Composite thermal interface material based on metal aerogel and preparation method and application thereof

Abstract

The present application relates to the technical field of thermal interface material, and particularly relates to a composite thermal interface material based on metal aerogel and a preparation method and application thereof.The composite thermal interface material based on metal aerogel prepared by the present application has excellent flexibility.Compared with the conventional polymer-based thermal pad in the prior art, the three-dimensional thermal conduction network formed by the metal aerogel greatly improves the deformability of the composite thermal interface material, can be self-adaptively attached to the surface of a complex structure, and has better processing conditions and process results, and reduces the interface thermal resistance of the thermal interface composite material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal interface materials, in particular to a composite thermal interface material based on metal aerogel and a preparation method and application thereof. BACKGROUND

[0002] Thermal interface materials (TIMs) are a class of materials used in electronic devices to improve the efficiency of heat transfer. When two solid surfaces come into contact, due to the microscopic irregularities of the surfaces, only a few points of contact are actually made, and the gaps between these points are occupied by air, which has very low thermal conductivity. This forms a so-called "contact thermal resistance" that hinders the effective transfer of heat. The role of thermal interface materials is to fill these small gaps and exclude air, thereby providing a low-thermal-resistance path that allows heat to be more effectively transferred from the heat source (such as an integrated circuit chip) to the heat sink or cooling system. The use of such materials is crucial for ensuring the temperature management of electronic components, as excessive heat can affect the performance, stability and lifespan of electronic components. Common thermal interface materials include thermal silicone grease, thermal gel, silicone-free thermal pads, thermal phase change materials, thermal elastomeric materials, thermal silicone cloth and carbon fiber thermal pads, etc.

[0003] Thermal interface materials in the field of chip packaging play a crucial role in the current industrial development, and their performance is directly related to the heat dissipation effect, stability and overall performance of the chip. The current situation of the thermal interface material industry presents a series of key trends, mainly analyzed from the two important angles of thermal conductivity and flexibility.

[0004] Firstly, thermal conductivity is one of the important indicators for evaluating the performance of thermal interface materials. With the continuous increase in chip power density, the demand for higher thermal conductivity is also gradually increasing. In traditional thermal interface materials, metal oxides and silicone grease are still common choices, with relatively high thermal conductivity. However, in order to meet the heat dissipation needs of high-performance chips, more and more research focuses on the introduction of new high-thermal-conductivity materials such as diamond and boron nitride. These new materials, with their excellent thermal conductivity performance, can effectively improve the heat dissipation performance of chip packaging and promote the industry towards a more efficient direction.

[0005] Secondly, compliance is another aspect of concern. During chip packaging, the thermal interface material needs to be able to adapt to the small deformation between the chip and the packaging substrate, in order to ensure good physical contact and heat conduction effect. Good compliance of the material helps to fill the microscopic unevenness and reduces the thermal stress caused by temperature changes. Traditional silicone grease performs well in terms of compliance, but its thermal conductivity is relatively low. Therefore, in recent years, researchers have begun to focus on new thermal interface materials that have both high thermal conductivity and compliance. Some emerging materials such as graphene have excellent flexibility and thermal conductivity, but still face cost and production problems in large-scale applications. Therefore, improving compliance while keeping costs under control has become a problem that needs to be solved in current research and development.

[0006] In addition, there are some potential defects and challenges in the field of chip packaging thermal interface materials, such as (1) volatility and aging: many TIMs contain volatile components that may precipitate or evaporate after long-term use, leading to material performance degradation and increased thermal resistance. (2) Mechanical properties: TIMs may not have sufficient mechanical strength to maintain stable performance in long-term pressure or vibration environments. In repeated thermal cycles, TIMs may deform or harden, leading to increased contact thermal resistance. (3) Chemical compatibility: Some components in TIMs may react with other materials in chip packaging (such as metals, plastics, ceramics, etc.), leading to corrosion or decomposition. (4) Thermal expansion coefficient mismatch: The mismatch between the thermal expansion coefficients of TIMs and adjacent materials can cause stress accumulation, leading to delamination, cracking or packaging failure. (5) Electrical insulation: Although most TIMs are designed to be electrically insulating, some materials may lose their insulation properties under certain conditions (such as humidity, temperature), posing a short circuit risk. (6) Thickness and uniformity: The thickness of TIMs must be controlled properly, as excessive thickness can lead to reduced thermal conduction efficiency, while uneven thickness can lead to uneven heat flow distribution, affecting overall heat dissipation. (7) Environmental stability: TIMs may not be stable in extreme environmental conditions (such as high and low temperatures, high humidity, corrosive gases), affecting long-term reliability. (8) Compatibility and interface adhesion: TIMs need to maintain good adhesion with the chip and heat sink surface, otherwise they may delaminate or fall off, affecting heat conduction.

