A radial microchannel heat sink and heat dissipation system with a manifold structure

Abstract

The present invention relates to the technical field of heat dissipation packaging for semiconductor devices, and discloses a radial microchannel heat sink and a heat dissipation system with a manifold structure. It includes a radially microchannel cold plate layer, an annular manifold layer, a first fluid distribution layer, a second fluid distribution layer, and a cover plate stacked in sequence. The connection surfaces of each layer are sealed, and a cooling medium inlet and a cooling medium outlet are provided on the cover plate; with the manifold radial microchannel structure, the present invention adds a manifold layer and a fluid distribution layer to the radial microchannels, which helps to more evenly distribute the fluid and obtain a lower pressure drop. At the same time, it retains the characteristic of uniform circumferential flow distribution of the radial microchannel structure, realizes a more uniform temperature distribution and lower pump power consumption, improves the heat dissipation performance, and meets the growing heat dissipation requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation packaging for semiconductor devices, and particularly relates to a radial microchannel heat sink and a heat dissipation system with a manifold structure. Background Art

[0002] With the miniaturization and integration of power electronic devices, the power density and heat flux density of devices and modules are continuously increasing, and traditional cooling solutions cannot meet the growing heat dissipation requirements. Since the concept of microchannel liquid cooling was proposed, scholars have carried out various optimizations on the microchannel structure on this basis to obtain better heat dissipation performance and lower pressure drop.

[0003] The most widely used type of microchannel is the straight microchannel, whose structural feature is that straight microchannels are distributed in parallel. Another commonly used type of microchannel is the radial microchannel, whose structural feature is that the channels are radially distributed from the center outwards and have central symmetry. Compared with the straight microchannel, the fluid distribution of the radial microchannel is more uniform, and on the premise of the same cold plate size, the inlet and outlet pressure drop can be reduced by more than half. The common disadvantage of both microchannel structures is that due to the small size of the microchannel structure, the pressure loss is large. In addition, since heat exchange occurs between the fluid and the wall during the flow process, the fluid temperature rises, and the heat transfer deterioration in the downstream causes temperature non-uniformity.

[0004] Due to the problem of heat transfer deterioration in the downstream, the temperature distribution of the radial microchannel shows the characteristic of low in the middle and high around. The peripheral area is the high-temperature point, and the temperature difference between the central area and the peripheral area can reach dozens of degrees Celsius, and the temperature uniformity in the radial direction is poor. In addition, the size of the channel determines that the inlet and outlet pressure drop is large, consuming more pump power. These disadvantages limit the application of the radial microchannel structure in single-phase liquid cooling and other aspects, and the advantages of the radial microchannel structure cannot be fully utilized. In the field of semiconductor heat dissipation packaging, the application of the radial microchannel is limited to two-phase flow boiling.

[0005] The specific surface area of the microchannel structure is large, so the contact area between the coolant and the heat source is large, and heat can be effectively transferred. However, the flow channel of the microchannel is tiny, the flow resistance of the fluid is large, and the pressure drop is large, resulting in an increase in system energy consumption. To solve this problem, a manifold structure is introduced into the straight microchannel to shorten the fluid flow distance and optimize the fluid distribution to obtain better temperature uniformity and lower pressure drop. Some scholars have proposed a manifold straight microchannel structure. The introduction of the manifold structure shortens the fluid flow distance, thereby reducing the pressure drop. In addition, the manifold structure makes the fluid distribution more uniform, which is beneficial to improving the temperature uniformity.

[0006] In a radial microchannel, the channel naturally expands gradually. When it is applied to two-phase flow boiling, it can suppress flow instability and countercurrent phenomena. However, due to the fact that the fluid flow in the radial microchannel radiates from the center to the outside, the flow velocity in the central region is relatively high, while the flow velocity in the peripheral region is relatively low, resulting in an obvious temperature difference between the central and peripheral regions. In addition, the large flow resistance is also one of the reasons restricting the application potential of the radial microchannel.

[0007] CN111678364A discloses a microchannel heat exchanger. By setting grooves on the side wall of the guide vane and creating a secondary heat exchange channel using the heat exchange space formed by the grooves, the heat exchange efficiency is increased to a certain extent. However, in this patent, due to the viscous force of the working fluid in the microchannel, a huge frictional loss will occur along the flow direction, and the flow loss is very large. This increases the overall energy consumption and affects the operating stability of the heat dissipation device.

