Micro-channel radiator with twisted elliptical rib walls

Abstract

The invention discloses a micro-channel radiator with twisted elliptical rib walls, which comprises a substrate and a packaging sheet which are arranged in an up-down overlapping manner, the packaging sheet and the substrate are fixedly and hermetically connected to form a closed space therebetween, the packaging sheet is respectively provided with a fluid inlet and a fluid outlet, the substrate in the closed space is provided with a groove, and the groove is communicated with the fluid inlet and the fluid outlet. A plurality of rows of rib walls are arranged in the groove area between the inlet flow channel area and the outlet flow channel area in the length direction of the groove at intervals in the front-back direction, and a primary channel area is formed between every two adjacent rows of rib walls in the front-back direction; each row of rib walls comprises a plurality of rib walls which are arranged at intervals in the left-right direction, a secondary channel area is formed between every two adjacent rib walls in the left-right direction, the cross section of each rib wall is oval, the included angle between the long axis of the oval of the cross section of each rib wall and the axis direction of the primary channel area is gradually increased from bottom to top, and the tops of the rib walls make contact with the packaging piece. By adopting the structure, the disturbance of fluid is effectively enhanced, and the heat dissipation efficiency is greatly improved.

Description

Technical Field

[0001] The present invention relates to a cooling device, and in particular to a high-power microelectronic chip cooling device. Background Art

[0002] Currently, the heat flux of very large scale integrated circuits is as high as 10 7 W / m 2 , and the ultra-high heat flux will cause the temperature on the chip surface to rise rapidly, increasing the temperature gradient on the surface of the electronic chip and further increasing the non-uniformity of the energy distribution during the operation of the electronic chip. Local overheating not only reduces the performance and service life of the chip, but even causes chip damage, posing a severe challenge to the thermal management of electronic chips. The problem of heat dissipation of electronic chips has become one of the key factors restricting the improvement of their performance and operation reliability. Therefore, there is an urgent need to develop efficient heat dissipation technologies.

[0003] Microscale heat dissipation technologies mainly include: micro heat pipes, microchannel heat sinks, micro thermoelectric refrigeration devices, miniaturized refrigeration units, and integrated micro coolers, etc. Chinese Patent with Application No. 2024213558833 discloses "an open microchannel heat sink with embedded micro pin fins", which includes a substrate and a packaging sheet stacked up and down. A fluid inlet and a fluid outlet are respectively opened on the packaging sheet. A groove is provided on the substrate, and an open microchannel with embedded micro pin fins is installed in the middle. The groove areas on both sides of the microchannel are inlet and outlet liquid storage tanks. The microchannel includes a plurality of rib walls arranged parallel to each other at intervals along the length direction of the substrate. A microchannel is formed between two adjacent rib walls in the front and back, and they are connected to each other. A plurality of pin fins are arranged along the length direction of the substrate in each microchannel. There are gaps between the top surface of the rib wall between the microchannels and the packaging sheet and between the pin fins and the packaging sheet, forming an open structure. This structure adds pin fins to the flow channel of the microchannel without improving the structure of the microchannel wall surface.

[0004] In the article "Optimization of elliptical pin-fin microchannel heatsink based on artificial neural network" published in the 205th issue of the International Journal of Heat and Mass Transfer in 2023, a structure with elliptical rib walls was proposed, the temperature uniformity and pressure drop of this structure were analyzed, and its comprehensive performance was evaluated. The article pointed out that compared with the structures of square, diamond, and triangular ribs, the comprehensive performance of the elliptical rib structure is significantly higher than the other three structures. The article studied the size of the elliptical ribs, but did not further optimize the structure of the elliptical rib walls using the torsion method. Summary of the Invention

[0005] The object of the present invention is to overcome the shortcomings of the existing technology and provide a microchannel heat sink with twisted elliptical rib walls, which can improve the uniform temperature of the chip, thereby ensuring the working stability and service life of high-power electronic chips.

[0006] In order to achieve the object of the present invention, the present invention adopts the following technical solutions:

[0007] A microchannel heat sink with twisted elliptical rib walls of the present invention includes a substrate and a packaging sheet stacked up and down. The packaging sheet is fixedly and hermetically connected to the substrate to form a sealed space therebetween. A fluid inlet and a fluid outlet are respectively opened on the packaging sheet. Grooves are provided on the substrate in the sealed space. The grooves are respectively set as an inlet flow channel area corresponding to the fluid inlet and an outlet flow channel area corresponding to the fluid outlet. Multiple rows of rib walls are arranged at intervals in the groove area between the inlet flow channel area and the outlet flow channel area and along the length direction of the groove. A primary channel area is formed between two adjacent rows of rib walls front and back; each row of rib walls includes a plurality of rib walls arranged at intervals left and right. A secondary channel area is formed between two adjacent rib walls left and right. The cross section of the rib wall is elliptical. The included angle between the major axis of the ellipse of the cross section of the rib wall and the axis direction of the primary channel area gradually increases from bottom to top. The top of the rib wall is in contact with the packaging sheet.

