Phase change heat dissipation device capable of rapidly eliminating local hot spots and preparation method of phase change heat dissipation device

Abstract

The invention discloses a phase change heat dissipation device capable of rapidly eliminating local hot spots and a preparation method thereof, and belongs to the technical field of electronic chip heat management. The phase change heat dissipation device comprises an upper bottom plate and a lower bottom plate, and the peripheries of the upper bottom plate and the lower bottom plate are welded and sealed. A plurality of hydrophilic arrow-sagittal series-connection grooves are formed in the binding surface of the upper bottom plate, and hydrophobic layers are arranged at other positions, so that a liquid absorption core is formed and used for transporting a liquid working medium; a hydrophilic rapid evaporation area is arranged on the binding surface of the lower bottom plate at the hot spot, and a super-hydrophilic common evaporation area is arranged at the other positions of the binding surface of the lower bottom plate. A working medium is condensed at the hydrophobic layer, is transported to the rapid evaporation area through the arrow-shaped series-connection grooves, and is further diffused to the common evaporation area, so that rapid response at a hot spot is realized, the working medium is uniformly distributed on the whole surface to absorb heat, and the overall heat dissipation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic chip thermal management, and in particular to a phase change heat dissipation device for rapidly eliminating local hot spots and a preparation method thereof. Background Art

[0002] With the continuous improvement of electronic chip performance and miniaturization, the chips show higher and higher heat flux density, and local hot spots will form in the core area under high load operation. The common heat dissipation method is mainly to accelerate the removal of heat by lowering the average temperature of the chip, but the heat at the hot spot needs to be transferred to the surface of the chip before it can be removed, which limits the energy density and main frequency of the chip to a certain extent. Moreover, if the local hot spot of the chip is in a high temperature state for a long time, it will cause the thermal stress inside the chip to increase, causing problems such as cracking of the chip package and melting of the solder, reducing the reliability of the chip. Therefore, it is necessary to design a heat dissipation system that can quickly eliminate local hot spots and regulate the surface temperature of electronic chips.

[0003] Phase change cooling is a heat dissipation method that uses a substance to absorb or release a large amount of heat during a phase change process. It is widely used in the thermal management of micro devices such as electronic chips. However, with the trend of miniaturization of chip integrated circuits, phase change cooling devices are limited by size and structure, and the heat dissipation effect is limited. It is necessary to design a more efficient phase change cooling system, and the system has the advantages of high heat dissipation efficiency and lightweight. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a phase change heat dissipation device and method for quickly eliminating local hot spots. The device can respond quickly at the hot spot and evenly distribute the heat to the entire surface to absorb, thereby improving the overall heat dissipation efficiency.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0006] A phase change heat dissipation device for rapidly eliminating local hot spots comprises an upper base plate and a lower base plate, wherein the edges of the upper base plate and the lower base plate are sealed and connected, the lower base plate is connected to the surface of a heat source as an evaporation plate, the docking area between the lower base plate and the high-temperature point of the heat source is a hot spot, the upper base plate is used as a condensation plate, a steam chamber is formed by evacuating the upper and lower base plates, a liquid working medium is poured into the steam chamber, at least four arrow-shaped series grooves with topological distribution are arranged on the lower surface of the upper base plate, the arrow-shaped series grooves start from different edges of the lower surface of the upper base plate, and finally converge at a position corresponding to the hot spot, the arrow-shaped series grooves are formed by connecting a plurality of arrow-shaped groove units in series, the tail end and the tip end of the arrow-shaped groove unit close to the edge of the lower surface of the base plate are narrower than the tail end and the tip end of the arrow-shaped groove unit far from the edge of the lower surface of the base plate, and the tip direction of each arrow-shaped groove unit points to the edge of the lower surface of the upper base plate.

[0007] To optimize the above technical solutions, the specific measures taken also include:

[0008] The lower surface of the upper base plate is a hydrophilic-hydrophobic composite surface, the arrow-shaped serial grooves present hydrophilic characteristics, and the remaining area presents hydrophobic characteristics.

[0009] The tip wedge angle of the arrow-shaped series grooves is 1-3°, and the length of a single arrow-shaped groove unit is 5-15 mm.

[0010] The distribution of arrow-shaped series grooves is topologically optimized according to the hot spot position. The topological optimization design follows the following principles: the four arrow-shaped series grooves start from the four corner points of the upper base plate respectively, and the end point is the center position of the lower surface of the upper base plate. The optimization goal is to make the longest path for the liquid working medium in the arrow-shaped series grooves to reach the hot spot position as short as possible.

