CN108231712B - Chip integrated boiling enhanced heat exchange structure based on MEMS technology and preparation method thereof - Google Patents
Chip integrated boiling enhanced heat exchange structure based on MEMS technology and preparation method thereof Download PDFInfo
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- H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
- H01L23/46—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements involving the transfer of heat by flowing fluids
Abstract
The invention provides a chip integrated boiling enhanced heat exchange structure based on an MEMS (micro-electromechanical system) technology and a preparation method thereof. The claw-shaped structure is obtained by preparing a suspended metal sheet structure by adopting a surface micromachining method and folding the suspended metal sheet structure along the plane normal direction. According to the invention, the array claw-shaped structure blocks the path of a large amount of bubbles on the surface and grows into an air film, so that the risk of dry burning is avoided; the side wall of the claw-shaped structure can be provided with a pore structure to ensure that liquid below the bubbles in the cavity is supplemented, the bubble separation efficiency at the position is enhanced, and the effects of increasing the heat exchange area through the claw-shaped structure and further enhancing the heat exchange by utilizing the convection of the bubble turbulent flow and the metal side wall can be realized. In addition, the substrate material and the processing mode of the design are both derived from a chip integration process, so that the structure is convenient to realize the application in the integration and heat dissipation of electronic devices.
Description
Technical Field
The invention relates to the technical field of boiling enhanced heat exchange with high heat flux density, in particular to a chip integrated boiling enhanced heat exchange structure based on an MEMS (micro-electromechanical system) technology and a preparation method thereof.
Background
Along with the rapid development of science and technology, the high density and miniaturization of electronic devices are inevitable trends, the heat productivity per unit volume is continuously increased, and the heat dissipation of high-power devices is a problem to be solved urgently. Boiling heat exchange is used as a phase-change heat transfer mode, and compared with the traditional air cooling and liquid convection heat exchange, the heat exchange coefficient has the difference of orders of magnitude, so that the heat exchange device is a very effective heat dissipation mode. However, the boiling heat exchange performance of high heat flux density is often seriously deteriorated, and the root cause is that bubbles generated by boiling are easy to combine on a heating surface to form a gas film which is difficult to separate so as to obstruct liquid supply and heat exchange, and finally, the electronic device is failed.
The existing boiling enhanced heat exchange structure mainly comprises a mechanical processing surface structure, a surface modification structure, a surface structure covering a porous material and a surface structure containing a micro-nano channel and a column manufactured by a micro-nano processing method.
The traditional method for machining the surface boiling enhanced heat exchange structure mainly comprises the following steps: 1) the surface of the solid is polished by adopting sand paper of different grades to adjust the surface roughness, and a microscopic concave-convex structure is added to increase surface nucleation points to promote boiling, but the method has limited effect on improving boiling heat exchange, and bubbles are not easy to escape; 2) the method is characterized in that a macroscopic or tiny groove is cut on the surface of the conductive solid by adopting an EDM (electric discharge machining) method, the machined surface has more corner structures which are beneficial to nucleation than a plane, nucleation sites are increased, and the gas-liquid interface behavior can be improved by adopting a special structure. However, the method is generally used for processing a larger block structure and is not suitable for integrated heat dissipation of electronic devices.
The surface modification structure can strengthen the boiling heat exchange performance to a great extent. There are many modification processes and various materials such as metal oxides, nanoparticles, SiO2, TiO2, Carbon Nanotubes (CNTs), and graphene oxide can be coated. Methods such as vapor deposition, Atomic Layer Deposition (ALD), sputtering, etching, nanofluid boiling, spin coating, etc. can also be used to create a layer of microstructure on the surface that alters the physical properties. Optimization of surface properties such as surface roughness, wettability, porosity and surface pore morphology can improve vaporization nucleation density, bubble size, bubble detachment frequency and the like, and reduce superheat degree of a boiling initiation wall surface. Although the number of nucleation sites can be greatly increased by virtue of high specific surface area in the surface microstructure modification, the microstructure is susceptible to external environmental influences, and particularly, the surface properties may be changed under the conditions of long-time contact with liquid and high-temperature working conditions, so that the risk of surface failure is great.