[0008] The present invention has the following advantages and effects:

[0009] 1. The microchannel with twisted elliptical rib walls effectively strengthens the disturbance of the fluid, greatly improving the heat dissipation efficiency and the uniformity of the temperature distribution on the heat dissipation surface;

[0010] 2. Compared with the rectangular parallel and parallel microchannel heat sink, under the same flow rate, the temperature of the heat dissipation surface is reduced, and the uniformity of the temperature distribution on the heat dissipation surface is improved. The average temperature of the bottom surface of the heat sink is reduced by up to 10.9 °C, and the temperature difference on the heat dissipation surface is reduced by up to 72.8%;

[0011] 3. Compared with the microchannel heat sink with parallelogram rib walls, under the same pressure drop, the heat transfer efficiency is increased significantly, and the heat transfer coefficient is increased by up to 30.8%;

[0012] 4. Compared with the optimized microchannel heat sink with elliptical rib walls in the literature, under the condition that the Reynolds number is equal to 280, the comprehensive performance is improved by 26.22%;

[0013] 5. Compared with the microchannel heat sink with untwisted elliptical rib walls, under the same heat dissipation, the pressure drop is significantly reduced, and the maximum reduction is 35.8%. Description of the Drawings

[0014] Figure 1 This is a schematic structural view of the microchannel heat sink with twisted elliptical rib walls of the present invention for cooling high-power microelectronic devices.

[0015] Figure 2 It is Figure 1 A schematic view of the platinum metal thin film attached to the back of the substrate of the heat sink shown in the figure.

[0016] Figure 3 It is Figure 1 A bottom view of the heat sink shown in the figure.

[0017] Figure 4 This is a top view of the substrate of the microchannel heat sink with twisted elliptical rib walls of the present invention.

[0018] Figure 5 It is Figure 4 A schematic view of the three-dimensional structure of the substrate shown in the figure.

[0019] Figure 6 It is Figure 5 A schematic view of the three-dimensional structure with twisted elliptical rib walls in the substrate shown in the figure.

[0020] Figure 7 It is Figure 6 A partial schematic view of the structure shown in the figure along A-A.

[0021] Figure 8 It is Figure 5 A partial schematic view of the structure shown in the figure along B-B.

[0022] Figure 9 This is a top view of the partial dimensions of the microchannel structure with twisted elliptical rib walls. Detailed implementation manners

[0023] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0024] As shown in the accompanying drawings, a microchannel heat sink 8 with twisted elliptical rib walls of the present invention includes a substrate 2 and a packaging sheet 1 which are stacked up and down. The packaging sheet 1 is fixedly and hermetically connected to the substrate 2 to form a sealed space therebetween. The fixedly and hermetically connected structure can be: if the substrate material is silicon, the connection method can be electrostatic bonding, and other metal materials can be hermetically connected by gluing, screws, etc.

[0025] A fluid inlet 3 and a fluid outlet 4 are respectively opened on the packaging sheet 1. The fluid inlet 3 and the fluid outlet 4 are respectively connected to external cooling working medium pipelines during actual use.

[0026] On the substrate 2 in a closed space, there are grooves, and the grooves are respectively set as an inlet flow channel region 6 corresponding to the fluid inlet 3 and an outlet flow channel region 7 corresponding to the fluid outlet 4. In the groove region between the inlet flow channel region and the outlet flow channel region and along the length direction of the groove (along the fluid flow direction), multiple rows of rib walls 5 are arranged at intervals before and after. A primary channel region is formed between two adjacent rows of rib walls before and after. The groove can be processed into three parts by deep etching technology.

[0027] Each row of rib walls includes multiple rib walls arranged at intervals on the left and right. A secondary channel region is formed between two adjacent rib walls on the left and right. The interrupted rib walls can enhance fluid disturbance and the effect of heat transfer enhancement. The cross-section of the rib wall 5 is elliptical, and the included angle between the major axis of the ellipse of the cross-section of the rib wall and the axis direction (fluid flow direction) of the primary channel region gradually increases from bottom to top. Preferably, the major axis of the ellipse at the bottom surface of the rib wall is consistent with the axis direction of the primary channel region, and the included angle between the major axis of the ellipse at the top surface of the rib wall and the axis of the primary channel region is 30°. By changing the angle, the flow condition of the fluid in the vertical direction is changed, the disturbance of the fluid in the vertical direction is increased, and the heat transfer capacity is enhanced. The included angle between the major axis of the ellipse of the cross-sections of two adjacent rib walls on the left and right and the axis of the primary channel region is the same.

