Embedded liquid cooling heat dissipation plate

Abstract

The invention provides an embedded liquid cooling heat dissipation plate. The embedded liquid cooling heat dissipation plate comprises a base body; the cavity structure is located in the base body; and the heat dissipation working medium is located in the cavity structure, and the heat dissipation working medium comprises liquid metal and diamond powder. According to the embedded liquid cooling heat dissipation plate, the heat transfer effect in the heat dissipation working medium is improved, the temperature uniformizing performance of the embedded liquid cooling heat dissipation plate is enhanced, the heat dissipation efficiency is improved, and the technical problem that an existing embedded heat dissipation structure is poor in reliability is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to an embedded liquid-cooled heat sink. Background Art

[0002] With the rapid development of the integrated circuit industry, the integration density of transistors on chips (over 180 million transistors / mm 2 ) is increasing rapidly, resulting in an increasingly significant heat accumulation effect caused by leakage current in the gate region of transistors in the chip. The working reliability of the chip is extremely sensitive to temperature. For every 1°C increase in the safe working temperature, its reliability will decrease by about 5%.

[0003] The heat dissipation path in the integrated circuit chip packaging structure is mainly to diffuse the local high heat generated in the small area of ​​the chip gate area to the substrate through the thermal interface material, and then to the tube shell, and then dissipate the heat into the atmosphere through thermal management technologies such as air cooling, water cooling, thin film evaporation, and micro spraying outside the tube shell. However, due to the low heat transfer coefficient of air cooling (20-100W / (m 2 ·K)), air cooling needs to improve the gas-solid heat exchange efficiency by increasing the contact area, which makes it difficult to miniaturize its heat dissipation structure; the low boiling point, active chemical properties, high dielectric constant and other physical properties of water lead to low reliability of water cooling; although thin film evaporation and micro-spraying technologies have high heat transfer coefficients, their implementation structures are relatively complex and the processing costs are high.

[0004] Based on this, the concept of near-junction heat dissipation is proposed in the prior art, that is, various heat dissipation structures are miniaturized and embedded in the electronic chip packaging structure, and the liquid cooling medium is brought close to the heating grid area of ​​the electronic chip (with a spacing of less than 100μm) by the embedded heat dissipation structure to achieve precise control of the junction temperature. For the embedded heat dissipation structure in the prior art, its common embedded liquid cooling medium includes water, ethanol, FC770 and gallium-based liquid metal, etc.; its common uniform temperature plate material includes copper.

[0005] However, due to the low boiling point and low viscosity of water, ethanol and FC770, they cannot fully meet the process compatibility test of the embedded cavity liquid cooling medium potting process (the embedded cavity liquid cooling medium potting process must withstand the process compatibility test in the actual engineering process such as microsystem packaging process (200-400℃), operating environment (-65-150℃), and rework process (100-200℃). For example, although water has a high latent heat of vaporization (1718kJ / kg), in many active and passive liquid cooling research, two-phase flow heat dissipation is a means to improve the mass transfer efficiency of liquid cooling medium and compensate for the low thermal conductivity of water (0.59W / (m·K)). However, the repeated solidification / vaporization / drying of the water film in the narrow embedded liquid cooling closed cavity will severely challenge the reliability of the packaging structure. Also, although gallium-based liquid metal has advantages such as high thermal conductivity and high process compatibility, it has high kinematic viscosity and large surface tension, and its thermal slip morphology on the silicon substrate is extremely complex and has weak fluidity. In addition, the chip may be in direct contact with the copper sheet of the embedded heat dissipation structure, which may cause electrical problems (short circuits) and stress problems (mechanical stress and thermal stress), which may damage the chip or copper sheet and even cause connection failure.

[0006] Therefore, a new embedded heat dissipation structure is urgently needed to solve the problem of poor reliability of the existing embedded heat dissipation structure. Summary of the invention

[0007] The main purpose of the present invention is to provide an embedded liquid-cooled heat sink to solve the problem of poor reliability of the embedded heat dissipation structure in the prior art.

[0008] To achieve the above objectives, according to one aspect of the present invention, there is provided an embedded liquid-cooled heat sink, comprising: a substrate; a cavity structure located in the substrate; a heat sink located in the cavity structure, and the heat sink comprises liquid metal and diamond powder.

