Liquid absorbing wick and manufacturing method therefor, and vapor chamber

Abstract

Disclosed in the present invention are a liquid absorbing wick and a manufacturing method therefor, and a vapor chamber. The liquid absorbing wick is used for being mounted on a shell, and the shell is provided with a cover plate. First flow guide grooves and second flow guide grooves are respectively formed in two sides of the liquid absorbing wick, the first flow guide grooves are used for defining first capillary pipes together with the cover plate, and the first capillary pipes and the second flow guide grooves are used for connecting a heat source area and a heat dissipation area. Capillary through holes allowing for passing of working liquid and vapor thereof are formed in the first flow guide grooves; vapor-liquid interfaces formed in the first capillary pipes and the second flow guide grooves serve as phase change interfaces; an evaporation interface is provided on a heat absorption end, and a condensation interface is provided on a heat dissipation end; and capillary pressure is formed to drive condensed working liquid to flow back to the heat source area. Compared with the prior art, the technical solution of the present invention can improve the capillary pressure and improve the backflow speed of working liquid flowing to a heat source area, thereby improving the heat transfer capacity of a vapor chamber. By regulating the sizes of capillary through holes and first capillary pipes, the characteristics of high capillary pressure and large flow can be achieved simultaneously.

Description

Liquid wick and preparation method thereof, and temperature equalizing plate Technical Field

[0001] The present invention relates to the technical field of heat dissipation devices, and in particular to a liquid wick and a preparation method thereof, and a temperature equalizing plate. Background Art

[0002] A vapor chamber is a commonly used thermally conductive component consisting of a shell, a wick, and a working fluid. The shell forms a cavity within which the wick and working fluid reside. When in use, the vapor chamber's cover contacts the heat source. The area directly opposite the heat source on the vapor chamber is the heat source area, and a heat dissipation area is located outside the heat source area. The wick can be constructed in a variety of structures, including wire mesh, sintered copper powder, micropillar arrays, grooves, and metal foam. It possesses capillary properties and is capable of absorbing the working fluid.

[0003] When the vapor chamber is operating, the working fluid in the heat source area evaporates due to the heat. The vapor overflows the wick and flows into the steam chamber of the shell. After leaving the heat source area, the vapor condenses, releasing heat, and turns back into liquid. The wick acts to return the vapor chamber to the heat source area. This cyclical process of evaporation and condensation transfers some of the heat from the heat source area to the heat dissipation area, reducing the temperature difference between the two areas and achieving a uniform temperature.

[0004] In existing wicks, capillary pressure is limited or uncontrollable, limiting the working length and thermal conductivity of the heat spreader. This is particularly true under conditions of acceleration, where limited capillary pressure can lead to a sharp drop in thermal conductivity or even cessation of operation. For example, in commonly used wicks with wire mesh structures and some foam structures, the capillary force generated by the working fluid flowing upwards is generated by the capillary structure formed between the filaments or between the filaments and the outer plate, resulting in poor capillary capacity. Alternatively, the flow path is the wick's own irregular, porous structure, resulting in a tortuous internal flow path, high resistance to liquid flow, and numerous ineffective paths. While some existing tightly woven wire or fiber structures enhance capillary force, they also have low porosity, high flow resistance, and often low capillary flow rate. In recent years, wicks with grooved or near-groove structures have also been widely developed, primarily due to their machinability. However, grooved structures, as open fluid channels, have poor capillary capacity, resulting in slow working fluid flow and low capillary flow rate, reducing the heat spreader's thermal conductivity. Therefore, a good wick must have the advantages of high capillary force and large capillary flow, so as to accelerate the circulation of the working fluid and improve the thermal conductivity of the temperature plate.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to provide a liquid wick and a preparation method thereof, and a temperature averaging plate, which are used to increase the reflux rate of the working fluid to the heat source area, thereby improving the cooling capacity of the temperature averaging plate.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention discloses a liquid absorbent core, which is used to be installed on a shell, wherein the shell has a cover plate, and the liquid absorbent core has a first guide groove; the first guide groove is used to form a first capillary channel together with the cover plate;

[0009] The first capillary tube is used to connect the heat source area and the heat dissipation area, so that the working fluid condensed in the heat dissipation area can flow back to the heat source area through the first capillary tube under the action of capillary pressure.

[0010] Preferably, the shell has a steam chamber, which is located on the side of the wick facing away from the cover plate; the wick is provided with a capillary through hole, which is used to connect the first guide groove and the steam chamber, so that the working fluid and its steam can flow between the first guide groove and the steam chamber.

[0011] Preferably, the wick further has a second guide groove, which is located on the side of the wick close to the steam chamber; the second guide groove is used to connect the heat source area and the heat dissipation area, so that the working fluid condensed in the heat dissipation area can flow back to the heat source area through the second guide groove under the action of capillary pressure.

[0012] Preferably, the first end of the first capillary tube is used to be placed in the heat source area, and the second end of the first capillary tube is used to be placed in the heat dissipation area; the effective capillary radius of the capillary hole located at the first end of the first capillary tube is smaller than the effective capillary radius of the capillary hole located at the second end of the first capillary tube, so as to increase the capillary pressure that causes the working fluid to flow back to the heat source area.

