Thermally conductive material suitable for local micro heat source of integrated chip and preparation method thereof

Abstract

The application provides a heat-conducting material suitable for local micro heat sources of integrated chips and a preparation method thereof, and the preparation method comprises the following steps: S1, obtaining a topological structure of a heat-conducting filler framework according to the parameters of the local micro heat source; S2, designing an ice template mold, comprising a heat-conducting metal block with a cavity protrusion on the upper surface and a heat insulation plate, the heat insulation plate is covered on the upper surface of the heat-conducting metal block and exposes the cavity protrusion as a cold source; S3, controlling the temperature to form uniform crystal nuclei on the cavity protrusion, adding a heat-conducting filler dispersion liquid, controlling the temperature of the cavity protrusion to be close to the freezing point, directional freezing, forming an ice template-heat-conducting filler composite, freeze-drying, and obtaining the heat-conducting filler framework; and S4, treating the heat-conducting filler framework and a polymer matrix prepolymer by a vacuum impregnation method to obtain the heat-conducting material. The heat-conducting material and method solve the problems of poor heat-conducting strengthening effect, and mismatching between the structure and the heat source of the existing material, and realize efficient reduction of the temperature of the micro heat source.

Description

Technical Field

[0001] This invention relates to the field of thermal interface materials technology, specifically to a thermally conductive material suitable for local micro-heat sources in integrated chips and its preparation method. Background Technology

[0002] As electronic devices become increasingly miniaturized and power-density, heat dissipation of local micro-heat sources (such as integrated chips) has become a key bottleneck restricting device performance and lifespan. Such heat sources need to quickly conduct heat to the substrate for heat dissipation. If the heat is not dissipated in time, it can easily lead to excessively high local temperatures, causing device performance degradation, increased failure rate, or even burnout.

[0003] Current heat dissipation solutions for millimeter-scale localized micro-heat sources in integrated chips mainly rely on traditional interface materials, such as disordered boron nitride / polymer composites and metal heat sinks, all of which suffer from the following core problems:

[0004] 1) Insufficient thermal conductivity: Disordered boron nitride nanosheets (BNNS) are prone to forming thermal conductivity barriers. The interfacial thermal conductivity of the composite material of disordered boron nitride nanosheets with a mass fraction of 1% and polydimethylsiloxane (PDMS) is usually lower than 0.18 W / (m·K), and the thermal resistance is high, which cannot meet the requirements of efficient heat dissipation of electronic devices.

[0005] 2) Mismatch between structure and heat source: Most existing materials are uniform block structures with dispersed internal materials, which fail to form a good heat conduction path. At the same time, there is no customized design for the heat flow path of the heat source. Local high-temperature heat sources cannot dissipate heat to low-heat areas in time, heat is easy to accumulate, and temperature uniformity is poor. In addition, the substrate can only dissipate heat in local high-heat areas, and the heat cannot be dissipated in time, resulting in low heat dissipation efficiency.

[0006] 3) Limitations of the preparation process: Traditional hot pressing, solution casting and other methods are difficult to achieve the directional and dense arrangement of boron nitride nanosheets, and cannot accurately reproduce the topological structure of composite heat flow characteristics, resulting in a disconnect between material structure and heat dissipation performance. Traditional ice template methods can only use ice crystal growth to create a loose skeleton according to the template, and the thermal conductivity enhancement effect is generally poor.

[0007] Therefore, there is an urgent need to provide a precisely controlled thermally conductive material to solve the problems of poor thermal conductivity enhancement effect and mismatch between structure and heat source of existing materials, so as to achieve efficient reduction of micro heat source temperature. Summary of the Invention

[0008] To address the problems existing in the background technology, this invention provides a thermally conductive material suitable for local micro heat sources in integrated chips and its preparation method, solving the problems of poor thermal conductivity enhancement effect and mismatch between structure and heat source of existing materials, and achieving efficient reduction of micro heat source temperature.

[0009] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0010] A method for preparing a thermally conductive material suitable for localized micro-heat sources in integrated chips includes the following steps:

[0011] S1. Based on the parameters of the local micro heat source, the topological structure of the thermally conductive filler skeleton in the thermally conductive material is designed, and the geometric model of the thermally conductive material is established;

[0012] S2. Design an ice template mold based on the topological structure of the thermally conductive filler skeleton. The ice template mold includes a thermally conductive metal block and an insulation board. The upper surface of the thermally conductive metal block is provided with cavity protrusions corresponding to the topological structure of the thermally conductive filler skeleton. The insulation board is provided with through holes corresponding to the cavity protrusions. It covers the upper surface of the thermally conductive metal block and exposes the cavity protrusions. The exposed cavity protrusions serve as the cold source of the ice template.