[0009] Optionally, the cavity structure has a first surface and a second surface opposite to each other, and the embedded liquid-cooled heat sink further includes: a support column located between the first surface and the second surface.

[0010] Optionally, there are multiple support pillars, and the multiple support pillars are arranged in an array.

[0011] Optionally, the embedded liquid-cooled heat sink further includes: a copper sheet located on one side surface of the embedded liquid-cooled heat sink.

[0012] Optionally, the base includes a first substrate and a second substrate which are stacked, and the cavity structure is located between the first substrate and the second substrate.

[0013] Optionally, the first substrate has a groove, and the second substrate is located on a side of the first substrate having the groove.

[0014] Optionally, both the first substrate and the second substrate are silicon substrates.

[0015] Optionally, the base is obtained by bonding the first substrate and the second substrate using a silicon-silicon direct bonding process.

[0016] Optionally, the diamond powder includes nano-scale diamond powder.

[0017] Optionally, the cavity structure is filled with an inert gas.

[0018] By applying the technical solution of the present invention, since liquid metal has a lower viscosity and a higher thermal conductivity, the above-mentioned embodiment of the present application uses liquid metal as one part of the heat dissipation medium of the above-mentioned embedded liquid-cooled heat sink, thereby improving the heat dissipation performance of the above-mentioned embedded liquid-cooled heat sink. In addition, since liquid metal has a lower surface tension and diamond powder has a higher surface energy than liquid metal, the wettability of liquid metal on the surface of diamond powder is poor. Therefore, in the above-mentioned embodiment of the present application, by using diamond powder as another part of the heat dissipation medium of the above-mentioned embedded liquid-cooled heat sink, the low wettability between diamond powder and liquid metal is utilized, so that the above-mentioned liquid metal can have a strong fluidity in the cavity structure of the above-mentioned embedded liquid-cooled heat sink under the action of diamond powder. In addition, since diamond is the material with the highest thermal conductivity in nature, with a thermal conductivity of up to 2000W / (m·K) at room temperature, the addition of the above-mentioned diamond powder further improves the heat transfer effect inside the heat dissipation medium, enhances the temperature uniformity performance of the above-mentioned embedded liquid cooling heat sink, improves the heat dissipation efficiency, and solves the technical problem of poor reliability of the existing embedded heat dissipation structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 A schematic cross-sectional structure diagram of an embedded liquid cooling heat sink according to an embodiment of the present invention is shown;

[0021] Figure 2 A schematic cross-sectional structure diagram of a first silicon substrate and a second silicon substrate provided in a preparation process of an embedded liquid-cooled heat sink according to an embodiment of the present invention is shown;

[0022] Figure 3 A schematic diagram showing the distribution of support parts in an embedded liquid cooling heat sink according to an embodiment of the present invention is shown;

[0023] Figure 4 A schematic cross-sectional structure diagram of a substrate in which a first substrate and a second substrate are bonded to form a cavity structure is shown;

[0024] Figure 5 Shown in Figure 4 A schematic diagram of the cross-sectional structure of the substrate after holes are formed;

[0025] Figure 6 Shown in Figure 5 A schematic diagram of the cross-sectional structure of the substrate after the cavity structure is filled with diamond powder based on the structure shown;

[0026] Figure 7 Shown in Figure 6 Based on the structure shown, a schematic diagram of a cross-sectional structure of a substrate after liquid metal is filled into the cavity structure;

[0027] Figure 8 Shown in Figure 7 Based on the structure shown, a schematic diagram of the cross-sectional structure of the substrate after the holes are filled.

[0028] The above drawings include the following reference numerals:

[0029] 10. substrate; 20. cavity structure; 30. heat dissipation medium; 301. liquid metal; 302. diamond powder; 40. support column; 50. first substrate; 60. second substrate; 120. groove; 140. protrusion; 150. hole; 160. high temperature ceramic adhesive. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. 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 creative work should fall within the scope of protection of the present invention.

