Micro-channel heat sink

Abstract

The invention discloses a micro-channel heat sink, which comprises a substrate and a packaging sheet which are stacked up and down, the packaging sheet is respectively provided with a fluid inlet and a fluid outlet, the substrate is provided with a groove, the middle of the substrate is provided with a micro-channel with a sectional parallelogram rib wall, and groove areas at two sides of the micro-channel are an inlet liquid storage groove and an outlet liquid storage groove. The front half part of the sectional type parallelogram rib wall micro-channel heat sink is a parallelogram micro pin fin cluster with a small size, and the rear half part of the sectional type parallelogram rib wall micro-channel heat sink is a parallelogram rib wall with a large size. A multi-stage channel is formed in the heat sink, a first-stage channel is formed in the flowing direction, a second-stage channel is formed between the large-size rib walls, and a third-stage channel is formed between the micro pin-fin clusters. According to the invention, the heat dissipation efficiency and the temperature uniformity of the heat sink can be effectively improved, and the voltage drop is effectively controlled. Compared with a traditional parallelogram pin-fin heat sink with a uniform size, the pressure drop is obviously reduced, and the comprehensive performance is improved by 24.9%.

Description

Technical Field

[0001] This invention relates to cooling devices, and more particularly to a cooling device for high-power microelectronic chips. Background Technology

[0002] The rapid development of artificial intelligence technology has placed higher demands on the performance of electronic chips. Electronic chips are constantly evolving towards miniaturization and high power density. For example, due to the ever-increasing performance requirements of computers, the data processing speed and operating frequency of central processing units (CPUs) and graphics processing units (GPUs) are increasing, while heat dissipation space is limited, causing chip temperatures to exceed 80°C, severely reducing chip performance and lifespan. Efficient heat dissipation has become crucial for ensuring the stable operation of electronic chips. In the field of thermal management for high-power electronic chips, microchannel heat sinks exhibit advantages such as compact structure, high heat dissipation efficiency, and ease of integration, showing broad application prospects. Microchannel heat sinks are a new type of high-efficiency heat dissipation device, with channel dimensions typically on the order of micrometers. Compared to traditional heat sinks, microchannel heat sinks have a larger specific surface area, thus significantly improving heat dissipation efficiency.

[0003] Existing microchannel heat sink patents suffer from significant structural design flaws. For example, traditional straight microchannels employ a parallel structure, which, while simple to manufacture, results in uneven fluid distribution, with higher flow rates in the central channel compared to the periphery, leading to poor temperature uniformity. Furthermore, the longer flow path causes substantial pressure drops, resulting in higher pump power consumption in liquid cooling systems. While radially arranged microchannels offer centrosymmetry, they suffer from significant velocity differences between the center and periphery, exhibiting a temperature distribution characterized by lower temperatures in the center and higher temperatures around the edges, with temperature differences reaching tens of degrees Celsius. Simultaneously, channel size limitations lead to substantial pressure drops. Some optimized manifold microchannel structures, while improving temperature uniformity through segmentation units, suffer from complex structural designs; the addition of a manifold increases the three-dimensional thickness, significantly raising installation difficulty and manufacturing costs. Jetting effects easily occur at the manifold-microchannel interface, causing impact-backflow phenomena, resulting in fluid blockage and a dramatic increase in pressure loss. In summary, these structural defects collectively limit the heat dissipation performance and industrial application potential of microchannel heat sinks. There is an urgent need to develop novel microchannel heat sinks to meet heat dissipation requirements.

[0004] Chinese patent publication number 2024213558833 discloses "An Open Microchannel Heat Sink with Embedded Micro-Pin Ribs". The microchannel includes multiple ribs spaced parallel to each other along the length of a substrate. Microchannels are formed between adjacent ribs and are interconnected. Multiple pin ribs are arranged within each microchannel along the length of the substrate. Gaps are provided between the top surface of the ribs and the encapsulation sheet, and between the pin ribs and the encapsulation sheet, forming an open structure. This microchannel structure is designed as an open microchannel, connecting multiple parallel and spaced channels to reduce pressure drop; and pin ribs are placed in the center of the flow channel to turbulence and enhance fluid heat transfer capacity. However, the rib structure itself is not optimized or improved.

