2J·g ^-1 ·K ^-1 ), ΔT is the temperature rise of water, and the temperature rise range of water intake is 5K, for example, from 20°C to 25°C, the above calculation It shows that the mass flow rate of cooling water is 24 grams per second, which can meet the CPU temperature control requirements.

Assuming that the cross-sectional area of the cooling liquid channel 17 of the cooling liquid plate is 10cm×0.5cm=5cm ² , the required flow rate of cooling water is

In the formula, ρ is the density of the cooling water (1 g·cm ⁻³ ), and S is the cross-sectional area (5 cm ² ) of the cooling liquid flow channel 17 of the cooling liquid plate. It can be seen that within this flow velocity range, the flow is laminar flow. The low flow rate can effectively reduce the energy consumption required to pump the cooling water.

In this embodiment, the radiator is provided with three layers, the uppermost layer and the lowermost layer are both flat heat pipe layers 18, the flat heat pipe layer 18 is provided with a plurality of row holes 22, and the row holes 22 are built with a porous medium layer 26, and the porous medium The layer 26 constitutes a liquid-absorbing wick built into the drain hole 22, and the flat-plate heat pipe layer 18 contacts the electronic heating element 15 (such as the CPU) to transmit the heat generated by it; 17. The heat transmitted through the plate heat pipe is taken away by the cooling liquid. The composite heat sink is made of metal with good thermal conductivity (such as aluminum or aluminum alloy).

Further, a plurality of cooling liquid flow channels 17 arranged in parallel are arranged in the cooling liquid plate layer, and the row holes 22 are arranged in parallel with the cooling liquid flow channels 17 . Both ends of the cooling liquid plate layer are provided with end caps 19, the end caps 19 are provided with a cooling liquid inlet and a cooling liquid outlet, and a distributor is arranged in the cooling liquid inlet.

In this embodiment, the cooling liquid plate layer is set as an intermediate layer, and the cooling liquid plate layer is provided with many parallel cooling liquid flow sub-chambers, and a plurality of cooling liquid flow channels 17 are formed, which serve as the equivalent of the cooling fins 23. It can cover the entire area where the flat plate heat pipe is located, that is, the effective heat transfer area of the cooling liquid plate to the cooling liquid is enlarged. As shown in Figure 6 and Figure 7. Both ends of the radiator are provided with end caps 19 and liquid inlet and outlet ports for the inflow and outflow of the cooling liquid, and the cooling liquid is evenly distributed into the cooling liquid flow channel 17 through the distributor.

Example 2

The difference between this embodiment and Embodiment 1 is that, as shown in FIGS. 8-9 , a heat sink with a composite structure of a flat plate heat pipe and a cooling liquid plate includes a base plate 20, and the base plate 20 includes a cooling liquid plate layer and A flat heat pipe layer 18 is arranged on the lower end face of the cooling liquid plate layer, and cooling liquid flow channels 17 are arranged in the cooling liquid plate layer. In this embodiment, the radiator is provided with two layers, one is the flat heat pipe layer 18, the flat heat pipe layer 18 is provided with a plurality of row holes 22, the row holes 22 have a built-in porous medium layer 26, and the porous medium layer 26 constitutes a built-in In the liquid absorbing core in the discharge hole 22, the flat heat pipe layer 18 contacts with the electronic heating element 15 (such as the CPU) to transmit the heat generated by it; The liquid removes the heat transferred through the flat heat pipe. The composite heat sink is made of metal with good thermal conductivity (such as aluminum or aluminum alloy).

Example 3

In this embodiment, the above-mentioned manufacturing method of the radiator with the composite structure of the flat heat pipe and the cooling liquid plate includes the following steps:

S1. Using pure aluminum as a material, an aluminum substrate 20 is produced by an extrusion molding method, and the aluminum substrate 20 includes a cold liquid plate fabrication layer and a flat heat pipe fabrication layer; the aluminum substrate 20 is a three-layer substrate 20 structure;

S2. A plurality of holes 22 are arranged in the production layer of the flat heat pipe; the holes 22 constituting the flat heat pipe are square holes, the size of which is 2×2 mm ² /piece, and the number of holes 22 is determined by the flat heat pipe layer. The width of 18 determines that the length and width of the flat heat pipe are larger than the size of the heating element 15 such as the CPU, so as to increase the effective heat transfer area;

S3, a porous medium layer 26 is provided on the inner wall surface of the row holes 22 of the flat-plate heat pipe fabrication layer;

S4. Block one end of the exhaust hole 22 to make it airtight, and use the plug to seal by laser welding to form a sealing plug 28; inject a low-boiling-point working medium into the exhaust hole 22; the working medium is acetone.