The action of porous surface media of several materials is mentioned in J.Y.Chang et al in the documents Enhanced binding heat Transfer from microporous surfaces of effects of a coating composition and method, int.J.Heat Mass Transfer40(18) (1997)4449 and 4460. The microporous surfaces of these materials were made by immersing the copper block surface in coating solutions made of different compositions (aluminum, copper, diamond and silver particles) and baking. Due to the increase of the number of vaporization cores and the capillary effect, the boiling heat exchange performance can be obviously enhanced, and the porous surface can effectively inhibit the expansion of dry spots and improve the critical heat flux density under certain conditions. However, the fine pore structure also causes an increase in vapor flow resistance, and a vapor film is easily formed on the heating surface to lower the heat transfer coefficient under high heat flow, and the transition from nucleate boiling to the film state region is advanced.
Honda, H et al, Enhanced decorating of FC-72on silicon chips with micro-pin-fins and sub-scale-depth [ J ]. Journal of Heat Transfer,2002,124(2): 383-. The improvement of the surface heat exchange performance of the columnar microstructure is caused by the increase of nucleation sites and the increase of heat exchange area on one hand, and on the other hand, micro-convection motion is generated among the micro-columns under the action of capillary pumping, and evaporation of a liquid micro-layer exists, which is also a main factor for heat exchange enhancement. However, this structure has a certain limitation even at high heat flux density, and the generated large bubbles are not easily released from the surface, and thus the problem of dry burning is encountered.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a chip integrated boiling enhanced heat exchange structure based on an MEMS technology and a preparation method thereof, which can well solve the technical problems.
According to one aspect of the invention, a chip integrated boiling enhanced heat exchange structure based on an MEMS technology is provided, which comprises a heat conducting substrate, wherein a supporting layer is arranged on the surface of the heat conducting substrate, and a plurality of claw-shaped structures are arranged on the supporting layer.
Preferably, the claw-shaped structure is composed of a bottom heat-conducting metal layer and a plurality of side wall metal sheets, the bottom heat-conducting metal layer is arranged on the supporting layer, one ends of the side wall metal sheets are fixed on the bottom heat-conducting metal layer, and the other ends of the side wall metal sheets are free ends which extend towards the liquid space to form a gripping shape.
More preferably, the free end extends into the liquid along the surface of the heat conducting substrate in a nearly vertical direction, and the plurality of side wall metal sheets enclose a three-dimensional cavity.
Preferably, the claw-shaped structure is a suspended metal sheet structure prepared by adopting a surface micromachining method, and the suspended metal sheet structure is folded along a plane normal direction to form a plurality of side wall metal sheets for blocking a path for merging and growing a gas film in the growth process of a large amount of bubbles on the surface.
Preferably, the claw-shaped structures are distributed on the surface of the heat-conducting substrate in an array.
Preferably, the side wall metal sheets of the claw-shaped structure are provided with through holes, and gaps are reserved between adjacent side wall metal sheets, so that peripheral liquid can be supplied to the bottoms of the bubbles by means of siphon effect, and the bubbles at the bottoms can be separated.
Preferably, the support layer is a metal solid plane structure.
Preferably, the joint of the fixed ends of the side wall metal sheets is preferably designed with a structure which is beneficial to bending and rigidity reduction, such as width reduction, thinning and the like, so as to prevent the claw-shaped structure from falling off due to overlarge stress when the claw-shaped structure is folded.