[0013] Preferably, the wick further has a connecting channel; the first capillary tubes include a plurality of first capillary tubes, and two adjacent first capillary tubes are connected through the connecting channel, so that the working fluid and the vapor of the working fluid can flow between different first capillary tubes.

[0014] Preferably, the connecting channel includes a connecting groove, and the connecting groove is used to form a second capillary channel together with the cover plate.

[0015] The present invention also discloses a temperature equalizing plate, comprising the above-mentioned liquid-absorbing core and the shell; the shell has the cover plate, one side of the cover plate is used to contact the heat source, and the other side of the cover plate and the first guide groove together form the first capillary channel.

[0016] Preferably, the shell has a steam chamber, which is located on the side of the wick facing away from the cover plate; the wick is provided with a capillary through hole, which is used to connect the first guide groove and the steam chamber, so that the working fluid and its steam can flow between the first guide groove and the steam chamber.

[0017] The present invention also discloses a method for preparing a liquid absorbent core, which is used to prepare the liquid absorbent core, comprising the following steps:

[0018] S1. Arranging a strip structure on the surface of a base to obtain a substrate, wherein a surface of the substrate having the strip structure is a deposition surface;

[0019] S2. Depositing a metal layer on the deposition surface of the substrate, wherein the metal layer covers at least a portion of the deposition surface; the material of the metal layer is different from that of the strip structure and the base;

[0020] S3. Remove the substrate and the strip structure; the first guide groove is formed after the strip structure is removed.

[0021] Preferably, the preparation method of the liquid absorbent core further comprises:

[0022] Step S4: machining capillary through holes on the first guide groove.

[0023] Compared with the prior art, the present invention has achieved the following technical effects:

[0024] The first guide groove of the wick is used to form a first capillary channel with the cover plate. The first capillary channel is a tubular structure with a defined direction. The cross-section of the tubular structure can be rectangular, trapezoidal, semicircular, major arc, minor arc, or similar shapes. Compared with existing technologies, such as groove structures or open structures (including wire mesh, sintered copper powder, and foam structures), the working fluid in the present invention flows along the first capillary channel during the process of returning from the heat dissipation area to the heat source area, rather than along an internally blocked path. Therefore, the working fluid has less flow resistance and a shorter flow distance, which can effectively increase the return speed of the working fluid to the heat source area, thereby improving heat transfer capacity.

[0025] In a preferred embodiment of the present invention, the first capillary channel is provided with a capillary through-hole. This allows the vapor-liquid interface within the first capillary channel and the second flow channel to jointly provide capillary pressure, thereby increasing the capillary pressure differential between the heat source and heat dissipation areas. This effectively increases the return velocity of the working fluid to the heat source, thereby improving heat transfer capacity. By adjusting the size of the capillary through-hole and the first capillary channel, high capillary pressure and high flow rate can be achieved simultaneously. This overcomes the randomness and difficulty in controlling the capillary pressure and working fluid flow rate in traditional solutions.

[0026] In a preferred embodiment of the present invention, the effective capillary radius of the capillary through holes in the heat source area is smaller than the effective capillary radius of the capillary through holes in the heat dissipation area, so as to further increase the capillary pressure for the working fluid to flow back to the heat source area.

[0027] The preparation methods of the temperature averaging plate and the liquid wick of the present invention both have corresponding technical effects as the liquid wick, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] FIG1 is a schematic diagram of the connection relationship between the liquid absorbent core and the cover plate according to an embodiment of the present invention;

[0030] FIG2 is another schematic diagram of the connection relationship between the absorbent core and the cover plate according to an embodiment of the present invention;

[0031] FIG3 is another schematic diagram of the connection relationship between the wick and the cover plate according to an embodiment of the present invention;

[0032] FIG4 is another schematic diagram of the connection relationship between the absorbent core and the cover plate according to an embodiment of the present invention;

[0033] FIG5 is another schematic diagram of the connection relationship between the wick and the cover plate according to an embodiment of the present invention;

[0034] FIG6 is another schematic diagram of the connection relationship between the absorbent core and the cover plate according to an embodiment of the present invention;

[0035] FIG7 is a schematic top view of a liquid absorbent core according to an embodiment of the present invention;

[0036] FIG8 is another schematic top view of the liquid absorbent core according to an embodiment of the present invention;

[0037] FIG9 is another schematic top view of the absorbent core according to an embodiment of the present invention;

[0038] FIG10 is another schematic top view of the absorbent core according to an embodiment of the present invention;

[0039] FIG11 is another schematic top view of the absorbent core according to an embodiment of the present invention;

[0040] FIG12 is another schematic top view of the liquid absorbent core according to an embodiment of the present invention;

[0041] FIG13 is another schematic top view of the absorbent core according to an embodiment of the present invention;

[0042] FIG14 is another schematic top view of the absorbent core according to an embodiment of the present invention;

[0043] FIG15 is a schematic diagram of an arrangement of a liquid absorbent core according to an embodiment of the present invention;

[0044] FIG16 is a schematic diagram of another arrangement of the absorbent core according to an embodiment of the present invention;

[0045] FIG17 is a cross-sectional schematic diagram of an arrangement of a liquid absorbent core on a single-sided shell of a steam chamber according to an embodiment of the present invention;

[0046] FIG18 is a cross-sectional schematic diagram of another arrangement of the wick on the single-sided shell of the steam chamber according to an embodiment of the present invention;