[0032] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0033] As described in the background technology, in the existing embedded heat dissipation structure, common embedded liquid cooling media include water, ethanol, FC770 and gallium-based liquid metal, and common uniform temperature plate materials include copper. On this basis, for the embedded liquid cooling media of the embedded heat dissipation structure: water, ethanol and FC770 have the physical properties of low boiling point and low viscosity, and they cannot fully meet the process compatibility test of the embedded cavity liquid cooling media encapsulation process (the embedded cavity liquid cooling media encapsulation process must withstand the process compatibility test in the actual engineering process such as microsystem packaging process (200-400℃), operating environment (-65-150℃), and rework process (100-200℃)); Gallium-based liquid metal has high kinematic viscosity and high surface tension, and its thermal slip morphology on the silicon substrate is extremely complex and has weak fluidity. For the uniform temperature plate (copper sheet) of the embedded heat dissipation structure: the chip may be in direct contact with the copper sheet, resulting in electrical problems (short circuit) and stress problems (mechanical stress and thermal stress), which may damage the chip or copper sheet, and even cause connection failure. Therefore, the reliability of the existing embedded heat dissipation structure is poor.

[0034] In order to solve the above technical problems, the embodiments of the present application provide an embedded liquid cooling heat sink. Figure 1 As shown, the embedded liquid-cooled heat sink includes: a substrate 10; a cavity structure 20 located in the substrate 10; a heat dissipation medium 30 located in the cavity structure 20, and the heat dissipation medium 30 includes liquid metal 301 and diamond powder 302.

[0035] Specifically, the liquid metal 301 may include, but is not limited to, mercury, gallium, indium, gallium-based alloys, etc. Further, the gallium-based alloys may include, but are not limited to, gallium-indium alloys and gallium-tin alloys.

[0036] In the above embodiment, since the liquid metal 301 has a lower viscosity and a higher thermal conductivity, the above embodiment of the present application uses the liquid metal 301 as a part of the heat dissipation medium 30 (liquid-cooling medium) of the above embedded liquid-cooled heat sink, thereby improving the heat dissipation performance of the above embedded liquid-cooled heat sink. In addition, since the liquid metal 301 has a lower surface tension and the diamond powder 302 has a higher surface energy than the liquid metal 301, the wettability of the liquid metal 301 on the surface of the diamond powder 302 is poor. Therefore, in the above embodiment of the present application, by using the diamond powder 302 as another part of the heat dissipation medium 30 of the above embedded liquid-cooled heat sink, the low wettability between the diamond powder 302 and the liquid metal 301 is utilized, so that the above liquid metal 301 can have a strong fluidity in the cavity structure 20 of the above embedded liquid-cooled heat sink under the action of the diamond powder 302. Furthermore, since diamond is the substance with the highest thermal conductivity in nature, with a thermal conductivity of up to 2000W / (m·K) at room temperature, the addition of the diamond powder 302 further enhances the heat transfer effect inside the heat sink 30, enhances the temperature uniformity of the embedded liquid cooling plate, improves the heat dissipation efficiency, and solves the technical problem of poor reliability of the existing embedded heat dissipation structure.

[0037] In some optional embodiments, such as Figure 1 As shown, the cavity structure 20 has a first surface and a second surface opposite to each other, and the embedded liquid-cooled heat sink further includes a support column 40 located between the first surface and the second surface.

[0038] Specifically, the cavity structure 20 is a hollow part of the embedded liquid heat sink, and the first surface and the second surface can be the inner surface of the embedded liquid heat sink. Optionally, the first surface and the second surface can be two inner surfaces parallel to each other, or two surfaces that match each other in a specific geometric shape.

[0039] What is important is that since the first surface and the second surface are arranged relative to each other, after the support column 40 is arranged between the first surface and the second surface, the support column 40 can serve as a supporting component in the cavity structure 20 of the embedded liquid-cooled heat sink, which can enhance the mechanical strength and rigidity of the embedded liquid heat sink, so that the embedded liquid-cooled heat sink has stronger structural stability.