In the invention, the included angle between the side wall metal sheet of the claw-shaped structure and the heat conduction substrate can be adjusted, but is preferably close to being vertical to the surface of the heat conduction substrate. If the angle between the side wall metal sheet of the claw-shaped structure and the heat conducting substrate is too small, the side wall metal sheet can block the movement of air bubbles below the side wall metal sheet, so that the air bubbles are accumulated outside the claw-shaped structure, the liquid-solid contact area is reduced, and the heat exchange is not facilitated; if the angle between the side wall metal sheet of the claw-shaped structure and the heat conducting substrate is too large, and the side wall metal sheet of the claw-shaped structure is close to being closed, the escape of bubbles is not facilitated, and bubbles which cannot escape from the top can escape from the side gap to cover the surface of the heat conducting substrate and also be not facilitated for heat exchange.
From the above description of the structure, the present invention proposes a novel concept of using MEMS technology to fabricate claw-type structures to promote boiling heat exchange. Bubbles grow and break away from the cavity formed by the side wall metal sheets after nucleating around the bottom supporting layer. The array is formed on the surface of the heat-conducting substrate by the claw-shaped structure, so that a path for combining and growing into an air film in the growth process of a large amount of bubbles on the surface is blocked, and the risk that the surface of the heat-conducting substrate in the air film is baked is avoided. The hole-shaped structure on the metal sheet and the gaps between the metal sheets enable surrounding liquid to enter the bottom of the bubbles by means of siphon effect, and the separation efficiency of the bubbles growing inside the claw-shaped structure is enhanced. The bubbles blocked to form a film effectively disturb the liquid flow outside the claw-shaped structure, and when the heat dissipation effect of the boiling heat exchange surface is enhanced, the bubbles and the outer wall of the side wall metal sheet extending to the inside of the liquid generate convective heat exchange, so that the boiling heat exchange effect is further enhanced.
According to another aspect of the present invention, a method for preparing a chip integrated boiling enhanced heat exchange structure based on MEMS technology is provided, the method comprising the following steps:
firstly, generating a conductive seed layer on the surface of a heat-conducting substrate by adopting a magnetron sputtering process;
secondly, spin-coating photoresist on the seed layer formed in the first step, and photoetching, developing and electroplating to form a pattern of the metal supporting layer;
thirdly, sputtering a conductive seed layer on the whole surface of the graph manufactured in the second step by adopting a magnetron sputtering method;
fourthly, spin-coating photoresist on the seed layer formed in the third step, and photoetching, developing and electroplating to form a designed plane graph which can be folded to form a claw-shaped structure;
and fifthly, removing the photoresist, and folding the suspended structure of the planar graph obtained in the fourth step along the edge normal direction of the supporting layer below the suspended structure.
Preferably, a chromium copper seed layer is selected in the first and third steps.
Preferably, the electroplating thickness of the support layer in the third step is 0.02-0.05 mm;
preferably, the electroplating pattern of the metal sheet on the side wall of the claw-shaped structure in the fourth step is not too thick, otherwise, the rigidity of the connection part of the metal sheet on the side wall and the center is too high, so that the side wall is not favorably folded, and the thickness is preferably 0.02-0.07 mm.
Preferably, in the fourth step, on the basis of the plane pattern which can be folded to form the claw-shaped structure, a plane patterning process is added, so that a micropore structure is further manufactured on the surface of the electroplating pattern, and the nucleation sites at the position of the micropore structure are increased during boiling.
Compared with the prior art, the invention has the following beneficial effects:
aiming at the phenomena that bubbles are accumulated on a heating surface in a large area during boiling heat exchange, so that the heat exchange efficiency is poor, and the temperature distribution on the heat exchange surface is uneven, the invention designs a three-dimensional claw-shaped structure, blocks paths for merging and growing into a gas film in the growth process of a large amount of bubbles on the surface, and strengthens the separation rate of the bubbles in the structure.