[0028] The top of the rib wall is in contact with the encapsulation sheet. Preferably, the height H of the rib wall is 80μm - 200μm, and more preferably 200μm. There is no gap between the top of the rib wall and the encapsulation sheet, and the heat transfer between the cold fluid at the top of the channel and the hot fluid at the bottom of the channel can be fully promoted through the elliptical torsion structure of the rib wall.

[0029] The major axis L1 of the ellipse of the rib wall is selected to be between 200μm and 110μm, and further preferably 200μm. At this width, the heat transfer capacity of the secondary channel region formed is the best. If the major axis of the ellipse is too short, the disturbance of the fluid in the secondary channel region will decrease;

[0030] The minor axis L2 of the ellipse of the rib wall is selected to be 50 - 125μm, and further preferably 100μm. This can prevent the decrease of heat transfer capacity when the minor axis is too small and the excessive pumping cost when the minor axis is too large, taking into account both the pressure drop loss and the heat transfer enhancement effect of fluid disturbance;

[0031] The centers of the ellipses at the bottom surface and the top surface of each rib wall are in the same position in the top view Figure 9 The distance L3 between the centers of the ellipses at the bottom surface of two adjacent rib walls on the left and right and between the centers of the ellipses at the top surface of two adjacent rib walls on the left and right is 250 - 400μm, and further preferably 400μm. If the adjacent rib walls are too close, the number of rib walls arranged in the same length will be too many, increasing the frictional resistance of fluid flow and instead affecting the heat transfer capacity. Therefore, 400μm is preferably selected;

[0032] The distance L4 between the adjacent vertices of the bottom ellipses between two adjacent rib walls on the left and right is 50 - 200 μm, and more preferably 200 μm. When the distance is reduced, the secondary channel area decreases, and the fluid cannot exchange heat sufficiently in the secondary channel. Therefore, 200 μm is preferably selected.

[0033] The centers of the bottom ellipses and the top ellipses of each rib wall are in the same position in the top view Figure 9 The distance L5 between the centers of the bottom ellipses of two adjacent rib walls in the front and back and the distance between the centers of the top ellipses of two adjacent rib walls in the front and back are both 150 - 200 μm, and more preferably 200 μm. When the distance is too close, the number of rib walls will increase, and the improvement of the heat exchange capacity is much lower than the increase in the pressure drop caused by the friction between the cooling working fluid and the rib wall surface;

[0034] The distance W between the adjacent vertices of the bottom ellipses of two adjacent rows of rib walls in the front and back ch is 50 - 100 μm, and more preferably 100 μm. When the distance is too close, the pressure drop in the primary channel is too high under the same flow rate, increasing the pumping cost;

[0035] The exterior angle and interior angle of the included angle between the major axis of the top ellipses of two adjacent rib walls on the left and right and the axis of the primary channel area are represented by ∠a and ∠b respectively. The exterior angle ∠a is selected to be between 15° and 60°, and more preferably 30°. The interior angle ∠b is selected to be between 120° and 165°, and more preferably 150°. This can increase the disturbance of the fluid in the vertical direction and keep the pressure drop within a reasonable range.

[0036] Preferably, the groove area with rib walls installed is consistent with the area of the microelectronic device to be cooled installed on the outer wall surface of the substrate.

[0037] The fluid inlet is arranged opposite to the inlet flow channel area so that the fluid flows vertically into the inlet flow channel area through the fluid inlet. The outlet flow channel area is arranged opposite to the fluid outlet so that the fluid flows vertically into the fluid outlet through the outlet flow channel area.

[0038] After the encapsulation sheet 1 and the substrate 2 are bonded and encapsulated, a microchannel heat sink is formed. The flow path of the cooling working fluid is as follows: The fluid flows into the inlet flow channel area 6 through the fluid inlet 3, flows through the rib wall 5 with a twisted ellipse, and takes away the heat of the microelectronic device 9 installed on the outer wall surface of the substrate from the bottom of the heat sink. After cooling the microelectronic device, it flows to the outlet flow channel area 7 and flows out of the heat sink through the fluid outlet 4.