S5, under negative pressure, seal the other end of the row hole 22, and use plug laser welding to seal the low-boiling point working medium in the row hole 22 to obtain a flat plate heat pipe layer 18 including a plurality of flat plate heat pipes;

A1. Insert a pin 21 in the center of each row of holes 22 along the axial direction, and the cross-sectional area of the pin 21 is sized to leave a gap of 0.6 mm with the inner wall surface of the row of holes 22; insert the pin 21 The aluminum substrate 20 is placed vertically, and the above-mentioned aluminum powder is filled in the remaining gaps of each row of holes 22; the aluminum powder is filled in the way of natural gravity accumulation, and mechanical vibration is applied to assist the filling;

A2. Put the aluminum substrate 20 workpiece into which the pins 21 have been inserted and filled with aluminum powder or aluminum alloy powder into the powder metallurgy sintering furnace, continue to vacuumize, and remove oxygen for 60 minutes;

A3. Fill the sintering furnace with nitrogen, and the partial pressure of moisture in the nitrogen atmosphere is 0.01kPa; heat the sintering furnace at a heating rate of 6 °C/min until 580 °C; keep it in a nitrogen protective atmosphere for at least 1h;

A4. After the sintering is completed, it is naturally cooled to normal temperature, and then the pin 21 is pulled out to obtain the porous medium layer 26; the porosity of the obtained sintered porous medium layer 26 is 46%;

Further, in the step A1, the porous medium layer 26 is made of aluminum powder through a powder metallurgy sintering process. The aluminum powder is spherical or approximately spherical particles, and the diameter is in the range of 50-100 μm;

The rest of the content of this embodiment is similar to that of Embodiment 1, and will not be repeated here.

Example 4

S1, using aluminum alloy as a material, an aluminum substrate 20 is made by means of precision casting, and the aluminum substrate 20 includes a cold liquid plate fabrication layer and a flat-plate heat pipe fabrication layer; the aluminum substrate 20 can be a two-layer substrate 20 structural schematic diagram;

S2. A plurality of holes 22 are arranged in the production layer of the flat heat pipe; the holes 22 constituting the flat heat pipe are square holes, the size of which is controlled at 3×3mm ² /piece; the number of holes 22 is determined by the flat heat pipe layer The width of 18 is determined. The length and width of the flat heat pipe are usually larger than the size of the heating element 15 such as the CPU, in order to increase the effective heat transfer area;

S4, block one end of the exhaust hole 22 to make it airtight, and use a plug for laser welding sealing or a plug for argon arc welding to form a sealing plug 28; inject a low-boiling point working medium into the exhaust hole 22; the working medium is R134a.

S5. Under negative pressure, seal the other end of the row hole 22, and seal the low-boiling point working medium in the row hole 22 by plugging argon arc welding to obtain a flat plate heat pipe layer 18 including a plurality of flat plate heat pipes. ;

A1. Insert a pin 21 in the center of each row of holes 22 along the axial direction, and the cross-sectional area of the pin 21 is sized to leave a gap of 0.5mm with the inner wall of the row of holes 22; insert the pin 21 The aluminum substrate 20 is placed vertically, and the above-mentioned aluminum-aluminum alloy powder is filled into the remaining gaps of each row of holes 22 to form a thin layer of porous medium; the aluminum alloy powder is filled in the way of natural gravity accumulation, and mechanical vibration can be applied. Auxiliary filling, but compaction without applying mechanical external force, so that the thin layer of porous medium maintains a high porosity;

A2. Place the workpiece of the aluminum substrate 20 that has been inserted into the pin 21 and filled with aluminum alloy powder into the powder metallurgy sintering furnace, and continue to vacuumize and remove oxygen for 70 minutes;

A3. Fill the sintering furnace with nitrogen, and the partial pressure of moisture in the nitrogen atmosphere is 0.02kPa; heat the sintering furnace at a heating rate of 5°C/min until it reaches 560°C; keep it in a nitrogen protective atmosphere for 1h;

A4. After the sintering is completed, it is naturally cooled to room temperature, and then the pin 21 is pulled out to obtain the porous medium layer 26; the porosity of the obtained sintered porous medium layer 26 is 42%;

Further, in the step A1, the aluminum alloy powder of the porous medium layer 26 is made by a powder metallurgy sintering process, and the aluminum alloy powder is spherical or approximately spherical particles with a diameter in the range of 50-100 μm, The alloy powder is evenly mixed with an appropriate amount of sintering aid, the sintering aid is composed of tin powder and magnesium powder according to a weight ratio of 1:1, and the addition amount of the sintering aid is 1 wt % of the aluminum alloy powder.

The rest of the content of this embodiment is similar to that of Embodiment 2, and will not be repeated here.