[0047] FIG19 is a cross-sectional schematic diagram of an arrangement of a liquid absorbent core on a double-sided shell of a steam chamber according to an embodiment of the present invention;

[0048] FIG20 is a cross-sectional schematic diagram of the first capillary channel of the wick transporting the working fluid according to an embodiment of the present invention;

[0049] FIG21 is a cross-sectional schematic diagram of the first capillary channel and the second guide groove of the liquid wick simultaneously transporting the working liquid according to an embodiment of the present invention;

[0050] FIG22 is a cross-sectional schematic diagram of a wick transporting working fluid in an evaporation region according to an embodiment of the present invention;

[0051] FIG23 is a cross-sectional schematic diagram of a wick transporting working fluid in a condensation region according to an embodiment of the present invention;

[0052] FIG24 is an exploded schematic diagram of a vapor chamber according to an embodiment of the present invention;

[0053] FIG25 is a schematic diagram of Example 1 of a method for preparing a liquid-absorbing wick according to an embodiment of the present invention;

[0054] FIG26 is a schematic diagram of Example 2 of a method for preparing a liquid-absorbing wick according to an embodiment of the present invention;

[0055] FIG27 is a schematic diagram of Example 3 of a method for preparing a liquid-absorbing wick according to an embodiment of the present invention;

[0056] FIG. 28 shows capillary performance test data of the absorbent core according to an embodiment of the present invention and comparison with commercial screen materials.

[0057] Explanation of the reference numerals: 100 - temperature uniformity plate; 101 - first cover plate; 102 - second cover plate; 103 - steam chamber; 104 - support member; 199 - deposited metal layer; 200 - liquid wick; 201 - photosensitive film; 201a - strip mold structure; 202 - base; 210 - first capillary channel; 220 - second guide groove; 230 - connecting channel; 250 - capillary through hole; 300 - working fluid; 310 - second vapor-liquid interface; 320 - first vapor-liquid interface; 400 - heat source area; 410 - insulation area; 420 - heat dissipation area. DETAILED DESCRIPTION

[0058] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0059] The purpose of the present invention is to provide a liquid wick and a preparation method thereof, and a temperature equalizing plate, which are used to increase the reflux rate of the working fluid to the heat source area, thereby improving the thermal conductivity of the temperature equalizing plate.

[0060] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0061] Referring to Figures 1 to 23 , this embodiment provides a wick 200 for mounting on a housing of a temperature-vaporizing plate 100, which has a cover. The wick 200 has a first flow channel that, together with the cover, forms a first capillary channel 210. The cover and wick 200 can be fixedly connected by sintering.

[0062] The first capillary tube 210 is used to connect the heat source area 400 (also called the evaporation area) and the heat dissipation area 420 (also called the condensation area) so that the working fluid 300 condensed in the heat dissipation area 420 can flow back to the heat source area 400 through the first capillary tube 210 under the action of capillary pressure.

[0063] Figures 7 to 14 provide schematic top views of several examples of the liquid absorbent core 200 of this embodiment. When there are multiple first guide grooves, the first guide grooves can be linear, refer to Figures 7, 8, and 11. In Figures 7 and 8, the multiple first guide grooves are parallel to each other. The first guide grooves can also be bent, refer to Figures 9, 10, 12, 13, and 14. In Figures 11, 12, and 13, the multiple first guide grooves are distributed radially. Referring to Figure 14, the first guide grooves can be designed into a forked structure along the flow direction to increase the contact area of ​​the condensation section so as to better collect the condensed working fluid 300 and reflux. However, the actual implementation is not limited to this. According to the design thermal conductivity requirements of the temperature equalization plate, the network shape of the channel can be flexibly designed to achieve the purpose of the present invention.

[0064] Figures 17 to 19 provide several exemplary cross-sectional shapes of the absorbent core 200 of this embodiment. The cross-sectional shape of the first guide groove can be a semicircular shape (see Figure 17), a square shape (see Figures 18 and 19), an arcuate shape, a trapezoidal shape, a triangle, or other shapes, and those skilled in the art can select the shape according to actual needs.

[0065] In the examples corresponding to FIG18 and FIG19 , the cross section of the first capillary channel 210 is rectangular, with a width of 10 μm to 2 mm and a height of 1 μm to 500 μm.

[0066] The working principle of the wick 200 of this embodiment is as follows:

[0067] The first guide groove of the wick 200 forms a first capillary channel 210 with the cover plate. The first capillary channel 210 is a tubular structure with a defined direction. Compared to the prior art, in this embodiment, the working fluid 300 flows along the first capillary channel 210 as it returns from the heat dissipation region 420 to the heat source region 400, without internal obstruction. This reduces the flow resistance and shortens the flow distance of the working fluid 300, effectively increasing the return velocity of the working fluid 300 to the heat source region 400 and, in turn, improving heat transfer capacity.