[0005] Chinese Patent Publication No. 2025105150639 discloses a "microchannel heat sink with torsional elliptical ribs", which includes a substrate and a package sheet stacked on top of each other. The package sheet and the substrate are fixedly and sealed together to form a closed space between them. The package sheet has a fluid inlet and a fluid outlet. The substrate in the closed space has a groove, which is 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 ribs are arranged in the groove area between the inlet flow channel area and the outlet flow channel area, and are spaced back and forth along the length of the groove. A primary channel area is formed between two adjacent rows of ribs. Each row of ribs includes multiple ribs spaced left and right. A secondary channel area is formed between two adjacent left and right ribs. The cross-section of the ribs is elliptical. The angle between the major axis of the ellipse of the rib cross-section and the axis of the primary channel area gradually increases from bottom to top. The top of the rib is in contact with the package sheet. The microchannel is designed with a torsion elliptical rib structure, which forms a primary channel region and a secondary channel region. This structure promotes fluid mixing and improves heat transfer capacity, but the specific surface area is small and its effect on fluid disturbance is limited. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems existing in the prior art and provide a microchannel heat sink that can increase the specific surface area, destroy the fluid boundary layer, and improve the heat transfer capacity, thereby improving the heat transfer efficiency and overall performance.

[0007] The present invention adopts the following technical solution: A microchannel heat sink of the present invention includes a substrate and an encapsulation sheet stacked on top of each other. The encapsulation sheet and the substrate are fixedly and sealed together to form a sealed space between them. A fluid inlet and a fluid outlet are respectively opened on the left and right sides of the encapsulation sheet. A groove is provided on the substrate within the sealed space. The left groove area opposite to the fluid inlet is an inlet reservoir, and the right groove area opposite to the fluid outlet is an outlet reservoir. Multiple wavy structures are arranged at intervals in the groove area between the inlet and outlet reservoirs and along the fluid flow direction. The multiple wavy structures are discontinuous at the crests and troughs, and the multiple wavy structures as a whole form a rhomboid honeycomb grid structure. Along the liquid flow direction, the channel formed by the gap between two wavy structures arranged at intervals is a primary channel. Multiple... The peaks and troughs of the wavy structure form secondary channels. Along the fluid flow direction, the rhomboid honeycomb grid structure is divided into left and right ribbed structure regions. Each edge of each rhomboid honeycomb grid unit in the left ribbed structure region is a microneedle rib cluster, formed by double-layered ribs spaced apart internally and externally. Each microneedle rib cluster consists of four parallelogram microneedles, positioned to form a cross-shaped region between them. The four parallelogram microneedles are located on a phase of the cross-shaped region, forming a tertiary channel. Each edge of each rhomboid honeycomb grid unit in the right ribbed structure region is composed of a parallelogram rib. The primary, secondary, and tertiary channels constitute microchannels. The tops of the multiple wavy structures are in contact with the encapsulation sheet.

[0008] The present invention has the following advantages and effects: 1. Under operating conditions with an inlet fluid temperature of 293K and a velocity of 1-4.5m / s, compared to rectangular parallel microchannel heat sinks, the segmented ribbed microchannel structure... make The maximum temperature of the heat dissipation surface decreased by 9.4℃, and the maximum temperature difference decreased by 62.8%. 2. Under the conditions of inlet fluid temperature of 293K and velocity of 1-4.5m / s, compared with the traditional large parallelogram needle rib structure with uniform size, the microchannel heat sink with segmented ribs can reduce the pressure drop by up to 89.3kPa, and has a larger heat exchange area, with an overall performance improvement of 24.9%.

[0009] 3. Under boiling heat transfer conditions, larger microneedle ribs are arranged on the fluid inlet side, and smaller microneedle rib clusters are arranged on the fluid outlet side. The corner regions formed by the microstructures can increase the nucleation density; when the fluid flows through a section of large-sized microneedle ribs, the microneedle ribs periodically interrupt the thermal boundary layer, forming secondary flow and local vortices, enhancing convective heat transfer, and promoting the detachment of bubbles from the nucleation point; when the fluid flows through a section of small-sized microneedle rib clusters, the rib clusters can enhance capillary wicking effect and liquid transport, maintain liquid wetting, and delay drying; the microneedle rib clusters can break elongated bubbles into smaller bubbles, promoting steam discharge; the connectivity effect of micropores provides more expansion space for bubbles, reduces pressure drop, promotes fluid mixing between adjacent channels, timely cools confined bubbles, inhibits steam backflow, and improves boiling stability and critical heat flux density.