[0011] A rapid evaporation zone is set at the hot spot on the upper surface of the lower base plate, and a normal evaporation zone is constructed at the rest of the upper surface. The upper surface of the base plate is a super hydrophilic surface, and the hydrophilicity of the rapid evaporation zone is lower than that of the normal evaporation zone.

[0012] The fast evaporation zone is provided with a fast evaporation zone spherical microstructure array, the array spacing is 50-80μm, the height of the spherical microstructure in the fast evaporation zone is 20-30μm, and the radius is 40-60μm. The ordinary evaporation zone is provided with a ordinary evaporation zone spherical microstructure array, the array spacing is 10-50μm, the height of the spherical microstructure in the ordinary evaporation zone is 10-20μm, and the radius is 20-40μm.

[0013] After the upper bottom plate and the lower bottom plate are sealed and connected, the arrow-shaped serial grooves serve as a liquid absorption core and are enclosed with the lower bottom plate to form a flow channel for transporting liquid working fluids.

[0014] The upper and lower base plates have the same size and a thickness of 1-5 mm.

[0015] A phase change heat dissipation device for rapidly eliminating local hot spots also includes a liquid working medium injection pipe, which is installed at an injection port, which is opened on an upper base plate or a lower base plate, is a normally closed port, and is connected to a steam chamber.

[0016] A method for preparing a phase change heat dissipation device for quickly eliminating local hot spots comprises the following steps:

[0017] Step S1: applying a hydrophobic coating to the lower surface of the upper base plate;

[0018] Step S2: Milling four arrow-shaped series groove contours at the diagonal line of the lower surface of the upper base plate, and the four arrow-shaped series grooves are connected end to end;

[0019] Step S3: scanning a groove in the longitudinal direction inside the arrow-shaped series groove, removing the hydrophobic coating, and forming a hydrophilic groove by laser high energy treatment;

[0020] Step S4: using a picosecond laser to process a spherical micro-nano structure in the rapid evaporation zone of the lower base plate;

[0021] Step S5: adjusting picosecond laser parameters, changing the scanning interval, scanning speed and scanning speed, and processing a spherical micro-nano structure in the common evaporation area;

[0022] Step S6: align the upper base plate or the lower base plate around the periphery and weld the edges to leave a liquid injection port and a perfusion pipe;

[0023] Step S7: injecting liquid working medium into the steam chamber through the liquid injection pipe, and evacuating the steam chamber to make it in a vacuum state;

[0024] Step S8: first weld and seal the liquid injection tube, and perform secondary degassing, then weld and seal the liquid injection port, remove the liquid injection tube, complete the packaging of the phase change heat dissipation device for quickly eliminating local hot spots, and obtain a phase change heat dissipation device for quickly eliminating local hot spots.

[0025] The beneficial effects of the present invention are:

[0026] (1) The composite arrow-shaped series groove pattern on the upper base plate can quickly transport the liquid working medium to the hot spot without a pump, and utilize the gas-liquid cycle phase change process of the liquid working medium to take away a large amount of heat within a small temperature change range through liquid evaporation, thereby controlling the local hot spot temperature. This is beneficial to maintaining the stability of the device temperature.

[0027] (2) The large hydrophobic treatment area of ​​the upper base plate provides a large number of nucleation sites for the condensation of the gaseous working fluid, thereby improving the condensation efficiency and preventing the lower base plate from drying up.

[0028] (3) The spherical microstructure of the lower base can reduce the evaporation time of the liquid and improve the heat dissipation efficiency.

[0029] (4) The gradient hydrophilic area of ​​the lower bottom plate can diffuse the liquid working fluid from the fast evaporation area to the normal evaporation area, achieve rapid response at the hot spot, and evenly distribute it on the surface.

[0030] (5) The phase change heat dissipation device has a simple structure and can achieve efficient heat dissipation in a very small space. It does not require external energy input and is highly economical and reliable.

[0031] (6) The preparation method of the phase change heat dissipation device for rapidly eliminating local hot spots of the present invention is simple, with low processing cost and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0033] Figure 2 is a structural schematic diagram of the upper base plate;

[0034] Figure 3 is a structural schematic diagram of the lower base plate;

[0035] Figure 4 This is a scanning electron microscope image of the spherical micro-nanostructure.

[0036] Figure 5 It is a structural schematic diagram of the arrow-shaped series groove pattern.