[0039] To solve the heat dissipation problem of high-power electronic chips, maintain the temperature uniformity and service performance of the chips, a rib wall 5 with a twisted elliptical rib wall is used to form a microchannel at the part where the heat sink contacts the heating film. This microchannel structure has the following characteristics: (1) Interrupt the straight channel, the shape of the rib wall is twisted ellipse, and the fluid flow area changes along the height direction of the rib wall. As Figure 8 , it can significantly enhance the heat transfer capacity of the microchannel heat sink; (2) A secondary channel area is formed in the middle of the adjacent left and right rib walls. As Figure 9 shows, it strengthens the disturbance of the horizontal and vertical directions and the fluid flow direction in the channel, and improves the heat dissipation performance of the heat sink. In addition, the shape of the twisted elliptical rib wall is close to streamline, avoiding excessive pressure drop and pump power consumption. Based on this, the microchannel heat sink with a twisted elliptical rib wall has obvious advantages in the heat dissipation of electronic chips, can significantly enhance the heat dissipation capacity of the microchannel heat sink, and reduce the pumping cost and save energy consumption.

[0040] There is a fluid inlet / outlet structure on the heat sink encapsulation sheet 1, and the cooling working medium flows into / out of the microchannel heat sink in the vertical direction. Considering different actual application scenarios and diverse heat dissipation requirements, refrigerants such as air, deionized water, and CO2 can be selected as the cooling working medium. The cooling working medium undergoes single-phase convective heat transfer or phase change heat transfer in the microchannel with a twisted elliptical rib wall to meet the heat dissipation requirements of high-power electronic chips and achieve the requirements of reducing the chip temperature and maintaining stable service performance.

[0041] The microchannel heat sink substrate 2 can be made of materials with a coefficient of thermal expansion matching that of the chip, such as aluminum, tungsten copper, and silicon. The overall shape of the heat sink (i.e., the shape of the substrate and the encapsulation sheet) is rectangular, suitable for cooling heat-generating surfaces such as strip-shaped and square-shaped ones. The overall geometric dimensions and the microchannel structure layout area can be determined according to the size of the device to be cooled and the overall encapsulation requirements.

[0042] Example:

[0043] As Figure 2 , the material of the encapsulation sheet 1 is heat-resistant borosilicate glass, and the material of the substrate 2 is silicon. Using the coating technology, as Figure 3The shown 100-nm-thick serpentine platinum metal thin film 9 is evenly arranged on the back of the silicon substrate, and the metal thin film is cooled by a microchannel heat sink with twisted elliptical rib walls (simulating the heat generation of microelectronic devices). A microchannel structure with a depth of 200 μm is processed on the 3.5-mm-thick silicon substrate 2 through deep etching technology. The silicon substrate is bonded to the 0.2-mm-thick encapsulation sheet 1 to form a closed microchannel heat sink. The encapsulation sheet 1 is provided with a fluid inlet / outlet with a diameter of 1 mm. The external dimensions of the heat sink are 10 mm in length, 2.6 mm in width, and 0.5 mm in height. In the microchannel with twisted elliptical rib walls 5, the height H of the twisted elliptical rib walls is 200 μm, 20 twisted elliptical rib walls are arranged at equal intervals in each row along the flow direction, and there are 10 rows in total. The dimensional parameters of the twisted elliptical rib walls are as Figure 9 shown. The major axis L1 of the bottom ellipse 11 of the rib wall is 200 μm; the major axis of the bottom ellipse is in the same direction as the axis of the primary channel region. The minor axis L2 of the bottom ellipse is 100 μm; the distance L3 between the centers of the bottom ellipses of two adjacent rib walls on the left and right and the distance between the centers of the top ellipses of two adjacent rib walls on the left and right are both 400 μm; the major axis L1 of the top ellipse 10 of the twisted elliptical rib wall is 200 μm; the angle between the major axis of the ellipse of the cross-section of the rib wall and the axis direction (fluid flow direction) of the primary channel region gradually increases from bottom to top. The external angle and internal angle of the angle between the major axis of the top ellipse and the axis of the primary channel region are represented by ∠a and ∠b respectively, where ∠a = 30° and ∠b = 150°; the distance L4 between the adjacent vertices of the bottom ellipses of two adjacent rib walls on the left and right is 200 μm; the distance L5 between the centers of the bottom ellipses of two adjacent rib walls in the front and back and the distance between the centers of the top ellipses of two adjacent rib walls in the front and back are 200 μm; the distance W ch between the adjacent vertices of the bottom ellipses of two adjacent rows of rib walls in the front and back is 100 μm; the areas of the microchannel region with rib walls and the platinum metal thin film region on the substrate 2 are the same. Deionized water is used as the cooling working medium and vertically flows into the inlet flow channel region 6 through the fluid inlet 3. After being evenly dispersed, it horizontally flows through the microchannel with rib walls 5, dissipates heat for the platinum metal thin film, then flows to the outlet flow channel region 7, and then flows out of the heat sink through the fluid outlet 4, realizing the heat dissipation of the microelectronic device.