[0010] 4. The heat sink is divided into two parts along the flow direction: smaller parallelogram micro-needle rib clusters and larger parallelogram rib walls, forming a segmented rib structure. This structure can increase the specific surface area, disrupt the fluid boundary layer, and improve heat transfer capacity, thereby enhancing heat transfer efficiency and overall performance, and solving the heat dissipation problem of electronic chips. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the microchannel heat sink with segmented parallelogram ribs of the present invention for cooling high-power microelectronic devices. Figure 2 yes Figure 1 A schematic diagram of the platinum metal film attached to the back of the substrate of the heat sink in the structure shown. Figure 3 yes Figure 1 The bottom view of the heat sink shown; Figure 4 This is a top view of the substrate of the microchannel heat sink with segmented parallelogram ribs of the present invention. Figure 5 yes Figure 4 A schematic diagram of the three-dimensional structure of the substrate shown; Figure 6 yes Figure 5 A schematic diagram of a three-dimensional microchannel structure with segmented parallelogram ribs in a substrate is shown. Figure 7 yes Figure 5 A partial schematic diagram of the structure shown in Figure AA; Figure 8 yes Figure 5 A partial schematic diagram of the structure shown in the figure; Figure 9 yes Figure 6 A partial schematic diagram of the CC portion of the structure shown; Figure 10It is a top view of the local dimensions of a microchannel structure with segmented parallelogram ribs. Specific implementation methods The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0012] As shown in the attached figures, a microchannel heat sink 8 of the present invention includes a substrate 2 and an encapsulation sheet 1 stacked on top of each other. The encapsulation sheet 1 and the substrate 2 are fixedly and sealed together to form a sealed space between them. The fixed and sealed connection structure can be as follows: if the substrate material is silicon, the connection method can be electrostatic bonding; for other metal materials, sealing connections can be made using adhesive, screws, or other methods.

[0013] Fluid inlets 3 and fluid outlets 4 are respectively opened on the left and right sides of the encapsulation sheet 1. In actual use, the fluid inlets 3 and fluid outlets 4 are respectively connected to external cooling fluid pipelines.

[0014] A groove is provided on the substrate 2 in the sealed space. The left groove area opposite to the fluid inlet is the inlet reservoir 6, and the right groove area opposite to the fluid outlet is the outlet reservoir 7. Multiple wavy structures are provided in the groove area between the inlet reservoir 6 and the outlet reservoir along the flow direction of the fluid. The multiple wavy structures are disconnected at the crests and troughs, and the multiple wavy structures form a diamond honeycomb grid structure.

[0015] Along the direction of liquid flow, the channel formed by the gap between two wave-shaped structures spaced at intervals is called the primary channel.

[0016] Along the direction perpendicular to the flow of the liquid, the peaks and troughs of the multiple wave-shaped structures form secondary channels.

[0017] Along the flow direction of the fluid, the rhombic honeycomb grid structure is divided into left and right ribbed structure regions. In the left ribbed structure region, each edge of each rhombic honeycomb grid unit is a microneedle rib cluster 10. Each microneedle rib cluster is formed by double-layered ribs spaced apart internally and externally. Each microneedle rib cluster consists of four parallelogram microneedles, positioned such that a cross-shaped region is formed between them. The four parallelogram microneedles are located on one phase of the cross-shaped region, which constitutes a tertiary channel. In the right ribbed structure region, each edge of each rhombic honeycomb grid unit is composed of a parallelogram rib 11. The primary, secondary, and tertiary channels constitute a microchannel 5.

[0018] Fluid flows through microchannel 5, carrying away heat from the microelectronic device 9 (heating film simulating electronic chip heating) mounted on the outer wall of the substrate from the bottom of the heat sink.