[0013] S3. Control the temperature of the cavity protrusion so that water vapor condenses on the surface of the cavity protrusion to form uniform crystal nuclei. Add the thermally conductive filler dispersion into the ice template mold, control the temperature of the cavity protrusion to near the freezing point, and perform directional freezing to form an ice template-thermally conductive filler composite. Then, freeze-dry the composite to obtain a thermally conductive filler skeleton with the aforementioned topological structure.

[0014] S4. Based on the geometric model of the thermally conductive material, the prepolymer of the thermally conductive filler skeleton and the polymer matrix is ​​processed by vacuum impregnation to obtain a thermally conductive material suitable for local micro heat sources of integrated chips.

[0015] According to the above scheme, in step S1, topology optimization simulation of the optimal heat flow path of the thermally conductive material is performed based on the local micro-heat source parameters. The initial topology of the thermally conductive filler skeleton is designed based on the heat flow path, and a geometric model of the thermally conductive material is established. Specifically, a simulation model of the thermally conductive material is constructed, and finite element analysis is used to optimize the topology of the heat flow path of the thermally conductive material. The simulation model uses volume constraints, and the objective function is to minimize the overall average temperature.

[0016] According to the above scheme, the discretely distributed thermally conductive packing material is designed to be continuous through topology optimization. The spacing and shape of the packing skeleton are then fine-tuned based on the range of ice crystal growth controlled by the subsequent cold source, resulting in the final topological structure of the thermally conductive packing skeleton. Designing the thermally conductive packing skeleton to be continuous facilitates molding and enhances in-plane heat conduction.

[0017] In step S2, ice template design is carried out based on the final topology of the fine-tuned thermally conductive filler skeleton, and an ice template mold with corresponding cavity is designed.

[0018] According to the above scheme, the material of the heat-conducting metal block is any one of copper, aluminum, aluminum alloy or titanium alloy.

[0019] The cavity protrusion and the heat-conducting metal block are made of the same material and are integrally formed.

[0020] According to the above scheme, in step S3, the temperature at which uniform crystal nuclei are formed on the cavity protrusions is ≤-3℃.

[0021] According to the above scheme, the near-freezing temperature in step S3 is 0℃ to -5℃, and the ice crystal growth rate is controlled to be 0.75μm / s to 1.25μm / s. The cavity protrusions on the upper surface of the thermally conductive metal block serve as the cold source for the ice template, causing the ice crystals to grow slowly at a certain speed in a direction perpendicular to the surface of the cavity protrusions. Accompanying the ice crystal growth, the thermally conductive filler is axially compressed into a dense thin wall along the designed direction, and the thin walls are interconnected to form a pattern.

[0022] Preferably, the near-freezing temperature is 0°C to -2°C.

[0023] Preferably, the ice crystal growth rate is controlled at 0.9 μm / s to 1.1 μm / s. More preferably, the ice crystal growth rate is controlled at 1 μm / s.

[0024] According to the above scheme, in step S3, the volume fraction of the thermally conductive filler in the thermally conductive filler dispersion is 0.1 vol% to 20 vol%.

[0025] According to the above scheme, the thermally conductive filler dispersion also contains a dispersant to improve the dispersibility of the thermally conductive filler in water.

[0026] According to the above scheme, the mass of the dispersant is 2.5% to 5% of the mass of the thermally conductive filler.

[0027] According to the above scheme, the dispersant is carboxymethyl cellulose (CMC).

[0028] According to the above scheme, in step S3, the parameters for freeze drying are: vacuum degree ≤10Pa, cold trap temperature ≤-50℃, and freeze drying time 12-24h.

[0029] According to the above scheme, the prepolymer of the polymer matrix in step S4 is obtained by mixing the polymer matrix and the curing agent.

[0030] According to the above scheme, the mass ratio of polymer matrix to curing agent is (9-11):1.

[0031] According to the above scheme, in step S4, the prepolymer of the polymer matrix is ​​injected into the thermally conductive filler skeleton, then cured, cooled, and demolded to obtain the thermally conductive material suitable for local micro heat sources of integrated chips.

[0032] According to the above scheme, the curing temperature is 90℃ to 100℃ and the time is 20-40 minutes.

[0033] According to the above scheme, the thermally conductive filler is any one of boron nitride, silicon carbide, graphene, or carbon nanotubes.

[0034] According to the above scheme, the polymer matrix is ​​any one of polydimethylsiloxane (PDMS), polyurethane, polyethylene or polyimide.

[0035] Secondly, the present invention provides a thermally conductive material suitable for local micro-heat sources in integrated chips, which is prepared by the above method.