[0068] The housing of the temperature plate 100 is generally a sealed structure, and its cover includes a second cover plate 102 and a second cover plate 101 positioned opposite each other, and the second cover plate 102 and the second cover plate 101 are connected by a number of side plates. The wick 200 is located between the second cover plate 102 and the second cover plate 101. The wick 200 has two layouts:

[0069] 1) One side of the wick 200 is connected to the second cover plate 102, and the other side is connected to the second cover plate 101. In this case, there are first capillary channels 210 between the second cover plate 102 and the wick 200 and between the second cover plate 101 and the wick 200 (this form is not shown in the figure);

[0070] 2) One side of the wick 200 is connected to the second cover plate 102 or the second cover plate 101, and the other side of the wick 200 forms the steam chamber 103 (see Figures 17-24). The wick 200 can be placed on both the second cover plate 102 and the second cover plate 101 (see Figure 19), or it can be placed on only one of the second cover plates 102 or 101 (see Figures 17-18 and 20-24).

[0071] As a possible example, for the second arrangement of the wick 200, the wick 200 is provided with a capillary through-hole 250 for connecting the first guide groove and the steam chamber 103, allowing the working fluid 300 and its vapor to flow between the first guide groove and the steam chamber 103. In the heat source region 400, the capillary through-hole 250 provides an evaporation interface; in the heat dissipation region 420, the capillary through-hole 250 provides a condensation interface.

[0072] The shape and arrangement of the capillary holes 250 can be flexibly selected, and the following is only an exemplary description. When the size of the capillary holes 250 is large, they can pass through the first guide groove, referring to Figures 4 and 6. At this time, the width of the capillary holes 250 should not be too large to avoid blocking the capillary flow; the width of the capillary holes 250 is controlled to be less than a few hundred microns, such as 1 micron, 10 microns, 50 microns, 100 microns, 200 microns, etc. When the size of the capillary holes 250 is small, they can also be arranged only at the bottom of the first guide groove (not passing through the first guide groove), referring to Figures 3 and 5. The capillary holes 250 in Figures 4 and 6 are strip-shaped. In Figure 4, the angle between the length direction of the capillary holes 250 and the length direction of the first guide groove is an acute angle α, and in Figure 6, the angle between the length direction of the capillary holes 250 and the length direction of the first guide groove is a right angle. The capillary through hole 250 in FIG. 3 is circular or elliptical, and the capillary through hole 250 in FIG. 5 is rectangular.

[0073] The capillary through hole 250 can be formed by laser processing, chemical etching, ion etching (RIE, DRIE), electrochemical processing, or mechanical processing. For example, the shape of the capillary through hole 250 can be circular, elliptical, arc-shaped, triangular, square, trapezoidal, star-shaped, bar-shaped, or a combination thereof. The minimum size of the capillary through hole 250 is determined by the required capillary pressure and can range from a few nanometers to a few millimeters.

[0074] As a possible example, referring to Figures 1 and 3 to 6, the wick 200 also has a second guide groove 220, which is located on the side of the wick 200 close to the steam chamber 103. The second guide groove 220 is used to connect the heat source area 400 and the heat dissipation area 420, so that the working fluid 300 condensed in the heat dissipation area 420 can flow back to the heat source area 400 through the second guide groove 220 under the action of capillary pressure. Compared with the first capillary tube 210, the second guide groove 220 does not form a complete tubular structure. It is the second guide groove 220, so the capillary pressure is relatively small, and it is used as an auxiliary channel for the working fluid 300. Referring to Figure 14, the first guide groove and the second guide groove 220 can be designed to have different widths along the flow direction of the working fluid 300 according to the shape of the temperature equalization plate to regulate the vapor-liquid contact surface and capillary force.

[0075] Depending on the heat dissipation requirements, the size and spacing of the first and second guide grooves 220 of different wicks 200 can be adjusted, and can also be adjusted at different locations on the same wick 200. As shown in Figures 17 and 18, the capillary channel width W1, spacing W2, and height H1 of the wick 200 can vary from a few nanometers to several thousand microns, such as 10 nanometers, 100 nanometers, 1 micron, 10 microns, 50 microns, 100 microns, 200 microns, 500 microns, 1000 microns, etc.

[0076] As a possible example, referring to Figures 2, 8, and 10, the wick 200 further includes a connecting channel 230. The wick 200 includes multiple first capillary channels 210, with two adjacent first capillary channels 210 connected by a connecting channel 230, allowing the working fluid 300 and its vapor to flow between the different first capillary channels 210. By connecting adjacent first capillary channels 210 via the connecting channels 230, a network structure can be formed, which facilitates the balanced distribution and rapid flow of the working fluid 300.

[0077] As a possible example, referring to FIG2 , the connecting channel 230 includes a connecting groove, which is used to form a second capillary channel together with the cover plate. It is understood that the connecting channel 230 may also include a connecting hole. In this example, the second capillary channel is rectangular, and its dimensions can refer to the selection of the capillary channel width W1 and height H1 above, ranging from a few nanometers to several thousand microns, such as 10 nanometers, 100 nanometers, 1 micron, 10 microns, 50 microns, 100 microns, 200 microns, 500 microns, 1000 microns, etc.

[0078] As a possible example, referring to FIG15 , a wick 200 connects a heat source region 400, a heat insulating region 410, and a heat dissipation region 420. The wick 200 is provided with capillary through-holes 250 in the heat source region 400 and the heat dissipation region 420. The capillary through-holes 250 can be shaped as described above or in combination thereof. The first capillary channel 210 and the second guide groove 220 of the wick 200 allow the condensed working fluid 300 in the heat dissipation region 420 to flow back to the heat source region 400 under capillary pressure.