Furthermore, in the invention, the claw-shaped structures form an array on the boiling heat exchange surface (the surface of the heat conducting substrate), and the existing boiling strengthening surface structures in the forms of porous materials, micro-channels, micro-columns, micro-holes and the like still have the phenomenon that bubbles are combined and stacked on the heating surface, are not easy to escape and cannot well exert the boiling heat exchange effect. According to the novel design provided by the invention, on one hand, a path of a gas film which is combined and grows in the growth process of a large amount of bubbles on the surface is blocked through the array claw-shaped structure, and the risk that the surface of the heat-conducting substrate in the gas film is baked is avoided. The bubbles blocked to form a film effectively disturb the liquid flow outside the side wall metal sheet of the claw-shaped structure, and when the heat dissipation effect of the boiling heat exchange surface is enhanced, the bubbles and the outer wall of the side wall metal sheet extending towards the inside of the liquid generate convective heat exchange, so that the boiling heat exchange effect is further enhanced. On the other hand, the metal sheet on the side wall of the claw-shaped structure can be used for preparing a pore structure to ensure that liquid below the bubbles in the cavity is supplied, so that the bubble separation efficiency at the position is enhanced.
Meanwhile, the claw-shaped enhanced heat exchange structure is prepared on the heat exchange surface by adopting a high-heat-conductivity material through sputtering and electroplating, the interface heat resistance is from a metal thin layer (a supporting layer and a bottom heat-conducting metal layer) with the thickness of micron order and can be almost ignored, so that the heat exchange area can be increased through the claw-shaped structure, and the effect of further enhancing the heat exchange by utilizing the convection of bubble turbulent flow and the side wall metal thin sheet can be realized.
In addition, the invention further solves the problem that the MEMS technology is not easy to process a millimeter-scale three-dimensional structure, and the substrate material and the processing mode are both derived from the chip integration technology, thereby facilitating the realization of the application of the structure in the integration and heat dissipation of electronic devices.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is an overall three-dimensional perspective view of embodiment 1 of the present invention;
FIG. 2 is an overall process flow diagram of example 1 of the present invention;
FIG. 3 is a schematic view of the fluid path during boiling in example 1 of the present invention;
FIG. 4 is an overall three-dimensional perspective view of embodiment 2 of the present invention;
FIG. 5 is an overall process flow diagram of example 3 of the present invention;
in the figure: 1 is a heat-conducting substrate, 2 is a supporting layer, 3 is a claw-shaped structure, 301 is a bottom heat-conducting metal layer, 302 is a side wall metal sheet, 303 is a hole-shaped structure, 304 is a root-part width-reducing structure, 4 is a plane pattern for manufacturing the claw-shaped structure, and 5 is a bubble.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
Referring to fig. 1-5, the boiling enhanced heat exchange structure proposed by the present invention is designed to fabricate a claw-shaped structure 3 on the surface of a heat-conducting substrate 1, wherein the claw-shaped structure 3 is disposed on the heat-conducting substrate 1 through a supporting layer 2.
The claw-shaped structure 3 is composed of a bottom heat conducting metal layer 301 and a side wall metal sheet 302 extending into the liquid along the vertical direction of the boiling heat exchange surface, and the side wall metal sheet 302 extends towards the liquid space to form a gripping shape. Further, the sidewall metal sheet 302 is designed with a hole-like structure 303, and a gap is left between the two sheets.
Further, the root portion widening 304 in fig. 1 is used to reduce the rigidity and prevent the structure 4 from falling off due to excessive stress during the folding into the claw structure 3. The bubbles 5 nucleate around the bottom support layer 2 and grow and detach from the cavity formed by the sidewall foils 302.
The plurality of claw-shaped structures 3 form an array on the boiling heat exchange surface, so that a path for merging and growing into an air film in the growth process of a large amount of bubbles on the surface is blocked, and the risk that the surface of the heat-conducting substrate 1 in the air film is dried is avoided.
