A heat dissipation device with adjustable convective heat transfer coefficient of the channel wall

Abstract

The present invention discloses a heat dissipation device with adjustable convective heat transfer coefficient of the channel wall, which comprises a heat dissipation cover plate, an upper partition plate, a lower partition plate and a bottom plate that are hermetically fitted in sequence from top to bottom. An inlet and an outlet are arranged on the heat dissipation cover plate. An inlet guiding hole and an outlet transition channel are arranged on the upper partition plate. An inlet transition channel and an outlet guiding groove are arranged on the lower partition plate. There are a number of groups of honeycomb-like microchannels on the bottom plate, and each group of honeycomb-like microchannels includes a channel inlet and a plurality of channel outlets. Ordered pits are machined at the bottom of the honeycomb-like microchannels, and each pit is filled with a heat-shrinkable temperature-sensitive polymer material. The heat dissipation device can adjust the local convective heat transfer coefficient of the channel wall according to the different power consumptions at different positions of the heat dissipation chip, so as to adjust the local performance of the radiator, thereby avoiding the failure of the high heat flux density heating chip caused by local high temperature, excessive temperature gradient (thermal stress), etc.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic chip cooling, and specifically, to a heat dissipation device with adjustable convective heat transfer coefficient on the channel wall surface. Background Art

[0002] With the rapid development of microelectronics technology, electronic chips are developing rapidly towards the direction of miniaturization, high power, and high integration, and their heat generation is increasing day by day. "Thermal failure" has become one of the most important failure forms of microelectronic devices. Currently, the increase in the heat load level of electronic chips mainly stems from three aspects: (1) the high packaging integration of microelectronic devices, making the heat flux density at the chip level reach 60 - 1100 W / cm 2 ; (2) the uneven power distribution inside the chip leads to frequent internal hot spots, resulting in too high local temperature, affecting the service life; (3) the increasingly wide range of applications of microelectronic devices, with high ambient temperature and large temperature difference, and the excessive thermal stress causes the chip structure to deform, greatly reducing its working performance and stability. Effectively guiding the heat accumulated on the high heat flux density electronic chip to maintain it at a normal working temperature and a lower thermal stress level (temperature gradient), and avoiding thermal failure of electronic components, is the key goal of the structural design of the chip heat dissipation device.

[0003] The microchannel liquid cooling heat dissipation technology is one of the most commonly used cooling methods for high heat flux density chips at present. However, the traditional straight microchannels mainly increase the heat transfer area to improve the heat transfer quantity, and their improvement of the heat transfer coefficient per unit area is limited. Also, due to the overly small water guiding pipes, a large driving pump power is required. In addition, the relatively fixed microchannel structure causes its local heat transfer coefficient to be unable to respond in a timely manner to the changes in the heat flux density and temperature at the local hot spots of the chip, and the uniformity of the overall temperature field distribution is poor. Therefore, only by sacrificing the high power at the chip hot spots can the normal operation of the overall chip be ensured. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide, in view of the deficiencies of the prior art, a microchannel liquid cooling heat dissipation device that can adaptively adjust the local heat transfer coefficient on the channel surface according to the chip working conditions. The heat dissipation device includes a honeycomb-like microchannel cooling structure with concave pit flow-around elements, which has low flow resistance, high heat transfer efficiency, and good temperature distribution uniformity, and can effectively cool high heat flux density chips.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A microchannel liquid cooling heat dissipation device with low flow resistance, high heat transfer efficiency, good temperature distribution uniformity, and capable of adaptively adjusting the local heat transfer coefficient of the channel surface according to the chip operating conditions, comprising a radiator cover plate, an upper partition plate, a lower partition plate, and a bottom plate that are sequentially sealed and fitted; an inlet and an outlet are provided on the radiator cover plate; an inlet guiding hole and an outlet transition channel are provided on the upper partition plate; an inlet transition channel and an outlet guiding groove are provided on the lower partition plate; a honeycomb-like microchannel composed of several groups of polygonal bifurcated circuits is machined on the bottom plate, and each group of honeycomb-like microchannels includes a channel inlet and multiple channel outlets; this structure draws on the honeycomb structure in nature, bifurcates 3 to 5 times, and after the first bifurcation, the secondary channels continuously bifurcate again and continuously merge and separate with the same-level channels to form a polygonal circuit in the shape of a honeycomb.