Example 3

S2. A plurality of holes 22 are arranged in the production layer of the flat heat pipe; the holes 22 constituting the flat heat pipe are circular holes with a diameter of 3 mm, and the number of holes 22 is determined by the width of the flat heat pipe layer 18. The length and width are larger than the size of the heating element 15 such as the CPU, so as to increase the effective heat transfer area;

S7. End caps 19 are respectively provided at both ends of the cooling liquid plate manufacturing layer with built-in cooling fins 23, and the end caps 19 are provided with a cooling liquid inlet and a cooling liquid outlet.

A1. Insert a pin 21 in the center of each row hole 22 along the axial direction, and the cross-sectional area of the pin 21 is sized to leave a gap of 1 mm with the inner wall surface of the row hole 22;

A2. Put the aluminum substrate 20 workpiece into which the pins 21 have been inserted and filled with aluminum powder or aluminum alloy powder into the powder metallurgy sintering furnace, continue to vacuumize, and remove oxygen for 70 minutes;

A3. Fill the sintering furnace with nitrogen, and the partial pressure of moisture in the nitrogen atmosphere is 0.001kPa; heat the sintering furnace at a heating rate of 8°C/min until it reaches 600°C; keep it in a nitrogen protective atmosphere for at least 1h;

A4. After the sintering is completed, it is naturally cooled to normal temperature, and then the pin 21 is pulled out to obtain the porous medium layer 26; the porosity of the obtained sintered porous medium layer 26 is 49%;

The rest of the content of this embodiment is similar to that of Embodiment 3, and will not be repeated here.

When the radiator of the present invention is used, the working principle is as follows:

Taking a radiator with a two-layer structure as an example, as shown in FIG. 9; the substrate 20 is an aluminum substrate 20, and a layer of aluminum-based powder metallurgy sintered porous medium is attached to the inner wall of the row of holes 22 of the aluminum-based flat heat pipe layer 18 to form a porous In the medium layer 26, a steam channel 27 is formed in the middle of the pipe of the row hole 22. The aluminum-based powder metallurgy sintered porous medium layer 26 is also called a liquid absorbing core, and its inner pores are connected to each other; the heat pipe contains a low-boiling-point working medium, and the inside of the pipe is in a negative pressure state. When the heat pipe works, at the heat source position, the working medium evaporates and boils, absorbs the latent heat of evaporation, and flows to the cold end along the steam passage 27 . The steam condenses and separates out at the cold end, releasing the latent heat of condensation; and then quickly returns to the location of the heat source through the capillary action of the wick. The radiator forms a condensation zone 24 and an evaporation zone 25 . The heat transported by the evaporation and condensation of the working fluid and its speed make the heat pipe have a thermal conductivity more than 10 times higher than that of a homogeneous metal conductor. The temperature difference of the heat pipe from the heat source (evaporating end) to the cold source (condensing end) is less than 0.1K, that is, the entire flat heat pipe has excellent temperature uniformity.

Since the flat heat pipe is integrated with the cooling liquid plate, for the cooling liquid (ie, the cooling source), this characteristic makes the heat transfer area from the high temperature heat source to the low temperature heat source from the position of the CPU (ie the dashed box in Figure 6). , extended to the position where the whole plate heat pipe is located, as shown in FIG.

Generally, a hollow heat pipe without a wick must be inclined at a certain angle during use. The heat source is at the lower end and the cold source is at the upper end. The condensed wages rely on gravity to return to the heat source. However, the flat heat pipe with the liquid-absorbing core of the present application can automatically return from the cold source end to the heat source end by means of capillary action, thereby forming an internal circulation of the working medium, and the heat pipe can work normally regardless of whether it is placed flat or at any angle.

The cooling liquid plate layer is provided with a plurality of parallel cooling liquid flow channels 17, and the discharge holes 22 are arranged in parallel with the cooling liquid flow channels 17; It is used for the inflow and outflow of the cooling liquid, and evenly distributes the cooling liquid to the cooling liquid flow channel 17 .

When used as a radiator, the flat heat pipe is in close contact with the high-density power heating device. The heat is transferred from the heating element 15 to the flat heat pipe, from the flat heat pipe to the cooling liquid, and then brought to the outside by the cooling liquid. After cooling, the coolant is pumped back to the coolant plate for circulation.

Through the arrangement of the above structure, the heat transfer from the electronic heating element 15 to the cooling liquid is strengthened, thereby reducing the thermal resistance from the heat source to the cooling source. It can be seen that the present invention is not intended to strengthen the connection between the CPU and the cooling liquid plate. The heat transfer and the reduction of the thermal resistance R ₁ enhance the heat transfer between the cooling liquid plate and the cooling liquid, that is, the R ₃ in the above calculation is reduced in a targeted manner.