[0037] Explanation of the reference numerals: upper base plate 1 , arrow-shaped serial grooves 11 , hydrophobic layer 12 , lower base plate 2 , rapid evaporation zone 21 , ordinary evaporation zone 22 . DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0039] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0040] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0041] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or units (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" / "several" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0042] A specific embodiment of the present invention provides a phase change heat dissipation device for rapidly eliminating local hot spots, assuming that the hot spot is located at the center of the heat dissipation device.

[0043] Reference Figures 1 to 5 The phase change heat dissipation device for rapidly eliminating local hot spots comprises an upper base plate 1 and a lower base plate 2, which are welded and sealed around. A plurality of hydrophilic arrow-shaped series grooves 11 are arranged on the bonding surface of the upper base plate 1, and a hydrophobic layer 12 is arranged at the rest of the positions; a hydrophilic rapid evaporation area 21 is arranged at the hot spot on the bonding surface of the lower base plate 2, and a super-hydrophilic ordinary evaporation area 22 is arranged at the rest of the positions.

[0044] like Figure 2 and Figure 5As shown, the upper base plate 1 constructs a hydrophobic coating surface on the bonding surface, which can provide a large number of nucleation sites for the condensation of gaseous working fluids, shorten the nucleation time, and continuously provide liquid working fluids for the lower base plate 2. Subsequently, four hydrophilic arrow-shaped series grooves 11 are processed on the hydrophobic surface according to the hot spot position. The distribution of the grooves is based on the level set topology optimization algorithm, which converts the topology optimization problem into the evolution problem of the level set function. In the optimization process, the dynamic change of the structural boundary is realized by solving the partial differential equation of the level set function, thereby ensuring that the condensed working fluid on the bonding surface can be transported to the hot spot through any position on the nearest arrow-shaped series groove 11. In addition, the arrow-shaped shape gradient and the wetting properties of the pattern affinity and sparseness can provide Laplace pressure and wetting gradient force for the condensed droplets, realizing spontaneous and rapid transport of the working fluid. At the same time, the tip direction of the series arrow shape always points to the periphery of the bonding surface, ensuring that the droplets can only move in one direction to the hot spot.

[0045] like Figure 3 and Figure 4 As shown, the lower base plate 2 is processed into a spherical micro-nano structure rapid evaporation zone 21 at the hot spot, showing a hydrophilic characteristic. After the liquid working medium is transported to the rapid evaporation zone 21 through the arrow-shaped series grooves 11, it will be immediately wicked and spread by the spherical micro-nano structure, and the droplets will be transformed from spherical to thin round cakes, absorbing heat and evaporating in the overheating area; when the droplets are covered with the rapid evaporation zone 21, they will gradually flow to the common evaporation zone 22 of the lower base plate 2. The common evaporation zone 22 is composed of spherical micro-nano structures with smaller spacing and shape sizes, showing super-hydrophilic characteristics, and also showing excellent droplet evaporation performance. The evaporation zone with a gradient hydrophilic design can ensure that there will be no droplet accumulation at the hot spot, resulting in increased thermal resistance and reduced heat dissipation efficiency. In addition, the droplets are spread to the common evaporation zone 22 in time, which can ensure that the thin liquid layer is in contact with a larger surface area of ​​the surface, covering every bubble nucleation site on the surface of the lower base plate 2, while not forming steam aggregation, achieving a rapid response at the hot spot, and evenly distributing it on the surface to absorb heat.

[0046] The method for preparing the phase change heat dissipation device for rapidly eliminating local hot spots comprises the following steps:

[0047] Step S1: The upper base plate 1 is a copper alloy plate with a thickness of 0.5 mm, and a hydrophobic coating is applied to the bonding surface;

[0048] Step S2: using micro-milling to mill four arrow-shaped serial grooves 11 at the diagonal of the mating surface of the upper base plate 1, the four grooves are connected end to end, the length of a single arrow shape is 5 mm, the tip wedge angle is 2°, and the total length of a single arrow-shaped serial groove 11 is 40 mm;

[0049] Step S3: using nanosecond laser direct writing to scan grooves in the arrow-shaped series grooves 11 along the longitudinal direction, removing the hydrophobic coating, and using laser high-energy treatment to form hydrophilic grooves;

[0050] Step S4: the lower base plate 2 is a copper alloy plate with a thickness of 0.5 mm, and a spherical micro-nano structure is processed in the rapid evaporation zone 21 with a central radius of 2 mm by using a picosecond laser. The array spacing is 50 μm, the height of the spherical microstructure is 25 μm, and the radius is 55 μm;