[0079] As a possible example, referring to FIG16 , a wick 200 connects a heat source region 400 and a heat dissipation region 420, without an insulating region 410 therebetween. The wick 200 is provided with capillary through-holes 250 in the heat source region 400 and the heat dissipation region 420. The capillary through-holes 250 can be shaped like a circle, an ellipse, an arc, a triangle, a square, a trapezoid, a star, a bar, or a combination thereof. The first capillary channel 210 corresponding to the wick 200 and the second guide groove 220 of the wick 200 allow the condensed working fluid 300 in the heat dissipation region 420 to flow directly back to the heat source region 400 under capillary pressure.

[0080] When steam does not enter, the first capillary channel 210 of the wick 200 is filled with the working liquid 300 (see FIG. 20A ). When steam enters, the first capillary channel 210 is partially filled with the working liquid 300 (see FIG. 20B ).

[0081] For the example in which the absorbent core 200 has the first guide groove, the second guide groove 220 and the capillary through hole 250 (abbreviated as Example A):

[0082] In the heat source region 400 and the heat dissipation region 420, the working fluid 300 in the first capillary channel 210 enters the second guide groove 220 (see FIG. 21A ). The first capillary channel 210 and the second guide groove 220 simultaneously transport the working fluid 300, and a second vapor-liquid interface 310 is formed in the second guide groove 220. FIG. 21B shows the flow of the first capillary channel 210 partially filled with the working fluid 300 when steam enters certain portions of the first capillary channel 210, and a vapor-liquid interface is formed in both the first capillary channel 210 and the second guide groove 220.

[0083] In the wick 200 in the heat source region 400 (see FIG. 22 ), a capillary through hole 250 is arranged in the first capillary channel 210. Both the first capillary channel 210 and the second guide groove 220 are filled with a working fluid 300. The first capillary channel 210 has a first vapor-liquid interface 320, and the second guide groove 220 has a second vapor-liquid interface 310. The vapor-liquid interface provides capillary pressure.

[0084] In the liquid wick 200 of the heat dissipation region 420 (see FIG. 23 ), the first capillary channel 210 is provided with a capillary through hole 250 . The first capillary channel 210 and the second guide groove 220 both contain a working fluid 300 . The first capillary channel 210 has a first vapor-liquid interface 320 , and the second guide groove 220 has a second vapor-liquid interface 310 . The vapor-liquid interface provides capillary pressure.

[0085] The second vapor-liquid interface 310 of the second guide groove 220 in the heat source area 400 and the heat dissipation area 420 generates different capillary pressures due to the evaporation and condensation processes and the different regulation of the size of the capillary holes 250, and finally forms a capillary pressure difference at both ends to drive the working fluid 300 to flow back from the second guide groove 220.

[0086] For example A above, this works as follows:

[0087] In Example A, one of the core working principles of the wick 200 is to increase the pressure difference by arranging and adjusting the size of the capillary holes 250. The capillary holes 250 are arranged on the first capillary tube 210 (Figures 22 and 23), and are connected to the steam chamber 103 through the first vapor-liquid interface 320, so that the working fluid 300 and its vapor flow between the two. Due to the evaporation and condensation processes and the different regulation of the size of the capillary holes 250, the first vapor-liquid interfaces 320 of the heat source area 400 and the heat dissipation area 420 respectively form different vapor-liquid interface curvature radii, thereby generating different capillary pressures, and finally forming a capillary pressure difference at both ends of the heat source area 400 and the heat dissipation area 420 to drive the working fluid 300 to flow back from the heat dissipation area 420 to the heat source area 400.

[0088] In Example A, the second guide groove 220 serves as an auxiliary channel for transporting the working fluid 300. In the heat source region 400, in addition to the first vapor-liquid interface 320 providing an evaporation interface, the second vapor-liquid interface 310 also provides an evaporation interface; in the heat dissipation region 420, in addition to the first vapor-liquid interface 320 providing a condensation interface, the second vapor-liquid interface 310 also provides a condensation interface. The second vapor-liquid interface 310 of the second guide groove 220 in the heat source region 400 and the heat dissipation region 420 generates different capillary pressures due to the different regulation of the evaporation and condensation processes and the size of the capillary through-hole 250, and ultimately forms a capillary pressure difference at both ends to drive the working fluid 300 to flow back from the second guide groove 220. Compared to the first capillary channel 210, the second guide groove 220 does not form a complete tubular structure, and therefore the capillary pressure is relatively small.

[0089] As a preferred example, the first end of the first capillary tube 210 is positioned in the heat source region 400, and the second end of the first capillary tube 210 is positioned in the heat dissipation region 420. The effective capillary radius of the capillary hole 250 at the first end of the first capillary tube 210 is smaller than the effective capillary radius of the capillary hole 250 at the second end of the first capillary tube 210, thereby increasing the capillary pressure that causes the working fluid to flow back to the heat source region. To facilitate understanding, the principle behind this is explained below.

[0090] For a capillary tube with a length of L, a hydraulic radius of R, and a cross-sectional area of ​​A, the flow rate Q is described by the following equation:

[0091] Where a is a dimensionless coefficient related to the cross-sectional shape of the capillary channel, μ is the dynamic viscosity of the fluid, and ΔP is the pressure difference across the capillary channel.