[0019] The multiple wavy structures are arranged in contact with the top of the encapsulation sheet. Preferably, the height H of the multiple wavy structures is 80μm-200μm, more preferably 200μm. There is no gap between the top of the multiple wavy structures and the encapsulation sheet, which can fully promote the heat exchange between the cold fluid at the top of the channel and the hot fluid at the bottom of the channel.

[0020] Along the direction of fluid flow, the length L1 of the parallelogram rib wall is selected to be 100μm-200μm, and more preferably 100μm. At this length, the heat exchange effect in the secondary channel is optimal. If the length of the parallelogram rib wall is too long, the turbulence of the fluid in the secondary channel will be reduced. The diagonal width W1 of the parallelogram rib wall is selected to be 100μm-200μm, and more preferably 100μm. The selected width is the same as the width of the primary channel where the fluid flows through the parallelogram rib wall, which allows the fluid to fully contact the rib wall, enhances the heat exchange capacity, and also reduces the flow pressure drop.

[0021] Along the fluid flow direction, the distance L3 between the closest positions of two adjacent parallelogram ribs is selected to be 50μm-100μm, and more preferably 50μm. Since these parallelogram ribs are arranged diagonally, if the distance is too far, the fluid disturbance will be too small, which will affect the heat transfer capacity.

[0022] Along the fluid flow direction, the length L2 of the parallelogram microneedle ribs is selected to be 20-40 μm, and the diagonal width W2 of the parallelogram microneedle ribs is 20-40 μm. On the one hand, this is to ensure that the fluid and the ribs are in full contact, improve the uniformity of the flow distribution, and obtain better temperature uniformity. On the other hand, it is also to ensure that the parallelogram microneedle rib cluster is easy to etch. Therefore, L2 is preferably 30 μm and W2 is preferably 30 μm. In this way, the fluid turbulence in the generated three-stage channel can be strengthened and the heat transfer capacity can be enhanced.

[0023] For the microneedle rib clusters upstream of the heat sink, each cluster consists of four parallelogram microneedles. The flow channels within the clusters are three-level channels. Along the fluid flow direction, the closest distance L4 between two adjacent parallelogram microneedles in each cluster is selected to be 20-60 μm, and more preferably, L4 is 40 μm. Along the direction perpendicular to the fluid flow direction, the distance W3 between the two front parallelogram microneedles and the two rear parallelogram microneedles in each cluster is selected to be 30-50 μm, and more preferably, W3 is 40 μm. At this distance, the heat exchange effect of the three-level channels formed inside the microneedle rib clusters is optimal, and the fluid disturbance is more uniform.

[0024] Preferably, along the fluid flow direction, the closest distance L5 between two adjacent clusters of microneedles is selected to be consistent with the closest distance L3 between two adjacent parallelogram rib walls, preferably both being 50 μm. Along the direction perpendicular to the fluid flow, the vertical distance between two adjacent rib walls on both sides of the primary channel and the closest vertical distance Wch between the parallelogram microneedles of two adjacent clusters of microneedles are both 50-100 μm, further preferably 100 μm. Smaller distances will lead to increased pressure drop, excessive pump power consumption, and affect the overall performance of the liquid cooling system.

[0025] Preferably, each parallelogram micro-needle rib is geometrically similar to the parallelogram rib wall, and the similarity ratio between the two is 3:10.

[0026] This microchannel structure has the following characteristics: it constructs a segmented turbulence structure. Upstream of the heat sink, there are small parallelogram-shaped micro-needle ribs designed to enhance turbulence under low flow friction conditions, preventing a sharp increase in pressure drop caused by the turbulence structure. Downstream, there are larger parallelogram-shaped ribs designed to suppress temperature rise along the flow direction and improve the temperature uniformity of the heat sink. Simultaneously, the combination of segmented parallelogram-shaped ribs forms primary, secondary, and tertiary channels, continuously interrupting the flow boundary layer and thermal boundary layer, allowing for thorough mixing of the fluid within each level of channel.