[0007] The channel inlet on the bottom plate is sequentially connected to the inlet transition channel on the lower partition plate, the inlet guiding hole on the upper partition plate, and the inlet on the cover plate to form an inlet passage for the coolant; the channel outlet on the bottom plate is sequentially connected to the outlet guiding groove on the lower partition plate, the outlet transition channel on the upper partition plate, and the outlet on the cover plate to form an outlet passage for the coolant.

[0008] Preferably, an orderly arranged concave pit array is machined at the bottom of the microchannel, and each concave pit is filled with a heat-shrinkable temperature-sensitive polymer material.

[0009] Preferably, the concave pits at the bottom of the channel are arranged according to a certain rule, that is, arranged in a single row or multiple rows along the flow direction.

[0010] Preferably, the ratio of the concave pit spacing to its projected diameter is 2 to 5.

[0011] Preferably, the projected diameter of the concave pit is larger than the projected diameter of the heat-shrinkable temperature-sensitive polymer material filled in the concave pit, and a linear positioning channel is machined along the projected diameter of the concave pit and perpendicular to the flow direction, so that the filling material can be reliably fixed in the concave pit.

[0012] Preferably, the projected surfaces of the concave pits are all circular, elliptical, water droplet-shaped, triangular, rhombic, trapezoidal, or rectangular.

[0013] Preferably, the ratio of the volume of the heat-shrinkable temperature-sensitive polymer material filled to the volume of the concave pit is 3 / 5 to 2 / 3.

[0014] Preferably, one side surface of the bottom plate is in close contact with the heat source to be cooled, and a high thermal conductivity material can be filled in the middle. The channel inlet on the bottom plate is connected to the outlet of the inlet transition channel on the lower partition plate.

[0015] Preferably, the adjacent honeycomb-like microchannels on the bottom plate are arranged in reverse symmetry.

[0016] Advantages of the present invention:

[0017] 1. The microchannel heat dissipation device applicable to high heat flux density chips provided in this application adopts a honeycomb-like microchannel cooling structure with a pit flow-around element, and a heat-shrinkable thermosensitive polymer material is filled in the pit. The honeycomb-like microchannels designed by referring to the efficient mass and energy transport characteristics unique to biological systems reduce the channel pressure drop, optimize the flow, and improve the cooling uniformity of the bottom plate at the same time. The pits at the bottom of the microchannels can generate strong and orderly vortices in the channels, which will cause the separation and reattachment of the airflow in the near-wall region. On the one hand, it can take away heat from the heat source surface more quickly, and on the other hand, it can strengthen the mixing of the fluid in the near-wall region and the fluid in the mainstream central region, thus effectively enhancing heat transfer;

[0018] 2. For the honeycomb-like microchannel cooling structure with a pit flow-around element provided in this application, the local heat transfer coefficient of the channel wall is related to the depth of the pit. The heat transfer increase is large for a large pit depth and small for a small pit depth. The heat-shrinkable thermosensitive polymer material filled in the pit has the characteristic of discontinuous volume change of swelling-shrinking with temperature change. When sensing the change in the heat source temperature, once the temperature of this material exceeds its lowest critical transition temperature, its volume will rapidly shrink, making the depth of the pit larger, so that the local heat transfer coefficient of the corresponding channel surface at the pit increases, and thus the heat transfer performance of the entire radiator is improved. Description of the Drawings

[0019] Figure 1 is an exploded view of the device group of the present invention;

[0020] Figure 2 is a partially enlarged schematic diagram of the honeycomb-like microchannel cooling structure of the present invention

[0021] Figure 3 is a schematic diagram of the cover plate structure of the present invention;

[0022] Figure 4 is a schematic diagram of the upper partition structure of the present invention;

[0023] Figure 5 is a schematic diagram of the lower partition structure of the present invention;

[0024] Figure 6 is a schematic diagram of the bottom plate structure of the present invention;

[0025] Figure 7 is a schematic diagram of the volume shrinkage behavior of the heat-shrinkable thermosensitive polymer material in the pit channel and the change in the vortex scale in the channel after sensing the heat source temperature change

[0026] Figure 8 It is the heat transfer simulation result. Detailed implementation manners