[0092] For a circular tube with radius R,

[0093] For a rectangular cross-section pipe with a bottom width of w and a height of h = βw,

[0094] From equation (1), we can see that increasing the cross-sectional size of the capillary tube and the pressure difference between the two ends can increase the capillary flow rate. When the influence of gravity is ignored, ΔP=ΔP ce -ΔP cc , (2)

[0095] where ΔP ce and ΔP cc The capillary pressures generated by the capillary through holes 250 at the evaporation end (corresponding to the first end of the first capillary channel 210 in Example A) and the condensation end (corresponding to the second end of the first capillary channel 210 in Example A) can be respectively determined by the effective capillary radius r of the capillary through hole 250 at the evaporation end and the capillary pressures generated by the capillary through holes 250 at the evaporation end and the capillary pressures generated by the capillary through holes 250 at the condensation end and the capillary pressures generated by the capillary through holes 250 at the evapor ... e and the effective capillary radius r of the capillary hole at the condensation end is 250 c To express:

[0096] Where σ is the surface tension coefficient, θ e and θ c are the contact angles at the evaporation end and the condensation end, respectively. Substituting into equation (2), the pressure difference between the two ends can be written as:

[0097] From equation (5), we can see that under a certain contact angle, the pressure difference can be increased by adjusting the effective radius of the capillary through hole 250, such as reducing the effective radius of the through hole and making r e <r c or a combination thereof.

[0098] The second core of the working principle of Example A is the size control of the first capillary channel 210. Under a certain capillary pressure, the cross-sectional size of the first capillary channel 210 determines the flow rate of the capillary channel, and increasing the cross-sectional size can increase the flow rate. This solves the contradiction that structures such as small-diameter capillaries or capillary grooves of traditional capillary materials have high capillary pressure but large flow resistance and small flow rate. Compared with the prior art, in Example A, when the working fluid 300 flows back from the heat dissipation area 420 to the heat source area 400 along the first capillary channel 210 and the second guide groove 220, the capillary pressure is greater and the flow resistance of the working fluid 300 is smaller, which can more effectively increase the reflux speed of the working fluid 300 to the heat source area 400, thereby improving the heat dissipation capacity.

[0099] Referring to Figure 24 , this embodiment further provides a heat spreader 100 comprising a wick 200 and a housing. The wick 200 is the aforementioned wick 200 having a first flow guide groove. The housing comprises a cover plate, one side of which contacts the heat source, and the other side of which, together with the first flow guide groove, forms a first capillary channel 210.

[0100] Since the temperature vapor chamber 100 of this embodiment includes the above-mentioned liquid wick 200 , it also has the above-mentioned advantages of the liquid wick 200 , which will not be described in detail here.

[0101] As one possible example, referring to Figure 24 , the housing has a steam chamber 103 located on the side of the wick 200 facing away from the cover. The wick 200 is provided with a through hole connecting the first guide groove and the steam chamber 103, allowing the working fluid 300 and its vapor to flow between the first guide groove and the steam chamber 103.

[0102] Referring to Figure 24 , the housing generally comprises a second cover plate 102 and a second cover plate 101, which are connected by a number of side panels. A wick 200 is positioned between the second cover plates 102 and 101. The wick 200 is secured to the second cover plate 102, and the vapor chamber 103 is positioned between the wick 200 and the second cover plate 101. For clarity, the side panels of the housing are omitted in Figure 24 , showing only the housing cover.

[0103] As a possible example, referring to FIG24 , the temperature homogenizing plate 100 further includes a support member 104, which is (wholly or partially) located within the steam chamber 103 to limit the minimum height of the steam chamber 103. When the support member 104 is entirely located within the steam chamber 103, the upper end of the support member 104 abuts against the wick 200, and the lower end of the support member 104 abuts against the lower cover plate. When the support member 104 is partially located within the steam chamber 103, the support member 104 passes through the wick 200, and the two ends of the support member 104 abut against the two cover plates, respectively. By providing the support member 104, the steam chamber 103 can be prevented from collapsing.

[0104] This embodiment also provides a method for preparing a liquid absorbent core 200, which is used to prepare the liquid absorbent core 200, with reference to FIG25, FIG26 and FIG27, and includes the following steps:

[0105] S1. Mold preparation:

[0106] The strip-shaped structures 201a are arranged on the surface of the base 202 to obtain a mold substrate.

[0107] The substrate 202 may be made of an inorganic material (such as copper, aluminum, nickel, zinc, tin, gold, iron, cobalt, cadmium, chromium, tin, silver, titanium, palladium, or alloys of stainless steel, zinc-nickel, zinc-copper, zinc-iron, nickel-iron, nickel-cobalt, copper-tin, zinc-nickel-iron, tin-zinc-antimony, zinc-tin-iron, tin-zinc-cobalt, or the like) or an organic material (such as ABS acrylonitrile-butadiene-styrene, EVA ethylene-vinyl acetate copolymer, EPS polystyrene, HDPE high-density polyethylene, LDPE low-density polyethylene, PI polyimide, PET polyester, PE polyethylene, PP polypropylene, PC polycarbonate, PVC polyvinyl chloride, PU polyurethane, PMMA polymethyl methacrylate, PS polystyrene, PDMS polydimethylsiloxane, PPS polyphenylene sulfide, Teflon, Nylon, PEEK polyetheretherketone, or the like) or a mixed material (such as a mixture of organic materials, a mixture of inorganic materials, or a mixture of organic and inorganic materials).