[0008] CN118960471A discloses a hierarchical topology microchannel radiator with a low-flow-resistance manifold structure, including a cover layer, a manifold layer, a return layer, and a heat dissipation layer arranged in sequence; the cooling working fluid flows into the manifold layer from the inlet on the heat dissipation layer and the inlet through-hole penetrating the return layer and the manifold layer, and is evenly divided into more than two paths in the flow-dividing manifold structure of the manifold layer. At the end of the flow-dividing manifold structure, it enters the heat dissipation structure on the heat dissipation layer through the jet through-hole and the annular through-hole on the annular boss structure in the return layer, and conducts convective heat transfer in the heat dissipation structure on the heat dissipation layer. Then, it enters the return layer through the return groove in the edge of the heat dissipation structure, and finally flows out through the return through-hole penetrating the return layer and the outlet of the heat dissipation layer; the present invention has the characteristics of low flow resistance, uniform flow distribution, and high heat exchange efficiency. By using topology optimization technology to optimize the design of the flow-dividing manifold structure and the microchannel fin structure, it can effectively realize the heat transport and heat dissipation of high heat flux density electronic devices.

[0009] In summary, although the existing microchannel heat dissipation devices have made certain progress, there are still many deficiencies. Further research and optimization to effectively solve the problems of uneven fluid distribution, reduce pressure drop, and at the same time have a simple manufacturing process and low cost for microchannel heat dissipation devices have important practical significance. Summary of the Invention

[0010] Aiming at the disadvantages of large temperature difference between the center and the periphery and large pressure drop at the inlet and outlet of the radial microchannel, the present invention provides an improved liquid-cooled radiator structure. The heat dissipation device of this structure is conducive to giving full play to the structural potential of the radial microchannel, and its application can be extended to scenarios such as single-phase liquid cooling and low pump power requirements.

[0011] To achieve the above object, the technical solution adopted by the present invention is:

[0012] A radial microchannel radiator with a manifold structure, comprising a microchannel cold plate layer, an annular manifold layer, a first fluid distribution layer, a second fluid distribution layer, and a cover plate stacked in sequence. The connection surfaces of each layer are sealed, and a cooling medium inlet and a cooling medium outlet are provided on the cover plate;

[0013] The second fluid distribution layer is provided with a central radial straight channel; the straight channel is divided into a liquid inlet channel and a liquid outlet channel. The liquid inlet channel is communicated with the cooling medium inlet of the cover plate, and the liquid outlet channel is communicated with the cooling medium outlet of the cover plate;

[0014] The first fluid distribution layer is provided with a central radial circular hole channel; the central radial circular hole channel is radially aligned with the central radial straight channel of the second fluid distribution layer and circumferentially aligned with the channels of the annular manifold layer;

[0015] The inlet annular manifolds and the outlet annular manifolds of the annular manifold layer are arranged alternately; the channel width of the radial microchannel cold plate layer gradually expands along the radial direction.

[0016] The present invention mainly improves the traditional radial microchannel, proposes a manifold radial microchannel structure, adds a manifold layer and a fluid distribution layer to the radial microchannel, which helps to distribute the fluid more evenly and obtain a lower pressure drop. At the same time, it retains the characteristic of uniform circumferential flow distribution of the radial microchannel structure, realizes a more uniform temperature distribution and lower pump power consumption, improves the heat dissipation performance, and meets the growing heat dissipation requirements.

[0017] The end of the straight channel of the second fluid distribution layer is connected to a circular cavity, and the circular cavity is vertically aligned with the cooling medium inlet and outlet of the cover plate layer. This circular cavity can help distribute the fluid from the circular cooling medium inlet and outlet on the cover plate into the second fluid distribution layer.

[0018] The liquid inlet channels and the liquid outlet channels in the straight channel of the second fluid distribution layer are arranged alternately, and all the liquid inlet channels converge at the center.

[0019] A pin fin array is provided in the central region of the radial microchannel cold plate layer in the radial microchannel radiator to enhance the heat dissipation effect in the central region.

[0020] The hole diameter of the circular hole channel of the first fluid distribution layer does not exceed the channel diameter of the annular manifold layer aligned with the circular hole to ensure the separate flow of the inlet and outlet fluids. The circular hole diameter needs to be reasonably set. The upper limit is the width of the corresponding annular manifold in the manifold layer, and the lower limit needs to be reasonably set. Too small a circular hole diameter may lead to uneven fluid distribution and cause too large a flow pressure drop.

[0021] The round hole structure of the first fluid distribution layer is replaced with an annular curved notch, and the width of the notch does not exceed the width of the inlet and outlet manifolds in the annular manifold layer. The interval between the notches on the same ring is greater than the central radial straight channels in the second fluid distribution layer to ensure the discrete flow of the inlet and outlet fluids. Compared with the round hole structure, the annular notch can further enhance the uniform distribution of the fluid.