[0051] Step S5: adjusting picosecond laser parameters, changing the scanning pitch, scanning speed and scanning speed, processing a spherical micro-nano structure in the common evaporation area 22, with an array pitch of 10 μm, a height of 15 μm and a radius of 25 μm for the spherical microstructure;

[0052] Step S6: Align the upper and lower bottom plates 2 so that they are placed on all sides, and leave a liquid injection port and a perfusion pipe after welding the edges;

[0053] Step S7: injecting liquid working medium into the closed cavity through the liquid injection pipe, and evacuating the cavity to make it a vacuum state;

[0054] Step S8: First weld and seal the liquid injection tube, and perform secondary degassing, then weld and seal the liquid injection port, remove the liquid injection tube, and complete the packaging of the phase change heat dissipation device that quickly eliminates local hot spots.

[0055] When comparing the heat dissipation effect of the phase change heat dissipation device of the present invention with that of the existing phase change heat dissipation device, the temperature control, heat dissipation efficiency, hot spot response speed, etc. are discussed. The following examples respectively list the test data of the traditional flat plate type, microchannel type phase change heat dissipation device and the device of the present invention in the same chip heating scenario, highlighting the advantages of the present invention in controlling the hot spot temperature, accelerating the heat dissipation speed, etc.

[0056] In the actual test comparison, the phase change heat sink of the present invention was compared with the traditional flat-plate phase change heat sink and the microchannel phase change heat sink. The experiment selected electronic chips of the same model and with constant heat generation power as the heat source to simulate the situation where the chip generates local hot spots under high load operation.

[0057] The experimental results show that within the same test time, the traditional flat-plate phase-change heat sink can reduce the average temperature of the chip to a certain extent, but the temperature at the hot spot is still more than 30°C higher than the average temperature of the chip, which indicates that the heat dissipation effect of the hot spot is poor and it is difficult to quickly eliminate the local hot spot. Although the microchannel phase-change heat sink improves the heat dissipation efficiency to a certain extent, making the hot spot temperature more than 15°C higher than the average temperature of the chip, its structure is complex, the processing cost is high, and the microchannel is easily blocked, which affects the long-term performance.

[0058] In contrast, the phase change heat sink of the present invention shows significant advantages. Under the same test conditions, the temperature at the hot spot is only 5°C-8°C higher than the average temperature of the chip, which can effectively and quickly eliminate local hot spots. This is due to the composite arrow-shaped series groove pattern of the upper base plate, which can quickly transport the liquid working fluid to the hot spot without a pump, and use the gas-liquid cycle phase change process of the liquid working fluid to take away a large amount of heat within a smaller temperature change range; the spherical microstructure of the lower base plate reduces the evaporation time of the liquid, and the gradient-set hydrophilic area diffuses the liquid working fluid from the rapid evaporation zone to the ordinary evaporation zone, achieving a rapid response at the hot spot, and evenly distributing it on the surface to absorb heat. Overall, the phase change heat sink of the present invention far exceeds the existing phase change heat sink in terms of heat dissipation effect, and provides a more efficient solution for thermal management of electronic chips.

[0059] It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solution described in the implementation of the calculation method of the present invention. Ordinary technicians in the field should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effect; as long as the requirements of the calculation method are met, they are all within the protection scope of the present invention.

Claims

1. A phase change heat dissipation device for rapidly eliminating local hot spots, comprising an upper base plate (1) and a lower base plate (2), wherein the upper base plate (1) and the lower base plate (2) are sealed at their edges, the lower base plate (2) serves as an evaporation plate in contact with the surface of a heat source, the butt joint area between the lower base plate (2) and the high temperature point of the heat source is a hot spot, the upper base plate (1) serves as a condensation plate, a steam chamber is formed by evacuating the upper and lower base plates, and a liquid working medium is poured into the steam chamber, wherein the upper and lower base plates are characterized by: The lower surface of the upper base plate (1) is provided with at least four topologically distributed arrow-shaped series grooves (11), the arrow-shaped series grooves (11) starting from different edges of the lower surface of the upper base plate (1) and finally converging at a position corresponding to the hot spot, the arrow-shaped series grooves (11) are formed by a plurality of arrow-shaped groove units connected in series, the tail end and the tip end of the arrow-shaped groove unit close to the edge of the lower surface of the base plate (1) are respectively narrower than the tail end and the tip end of the arrow-shaped groove unit far from the edge of the lower surface of the base plate (1), and the tip end direction of each arrow-shaped groove unit points to the edge of the lower surface of the upper base plate (1).