The hole-like structure 303 on the sidewall metal sheet 302 and the gap between the sidewall metal sheets 302 make the surrounding liquid enter the bottom of the bubble by siphon effect, which enhances the detachment efficiency of the bubble growing inside the claw-shaped structure 3. The bubbles blocked from forming the film effectively disturb the liquid flow outside the claw-shaped structure 3, so that the heat dissipation effect on the surface of the heat-conducting substrate 1 is enhanced, and meanwhile, the heat convection with the outer wall of the side wall metal sheet 302 extending towards the inside of the liquid is realized, and the boiling heat transfer effect is further enhanced. Specifically, in some preferred embodiments, the following parameters may be used:
-the planar dimensions of the support layer 1 are 0.5 x 0.5mm2-1 x 1mm 2;
-the thickness of the support layer 1 is 0.02-0.05 mm;
the bottom thermally conductive metal layer 301 of the claw structure 3 has a size of 0.5 × 0.5mm2-1 × 1mm 2;
the side wall foils 302 of the claw structures 3 are 0.4-0.9mm wide and 0.8-1.5mm high;
the thickness of the side wall foil 302 of the claw-like structure is 0.02-0.07 mm;
the thickness of the heat-conducting substrate 1 is 0.3-1 mm.
In order to better illustrate the above structure of the present invention and the preparation thereof, specific examples are provided below, which are only some examples of the present invention and are not intended to limit the practice of the present invention.
Example 1
As shown in fig. 1, the present embodiment provides a chip integrated boiling enhanced heat exchange structure based on MEMS technology, including: heat conduction base plate 1, supporting layer 2, claw type structure 3, wherein:
the heat conducting substrate 1 is made of AlN materials, and the supporting layer 2 and the claw-shaped structures 3 are made of copper materials.
The supporting layer 2 is uniformly distributed on the surface of the heat conducting substrate 1, and the bottom heat conducting metal layer 301 of each claw-shaped structure 3 is connected and fixed with the supporting layer 2;
the claw-shaped structure 3 is composed of a bottom heat conducting metal layer 301 and a plurality of side wall metal sheets 302, the bottom heat conducting metal layer 301 is disposed on the support layer 2, one end of each of the plurality of side wall metal sheets 302 is fixed on the bottom heat conducting metal layer 301, and the other end of each of the plurality of side wall metal sheets 302 is a free end which extends to the liquid space to form a gripping shape.
The side wall metal sheets 302 of the claw-shaped structure 3 are provided with the porous structures 303, and gaps are reserved among the side wall metal sheets 302, so that liquid supply below the bubbles in the cavity is ensured, and the bubble separation efficiency at the position is enhanced.
Preferably, the components of the chip integrated boiling enhancement structure have the following dimensions:
the size of the heat-conducting substrate 1 is 10mm by 0.38 mm;
the size of the support layer 2 is 1mm by 0.03 mm;
the side wall foils 302 of the claw structures 3 are dimensioned to be 0.9mm wide, 1.5mm high and 0.03mm thick.
As shown in fig. 2, in this embodiment, the overall processing process of the boiling enhanced heat exchange structure is provided at the same time, and the specific flow is as follows:
firstly, generating a chromium-copper seed layer on the surface of the heat-conducting substrate 1 by adopting a magnetron sputtering process;
secondly, spin-coating a layer of positive photoresist on the seed layer formed in the first step, and photoetching, developing and electroplating to obtain a supporting layer pattern 2 (shown as (a) in fig. 2) uniformly distributed on the surface of the heat-conducting substrate 1;
thirdly, sputtering a chromium-copper seed layer on the whole surface of the graph manufactured in the second step by adopting a magnetron sputtering method;
fourthly, spin-coating a layer of positive photoresist on the seed layer formed in the third step, and photoetching, developing and electroplating to form a plane pattern 4 for manufacturing a claw-shaped structure (as shown in (b) in fig. 2);
and fifthly, removing the photoresist, and folding the suspended metal sheet structures around the planar graph 4 for manufacturing the claw-shaped structures obtained in the fourth step along the edge normal direction of the lower supporting layer 2 to obtain the three-dimensional claw-shaped structures 3 (as shown in (c) in fig. 2).
