A microchannel heat sink with a concave structure

Abstract

The present invention discloses a microchannel heat spreader with a concave structure, comprising a base plate, a capillary wick and a cover plate, wherein the upper surface of the base plate is provided with a concave cavity, the capillary wick is provided in the concave cavity, the upper surface of the cover plate is processed with a microchannel structure, the inner surface of the microchannel structure is provided with concave structures on both sides, the base plate and the cover plate are welded to form a closed cavity, and the microchannel heat spreader with the concave structure is formed by vacuuming and injecting liquid. The present invention adopts a microchannel array with a concave structure to replace the conventional condensation end liquid absorption core structure, which is beneficial to the transmission and uniform distribution of the working fluid, increases the working fluid condensation area, shortens the condensation reflux path, and achieves lower flow resistance and superior anti-drying characteristics; on the other hand, the concave structure can increase the heat transfer area, produce a jet throttling effect, disturb the steam flow, inhibit the formation of the condensate film, promote condensation reflux, increase the anti-drying limit, and thus improve the heat transfer efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of microelectronic devices and chip heat dissipation, and in particular to a microchannel heat spreader with a concave structure. Background Art

[0002] As electronic devices become smaller, more integrated, and more complex, the heat generation power of electronic chips is getting higher and higher. At present, the average surface heat flux density of electronic chips has exceeded 100W / cm 2 , and there is a trend of continued increase. At the same time, high heat flux density will form "hot spots" on the surface of electronic devices, resulting in reduced performance and reliability of electronic chips.

[0003] A vapor chamber is a heat dissipation component that transfers heat through phase change. It can quickly transfer the heat flux accumulated on the surface of electronic components and diffuse it to the condensation surface to dissipate the heat, thereby effectively reducing the surface heat flux density of electronic components. In recent years, vapor chambers have been widely used in the field of heat dissipation technology for electronic devices and chips.

[0004] The heat spreader is generally composed of an upper and lower shell and a liquid wick structure. Among them, the liquid wick structure, as the core of the heat spreader, is the top priority of the heat spreader design. At present, the liquid wick structure of the heat spreader mainly includes porous metal sintering and microchannel array. The porous metal sintering liquid wick has the advantages of large capillary suction and good anti-burning properties, and is the most widely used liquid wick structure. However, the porous metal sintering liquid wick has large flow resistance and low permeability, and often needs to be used with a steam chamber and a support column, resulting in low support strength of the heat spreader, complex processing, and high manufacturing cost. In addition, the porous metal sintering liquid wick structure is easy to cause the heat spreader to deform during the high-temperature packaging process, resulting in a low yield rate. At the same time, the shell plate is prone to deformation under long-term heat exposure, resulting in poor contact with the chip. The use of a microchannel liquid wick structure can well avoid this problem. The microchannel liquid wick structure, by directly processing a microchannel structure on a substrate, has the advantages of small contact thermal resistance, large heat transfer area, small flow resistance, and high permeability. In addition, the use of microchannel structures to replace the steam chamber and support column structures can effectively improve the pressure and heat resistance of the heat spreader, shorten the condensation reflux path, and thus effectively improve the heat transfer capacity of the heat spreader. In recent years, with the miniaturization of electronic equipment and the advancement of advanced processing technology, the heat spreader has also developed towards ultra-thin, flexible and high heat transfer performance. The microchannel wick has the advantages of high support strength, low flow resistance, and high permeability, which is more in line with the development trend of ultra-thin and flexible heat spreaders.

[0005] However, the current microchannel wick structure is relatively simple, mostly in the form of a straight channel array structure. The straight channel array structure wick has a smooth inner surface. When the steam is cooled and condensed on the inner surface of the channel, it is easy to form a layer of liquid film on the surface, which hinders the direct contact between the steam and the condensation plate, thereby increasing the heat transfer resistance of the microchannel condensation plate and reducing the heat exchange capacity. In addition, when the steam is cooled and forms droplets on the inner surface of the channel, due to the smooth inner surface of the straight channel and the large surface tension, it is not easy to drip back to the evaporation end, thereby reducing the dry-out limit of the heat spreader and reducing the overall heat dissipation performance of the heat spreader. Summary of the invention

[0006] In order to overcome the shortcomings and deficiencies of the prior art, the present invention provides a microchannel vapor chamber with a concave structure. By setting the concave structure on both sides of the microchannel, the fluid boundary layer can be effectively destroyed, the fluid flow can be disrupted, and the formation of the condensate film can be inhibited, thereby effectively promoting heat transfer. At the same time, the concave structure in the microchannel will form a low-temperature retention zone, promote the condensation and reflux of steam, and achieve higher heat transfer capacity and superior anti-drying characteristics.