[0044] The platinum metal thin film 9 at the bottom of the heat sink is connected to a DC power supply to simulate the heat generation of an electronic chip. The input power of the DC power supply is adjusted to control the temperature of the platinum metal thin film, simulating the performance of the microchannel heat sink under different chip powers. The results show that this structure can effectively improve the heat dissipation effect, solve the bottom hot spot problem existing in the microchannel with parallelogram rib walls, improve the temperature uniformity. Compared with the rectangular parallel and parallel microchannel heat sink, when the thermal resistance is 0.92 K / W, the pump power is reduced by 75.8%, and the energy consumption is significantly reduced; when the flow rate is 1 m / s, the convective heat transfer coefficient increases by 79.2%, and the comprehensive performance is significantly improved.

Claims

1. A microchannel heat sink with twisted elliptical ribbed walls, comprising a substrate and a packaging sheet stacked up and down. The packaging sheet is fixedly and sealedly connected to the substrate to form a sealed space therebetween. A fluid inlet and a fluid outlet are respectively formed on the packaging sheet. Grooves are provided on the substrate within the sealed space. The grooves are respectively set as an inlet flow channel area corresponding to the fluid inlet and an outlet flow channel area corresponding to the fluid outlet, and it is characterized in that :There are multiple rows of rib walls arranged at intervals in the front and back directions along the length of the groove in the groove area between the inlet flow channel area and the outlet flow channel area, and a primary channel area is formed between two adjacent rows of rib walls in the front and back; each row of rib walls includes a plurality of rib walls arranged at intervals on the left and right, and a secondary channel area is formed between two adjacent rib walls on the left and right. The cross-section of the rib wall is oval, and the included angle between the major axis of the ellipse of the cross-section of the rib wall and the axis direction of the primary channel area gradually increases from bottom to top. The top of the rib wall is in contact with the encapsulation sheet.

2. The microchannel heat sink with torsion elliptical ribbed walls according to claim 1, wherein: The major axis of the ellipse of the bottom surface of the rib wall is consistent with the axis direction of the primary channel area. The included angle between the major axis of the ellipse of the top surface of the rib wall and the axis of the primary channel area is 30°. The interior angles of the included angles between the major axes of the ellipses of the cross-sections of two adjacent rib walls on the left and right and the axis of the primary channel area are the same.

3. The microchannel heat sink with twisted elliptical ribbed walls according to claim 1, characterized in that: The height H of the rib wall is 80μm - 200μm.

4. The microchannel heat sink with torsion elliptical ribbed walls according to claim 1, characterized in that: The major axis L1 of the ellipse of the rib wall is between 200μm and 110μm.

5. The microchannel heat sink with twisted elliptical ribbed walls according to claim 1, wherein: The minor axis L2 of the ellipse of the rib wall is 50 - 125μm.

6. The microchannel heat sink with torsion elliptical ribbed walls according to claim 5, characterized in that: The minor axis of the ellipse of the rib wall is 100μm.

7. The microchannel heat sink with torsion elliptical ribbed walls according to claim 1, wherein: The distances L3 between the centers of the bottom ellipses of two adjacent rib walls on the left and right and between the centers of the top ellipses of two adjacent rib walls on the left and right are both 250 - 400μm.

8. The microchannel heat sink with torsion elliptical ribbed walls according to claim 1, wherein: The distance L4 between the adjacent vertices of the bottom ellipses between two adjacent rib walls on the left and right is 50 - 200μm.

9. The microchannel heat sink with torsion elliptical ribbed walls according to claim 1, characterized in that: The distance L5 between the centers of the bottom ellipses of two adjacent rib walls in the front and back directions and between the centers of the top ellipses of two adjacent rib walls in the front and back directions is 150 - 200 μm; the distance W between the adjacent elliptical vertices at the bottom of two adjacent rows of rib walls in the front and back directions ch is 50 - 100 μm; the exterior and interior angles formed by the major axis of the top ellipse of two adjacent rib walls on the left and right and the axis of the primary channel region are represented by ∠a and ∠b respectively. The exterior angle ∠a is between 15° and 60°, and the interior angle ∠b is between 120° and 165°.

10. The microchannel heat sink with torsion elliptical ribbed walls according to claim 9, characterized in that: The exterior angle ∠a is 30°, and the interior angle is 150°.

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