[0040] In addition, since there is a cavity structure 20 in the base 10 of the above-mentioned embedded liquid-cooled heat sink, the thickness at different positions of the above-mentioned embedded liquid-cooled heat sink may be different. For example, the cavity structure 20 of the embedded liquid-cooled heat sink is located at the center of the base 10, resulting in a difference in thickness between the center and edge of the embedded liquid-cooled heat sink, so that when the embedded liquid-cooled heat sink is heated, the degree of thermal deformation at the center and edge of the embedded liquid-cooled heat sink will be different, which will lead to uneven stress distribution and the risk of damage to the embedded liquid-cooled heat sink. Based on this, it is also important that the embodiment of the present application sets a support column 40 in the cavity structure 20. Since the support column 40 enhances the overall rigidity of the embedded liquid-cooled heat sink, the embedded liquid-cooled heat sink is more resistant to thermal deformation, thereby dispersing hot keys and solving the problem of uneven stress distribution of the embedded liquid-cooled heat sink due to the presence of the cavity structure 20, reducing the risk of damage to the embedded liquid-cooled heat sink and improving the reliability of the embedded liquid-cooled heat sink.

[0041] Optionally, the number of the support columns 40 may be one or more, and those skilled in the art may reasonably set them according to actual needs.

[0042] Among them, when there are multiple support columns 40, the multiple support columns 40 can be arranged in an array. It can be understood that the multiple support columns 40 arranged in an array can better even out the stress of the embedded liquid-cooled heat sink, so that the embedded liquid-cooled heat sink has a stronger ability to even out the thermal stress during use. Furthermore, after the multiple support columns 40 are arranged in an array in the cavity structure 20, a certain degree of isolation of the heat sink 30 located in the cavity structure 20 can be achieved, thereby forming a thermal gradient in the embedded liquid-cooled heat sink, improving the fluidity of the heat sink 30, and then improving the heat dissipation efficiency of the above-mentioned embedded liquid-cooled heat sink.

[0043] Combination Figure 2 , Figure 3 and Figure 4 As shown, in some optional embodiments, the base 10 includes a first substrate 50 and a second substrate 60 which are stacked, and the cavity structure 20 is located between the first substrate 50 and the second substrate 60 .

[0044] Specifically, Figure 2 As shown, one side surface of the first substrate 50 may have a groove 120. On this basis, in order to form an embedded liquid-cooled heat sink having a cavity structure 20, the second substrate 60 may be located on the side of the first substrate 50 having the groove 120, so that the second substrate 60 may close the groove 120 of the first substrate 50 to form a cavity structure 20 between the first substrate 50 and the second substrate 60.

[0045] Optionally, since a support column 40 may also be provided in the cavity structure 20 of the embedded liquid-cooled heat sink, in order to make the support column 40 located between the first surface and the second surface opposite to each other of the cavity structure 20, in the case where the surface of the first substrate 50 has a groove 120, the groove 120 may have one or a plurality of protrusions 140 arranged at intervals, and then after the second substrate 60 is placed on the side of the first substrate 50 having the groove 120, each protrusion 140 of the first substrate 50 may contact the surface of the second substrate 60, so that after the embedded liquid-cooled heat sink is formed, the protrusion 140 of the first substrate 50 may correspond to the support column 40 of the embedded liquid-cooled heat sink.

[0046] In some optional embodiments, in order to further improve the heat dissipation efficiency of the embedded liquid-cooled heat sink, the embedded liquid-cooled heat sink may further include a copper sheet (not shown in the figure), which may be located on one side surface of the embedded liquid-cooled heat sink. For example, the copper sheet may be located on the side of the first substrate 50 away from the second substrate 60, or the copper sheet may be located on the side of the second substrate 60 away from the first substrate 50. In this embodiment, since copper has a high thermal conductivity, in this embodiment, by arranging the copper sheet on one side surface of the embedded liquid-cooled heat sink, heat can be conducted from the heat source to the surface of the embedded liquid-cooled heat sink more quickly, thereby dissipating heat more effectively. In addition, since the electrical conductivity of silicon is much lower than that of copper in the chip operating temperature range, when the first substrate 50 and the second substrate 60 are both silicon substrates, the copper sheet is used as the heat dissipation base plate of the embedded liquid-cooled heat sink, and the embedded liquid-cooled heat sink can be electrically isolated between the copper sheet and the chip.