[0007] Overall, chip packaging thermal interface materials are developing towards high thermal conductivity, superior compliance and other comprehensive performance. This development momentum will provide more efficient and reliable heat dissipation solutions for electronic devices, driving innovation and progress in the semiconductor industry. Therefore, new thermal interface materials that can comprehensively solve the above problems are needed. SUMMARY

[0008] The first aspect of the present application provides a preparation method of a metal aerogel-based composite thermal interface material, comprising the following steps:

[0009] S1. preparing a metal hydrogel, washing and drying the metal hydrogel to obtain a metal aerogel;

[0010] S2. dispersing high-thermal-conductivity particles in an organic carrier to obtain a mixture, blending and soaking the mixture with the metal aerogel, and then obtaining a metal hydrogel-based composite material through solution repositioning;

[0011] S3. drying the metal hydrogel-based composite material to obtain a metal aerogel-based composite material, and obtaining the composite thermal interface material through mechanical cutting and laser processing;

[0012] In some embodiments, the metal material of the metal hydrogel is at least one of silver, copper, nickel, gold and tin.

[0013] In the present application, the preparation method of the metal hydrogel is not particularly limited, and a general method in the art can be used, for example, a chemical in-situ reduction method.

[0014] In some embodiments, the metal hydrogel is prepared by a chemical in-situ reduction method: dissolving PVP, AgNO3 and FeCl3 in ethylene glycol and stirring uniformly, then placing them in a drying oven for reaction at 120-150℃ for 3-5h to obtain the metal hydrogel.

[0015] In some embodiments, the washing is first soaking in a salt solution for 3-8 times, each time for 5-15min, and then soaking in alcohol for 5-15min; the salt solution is a 0.002M NaBH4 aqueous solution or a 0.1M NaCl aqueous solution.

[0016] In some embodiments, the drying is freezing the prepared metal hydrogel with liquid nitrogen, vacuum drying or supercritical drying to obtain the metal aerogel.

[0017] In some embodiments, the high-thermal-conductivity particles include at least one of Ag, Cu, Ga and GaInSn.

[0018] In some embodiments, the volume proportion of the high-thermal-conductivity particles in the composite thermal interface material is 40-80%.

[0019] Both metal nanoparticles and metal nanowires have high specific surface area, which makes them have high surface activity, and this activity promotes the interaction between the particles and the wires, so that the metal nanoparticles can be adsorbed on the metal nanowires.

[0020] In some embodiments, the high-thermal-conductivity particles have a particle size of 0.5-13 μm.

[0021] In some embodiments, the organic carrier comprises an organic solvent and a stabilizer, the organic solvent comprises at least one of methanol, ethanol, ethylene glycol, isopropyl alcohol, butanediol, and the stabilizer comprises at least one of polyvinylpyrrolidone, citric acid, sodium citrate, polyethylene glycol, cetyltrimethylammonium chloride, and sodium dodecyl sulfate.

[0022] Preferably, the organic solvent is ethanol and the stabilizer is citric acid.

[0023] In some embodiments, the mixture is prepared by dispersing 0.5 g of high-thermal-conductivity particles in a mixture of 30 mL of ethanol and 0.1 g of citric acid, and ultrasonically dispersing for 1-30 min at 50-300 W.