[0027] The heat sink package 1 has a fluid inlet / outlet structure, allowing the cooling medium to flow into / out of the microchannel heat sink in a vertical direction. Considering different practical application scenarios and diverse heat dissipation requirements, refrigerants such as air, deionized water, and CO2 can be selected as the cooling medium. The cooling medium undergoes single-phase convective heat transfer or phase change heat transfer in the segmented parallelogram ribbed microchannel to meet the heat dissipation requirements of high-power electronic chips, thereby reducing chip temperature and maintaining stable performance.

[0028] The microchannel heat sink substrate 2 can be made of materials such as aluminum, copper, and silicon, whose coefficients of thermal expansion match those of the chip. The overall shape of the heat sink (i.e., the shape of the substrate and the package) is rectangular, suitable for cooling heat-generating surfaces such as strips and squares. The overall geometric dimensions and the microchannel structure layout area can be determined according to the size of the device being cooled and the overall packaging requirements.

[0029] Example: like Figure 1 The encapsulation chip 1 is made of heat-resistant high borosilicate glass, and the substrate 2 is made of silicon. Using a coating technology, such as... Figure 2A 100nm thick serpentine platinum metal film 9 is uniformly arranged on the back of a silicon substrate (simulating heat generation in microelectronic devices), and the metal film is cooled by microchannels with segmented parallelogram ribs. A microchannel structure with a depth of 200μm is fabricated on a 3.5mm thick silicon substrate 2 using deep reactive ion etching. The silicon substrate is bonded to a 0.2mm thick package 1 to form a closed microchannel heat sink. The package 1 has a 1mm diameter fluid inlet / outlet. The heat sink has dimensions of 10mm long, 2.6mm wide, and 0.5mm high. The microchannels 5 with segmented parallelogram ribs have multiple wavy structures at varying heights. H The microchannel heat sink has a diameter of 200 μm and consists of 10 parallelogram-shaped microneedle rib clusters (40 parallelogram-shaped microneedles in total) and 10 parallelogram-shaped rib walls arranged equidistantly along the flow direction, in 10 rows. The dimensional parameters of the microchannel heat sink with segmented parallelogram-shaped rib walls are as follows: Figure 10 As shown. The parallelogram rib wall has a side length of 100 μm and a diagonal width of 100 μm. Along the fluid flow direction, the closest distance between two adjacent parallelogram rib walls and the closest distance between two adjacent clusters of microneedles are both 50 μm. Along the direction perpendicular to the fluid flow, the vertical distance between two adjacent rib walls on the front and rear sides of the primary channel and the closest vertical distance between two adjacent clusters of microneedles are both 100 μm. A single parallelogram microneedle is scaled down proportionally to the parallelogram rib wall, with a side length of 30 μm and a diagonal width of 30 μm. Along the fluid flow direction, the closest distance between two adjacent parallelogram microneedles in each cluster is 40 μm. Along the direction perpendicular to the fluid flow, the distance between the two front parallelogram microneedles and the two rear parallelogram microneedles in each cluster is 40 μm. Four parallelogram-shaped microneedle ribs are combined to form a microneedle rib cluster, with the arrangement and combination having the same dimensions as a single parallelogram rib wall. At the microchannel inlet, the distance between the parallelogram-shaped microneedle rib cluster and the inlet reservoir is 20 μm. At the microchannel outlet, the distance between the parallelogram-shaped rib wall and the outlet reservoir is 30 μm. Deionized water, as the cooling medium, flows vertically into the inlet reservoir 6 through fluid inlet 3, and after being uniformly dispersed, flows horizontally through microchannel 5, which consists of primary, secondary, and tertiary channels, dissipating heat for the platinum metal thin film before flowing to the outlet reservoir 7. Finally, it flows out through fluid outlet 4 to the heat sink, thus achieving heat dissipation for the microelectronic device.

[0030] A platinum metal 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 film, simulating the performance of the microchannel heat sink under different chip power levels. The results show that this microchannel heat sink has good heat dissipation, temperature control, and overall performance, meeting the heat dissipation requirements of microelectronic components. Compared with an open microchannel heat sink with embedded micro-needle fins, at a flow rate of 3 m / s, the pressure drop is reduced by 47.9 kPa, and the overall heat transfer performance is improved by 33.4%. Compared with a microchannel heat sink with torsional elliptical fins, at the same flow rate, less pump power is required; at a flow rate of 4.5 m / s, the fluid outlet temperature is reduced by 0.1℃, the pressure drop is reduced by 20.9 kPa, and the overall heat transfer performance is improved by 6.7%.