[0047] In some optional embodiments, the first substrate 50 and the second substrate 60 may both be silicon substrates. It is explained here that in this embodiment, by setting the first substrate 50 and the second substrate 60 as silicon substrates, the main material of the embedded liquid-cooled heat sink finally formed is silicon, and then when the embedded liquid-cooled heat sink is used as a temperature-uniform plate for the chip, since the thermal expansion coefficient of silicon is similar to that of many semiconductor chip materials (such as silicon chips), the thermal expansion coefficients of the embedded liquid-cooled heat sink made of silicon and the chip are matched with each other, so that the expansion or contraction degree when the temperature changes is similar, which can reduce the mechanical stress caused by the temperature change.

[0048] Among them, the maximum compressive strength of silicon is in the range of 3.5 to 4.0 GPa. In an exemplary embodiment, when the silicon-silicon thermal bond is formed, the maximum stress of the embedded liquid cooling heat sink without the support column 40 is 1.56 GPa, and the stress of the embedded liquid cooling heat sink with the support column 40 is 0.232 GPa, which shows that the stress is reduced by 85.13%.

[0049] like Figure 2As shown, for the actual manufacturing process of an embedded liquid-cooled heat sink of an embodiment of the present application, the provided first silicon substrate (first substrate 50) can firstly be subjected to deep reactive ion etching (DRIE, Deep Reactive Ion Etching) using an ion etcher, thereby etching a groove 120 on the surface of the first silicon substrate (first substrate 50).

[0050] Furthermore, combined with Figure 2 and Figure 4 As shown, a wafer bonding machine can be used to directly bond the first silicon substrate (first substrate 50) having the groove 120 with the provided second silicon substrate (second substrate 60) using a silicon-silicon direct bonding process, so that the first silicon substrate (first substrate 50) and the second silicon substrate (second substrate 60) are tightly combined, thereby forming a cavity structure 20 between the first silicon substrate (first substrate 50) and the second silicon substrate (second substrate 60). It can be understood that the surface of the second silicon substrate close to the groove 120 can be used as the upper surface of the groove 120 in the first silicon substrate, and the bottom surface of the groove 120 in the first silicon substrate (first substrate 50) and the surface of the second silicon substrate (second substrate 60) close to the above-mentioned groove 120 can be considered as two oppositely arranged surfaces of the cavity structure 20.

[0051] Furthermore, combined with Figure 1 As shown, when the thickness of the first silicon substrate (first substrate 50) and the second silicon substrate (second substrate 60) is greater than the target thickness, a chemical mechanical polishing machine can be used to perform chemical mechanical polishing on the first silicon substrate (first substrate 50) and the second silicon substrate (second substrate 60), so as to thin the side of the first silicon substrate (first substrate 50) away from the second silicon substrate (second substrate 60) and the side of the second silicon substrate (second substrate 60) away from the first silicon substrate (first substrate 50). The remaining first silicon substrate (first substrate 50) and the remaining second silicon substrate (second substrate 60) after thinning serve as the base 10 of the embedded liquid cooling heat sink.

[0052] Of course, if the process allows, the first silicon substrate (first substrate 50) and the second silicon substrate (second substrate 60) of the target thickness can be directly provided, and then after the first silicon substrate (first substrate 50) and the second silicon substrate (second substrate 60) are directly bonded by the silicon-silicon direct bonding process, it is not necessary to thin the first silicon substrate (first substrate 50) and the second silicon substrate (second substrate 60), and the first silicon substrate can be directly used as the first substrate 50 with an embedded liquid cooling heat sink, and the second silicon substrate can be used as the second substrate 60 with an embedded liquid cooling heat sink. It can be considered that: by directly providing the first substrate 50 and the second substrate 60 with the target thickness, and by directly bonding the first substrate 50 and the second substrate 60 by the silicon-silicon bonding process, the cavity structure 20 can be formed between the first substrate 50 and the second substrate 60.

[0053] Alternatively, if Figure 2 As shown, one or more spaced protrusions 140 may be provided in the groove 120 of the first silicon substrate (first substrate 50). For example, when there are 6×8 protrusions 140 in the groove 120 of the first silicon substrate (first substrate 50), the number of support portions that can be obtained in the cavity structure 20 after bonding is also 6×8, as shown in FIG. Figure 3 shown.