[0024] In some embodiments, the standing and soaking is performed for 1-16 h, and at the same time, ultrasonic, stirring and liquid-peristalsis devices are loaded to facilitate liquid flow and dispersion.

[0025] In some embodiments, the drying in step S3 is performed for 0.5-5 h, and the drying method is freeze-drying or supercritical drying.

[0026] In some embodiments, the laser processing power is 5-30 W, and the laser processing speed is 50-200 mm / min.

[0027] The second aspect of the present application provides a metal aerogel-based composite thermal interface material obtained by the above preparation method.

[0028] In some embodiments, the composite thermal interface material has a thermal resistance of 0.16 ℃·cm 2 / W and an elastic modulus of 400 Pa.

[0029] In some embodiments, the composite thermal interface material has a three-dimensional porous structure formed by cross-linking of nanowires, and the nanowires have a diameter of 30-550 nm.

[0030] The third aspect of the present application provides the use of the above composite thermal interface material in the field of semiconductors.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] 1. The metal aerogel-based composite thermal interface material prepared by the present application is a key material for ensuring the stable heat dissipation of electronic systems in the semiconductor field. Unlike the paste-like thermal conductive silicone grease and the traditional thermal conductive pads (0.5mm) with high modulus and large thickness in the prior art, the novel thermal conductive pad of the present application has a single composition, a low bonding zone thickness (30um), no fluidity, and anti-aging, and does not have phenomena such as liquid pumping out and flux volatilization during the packaging process, which can solve the problems such as pumping out of traditional thermal conductive silicone grease paste, high thickness and large thermal resistance of thermal conductive pads, and volatilization of flux during the use of indium sheets, and thus has better production stability and performance reliability.

[0033] 2. The metal aerogel-based composite thermal interface material prepared by the present application has excellent flexibility. Compared with the conventional polymer-based thermal conductive pad in the prior art, the three-dimensional thermal conductive network formed by the metal aerogel greatly improves the deformability of the composite thermal interface material, and therefore the skeleton structure constructed based on the metal aerogel can not only exhibit excellent thermal conductivity, but also can quickly fill the gap between the device and the heat sink, tightly adhere to the solid surface, eliminate local structural mismatch and assembly stress, and has outstanding advantages for connecting non-planar structures, can self-adapt to complex structure surfaces and has better processing conditions and process results, and reduces the interfacial thermal resistance of the thermal interface composite material.

[0034] 3. The metal aerogel-based composite thermal interface material prepared by the present application is a metal nanoparticle, which further improves the thermal conductivity of the thermal interface material, and can be used for heat dissipation of high-power devices and high-performance reliable connection. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 a is a macroscopic graph of the dried nanosilver aerogel prepared in Example 1, Figure 1 b is an internal micrograph of the dried nanosilver aerogel.

[0036] Figure 2 is a schematic diagram of the nanosilver aerogel before compounding nanoparticles.

[0037] Figure 3 is a schematic diagram of the composite thermal interface material after compounding nanoparticles of the nanosilver aerogel.

[0038] Figure 4 is a surface micrograph of the composite thermal interface material after compounding nanoparticles of the nanosilver aerogel. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0040] Embodiment 1

[0041] The embodiment provides a composite thermal interface material based on metal aerogel, and a preparation method thereof includes the following steps:

[0042] S1. Prepare a nano-silver hydrogel by using a chemical in-situ reduction method: 0.2g of PVP, 0.5g of AgNO 3、 0.2g of FeCl3 is dissolved in 50mL of ethylene glycol and stirred uniformly, and then placed in a drying box for reaction at 130℃ for 4h to obtain a nano-silver hydrogel. The nano-silver hydrogel is soaked in a 0.002M NaBH4 aqueous solution for 5 times, 10min each time, and a new NaBH4 aqueous solution is used for each soaking. Finally, the nano-silver hydrogel is soaked in alcohol for 10min. After cleaning, the nano-silver hydrogel is subjected to supercritical drying, and then cut into a nano-silver aerogel with a size of 25mm*25mm*5mm;

[0043] The macroscopic view of the dried nano-silver aerogel is shown in Figure 1 a. The internal microscopic electron microscope view of the dried nano-silver aerogel is shown in Figure 1 b. The diameter size of the silver nanowire is 30-550nm.