[0027] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations for the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0028] Example 1: As Figures 1 - 6 shown, a microchannel liquid cooling device with low flow resistance, high heat transfer efficiency, good temperature distribution uniformity, and capable of adaptively adjusting the heat transfer coefficient of the channel surface according to the chip conditions, includes a heat dissipation cover plate 1, an upper partition plate 2, a lower partition plate 3, and a bottom plate 4 that are hermetically fitted in sequence from top to bottom. The heat dissipation cover plate is provided with a liquid inlet 11 and a liquid outlet 12; the upper partition plate is provided with a liquid inlet diversion hole 21 and a liquid outlet transition channel 22; the lower partition plate 3 is provided with a liquid inlet transition channel 31 and a liquid outlet diversion groove 32; the bottom plate 4 is processed with a honeycomb-like microchannel 5 composed of several groups of polygonal bifurcation circuits. Each group of honeycomb-like microchannels 5 includes a channel inlet 51 and multiple channel outlets 52;

[0029] The channel inlet 51 on the bottom plate is sequentially connected to the liquid inlet transition channel 31 on the lower partition plate, the liquid inlet diversion hole 21 on the upper partition plate, and the liquid inlet 11 on the cover plate to form a liquid inlet passage for the coolant; the channel outlet 52 on the bottom plate is sequentially connected to the liquid outlet diversion groove 32 on the lower partition plate, the liquid outlet transition channel 22 on the upper partition plate, and the liquid outlet 12 on the cover plate to form a liquid outlet passage for the coolant; the heat dissipation cover plate 1, the upper partition plate 2, the lower partition plate 3, and the bottom plate 4 are made of the same material, which is a highly thermally conductive metal such as copper or aluminum, and the plates are seamlessly welded together by using the method of polymer diffusion welding, or manufactured by using the metal 3D printing process to ensure good sealing performance.

[0030] The bottom of the honeycomb-like microchannel 5 is processed with orderly arranged pits 53. The projection surface of the pits is circular, and each pit is filled with a heat-shrinkable temperature-sensitive polymer material 6. The projection diameter of the pits is larger than the projection diameter of the heat-shrinkable temperature-sensitive polymer material 6 filled in the pits, and a linear positioning channel 531 is processed along the projection diameter of the pits and perpendicular to the flow direction, so that the filling material 6 can be reliably fixed in the pits.

[0031] Working process: One surface of the bottom plate 4 is in close contact with the heat source to be cooled, and a high thermal conductivity material can be filled in the middle to reduce the influence of contact thermal resistance; the other surface of the bottom plate 4 is connected to and reliably sealed with the lower partition plate 3. The channel inlet 51 on the bottom plate 4 is communicated with the outlet 312 of the liquid inlet transition flow channel on the lower partition plate; the channel outlet 52 on the bottom plate is communicated with the liquid outlet diversion groove 32 on the lower partition plate.

[0032] One surface of the upper partition plate 2 is connected to and reliably sealed with the lower partition plate 3, and the other surface is connected to and reliably sealed with the radiator cover plate 1. The liquid inlet diversion holes 21 on the upper partition plate 2 are respectively communicated with the inlet 311 of the liquid inlet transition flow channel on the lower partition plate 3 and the liquid inlet 11 on the radiator cover plate 1. The inlet 222 of the liquid outlet transition flow channel on the upper partition plate 2 is communicated with the liquid outlet 12 on the radiator cover plate; the outlet 221 of the liquid outlet transition flow channel on the upper partition plate 2 is communicated with the liquid outlet diversion groove 32 on the lower partition plate 3.

[0033] In other embodiments, the projection surface of the pit can also be oval, drop-shaped, triangular, rhombic, trapezoidal or rectangular.

[0034] In order to further improve the cooling effect, the equivalent diameter of the microchannel inlet 51 is not greater than 3 mm, and the equivalent diameter of the microchannel outlet 52 is not less than 0.3 mm; the honeycomb-like microchannels 5 of adjacent structures on the bottom plate are arranged in reverse symmetry.