[0022] The structures of the annular manifold layer, the first fluid distribution layer, and the second fluid distribution layer are precisely optimized to ensure that the fluids maintain strict discreteness during the flow process, avoiding the intersection or short-circuit flow of the inlet fluid and the outlet fluid before entering the microchannel layer.

[0023] The channels of each layer in the radial microchannel heat sink are prepared by machining, additive manufacturing, or micro-nano processing technology.

[0024] The annular manifold layer, the first fluid distribution layer, and the second fluid distribution layer can be directly manufactured as a whole by an integral molding process, such as additive manufacturing or integral milling technology. The integral molding technology can reduce the assembly steps, lower the interfacial thermal resistance, and improve the mechanical stability and thermal management performance.

[0025] The preparation process includes: cleaning to remove impurities on the surface of the substrate, preparing the microchannels by machining, additive manufacturing, or micro-nano processing technology according to the designed microchannel structure and size, and then connecting and forming each layer by pressure silver sintering or bonding technology to obtain the radial microchannel heat sink.

[0026] The first characteristic of this manufacturing method is that for heat dissipation structures with a scale below hundreds of micrometers, micro-nano processing technology can be used to prepare microchannels. Specifically, an etching mask can be obtained through photolithography-sputtering-lift-off, and then deep reactive ion etching or wet etching can be carried out. For materials with high hardness, laser processing can also be used to prepare microchannels.

[0027] The second characteristic of this manufacturing method is that the pressure silver sintering method has higher thermal conductivity, excellent mechanical properties and thermal stability compared with the traditional welding method, and the low-temperature silver sintering can be completed at a lower temperature, reducing the thermal stress of the power device and avoiding the damage caused by high-temperature welding.

[0028] The third characteristic of this manufacturing method is that for the bonding between semiconductor materials such as silicon, bonding methods such as plasma bonding, eutectic bonding, thermocompression bonding, and molecular bonding can be used. Different process means can be selected according to the structure, material, and application scenario of the heat sink.

[0029] The substrates of each layer in the radial microchannel heat sink are made of metal materials or transparent polymer materials, and the channels are made of metal or semiconductor materials; the substrate materials of each layer are the same or different, and the channel materials of each layer are the same or different.

[0030] The metals include metals such as copper and aluminum, alloy materials such as brass, or metal matrix composites such as diamond copper; the semiconductors include any one or more of silicon, silicon carbide, gallium nitride, gallium oxide, or diamond; the transparent materials include one or more of glass, acrylic, and polydimethylsiloxane (PDMS). The use of transparent materials facilitates the observation of the flow of the cooling medium.

[0031] The present invention also provides a radial microchannel heat dissipation system with a manifold structure, including the radial microchannel radiator with the manifold structure described above.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention solves the problems of large temperature difference between the center and the periphery of the radial microchannel radiator and large pressure drop at the inlet and outlet. Through the structure of the annular manifold layer, the fluid is more evenly distributed, achieving a more uniform temperature distribution and lower pump power consumption. Description of the Drawings

[0034] Figure 1 It is a schematic exploded view of the structure of the radial microchannel radiator with the manifold structure in the embodiment.

[0035] Figure 2 It is a front view of the integrally formed annular manifold layer and fluid distribution layer of the radial microchannel radiator with the manifold structure in the embodiment.

[0036] Figure 3 It is a schematic back view of the integrally formed annular manifold layer and fluid distribution layer of the radial microchannel radiator with the manifold structure in the embodiment.

[0037] Figure 4 It is a schematic diagram of the structure of the radial microchannel cold plate layer of the radial microchannel radiator with the manifold structure in the embodiment.

[0038] Figure 5 It is a schematic diagram of the structure of the annular manifold layer of the radial microchannel radiator with the manifold structure in the embodiment.

[0039] Figure 6 It is a schematic diagram of the structure of the first fluid distribution layer of the radial microchannel radiator with the manifold structure in the embodiment.

[0040] Figure 7 It is a schematic diagram of the structure of the second fluid distribution layer of the radial microchannel radiator with the manifold structure in the embodiment.

[0041] Figure 8 It is a schematic diagram of the structure after the radial microchannel cold plate layer and the annular manifold layer of the radial microchannel radiator with the manifold structure in the embodiment are combined.

[0042] Figure 9Schematic diagram of the preparation process flow of the radial microchannel radiator with a manifold structure in the embodiment.

[0043] Figure 10 Schematic diagram of the structure of the traditional radial microchannel radiator in the comparative example.