[0007] The present invention adopts the following technical solution:

[0008] A microchannel heat spreader with a recessed structure comprises a base plate, a capillary core and a cover plate, wherein the upper surface of the base plate is provided with a recessed cavity, the capillary core is arranged in the recessed cavity, the upper surface of the cover plate is processed with a microchannel structure, recessed structures are arranged on both sides of the inner surface of the microchannel structure, the base plate and the cover plate are welded to form a closed cavity, and the microchannel heat spreader with the recessed structure is formed by vacuuming and injecting liquid.

[0009] The capillary core is a structure of sintered copper powder, foamed metal or wire mesh.

[0010] The microchannel structure is in the form of an array consisting of a plurality of microchannels, and the array form includes a linear array and a circular array.

[0011] The concave structure is a two-dimensional concave structure, which includes a plurality of concave holes. The shapes of the concave holes include rectangle, triangle, semicircle or trapezoid.

[0012] The plurality of recesses are symmetrically distributed on both sides of the inner surface of the microchannel.

[0013] The cross section of the microchannel is arc-shaped, triangular, rectangular or trapezoidal.

[0014] The depth of the microchannel array is equal to the depth of the bottom plate cavity minus the height of the capillary core.

[0015] The bottom plate and the cover plate have the same shape.

[0016] The bottom plate and the cover plate may be in a circular or square shape.

[0017] When the capillary core is a copper powder sintered liquid wick, the particle size of the copper powder particles is 0.075mm-0.150mm.

[0018] Beneficial effects of the present invention:

[0019] (1) The present invention adopts a microchannel wick structure to replace the traditional porous metal sintered wick structure. On the one hand, the microchannel structure is conducive to the transmission and uniform distribution of the working fluid vapor, and the channel wall also expands the area of ​​working fluid condensation, shortens the path of liquid condensation reflux, and achieves lower flow resistance and excellent anti-drying characteristics; on the other hand, the microchannel structure also serves as the upper and lower shell plate support columns, and has greater strength than the porous metal sintered wick structure, which can better ensure that the heat sink is closely attached to the chip under long-term heating;

[0020] (2) The two sides of the microchannel in the vapor chamber of the present invention are processed with a concave structure, which can destroy the fluid boundary layer and cause fluid disturbance, thereby inhibiting the formation of condensate film, enhancing the convective heat transfer capacity between steam and the condensation plate, and improving the heat transfer performance of the vapor chamber; on the other hand, the insertion of the concave structure will lead to the formation of a low-temperature retention zone (such as Figure 6 He Ru Figure 7 As shown in the figure), the condensation of steam at the concave cavity is strengthened (condensation strengthening point), the condensation reflux of liquid working medium is promoted, and the anti-drying property of the vapor chamber is enhanced;

[0021] (3) Adding a concave structure to the microchannel vapor chamber can effectively increase the heat transfer area. At the same time, an injection effect occurs at the inlet of the concave and a throttling effect occurs at the outlet. These two effects effectively promote the formation of secondary flow, thereby reducing the steam flow resistance and improving the steam convection heat transfer coefficient, ultimately effectively improving the temperature uniformity and heat dissipation performance of the vapor chamber;

[0022] (4) The microchannel vapor chamber with a concave structure involved in the present invention has high support strength, low flow resistance, good temperature uniformity, and high heat transfer efficiency, which is more in line with the development trend of ultra-thin and flexible vapor chambers;

[0023] (5) The microchannel heat sink with a concave structure involved in the present invention is easy to manufacture, has low processing cost, and is convenient for large-scale production and manufacturing of products. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of a microchannel vapor chamber with a concave structure in Example 1 of the present invention;

[0025] Figure 2 yes Figure 1 A cross-sectional view of

[0026] Figure 3 yes Figure 1 Schematic diagram of the cover structure in FIG.