[0035] As Figure 7 shown, it shows the schematic diagram of the change of the flow field structure of the cooling working medium in the region near the channel wall surface with the pit scale. It can be seen that when the heat source temperature is low, the volume of the heat-shrinking type thermosensitive polymer material 6 in the pit does not change significantly. Therefore, the pit depth is relatively shallow, and the induced fluid vortex scale and intensity are both small, resulting in a relatively low convective heat transfer coefficient of the wall surface in this region. Once the heat accumulation of the heat source causes the temperature of the heat-shrinking type thermosensitive material to exceed its own lowest critical temperature, the volume of this material will shrink sharply, causing the pit space to expand, thereby inducing larger and stronger fluid vortices, and significantly enhancing the convective heat transfer coefficient of the wall surface in this region.

[0036] Figure 8 It shows the temperature cloud diagram and the channel surface heat transfer coefficient cloud diagram distribution of the heating surface of the three-channel heat sink when the inlet flow rate of the cooling working medium is 1 m / s and the heat flux density is 100 kW / m 2 ². Table 1 gives the heat dissipation results of a single smooth wall bifurcated microchannel and a pit-filled bifurcated microchannel under the same heat flux boundary and inlet velocity conditions. It can be seen the advantage of the bifurcated microchannel filled with heat-shrinking type thermosensitive polymer material in enhancing heat transfer.

[0037] Table 1 Chip Heat Dissipation Results

[0038]

[0039]

[0040] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A heat dissipation device with adjustable convective heat transfer coefficient of the channel wall surface, comprising a heat dissipation cover plate (1), an upper partition plate (2), a lower partition plate (3) and a bottom plate (4) which are hermetically fitted in sequence from top to bottom. An inlet port (11) and an outlet port (12) are provided on the heat dissipation cover plate. An inlet port diversion hole (21) and an outlet port transition flow channel (22) are provided on the upper partition plate. An inlet port transition flow channel (31) and an outlet port diversion groove (32) are provided on the lower partition plate. It is characterized in that, On the bottom plate, there is a honeycomb-like microchannel (5) composed of several groups of polygonal bifurcated circuits. Each group of honeycomb-like microchannels (5) includes a channel inlet (51) and multiple channel outlets (52); on the bottom of the honeycomb-like microchannel (5), orderly arranged pits (53) are processed, and each pit is filled with a heat-shrinkable temperature-sensitive polymer material (6). The channel inlet (51) is sequentially communicated with the liquid inlet transition channel (31), the liquid inlet guide hole (21) and the liquid inlet (11) to form a liquid inlet passage for the coolant; the channel outlet (52) is sequentially communicated with the liquid outlet guide groove (32), the liquid outlet transition channel (22) and the liquid outlet (12) to form a liquid outlet passage for the coolant.

2. The heat dissipation device according to claim 1, wherein The ratio of the distance between adjacent pits (53) to their projected diameter is 2 - 5.

3. The heat dissipation device according to claim 2, wherein The projected surface of the pit is circular, oval, drop-shaped, triangular, rhombic, trapezoidal or rectangular.

4. The heat dissipation device according to claim 2, wherein, The projected diameter of the pit (53) is larger than the projected diameter of the heat-shrinkable temperature-sensitive polymer material (6), and a linear positioning channel (531) is processed along the projected diameter of the pit and perpendicular to the flow direction.

5. The heat dissipation device according to claim 4, wherein The ratio of the volume of the filled heat-shrinkable temperature-sensitive polymer material (6) to the volume of the pit (53) is 3 / 5 - 2 / 3.

6. The heat dissipation device according to claim 1, wherein, One side surface of the bottom plate (4) is in close contact with the heat source to be cooled, and a high thermal conductivity material is filled in the middle. The channel inlet (51) on the bottom plate (4) is communicated with the outlet (312) of the liquid inlet transition channel (31) on the lower partition plate.

7. The heat dissipation device according to claim 1, characterized in that, The adjacent honeycomb-like microchannels (5) on the bottom plate (4) are arranged in reverse symmetry.

8. The heat dissipation device according to any one of claims 1-7, characterized in that, When the change in the temperature of the heat source is sensed, the volume of the heat-shrinkable temperature-sensitive polymer material will change rapidly, causing the depth and volume of the pit to change accordingly, thereby changing the size and strength of the vortex induced by the pit, and thus realizing the adaptive adjustment of the convective heat transfer coefficient of the channel wall.

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