[0044] The internal microscopic view of the dried nano-silver aerogel is shown in Figure 2 As shown in the figure, the line-to-line lapping in the aerogel ensures the formation of the heat conduction path.

[0045] S2. 0.5g of liquid metal GaInSn nanoparticles are dispersed in a mixture of 30mL of ethanol and 0.1g of citric acid by ultrasonic dispersion to obtain a mixture, the ultrasonic time is 10min, the power is 50W, and the diameter size of the nanoparticles is 2-7um. The mixture is blended with the nano-silver aerogel and soaked for 2h. During the soaking process, the nanoparticles are compounded on the surface of the aerogel to obtain a nano-silver hydrogel-based composite material. The volume proportion of the GaInSn nanoparticles in the nano-silver hydrogel-based composite material is 80%.

[0046] S3. The nano-silver hydrogel-based composite material is dried by a supercritical drying method to obtain a nano-silver aerogel-based composite material. The composite thermal interface material is obtained by mechanical cutting and laser processing.

[0047] The processing power of the laser processing is 20W, and the laser processing speed is 100mm / min.

[0048] The schematic diagram and macrograph of the composite thermal interface material after the nano-silver aerogel composite nanoparticles are shown in FIGS. 1 and 2. Figure 3 and Figure 4 As shown in the figures, the particles are mainly compounded on the surface of the aerogel, and there are contact points between the particles and between the particles and the nanowires. The thermal conduction path is increased on the basis of the nanowire aerogel.

[0049] Example 2

[0050] This example provides a composite thermal interface material based on metal aerogel, and the specific implementation is the same as that of Example 1, except that:

[0051] S2. 0.5 g of liquid metal GaInSn nanoparticles were dispersed in a mixture of 30 mL of ethanol and 0.1 g of citric acid by ultrasonic dispersion, the ultrasonic time was 10 min, the power was 50 W, and the diameter of the nanoparticles was 2-7 um. The silver aerogel was soaked in the ethanol solution, and then the liquid metal GaInSn mixed solution was slowly added to the nano-silver wire aerogel ethanol solution at a flow rate of 10-300 μL / s by using a self-flowing device, and the liquid metal was dispersed and filled into the three-dimensional network structure of the nano-silver wire aerogel using ultrasonic waves (power 20 W, frequency 40 kHz). The volume proportion of GaInSn nanoparticles in the nano-silver hydrogel-based composite material was 60%.

[0052] In addition to the advantages of Example 1, the self-flowing device can accurately control the flow rate of the liquid metal particle mixture, thereby controlling the amount of liquid metal compounded on the surface of the metal aerogel.

[0053] Comparative Example 1

[0054] The specific implementation of this comparative example is the same as that of Example 1, except that the ultrasonic power in S2 is 50 W; Cu particles are used to replace the liquid metal GaInSn nanoparticles, and the volume proportion of Cu particles in the nano-silver hydrogel-based composite material is 80%.

[0055] Comparative Example 2

[0056] The specific implementation of this comparative example is the same as that of Example 1, except that the ultrasonic power in S2 is 50 W; Ga particles are used to replace the liquid metal GaInSn nanoparticles, and the volume proportion of Ga particles in the nano-silver hydrogel-based composite material is 80%.

[0057] Comparative Example 3

[0058] The specific implementation of the comparative example is the same as that of Example 1, except that the ultrasonic power in S2 is 50 W; liquid metal GaInSn nanoparticles are replaced by Ag particles, and the volume ratio of Ag particles in the nanosilver hydrogel-based composite material is 60%.

[0059] Comparative Example 4

[0060] The specific implementation of the comparative example is the same as that of Example 1, except that the ultrasonic power in S2 is 90 W; the volume ratio of GaInSn particles in the nanosilver hydrogel-based composite material is 30%.