[0054] Optionally, no protrusions may be provided in the groove of the first silicon substrate, but one or more protrusions may be provided on the surface of the second silicon substrate at intervals, so that in a subsequent silicon-silicon direct bonding process, the protrusions of the second silicon substrate may be bonded to the bottom surface of the groove of the first silicon substrate.

[0055] It is worth mentioning that, in addition to the grooves that can be formed on the surface of the first silicon substrate, grooves can also be formed on the surface of the second silicon substrate. Exemplarily, the surface of the first silicon substrate and the surface of the second silicon substrate can each have a groove, and during the bonding process of the first silicon substrate and the second silicon substrate, a side surface of the first silicon substrate having the groove and a side surface of the second silicon substrate having the groove are bonded, and the groove of the first silicon substrate and the groove of the second silicon substrate at least partially overlap, so that a cavity structure can also be formed between the first silicon substrate and the second silicon substrate.

[0056] Similarly, in the case where both the first silicon substrate and the second silicon substrate have grooves, one or more spaced-apart protrusions may be respectively provided in the grooves of the first silicon substrate and the second silicon substrate.

[0057] On the one hand, considering the thickness of the embedded liquid-cooled heat sink after bonding, the raised portion of the first silicon substrate can be directly bonded to the bottom surface of the groove of the second silicon substrate, and the raised portion of the second silicon substrate can be directly bonded to the bottom surface of the groove of the first silicon substrate, so that after the first silicon substrate and the second silicon substrate are bonded using a silicon-silicon direct bonding process, the cavity structure formed between the first silicon substrate and the second silicon substrate can have a plurality of support columns arranged at intervals.

[0058] On the other hand, considering the difficulty of implementing the bonding process, during the bonding process between the first silicon substrate and the second silicon substrate, the protrusions of the first silicon substrate can be arranged one-to-one with the protrusions of the second silicon substrate, that is, the protrusions of the first silicon substrate can be bonded with the protrusions of the second silicon substrate.

[0059] In some optional embodiments, such as Figure 5 As shown, after the cavity structure 20 is formed, in order to place the heat dissipation medium 30 in the cavity structure 20 between the first substrate 50 and the second substrate 60, an ion etcher can be used to etch the structure after the first substrate 50 and the second substrate 60 are bonded, thereby etching a hole 150 for encapsulation in the first substrate 50. It can be understood that the hole 150 extends from the surface of the first substrate 50 away from the second substrate 60 to the cavity structure 20, so as to inject liquid metal 301 and diamond powder 302 into the cavity structure 20, thereby forming an embedded liquid-cooled heat sink having a cavity structure 20 and a heat dissipation medium 30.

[0060] The process steps of injecting the liquid metal 301 and the diamond powder 302 into the cavity structure 20 may be sequential, that is, the diamond powder 302 may be injected into the cavity structure 20 first, such as Figure 6 As shown, the liquid metal 301 is then injected into the cavity structure 20 already having the diamond powder 302, as shown in FIG. Figure 7 shown.

[0061] For example, in the step of injecting the diamond powder 302 into the cavity structure 20, a sealing platform may be used to inject the suspension formed by the diamond powder 302+deionized water into the cavity structure 20 from the hole 150 in a negative pressure manner, and then the first substrate 50 and the second substrate 60 after bonding may be heated to evaporate the deionized water in the cavity structure 20, leaving only the diamond powder 302 in the cavity structure 20. Optionally, the suspension of diamond powder 302+deionized water may be repeatedly injected into the cavity structure 20 and heated to evaporate the deionized water, so as to achieve the purpose of making the diamond powder 302 in the cavity structure 20 reach the target mass range.

[0062] Optionally, since diamonds below the micron level have smooth surfaces, which is beneficial for improving the internal fluidity of the liquid metal 301 , the diamond powder 302 may be nano-level diamond powder.