As shown in fig. 3, for the fluid path of the chip-integrated boiling enhanced heat exchange structure in the present embodiment during operation, the hole-shaped structure 303 on the sidewall metal sheet 302 of the claw-shaped structure 3 and the gap of the sidewall metal sheet 302 enable the surrounding liquid to enter the bottom of the bubble by siphon effect, thereby enhancing the detachment efficiency of the bubble 5 growing inside the claw-shaped structure 3. And the bubbles 5 blocked from forming the film effectively disturb the liquid flow outside the claw-shaped structure 3. Therefore, the gas path escapes upward, and the liquid supply path diffuses and supplies from the top to the bottom of the claw-shaped structure 3.
In this embodiment, deionized water is selected as the heat exchange liquid working medium, and the chip integrated boiling enhanced heat exchange structure obtained in this embodiment is placed in a visual test cavity to perform a boiling test in a large-volume pool. The density of heat flow generated on the chip is 80W/cm2When the superheat degree of the wall surface of the structure is measured to be 15 ℃, the structure has a good boiling heat exchange effect.
Example 2
As shown in fig. 4, the present embodiment provides a chip integrated boiling enhanced heat exchange structure based on MEMS technology, and compared with embodiment 1, the present embodiment changes the material of the heat conducting substrate and the size and distribution density of the claw-shaped structure. Specifically, the chip integrated boiling enhanced heat exchange structure comprises: heat conduction base plate 1, supporting layer 2, claw type structure 3, wherein:
the heat conducting substrate 1 is cut by a silicon wafer, and the supporting layer 2 and the claw-shaped structures 3 are made of copper materials. The supporting layer 2 is uniformly distributed on the surface of the heat conducting substrate 1, and the bottom heat conducting metal layer 301 of each claw-shaped structure 3 is fixedly connected with the copper supporting layer 2; the side wall metal sheets 302 of the claw-shaped structure 3 are provided with holes 303, and gaps are reserved among the side wall metal sheets 302, so that liquid below the bubbles in the cavity is supplied, and the bubble separation efficiency at the position is enhanced.
Preferably, the components of the chip integrated boiling enhancement adopt the following sizes:
the size of the heat-conducting substrate 1 is 10mm by 0.5 mm;
the size of the support layer 2 is 0.7mm 0.03 mm;
the dimensions of the side walls of the claw-shaped structures 3 are 0.6mm wide, 1.1mm high and 0.03mm thick.
In this embodiment, the processing flow and the fluid path during operation of the boiling enhanced heat exchange structure are the same as those in embodiment 1.
Example 3
As shown in fig. 5, the present embodiment provides an appearance of a chip integrated boiling enhanced heat exchange structure based on MEMS technology, which is the same as that of embodiment 1, and includes: heat conduction base plate 1, supporting layer 2, claw type structure 3, wherein:
the heat conducting substrate 1 is made of AlN materials, and the supporting layer 2 and the claw-shaped structures 3 are made of copper materials. The structure and the size of each component of the chip integrated boiling enhancement are also the same as those of the embodiment 1.