[0061] Performance test

[0062] The composite materials prepared in the above examples and comparative examples are subjected to the following tests, and the results are shown in Table 1:

[0063] Thermal resistance value: The thermal resistance of the material is tested by the total thermal resistance steady-state method of the interface material thermal conductivity and thermal resistance measuring device LW-9389 (Long Win Co., Ltd. China) designed based on the ASTM-D5470 standard test method.

[0064] Elastic modulus: The universal testing machine is used for testing, the stress and strain in the compression process of the material are measured, and the elastic modulus is calculated by analyzing the stress-strain curve.

[0065] Thickness: Measured by a nanometer thickness meter.

[0066] Compression amount: The ratio of the difference in material height before and after compression to the original thickness of the material, i.e. the size of the height direction compressed and reduced / the original thickness of the material x 100%.

[0067] Table 1

[0068] Thermal resistance value Elastic modulus (Pa) Example 1 0.16 °C-cm 2 / W]] 408 Example 2 0.17 °C-cm 2 / W]] 412 Comparative Example 1 0.3 °C-cm 2 / W]] 513 Comparative Example 2 0.5 °C-cm 2 / W]] 526 Comparative Example 3 0.25 °C-cm 2 / W]] 857 Comparative Example 4 0.27 °C-cm 2 / W]] 647

[0069] From the above performance test results, it can be seen that the composite thermal interface material of Example 1 and has excellent flexibility and electrical conductivity, which is mainly because the three-dimensional thermal conduction network formed by the metal aerogel greatly improves the deformability of the composite thermal interface material, and can exhibit excellent thermal conductivity.

[0070] The comparative examples do not use the necessary technical solutions, resulting in a significant difference in the corresponding performance tests compared with the examples. In Comparative Example 1, the ultrasonic power and the type of conductive particles are changed, and it can be seen that the conductive effect and the flexibility effect are decreased to different degrees, proving that the scheme of Example 1 has an important influence on the effect of the present application.

[0071] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles described in the present application, can also make several improvements and refinements, these improvements and refinements should also be considered as the scope of protection of the present application.

Claims

1. A method of preparing a metal aerogel-based composite thermal interface material, characterized by, The method comprises the following steps: S1. Preparing a nano-silver hydrogel, washing and drying the nano-silver hydrogel to obtain a nano-silver aerogel; S2. Dispersing high-thermal-conductivity particles in an organic carrier to obtain a mixture, blending the mixture with the nano-silver aerogel and standing for soaking, and then obtaining a nano-silver hydrogel-based composite material through solution resetting; S3. Drying the nano-silver hydrogel-based composite material to obtain a nano-silver aerogel-based composite material, and obtaining the composite thermal interface material through mechanical cutting and laser processing; The high-thermal-conductivity particles comprise at least one of Ga, GaInSn; The volume proportion of the high-thermal-conductivity particles in the composite thermal interface material is 40-80%; The organic carrier comprises an organic solvent and a stabilizer, the organic solvent comprises at least one of methanol, ethanol, ethylene glycol, isopropyl alcohol and butanediol, and the stabilizer comprises at least one of polyvinylpyrrolidone, citric acid, sodium citrate, polyethylene glycol, cetyltrimethylammonium chloride and sodium dodecyl sulfate; The composite thermal interface material has a three-dimensional network structure formed by cross-linking of silver nanowires, and the diameter of the silver nanowires is 30-550 nm.

2. The production method according to claim 1, characterized by, The particle size of the high-thermal-conductivity particles is 1-5 μm.

3. The preparation method according to claim 2, characterized in that, The standing time for soaking is 1-16 h.

4. The preparation method according to claim 3, characterized in that, The drying time in S3 is 0.5-5 h.

5. A metal aerogel-based composite thermal interface material, characterized in that, The method is obtained according to any one of claims 1-4.

6. The composite thermal interface material of claim 5, wherein, The thermal resistance of the composite thermal interface material is 0.16-2.0℃·cm 2 / W, the elastic modulus is 400-1400 Pa, and the compression amount is 80-99.6%.

7. Application of the composite thermal interface material of claim 5 in the field of semiconductors.

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