[0108] The strip structure 201a can be prepared by photolithography (such as soft lithography, laser etching), printing (including 2D and 3D printing, printing), printing (such as screen printing), spraying (including cold spraying and hot spraying), etching, machining and other methods. Soft lithography is a commonly used micro-nano processing method and will not be described in detail here. For the printing method, it is necessary to first prepare the slurry, and then print it onto the substrate by a printing method to obtain a mold substrate. Depending on the technical route, the main material of the slurry can be based on a photosensitive material or a material based on metal particles. Depending on the capillary preparation scheme, the surface of the mold substrate sometimes needs to be pre-treated in advance, for example, to make it conductive.

[0109] S2. Capillary channel preparation:

[0110] A metal layer 199 is deposited on the substrate, covering the strip structures 201a and at least a portion of the surface where the strip structures 201a are located. The material of the metal layer 199 is different from that of the strip structures 201a and the substrate 202. The substrate 202 and strip structures 201a are removed to obtain an independent wick 200. The wick 200 has a first guide groove, which is formed after the strip structures 201a are removed.

[0111] The material of the metal layer 199 is preferably copper, aluminum, nickel, zinc, tin, gold, iron, cobalt, cadmium, chromium, tin, silver, titanium, palladium, etc. or alloys such as stainless steel, zinc-nickel, zinc-copper, zinc-iron, nickel-iron, nickel-cobalt, copper-tin, zinc-nickel-iron, tin-zinc-antimony, zinc-tin-iron, and tin-zinc-cobalt.

[0112] S3. Preparation of capillary through hole 250:

[0113] Capillary holes 250 are formed on the wick 200. The capillary holes 250 can be formed by laser processing, chemical etching, etching (e.g., ICP, RIE, DRIE), electrochemical processing, or mechanical processing. The capillary holes 250 can be shaped like a circle, an ellipse, an arc, a triangle, a square, a trapezoid, a star, a bar, or a combination thereof.

[0114] As a possible example, the materials of the strip structure 201a and the substrate 202 can be the same or different. The strip structure 201a and the substrate 202 can be removed by etching, hot melting (for example, polymer materials such as PC polycarbonate, PU polyurethane, PDMS polydimethylsiloxane), or etching and stripping (for example, mixed materials such as a mixture of metal and polymer or a mixture of salt and polymer). The metal layer 199 is preferably made of copper, aluminum, nickel, zinc, tin, etc., and can be deposited by PVD (physical vapor deposition), electroplating, etc.

[0115] As a possible example, the thickness of the metal layer can be determined according to the size of the heat sink. The thickness can vary from a few nanometers to a few millimeters, but the general application thickness is controlled between 1 and 50 microns.

[0116] As a possible example, the size of the capillary hole 250 (such as radius or length and width) can be determined according to the heat dissipation requirements of the heat spreader, the speed requirements of the capillary circulation of the working fluid, and the working conditions (such as the influence of gravity or other acceleration effects). This size can vary from a few nanometers to a few millimeters, but the general application size is controlled between microns and hundreds of microns.

[0117] The preparation method of the liquid absorbent core 200 is described below with reference to Examples 1 to 3.

[0118] Referring to Figure 25 , in Example 1, (S1) mold preparation is first performed: strip structures 201a are formed on substrate 202 using photolithography. The cross-section of strip structures 201a can be rectangular, trapezoidal, semi-arc-shaped, or similar shapes. (S2) Metal layer deposition is performed: necessary surface pretreatment is performed on the substrate, and then a metal layer 199 is deposited on the substrate. The substrate 202 and strip structures 201a are then removed, ultimately obtaining an independent wick 200. (S3) Capillary holes 250 are machined: capillary holes 250 are machined on the wick 200 to obtain a porous wick 200. The formation of capillary holes 250 can be accomplished by laser processing, chemical etching, etching (e.g., ICP, RIE, DRIE), electrochemical processing, or mechanical processing. The shape of capillary holes 250 can be circular, elliptical, arc-shaped, triangular, square, trapezoidal, star-shaped, strip-shaped, or a combination thereof.

[0119] Referring to Figure 26, in Example 2, a strip-like structure 201a is formed on a substrate 202 by printing to obtain a substrate. The cross-section of the strip-like structure 201a can be semicircular, major arc, minor arc, or the like. Subsequently, a metal layer 199 is deposited on the substrate, and the substrate 202 and strip-like structure 201a are removed to obtain a wick 200. Finally, capillary through-holes 250 are laser-machined into the wick 200 to obtain a porous wick 200.

[0120] Referring to Figure 27 , in Example 3, a wire 201a was laid on a substrate 202 to form a mold substrate. A metal layer 199 was then deposited on the substrate. The substrate 202 and strip structures 201a were then removed to form a wick 200. Finally, capillary through-holes 250 were laser-machined into the wick 200, ultimately resulting in a porous wick 200. The wire was made of the same material as the strip structures 201a described above.