[0063] Exemplarily, in the step of injecting the liquid metal 301 into the cavity structure 20, a potting platform can be used to pour the liquid metal 301 into the cavity structure 20 in a negative pressure manner. Furthermore, in order to adapt to the thermal expansion and contraction of the liquid metal 301, the cavity structure 20 can also be filled with an inert gas. Optionally, the liquid metal 301 can be a gallium-based liquid metal 301, and the inert gas can be nitrogen. Considering that the gallium-based liquid metal 301 has a 2% to 3% thermal expansion and contraction volume change within the operating temperature range (-65°C to 150°C), 20% to 30% of the volume of the inert gas (such as nitrogen) can be retained in the cavity structure 20 when potting the gallium-based liquid metal 301.

[0064] It is mentioned here that the high thermal conductivity formed by the thermal slip of liquid metal 301 can effectively solve the challenges of hot spot concentration and unbalanced thermal gradients in multifunctional heterogeneous heterogeneous integrated systems. With the help of the adaptive heat return path formed by the embedded liquid metal 301, the non-uniform temperature gradient can be effectively balanced, and the radial heat transfer capacity of the embedded liquid-cooled heat sink can be improved, thereby achieving the goal of a local radial thermal conductivity of 1657.3W / (m·K). This will significantly improve the thermal reliability of the multifunctional heterogeneous heterogeneous integrated system and extend the life of the equipment. Liquid metal 301 exhibits a process tolerance temperature of up to 450°C in the embedded liquid-cooled heat sink, providing reliability guarantee for the stable operation of the system under various environmental conditions.

[0065] Finally, if Figure 8 As shown, the above-mentioned hole 150 for encapsulating the liquid metal 301 and the diamond powder 302 can be filled with a high-temperature ceramic adhesive 160. Optionally, the embedded liquid cooling heat sink after the hole 150 is filled with the high-temperature ceramic adhesive 160 can be placed in a high-temperature oven to cure the high-temperature ceramic adhesive 160. Exemplarily, the curing temperature can be 200° C. for a certain period of time to completely cure the ceramic adhesive.

[0066] The high temperature ceramic adhesive 160 can also interact with the support column 40 to improve the stress resistance of the embedded liquid cooling heat sink. In an exemplary embodiment, during the heating and curing process of the high temperature ceramic adhesive 160, the maximum stress of the embedded liquid cooling heat sink without the support column 40 is 0.415GPa, and the stress of the embedded liquid cooling heat sink with the support column 40 is 0.392GPa. It can be seen that the stress is reduced by 5.54%.

[0067] In addition, the embedded liquid cooling heat sink after solidification can also be processed, such as cutting and packaging, to complete the final product manufacturing of the embedded liquid metal temperature uniformity product. These processing steps can be carried out according to specific needs to improve the function of the embedded liquid metal temperature uniformity product and improve the reliability of the embedded liquid metal temperature uniformity product.

[0068] The following is a method for measuring the heat dissipation of an embedded liquid cooling heat sink according to an embodiment of the present application:

[0069] First, the overall structure of an embedded liquid cooling heat sink in the embodiment of the present application is silicon, and liquid metal is used for heat transfer inside to achieve efficient and rapid heat dissipation. In addition, the working environment temperature of the embedded liquid cooling heat sink is relatively high, so the national standard comparison scheme adopted by the method for measuring the heat dissipation of an embedded liquid cooling heat sink in the embodiment of the present application is: the metal high temperature thermal conductivity measurement method with the standard number GB / T3651-2008.

[0070] The general test device of the national standard comparison scheme corresponding to the method for measuring the heat dissipation of an embedded liquid-cooled heat sink in the embodiment of the present application is as follows: the entire sample to be tested is placed in an insulated furnace, and then the insulation material is arranged on the outer wall of the insulated furnace. In addition, thermocouples need to be installed between the insulated furnace walls to measure the actual temperature change. Thermocouples are used here mainly because thermocouples perform temperature detection based on the thermoelectric effect, with high sensitivity and low overall cost. One thing to note when using thermocouples is that it is necessary not only to test the temperature of the sample to be tested, but also to pay attention to the temperature of the environment. In addition, the distribution of thermocouples must also be uniform, so as to ensure the validity of the results as much as possible. After the experimental equipment is arranged, a direct current is passed through the sample, and the Joule heat generated will propagate along the sample. When the entire sample reaches a thermally stable state, it is tested according to the formula. Due to the different sizes of the materials, the specific formulas vary, but the overall calculation formula for the thermal conductivity coefficient is as follows:

[0071]

[0072] Where λ is the thermal conductivity of the sample to be tested, P is the DC source power, d is the distance between the thermocouples, ΔT is the temperature difference when the entire sample to be tested is in a thermally stable state, and d is the cross-sectional area of ​​the thermally conductive sample.