[0044] Figure 11 Comparison chart of the simulated inlet and outlet pressure drops of the radial microchannel radiator with a manifold structure and the traditional radial microchannel radiator in the application example.

[0045] Figure 12 Comparison chart of the simulated temperature difference on the chip surface between the radial microchannel radiator with a manifold structure and the traditional radial microchannel radiator in the application example.

[0046] Figure 13 Schematic diagram of the replacement structure of the first fluid distribution layer of the radial microchannel radiator with a manifold structure in the embodiment. Detailed implementation manners

[0047] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Those skilled in the art who make modifications or equivalent replacements on the basis of understanding the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall all be covered within the protection scope of the present invention.

[0048] The raw materials used in the following detailed implementation manners are all purchased from the market.

[0049] Embodiment

[0050] As Figures 1 - 3 shown, a radial microchannel radiator with a manifold structure includes a radial microchannel cold plate layer 1, an annular manifold layer 2, a first fluid distribution layer 3, a second fluid distribution layer 4, and a cover plate 5 stacked in sequence. The connection surfaces of each layer are sealed, and a cooling medium inlet and a cooling medium outlet are provided on the cover plate 5; the microchannel cold plate layer uses a copper-based cold plate, the width of the microchannel is 100 microns, the depth is 500 microns, and the total thickness of the cold plate layer is 1 mm.

[0051] As Figures 4 - 7 shown, the second fluid distribution layer 4 is provided with a central radial straight channel, and all the liquid inlet channels converge at the center; the straight channels are divided into liquid inlet channels and liquid outlet channels, and the two are arranged alternately; the liquid inlet channels are communicated with the cooling medium inlet of the cover plate 5, and the liquid outlet channels are communicated with the cooling medium outlet of the cover plate; the end of the straight channel of the second fluid distribution layer 4 is connected to a circular cavity, and the circular cavity is aligned upward with the cooling medium inlet and outlet of the cover plate layer. This circular cavity can help distribute the fluid from the circular cooling medium inlet and outlet on the cover plate into the second fluid distribution layer 4.

[0052] The first fluid distribution layer 3 is provided with a central radial circular hole channel; the central radial circular hole channel is radially aligned with the central radial straight channel of the second fluid distribution layer and circumferentially aligned with the channel of the annular manifold layer; the hole diameter of the circular hole channel of the first fluid distribution layer does not exceed the channel diameter of the annular manifold layer aligned with the circular hole to ensure the separate flow of the inlet and outlet fluids.

[0053] The inlet annular manifolds and the outlet annular manifolds of the annular manifold layer 2 are arranged alternately; the channel width of the radial microchannel cold plate layer 1 gradually expands along the radial direction. As Figure 8 shown, a pin fin array is provided in the central region of the radial microchannel cold plate layer 1 to improve the heat transfer capacity of the central region.

[0054] According to Figure 9 the preparation process, a picosecond laser etching process is used to manufacture the radial microchannel cold plate layer on a copper metal substrate; a milling machine is used to machine a composite integrated substrate of the annular manifold layer, the first fluid distribution layer, and the second fluid distribution layer, with the material being copper, collectively referred to as the fluid distribution layer; first, the central radial straight channel and the circular cavity shown in the second fluid distribution layer are machined on the front surface of the copper sheet, and then the copper sheet is drilled through at the circular hole or annular notch shown in the first fluid distribution layer. Finally, the annular manifold is machined at the manifold position corresponding to the annular manifold layer on the front surface of the copper sheet.

[0055] After the fluid distribution layer and the microchannel layer are manufactured, the metal surface of the radial microchannel cold plate layer is polished, pickled to remove impurities, nano silver paste is printed on the upper surface of the radial microchannel cold plate layer and the bottom surface of the fluid distribution layer, and the device is sintered into one body by a low-temperature silver sintering method. Finally, the glass cover plate and the device are sealed with a silicone gasket.

[0056] The present invention mainly improves the traditional radial microchannel by adding a manifold layer and a fluid distribution layer. After the fluid enters from the cooling medium inlet of the cover plate, it passes through the liquid inlet channel of the second fluid distribution layer 4, is distributed into the first fluid distribution layer 3 and then into the annular manifold layer 2. The fluid expands in the annular manifold layer 2, moves downward into the radial microchannel cold plate layer 1, then flows along the radial microchannel, moves to the lower part of the outlet annular manifold layer 2, moves upward to the outlet of the annular manifold layer, passes through the first fluid distribution layer 3 to the second fluid distribution layer 4 for collection and flows out from the cooling medium outlet of the cover plate 5.