Claims

1. A microchannel heat sink, comprising a substrate and an encapsulation sheet stacked vertically, wherein the encapsulation sheet (1) and the substrate (2) are fixedly and sealed together to form a sealed space between them, and a fluid inlet (3) and a fluid outlet (4) are respectively opened on the left and right sides of the encapsulation sheet, and a groove is provided on the substrate within the sealed space, wherein the left groove area opposite to the fluid inlet is an inlet reservoir (6), and the right groove area opposite to the fluid outlet is an outlet reservoir (7), characterized in that: In the recessed area between the inlet and outlet liquid storage tanks, multiple wavy structures are arranged at intervals along the direction of fluid flow. The multiple wavy structures are discontinuous at the crests and troughs, and the multiple wavy structures as a whole form a rhomboid honeycomb grid structure. The channel formed by the gap between two wavy structures arranged at intervals along the direction of liquid flow is a primary channel. The discontinuous area at the crests and troughs of the multiple wavy structures along the direction perpendicular to the direction of liquid flow is a secondary channel. Along the flow direction of the fluid, the rhombic honeycomb grid structure is divided into two rib wall structure regions, left and right. Each side of each rhombic honeycomb grid unit in the left rib wall structure region is a microneedle rib cluster (10). The microneedle rib cluster is formed by double-layer rib walls with inner and outer spacing. Each microneedle rib cluster is composed of four parallelogram microneedles. The positions of the four parallelogram microneedles are set such that a cross-shaped region is formed between the four parallelogram microneedles. The four parallelogram microneedles are located on one phase of the cross-shaped region. The cross-shaped region is a three-level channel. Each side of each rhombic honeycomb grid unit in the right rib wall structure region is composed of a parallelogram rib wall (11). The first-level channel, the second-level channel and the third-level channel form a microchannel (5). The top of the multiple wavy structures is in contact with the encapsulation sheet.

2. The microchannel heat sink according to claim 1, characterized in that: Each parallelogram micro-needle rib is geometrically similar to the parallelogram rib wall, and the similarity ratio between the two is 3:

10.

3. The microchannel heat sink according to claim 1 or 2, characterized in that: The height H of the multiple wave-shaped structures is 80μm-200μm.

4. The microchannel heat sink according to claim 1 or 2, characterized in that: Along the direction of fluid flow, the length L1 of the parallelogram rib wall is selected as 100μm-200μm, the diagonal width W1 of the parallelogram rib wall is selected as 100μm-200μm, the distance L3 between the closest positions of two adjacent parallelogram rib walls is selected as 50μm-100μm, the length L2 of the parallelogram microneedle rib is selected as 20-40μm, and the diagonal width W2 of the parallelogram microneedle rib is 20-40μm.

5. The microchannel heat sink according to claim 4, characterized in that: L2 is 30 μm, and W2 is 30 μm.

6. The microchannel heat sink according to claim 1 or 2, characterized in that: Along the fluid flow direction, the closest distance L4 between two adjacent parallelogram microneedle ribs in each microneedle rib cluster is selected to be 20-60 μm.

7. The microchannel heat sink according to claim 6, characterized in that: L4 is 40 μm.

8. The microchannel heat sink according to claim 6, characterized in that: Along the direction perpendicular to the fluid flow, the spacing W3 between the two parallelogram microneedle ribs on the front side and the two parallelogram microneedle ribs on the rear side of each microneedle rib cluster is selected to be 30-50 μm.

9. The microchannel heat sink according to claim 8, characterized in that: W3 is 40μm.

10. The microchannel heat sink according to claim 8, characterized in that: Along the fluid flow direction, the nearest distance L5 between two adjacent clusters of microneedles is selected to be consistent with the nearest distance L3 between two adjacent parallelogram rib walls; along the direction perpendicular to the fluid flow, the vertical distance between two adjacent rib walls on the front and rear sides of the primary channel and the nearest vertical distance Wch between the parallelogram microneedles of two adjacent clusters of microneedles are both 50-100μm.

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