[0121] The absorbent core 200 prepared according to the above method has greater capillary pressure when transporting the working fluid and less flow resistance of the working fluid, making it more efficient. In order to verify the advanced nature of this absorbent core 200, we prepared a absorbent core 200 and conducted a test comparison with a commonly used copper wire mesh material. The length of both is 75mm. The copper wire mesh material is 300 mesh, the diameter of the copper wire therein is 30 microns, and the total thickness of the copper wire mesh material is 60 microns; the total thickness of the absorbent core 200 prepared according to the preparation method of this embodiment is 51 microns, of which the thickness of the first guide groove is 36 microns. The absorbent core 200 has capillary holes 250 at both the evaporation end and the condensation end. The width of the capillary holes 250 is 100 microns, and the aspect ratio is 1:10 (that is, the effective capillary radius of the capillary holes 250 at both ends of the first guide groove is the same). As for the length of the through-hole area, the condensation end and the evaporation end are both 25 mm. The wick 200 and the copper mesh material are sintered onto a copper sheet (equivalent to the cover plate) through the same heat treatment process, resulting in a sintered structure (see Figure 15 for the sintered structure of the wick 200 and cover plate). The wick 200 and the copper sheet form a first capillary channel 210 and a second flow channel 220. Capillary holes 250 are laser-machined at both ends of the first capillary channel 210. After cleaning, drying, and reducing, the two sintered structures are immersed in deionized water at one end, and a camera is used to capture the water's rise through the material. Image analysis is then used to measure the water surface position at each time point.

[0122] FIG28 shows the theoretical water climbing time curve of the wick 200, the water climbing time curve of the copper wire mesh material, and the actual water climbing process of four wicks 200 prepared according to the preparation method of this embodiment. The climbing curves of the sintered structures of the four wicks 200 prepared according to the preparation method of this embodiment are very similar, demonstrating the consistency of the material preparation process. In addition, the climbing speed and height are far superior to the sintered structure of the copper wire mesh material. In the initial stage of climbing, the climbing speed of the wick 200 is 3 to 4 times that of the copper wire mesh, and the final climbing height is almost twice that of the copper wire mesh material. Therefore, the wick 200 has a stronger capillary diversion effect on the working fluid.

[0123] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A liquid absorbent core, for installation on a housing, wherein the housing has a cover plate, characterized in that: The liquid absorbent core has a first guide groove; the first guide groove is used to form a first capillary channel together with the cover plate; The first capillary channel is used to connect the heat source region and the heat dissipation region, so that the working fluid condensed in the heat dissipation region can flow back to the heat source region through the first capillary channel under the action of capillary pressure.

2. The absorbent core according to claim 1, characterized in that The shell has a steam chamber, which is located on the side of the wick away from the cover plate; the wick is provided with a capillary through hole, which is used to connect the first guide groove and the steam chamber to allow the working fluid and its steam to flow between the first guide groove and the steam chamber.

3. The absorbent core according to claim 2, characterized in that: The absorbent core also has a second guide groove, which is located on a side of the absorbent core close to the steam chamber; the second guide groove is used to connect the heat source area and the heat dissipation area, so that the working fluid condensed in the heat dissipation area can flow back to the heat source area through the second guide groove under the action of capillary pressure.

4. The absorbent core according to claim 3, characterized in that: The first end of the first capillary tube is used to be placed in the heat source area, and the second end of the first capillary tube is used to be placed in the heat dissipation area; the effective capillary radius of the capillary hole located at the first end of the first capillary tube is smaller than the effective capillary radius of the capillary hole located at the second end of the first capillary tube, so as to increase the capillary pressure that causes the working fluid to flow back to the heat source area.

5. The absorbent core according to claim 1, characterized in that: The liquid absorbent core also has a connecting channel; the first capillary tubes include a plurality of first capillary tubes, and two adjacent first capillary tubes are connected through the connecting channel, so that the working liquid and the steam of the working liquid can flow between different first capillary tubes.

6. The absorbent core according to claim 5, characterized in that: The connecting channel comprises a connecting groove, and the connecting groove is used to form a second capillary channel together with the cover plate.

7. A temperature equalizing plate, characterized in that: The absorbent core comprises the liquid absorbent core as described in claim 1, 5 or 6, and also comprises the shell; the shell has the cover plate, one side of the cover plate is used to contact the heat source, and the other side of the cover plate and the first guide groove together form the first capillary channel.

8. The temperature equalizing plate according to claim 7, characterized in that: The shell has a steam chamber, which is located on the side of the wick away from the cover plate; the wick is provided with a capillary through hole, which is used to connect the first guide groove and the steam chamber to allow the working fluid and its steam to flow between the first guide groove and the steam chamber.

9. A method for preparing a liquid absorbent core, used for preparing the liquid absorbent core as claimed in claim 1, characterized in that: The steps include: S1. Arranging a strip structure on the surface of a base to obtain a substrate, wherein a side of the substrate having the strip structure is a deposition side; S2, depositing a metal layer on the deposition surface of the substrate, wherein the metal layer covers at least a portion of the deposition surface; the material of the metal layer is different from that of the strip structure and the substrate; S3, removing the substrate and the strip structure; the first guide groove is formed after the strip structure is removed.

10. The method for preparing the liquid absorbent core according to claim 9, characterized in that: Also includes: Step S4, machining capillary through holes on the first guide groove.

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