[0027] Figure 4 is a schematic structural diagram of Embodiment 2 of the present invention;

[0028] Figure 5 is a schematic diagram of a top view of the cover plate of Embodiment 2 of the present invention;

[0029] Figure 6 This is a heat dissipation temperature distribution diagram of the microchannel vapor chamber of Example 1 of the present invention;

[0030] Figure 7 This is a heat dissipation flow rate distribution diagram of Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0032] Example 1

[0033] like Figure 1-Figure 3 As shown, a microchannel heat spreader with a concave structure includes a bottom plate 1, a capillary core 2 and a cover plate 3. A concave cavity is set on the inner surface of the bottom plate, and the capillary core 2 is embedded in the bottom plate concave cavity to form the evaporation end of the heat spreader. In this embodiment, the cover plate and the bottom plate are both circular, and a circular array of microchannel structures 31 are processed on the inner surface of the cover plate. The microchannel structure is composed of multiple microchannels, and the multiple microchannels diverge from the center point of the cover plate to the edge and are evenly arranged. In this embodiment, there are 20 microchannels, and concave structures 32 are processed on both sides of the inner surface of the microchannel.

[0034] like Figure 3 As shown, in this embodiment, the recess structure is composed of a plurality of semicircular recesses 32, which are symmetrically distributed on both sides of the microchannel, the diameter of the semicircular recesses 32 is equal to the channel width, and the number of semicircular recesses in each microchannel is 10.

[0035] The bottom plate and the cover plate are welded to form a closed cavity, and then a final microchannel heat spreader with a concave structure is formed by vacuuming and injecting liquid.

[0036] In this embodiment, the material of the bottom plate and the cover plate is copper.

[0037] In this embodiment, the bottom plate 1 is formed in one piece by directly stamping a circular copper plate.

[0038] In this embodiment, the capillary core is a copper powder sintered liquid wick, and the copper powder particle size is 0.075mm-0.150mm. During processing, the designed graphite mold is first covered on the upper surface of the bottom plate cavity, and then the copper powder particles are quantitatively filled into the gap between the bottom plate and the mold, and then placed in a sintering furnace for sintering and forming.

[0039] Example 2

[0040] See also Figure 4 and Figure 5 The difference between this embodiment and embodiment 1 is that the cover plate and the bottom plate are square in shape, the microchannel array on the cover plate is a parallel rectangular straight microchannel array, and the cavity structure is a rectangular cavity.

[0041] The other parameter settings and processing methods of this embodiment are the same as those of Embodiment 1.

[0042] Figure 6 Here, Temperature represents temperature, and 340, 342, 344, etc. represent temperature changes. Figure 7 Velocity means flow rate.

[0043] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A microchannel vapor chamber with a concave structure, characterized in that: It includes a base plate, a capillary core and a cover plate. The upper surface of the base plate is provided with a concave cavity, the capillary core is arranged in the concave cavity, the upper surface of the cover plate is processed with a microchannel structure, and concave hole structures are arranged on both sides of the inner surface of the microchannel structure. The base plate and the cover plate are welded to form a closed cavity, and a microchannel heat spreader with a concave hole structure is formed by vacuuming and injecting liquid.

2. The microchannel vapor chamber according to claim 1, characterized in that: The capillary core is a structure of sintered copper powder, foamed metal or wire mesh.

3. The microchannel vapor chamber according to claim 1, characterized in that: The microchannel structure is in the form of an array consisting of a plurality of microchannels, and the array form includes a linear array and a circular array.

4. The microchannel vapor chamber according to claim 1, characterized in that: The concave structure is a two-dimensional concave structure, which includes a plurality of concave holes. The shapes of the concave holes include rectangle, triangle, semicircle or trapezoid.

5. The microchannel vapor chamber according to claim 4, characterized in that: The plurality of recesses are symmetrically distributed on both sides of the inner surface of the microchannel.

6. The microchannel vapor chamber according to claim 1, characterized in that: The cross section of the microchannel is arc-shaped, triangular, rectangular or trapezoidal.

7. The microchannel vapor chamber according to claim 1, characterized in that: The depth of the microchannel array is equal to the depth of the bottom plate cavity minus the height of the capillary wick.

8. The microchannel vapor chamber according to claim 1, characterized in that: The bottom plate and the cover plate have the same shape.

9. The microchannel vapor chamber according to claim 1, characterized in that: The bottom plate and the cover plate may be in a circular or square shape.

10. The microchannel vapor chamber according to claim 2, characterized in that: When the capillary core is a copper powder sintered liquid wick, the particle size of the copper powder particles is 0.075mm-0.150mm.

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