The present invention adopts the above-mentioned cold liquid plate radiator, and the heat transfer effect from the cold liquid plate to the cooling liquid will be greatly improved (theoretical calculation, the thermal resistance of the cold liquid plate without heat pipes is 0.0842K·W ^-1 , and the heat transfer with embedded heat pipe arrays is 0.0842K·W -1 . The cooling liquid plate, that is, the thermal resistance of the radiator in this application is 0.03-0.04K·W ^-1 , which is about 50% of the original thermal resistance); due to the increase in the actual heat transfer effect, the size of the cooling liquid plate can be adjusted from the original one. The size of the circuit board is reduced to a size that is roughly equal to or slightly larger than the CPU, and the length is comparable to the circuit board, which is reduced to about 1/3 of the original cooling plate.

The above-mentioned embodiment is the preferred implementation scheme of the present invention, in addition, the present invention can also be realized in other ways, and any obvious replacement under the premise of not departing from the inventive concept is all within the protection scope of the present invention.

Claims

A radiator with a composite structure of a flat plate heat pipe and a cooling liquid plate, characterized in that it includes a base plate, and the base plate includes a cooling liquid plate layer and a flat plate heat pipe layer disposed on the upper end face and/or the lower end face of the cooling liquid plate layer , a cooling liquid flow channel is arranged in the cooling liquid plate layer.
A radiator with a composite structure of a flat heat pipe and a cooling liquid plate according to claim 1, wherein a plurality of parallel holes are arranged in the flat heat pipe layer.
A radiator with a composite structure of a flat heat pipe and a cooling liquid plate according to claim 2, characterized in that: the inner wall of the row of holes is provided with a porous medium layer.
A radiator with a composite structure of a flat plate heat pipe and a cooling liquid plate according to claim 2, wherein sealing plugs are provided at both ends of the perforation channel.
A radiator with a composite structure of a flat heat pipe and a cooling liquid plate according to claim 2, wherein a plurality of cooling liquid flow channels arranged in parallel are arranged in the cooling liquid plate layer, and the row holes are arranged in parallel with each other. The coolant passages are arranged in parallel.
A radiator with a composite structure of a flat heat pipe and a cooling liquid plate according to claim 5, wherein both ends of the cooling liquid plate layer are provided with end caps, and the end caps are provided with a cooling liquid inlet and coolant outlet.
A radiator with a composite structure of a flat plate heat pipe and a cooling liquid plate according to claim 1, wherein the substrate is an aluminum substrate, and the cooling liquid plate layer and the flat plate heat pipe layer are integrally formed.
A method for manufacturing a radiator with a composite structure of a flat heat pipe and a cooling liquid plate as claimed in claim 3, wherein the method comprises the following steps:

S1. Use pure aluminum or aluminum alloy as a material to make an aluminum substrate, and the aluminum substrate includes a cold liquid plate production layer and a flat heat pipe production layer;

S2. A plurality of rows of holes are arranged in the production layer of the flat-plate heat pipe;

S3. A porous medium layer is arranged on the inner wall surface of the row holes of the production layer of the flat heat pipe;

S4. Block one end of the exhaust hole to make it airtight; inject a low-boiling-point working medium into the exhaust hole;

S5, under negative pressure, seal the other end of the row of holes, and seal the low-boiling point working medium in the row of holes to obtain a flat-plate heat pipe layer including a plurality of flat-plate heat pipes;

S6, a porous medium layer is arranged on the inner wall surface of the row holes of the flat-plate heat pipe fabrication layer;

S7. End caps are respectively provided at both ends of the cold liquid plate fabrication layer, and the end caps are provided with a cooling liquid inlet and a cooling liquid outlet.
A radiator with a composite structure of a flat heat pipe and a cooling liquid plate according to claim 8, characterized in that: in the step S4, the manufacturing method of the porous medium layer comprises the following steps:

A1. Insert a pin into the center of each row of holes. The cross-sectional area of the pin is set to leave a gap of 0.5-1mm with the inner wall of the row of holes after insertion; the aluminum substrate into which the pin is inserted is vertical Place, fill the remaining gaps of each row of holes with aluminum powder or aluminum alloy powder;

A2. Put the aluminum substrate workpiece with inserted pins and filled with aluminum powder or aluminum alloy powder into the powder metallurgy sintering furnace, and continue to vacuumize to remove oxygen;

A3. Fill the sintering furnace with nitrogen, heat up in a nitrogen protective atmosphere, and heat the sintering furnace for sintering;

A4. After the sintering is completed, it is naturally cooled to normal temperature, and then the pin is pulled out to obtain a porous medium layer.
A radiator with a composite structure of a flat heat pipe and a cooling liquid plate according to claim 1, characterized in that: in the step A3, the partial pressure of moisture in the nitrogen atmosphere is 0.001-0.02kPa; The heating rate of /min heats the sintering furnace until 560-600 ° C; maintains it for at least 1 h in a nitrogen protective atmosphere.