Different from the embodiments 1 and 2, in the present embodiment, a patterned layer is added in the process of the chip integrated boiling enhanced heat exchange structure to fabricate the micropores on the inner wall surface of the claw-shaped structure 3, so as to increase nucleation sites there. As shown in fig. 5, in this embodiment, the overall process flow of the boiling enhanced heat exchange structure is as follows:
firstly, generating a chromium-copper seed layer on the surface of the heat-conducting substrate 1 by adopting a magnetron sputtering process;
secondly, spin-coating a layer of positive photoresist on the seed layer formed in the first step, and photoetching, developing and electroplating to obtain a supporting layer pattern 2 uniformly distributed on the surface of the heat-conducting substrate 1 (as shown in (a) in fig. 5);
thirdly, sputtering a chromium-copper seed layer on the whole surface of the graph manufactured in the second step by adopting a magnetron sputtering method;
step four, spin-coating a layer of positive photoresist on the seed layer formed in the step three, and photoetching, developing and electroplating to form a planar pattern bottom layer pattern 401 for manufacturing a claw-shaped structure, wherein the electroplating thickness is 0.01mm (as shown in (b) in fig. 5);
and fifthly, spin-coating a layer of positive photoresist on the pattern layer formed in the fourth step, and photoetching, developing and electroplating to obtain a top pattern 402 of the planar pattern for manufacturing the claw-shaped structure. In the area of the previous electroplating pattern 401, micro circular hole structures 403 with the diameter of 0.1mm are uniformly arranged on the pattern 402 in the previous step, and the electroplating thickness of the pattern 402 is 0.02mm (as shown in (c) of fig. 5);
and sixthly, removing the photoresist, and folding the suspended metal sheet structure 4 obtained in the fourth step and the fifth step along the edge normal direction of the lower support layer 2 to obtain the three-dimensional claw-shaped structure 3 (as shown in (d) in fig. 5).
In this embodiment, the fluid path during operation is the same as in embodiment 1.
The above are only some of the embodiments of the present invention, and other embodiments of the present invention are also possible, such as:
in some embodiments of the present invention, the heat conducting substrate may be made of a substrate material which has high thermal conductivity such as AlN and Si and can be integrated with an electronic chip, so that the heat exchanging structure can be more easily applied to heat dissipation of electronic devices.
In some embodiments of the present invention, the metal supporting layer and the three-dimensional claw-shaped metal microstructure may be made of, but not limited to, one or a combination of Cu, Al, Au, Zn, Ag, or Ni materials. In some preferred embodiments, the supporting layer and the claw-shaped structures are made of copper materials, so that the heat conduction effect is enhanced, and meanwhile, a certain superheat degree is ensured at the positions, so that the claw-shaped structures can also be used as the surfaces of boiling nucleation to enhance the boiling heat exchange effect.
In some embodiments of the present invention, the surface features of the heat conducting substrate and the claw-shaped structure include, but are not limited to, a surface structure such as a nanoparticle close-packed structure, a nanopore array structure, a nanowire array structure, and a nanoporous coating layer, which are obtained by a surface modification method such as coating, vapor deposition, Atomic Layer Deposition (ALD), sputtering, etching, and nanofluid boiling.
In some embodiments of the invention, deionized water is used as the heat exchange working medium, or other liquids such as FC-72, ethanol, nanofluid and the like can be used as the heat exchange working medium, and different liquids or corresponding to different claw-shaped structure sizes and side wall patterns can be optimized and adjusted.
In some embodiments of the present invention, the surface structures of the layers are prepared by surface micromachining methods including, but not limited to, sputtering, photolithography, development, electroplating, and the like.
In conclusion, the embodiment can show that on one hand, the array claw-shaped structure blocks a path of a large number of bubbles on the surface and growing into an air film, and the dry burning risk is avoided; on one hand, the side wall of the claw-shaped structure can be provided with a pore structure to ensure that liquid below the bubbles in the cavity is supplied, and the bubble separation efficiency at the position is enhanced. Meanwhile, the supporting layer and the claw-shaped structure are prepared on the heat exchange surface by adopting high-heat-conductivity materials through sputtering and electroplating, the interface heat resistance is from a metal thin layer with the thickness of micron order and can be almost ignored, and therefore the effects of increasing the heat exchange area through the claw-shaped structure and further strengthening the heat exchange by utilizing the convection of bubble turbulent flow and the metal side wall can be realized. In addition, the substrate material and the processing mode of the design are both derived from a chip integration process, so that the structure is convenient to realize the application in the integration and heat dissipation of electronic devices.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of simplifying the description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.