2. A phase change heat dissipation device for rapidly eliminating local hot spots according to claim 1, characterized in that: The lower surface of the upper base plate (1) is a hydrophilic and hydrophobic composite surface, the arrow-shaped serial grooves (11) present hydrophilic characteristics, and the remaining area presents hydrophobic characteristics.

3. A phase change heat dissipation device for rapidly eliminating local hot spots according to claim 1, characterized in that: The tip wedge angle of the arrow-shaped serial grooves (11) is 1-3°, and the length of a single arrow-shaped groove unit is 5-15 mm.

4. A phase change heat dissipation device for rapidly eliminating local hot spots according to claim 1, characterized in that: The distribution of the arrow-shaped serial grooves (11) is topologically optimized according to the hot spot position, and the topological optimization design follows the following principle: the four arrow-shaped serial grooves (11) start from the four corner points of the upper base plate (1) respectively, and the end point is the center position of the lower surface of the upper base plate (1), and the optimization goal is to make the longest path for the liquid working medium in the arrow-shaped serial grooves (11) to reach the hot spot position as short as possible.

5. A phase change heat dissipation device for rapidly eliminating local hot spots according to claim 1, characterized in that: The upper surface of the lower base plate (2) is provided with a rapid evaporation zone (21) at a hot spot, and the remaining positions of the upper surface are formed into a normal evaporation zone (22). The upper surface of the base plate (2) is a super-hydrophilic surface, and the rapid evaporation zone (21) has a lower hydrophilicity than the normal evaporation zone (22).

6. A phase change heat dissipation device for rapidly eliminating local hot spots according to claim 5, characterized in that: The rapid evaporation zone (21) is provided with a rapid evaporation zone spherical microstructure array, the array spacing is 50-80 μm, the height of the rapid evaporation zone spherical microstructure is 20-30 μm, and the radius is 40-60 μm. The common evaporation zone (22) is provided with a common evaporation zone spherical microstructure array, the array spacing is 10-50 μm, the height of the common evaporation zone spherical microstructure is 10-20 μm, and the radius is 20-40 μm.

7. A phase change heat dissipation device for rapidly eliminating local hot spots according to claim 1, characterized in that: After the upper base plate (1) and the lower base plate (2) are sealed and connected, the arrow-shaped serial grooves (11) serve as a liquid absorption core and are enclosed with the lower base plate (2) to form a flow channel for transporting liquid working fluid.

8. A phase change heat dissipation device for rapidly eliminating local hot spots according to claim 1, characterized in that: The upper base plate (1) and the lower base plate (2) have the same size and a thickness of 1-5 mm.

9. A phase change heat dissipation device for rapidly eliminating local hot spots according to claim 1, characterized in that: It also includes a liquid working medium injection pipe, which is installed on the injection port. The injection port is opened on the upper base plate (1) or the lower base plate (2). The injection port is a normally closed port and is connected to the steam chamber.

10. A method for preparing a phase change heat dissipation device for rapidly eliminating local hot spots, characterized in that: The following steps are involved: Step S1: applying a hydrophobic coating to the lower surface of the upper base plate (1); Step S2: Milling four arrow-shaped serial grooves (11) at the diagonal of the lower surface of the upper base plate (1), wherein the four arrow-shaped serial grooves (11) are connected end to end; Step S3: scanning a groove in the longitudinal direction inside the arrow-shaped series groove (11), removing the hydrophobic coating, and forming a hydrophilic groove by laser high-energy treatment; Step S4: using a picosecond laser to process a spherical micro-nano structure in the rapid evaporation zone (21) of the lower base plate (2); Step S5: adjusting picosecond laser parameters, changing the scanning interval, scanning speed and scanning speed, and processing a common evaporation area spherical micro-nano structure in the common evaporation area (22); Step S6: aligning the upper base plate (1) or the lower base plate (2) on all sides and welding the edges to leave a liquid injection port and a perfusion pipe; Step S7: injecting liquid working medium into the steam chamber through the liquid injection pipe, and evacuating the steam chamber to make it in a vacuum state; Step S8: first weld and seal the liquid injection tube, and perform secondary degassing, then weld and seal the liquid injection port, remove the liquid injection tube, complete the packaging of the phase change heat dissipation device for quickly eliminating local hot spots, and obtain a phase change heat dissipation device for quickly eliminating local hot spots.

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