[0073] According to the above national standard comparison scheme, the thermal conductivity measurement experimental data of the embedded liquid cooling heat sink can be obtained as shown in Table 1:

[0074] Table 1

[0075]

[0076] As can be seen from Table 1, the thermal conductivity of the embedded liquid cooling heat sink is measured to be 903.63W / (m·K). The results are then combined with the proportion of the embedded layer (cavity structure) in the embedded liquid cooling heat sink (50% thickness of the embedded liquid cooling heat sink) to calculate the equivalent thermal conductivity of the embedded layer. The specific result is that the equivalent thermal conductivity of the embedded layer of the embedded liquid cooling heat sink with gallium metal as liquid metal is 1657.3W / (m·K). Therefore, under the natural convection conditions of 7 hot spots, a single hot spot power of 30W, and an ambient temperature of 20°C, the highest temperature on the embedded liquid cooling heat sink is 45°C.

[0077] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0078] Through the above implementation of the present application, since the liquid metal has a lower viscosity and a higher thermal conductivity, the above embodiment of the present application uses the liquid metal as one part of the heat dissipation medium of the above-mentioned embedded liquid-cooled heat sink, thereby improving the heat dissipation performance of the above-mentioned embedded liquid-cooled heat sink. In addition, since the liquid metal has a lower surface tension and the diamond powder has a higher surface energy than the liquid metal, the wettability of the liquid metal on the surface of the diamond powder is poor. Therefore, in the above implementation of the present application, by using the diamond powder as another part of the heat dissipation medium of the above-mentioned embedded liquid-cooled heat sink, the low wettability between the diamond powder and the liquid metal is utilized, so that the above-mentioned liquid metal can have a strong fluidity in the cavity structure of the above-mentioned embedded liquid-cooled heat sink under the action of the diamond powder. In addition, since diamond is the material with the highest thermal conductivity in nature, with a thermal conductivity of up to 2000W / (m·K) at room temperature, the addition of the above-mentioned diamond powder further improves the heat transfer effect inside the heat dissipation medium, enhances the temperature uniformity performance of the above-mentioned embedded liquid cooling heat sink, improves the heat dissipation efficiency, and solves the technical problem of poor reliability of the existing embedded heat dissipation structure.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An embedded liquid cooling heat sink, characterized in that: include: matrix; A cavity structure located in the substrate; The heat dissipation medium is located in the cavity structure, and the heat dissipation medium includes liquid metal and diamond powder.

2. The embedded liquid cooling heat sink according to claim 1, characterized in that: The cavity structure has a first surface and a second surface opposite to each other, and the embedded liquid cooling heat sink further comprises: A support column is located between the first surface and the second surface.

3. The embedded liquid cooling heat sink according to claim 2, characterized in that: There are multiple support columns, and the multiple support columns are arranged in an array.

4. The embedded liquid cooling heat sink according to any one of claims 1 to 3, characterized in that: Also includes: The copper sheet is located on one side surface of the embedded liquid cooling heat sink.

5. The embedded liquid cooling heat sink according to any one of claims 1 to 3, characterized in that: The base includes a first substrate and a second substrate which are stacked, and the cavity structure is located between the first substrate and the second substrate.

6. The embedded liquid cooling heat sink according to claim 5, characterized in that: The first substrate has a groove, and the second substrate is located on a side of the first substrate having the groove.

7. The embedded liquid cooling heat sink according to claim 5, characterized in that: The first substrate and the second substrate are both silicon substrates.

8. The embedded liquid cooling heat sink according to claim 7, characterized in that: The base is obtained by bonding the first substrate and the second substrate by using a silicon-silicon direct bonding process.

9. The embedded liquid cooling heat sink according to any one of claims 1 to 3, characterized in that: The diamond powder includes nano-scale diamond powder.

10. The embedded liquid cooling heat sink according to any one of claims 1 to 3, characterized in that: The cavity structure is filled with an inert gas.

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