Claims (8)
1. A chip integrated boiling enhanced heat exchange structure based on MEMS technology is characterized by comprising: the heat conduction substrate is provided with a supporting layer on the surface, and a plurality of claw-shaped structures are arranged on the supporting layer;
the claw-shaped structure consists of a bottom heat-conducting metal layer and a plurality of side wall metal sheets, the bottom heat-conducting metal layer is arranged on the supporting layer, one ends of the side wall metal sheets are fixed on the bottom heat-conducting metal layer, the other ends of the side wall metal sheets are free ends, and the free ends extend towards the liquid space to form a gripping shape;
the claw-shaped structure is formed by preparing a suspended metal sheet structure by adopting a surface micromachining method, and folding the suspended metal sheet structure along the plane normal direction to form a plurality of side wall metal sheets for blocking a path of a gas film which is formed by merging and growing in the growth process of a large amount of bubbles on the surface.
2. The MEMS technology-based chip integrated boiling enhanced heat exchange structure as claimed in claim 1, wherein the free end extends into the liquid along the surface of the heat conducting substrate in a nearly vertical direction, and a plurality of side wall metal sheets enclose a three-dimensional cavity.
3. The MEMS technology-based chip integrated boiling enhanced heat exchange structure of claim 1, wherein the side wall metal sheets are provided with through holes, and a gap is reserved between adjacent side wall metal sheets for supplying surrounding liquid to the bottoms of the bubbles in the claw-shaped structures to promote the separation of the bubbles.
4. The MEMS technology based chip integrated boiling enhanced heat exchange structure as claimed in claim 1, wherein a structure beneficial to bending and rigidity reduction is designed at the joint of the fixed end of the side wall metal sheet, so as to prevent the claw-shaped structure from falling off due to overlarge stress when folded.
5. The MEMS technology based chip integrated boiling enhanced heat exchange structure as claimed in any one of claims 1 to 4, characterized by one or more of the following features:
-the support layer is a metallic solid planar structure;
-the planar dimension of the support layer is 0.5 x 0.5mm2-1*1mm2；
-the thickness of the support layer is 0.02-0.07 mm;
-the bottom thermally conductive metal layer of the claw structure has a size of 0.5 x 0.5mm2-1*1mm2；
-the side wall foils of the claw structure have a width of 0.4-0.9mm and a height of 0.8-1.5 mm;
-the thickness of the side wall foils of the claw structure is 0.02-0.07 mm;
-the thickness of the heat conducting substrate is 0.3-1 mm;
the heat conducting substrate is made of a substrate material which has high heat conductivity and can be integrated with an electronic chip.
6. The MEMS technology-based chip integrated boiling enhanced heat exchange structure as claimed in any one of claims 1 to 4, wherein the claw structures are distributed on the surface of the heat conducting substrate in an array.
7. A preparation method of the chip integrated boiling enhanced heat exchange structure based on the MEMS technology as claimed in any one of claims 1 to 6, wherein: the method comprises the following steps:
firstly, generating a conductive seed layer on the surface of a heat-conducting substrate by adopting a magnetron sputtering process;
secondly, spin-coating photoresist on the conductive seed layer formed in the first step, and photoetching, developing and electroplating to form a pattern of the supporting layer;
thirdly, a magnetron sputtering method is adopted, and a conductive seed layer is sputtered on the whole surface of the graph manufactured in the second step;
fourthly, spin-coating photoresist on the conductive seed layer formed in the third step, and photoetching, developing and electroplating to form a plane figure which can be folded to form a claw-shaped structure;
and fifthly, removing the photoresist, and folding the suspended structure of the planar graph obtained in the fourth step along the plane normal direction to obtain the claw-shaped structure.
8. The method for preparing the chip integrated boiling enhanced heat exchange structure based on the MEMS technology as claimed in claim 7, wherein in the fourth step, a planar patterning process is added on the basis of the planar pattern which can be folded to form the claw-shaped structure, so as to manufacture a microporous structure on the surface of the electroplating pattern and increase nucleation sites at the position during boiling.
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