[0057] Comparative Example

[0058] According to the above preparation process, prepare Figure 10 the radial microchannel cold plate shown, combine it with a glass cover plate to obtain a traditional radial microchannel radiator in the prior art, and use it as a comparative example to compare the heat dissipation effect. The microchannel dimensions of the comparative example are the same as those in the embodiment, with the microchannel width being 100 microns and the depth being 500 microns.

[0059] Application Example

[0060] Using the finite element simulation software ANSYS FLUENT, a simulation model was established for the microchannel heat sink prepared according to the examples and comparative examples. During the simulation, a heat flux density was applied to the back of the microchannel layer to simulate the heat generation of the actual chip. The material properties settings of the examples and comparative examples were kept consistent, the simulation models were kept consistent, the mass flow rate of the inlet cooling medium was kept consistent, and the size and heat flux density of the simulated heat source were kept consistent. The temperature difference on the chip surface was the difference between the highest temperature and the lowest temperature of the heat source surface. The pressure drop between the inlet and outlet was the difference between the average pressure at the inlet and the average pressure at the outlet.

[0061] The results are as Figures 11 - 12 , in the present invention, the radial microchannel heat sink with a manifold design has significantly lower pressure drop between the inlet and outlet and temperature difference on the chip surface than the traditional radial microchannel heat sink.

[0062] In the present invention, the second fluid distribution layer can also be replaced with an annular curved notch as Figure 13 shown, or other similar structures for fluid distribution.

[0063] Figure 1 The cover plate shown in has four inlets and four outlets. The cover plate can also further distribute the fluid to combine the four inlets and outlets into one inlet and one outlet or any number of inlets and outlets. An inlet can also be provided at the center of the cover plate, which is aligned upward with the position where all the inlet ports in the second fluid distribution layer converge at the center.

Claims

1. A radial microchannel radiator with a manifold structure, characterized in that It includes a radially microchannel cold plate layer, an annular manifold layer, a first fluid distribution layer, a second fluid distribution layer and a cover plate which are stacked in sequence. The connection surfaces of each layer are sealed. The cover plate is provided with a cooling medium inlet and a cooling medium outlet. The second fluid distribution layer is provided with a central radially straight channel. The straight channel is divided into a liquid inlet channel and a liquid outlet channel. The liquid inlet channel communicates with the cooling medium inlet of the cover plate, and the liquid outlet channel communicates with the cooling medium outlet of the cover plate. In the straight channel of the second fluid distribution layer, the liquid inlet channels and the liquid outlet channels are arranged alternately, and all the liquid inlet channels converge at the center. The end of the straight channel of the second fluid distribution layer is connected to a circular cavity, and the circular cavity is aligned upward with the cooling medium inlet and outlet of the cover plate layer. The first fluid distribution layer is provided with a central radially circular hole channel. The central radially circular hole channel is radially aligned with the central radially straight channel of the second fluid distribution layer and circumferentially aligned with the channels of the annular manifold layer. The inlet annular manifolds and the outlet annular manifolds of the annular manifold layer are arranged alternately. The channel width of the radially microchannel cold plate layer gradually expands along the radial direction. A pin fin array is provided in the central area of the radially microchannel cold plate layer in the radially microchannel radiator.

2. The radial microchannel heat sink of the manifold structure according to claim 1, wherein, The hole diameter of the circular hole channel of the first fluid distribution layer does not exceed the channel diameter of the annular manifold layer aligned with the circular hole.

3. The radial microchannel radiator of the manifold structure according to claim 1, wherein The circular hole structure of the first fluid distribution layer is replaced with an annular curved notch. The notch width does not exceed the width of the inlet and outlet manifolds in the annular manifold layer, and the interval between the notches on the same circle is greater than the central radially straight channel in the second fluid distribution layer.

4. The radial microchannel radiator of the manifold structure according to claim 1, wherein The channels of each layer in the radially microchannel radiator are prepared by machining, additive manufacturing or micro-nano processing technology.

5. The radial microchannel radiator of the manifold structure according to claim 1, wherein, The substrates of each layer in the radially microchannel radiator are made of metal materials or transparent polymer materials, and the channels are made of metal or semiconductor materials. The substrate materials of each layer are the same or different, and the channel materials of each layer are the same or different.

6. The radial microchannel heat sink of the manifold structure according to claim 5, characterized in that, The metal includes elemental metal, alloy material or metal matrix composite material. The semiconductor includes any one or more of silicon, silicon carbide, gallium nitride, gallium oxide or diamond. The transparent polymer material includes one or more of glass, acrylic, polydimethylsiloxane.

7. A radial microchannel heat dissipation system for a manifold structure, characterized in that, A radially microchannel radiator including the manifold structure according to any one of claims 1-6.

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