[0036] According to the above scheme, the thermally conductive material suitable for local micro heat sources of integrated chips includes a polymer matrix and a thermally conductive filler skeleton with a topological structure. The thermally conductive filler skeleton is a patterned dense thin-walled structure with a thin-wall thickness of 10μm to 60μm and a density of ≥85%. The inter-surface thermal conductivity of the thermally conductive material is ≥1W / (m·K).

[0037] Thirdly, the present invention provides the application of the above-mentioned thermally conductive material suitable for local micro-heat sources of integrated chips in the heat dissipation of local micro-heat sources of integrated chips.

[0038] According to the above scheme, the local micro heat source is the core heating unit of the integrated chip.

[0039] According to the above scheme, when applying it, the thermally conductive material is attached to the central heat source of the local micro heat source.

[0040] According to the above scheme, the local micro heat source is a millimeter-level local micro heat source.

[0041] This invention designs thermally conductive materials to meet the heat dissipation requirements of local micro-heat sources in integrated chips. It adopts topology optimization to customize the heat flow path and achieves accurate reproduction of the topology of the thermally conductive filler and dense arrangement of the thin-walled thermally conductive filler by controlling the pre-nucleated ice template, thus preparing a thermally conductive material suitable for local micro-heat sources in integrated chips.

[0042] The beneficial effects of this invention are:

[0043] This invention designs and prepares a thermally conductive material with thermally conductive filler. The preparation of the thermally conductive material is achieved through the topological design of the thermally conductive filler and a pre-nucleation ice template method. In the pre-nucleation ice template method, pre-nucleation is first used to form crystal nuclei, increasing the nucleation sites for subsequent ice crystal growth and promoting the ice crystals to overcome the nucleation energy barrier in the near-freezing temperature range. Then, directional freezing is performed at near-freezing temperatures, and the ice crystals grow slowly and uniformly along a direction perpendicular to the protruding surface of the cavity. This achieves directional and dense arrangement of the thermally conductive filler along the topological direction, with a density ≥85%. This overcomes the bottleneck of loose arrangement and low thermal conductivity enhancement effect caused by the random growth direction of ice crystals in traditional ice template processes, significantly improving the inter-surface thermal conductivity enhancement effect of the material, increasing the inter-surface thermal conductivity by 593.25%. Meanwhile, the thermally conductive filler skeleton in the thermally conductive material of the present invention is distributed in a “patterned dense thin wall”, which matches the thermal conduction characteristics of the heat source. While ensuring the heat dissipation of the conventional substrate, the heat is transferred from the high temperature area to the low temperature area by in-plane heat dissipation, avoiding the problem of local high temperature, solving the problem of low heat dissipation efficiency of traditional discrete structure, and improving the in-plane thermal conductivity enhancement effect of the material. Attached Figure Description

[0044] Figure 1 The thermal interface material topology optimization simulation model (material volume factor diagram) for heat dissipation of micro heat source in this embodiment of the invention.

[0045] Figure 2 This is a structural design diagram of the thermally conductive material in an embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of the ice template mold in an embodiment of the present invention, wherein (a) is an overall top view and (b) is a sectional view;

[0047] Figure 4 The images shown are morphological images of the boron nitride framework in the embodiments of the present invention, wherein (a) is an optical microscope image of the overall topological structure and (b) is a scanning electron microscope (SEM) image of the microstructure of the dense thin-walled structure.

[0048] Figure 5 The figure shows the experimental results of the heat dissipation performance comparison of the present invention.

[0049] In the diagram: 1 is a heat-conducting metal block, 2 is a cavity protrusion, and 3 is an insulation plate. Detailed Implementation

[0050] The principles and features of the present invention are described below with reference to the accompanying drawings and specific embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0051] This embodiment provides a method for preparing a thermally conductive material suitable for local micro-heat sources in integrated chips, including the following steps:

[0052] S1. Based on the parameters of the local micro heat source, the topological structure of the thermally conductive filler skeleton in the thermally conductive material is designed, and the geometric model of the thermally conductive material is established;

[0053] S2. Design an ice template mold according to the topological structure of the thermally conductive filler skeleton. The ice template mold includes a thermally conductive metal block and an insulation plate. The upper surface of the thermally conductive metal block is provided with cavity protrusions corresponding to the topological structure of the thermally conductive filler skeleton. The insulation plate is provided with through holes corresponding to the cavity protrusions. It covers the upper surface of the thermally conductive metal block and exposes the cavity protrusions. The exposed cavity protrusions serve as the cold source of the ice template.

[0054] S3. Control the temperature of the cavity protrusion so that water vapor condenses on the surface of the cavity protrusion to form uniform crystal nuclei. Add the thermally conductive filler dispersion into the ice template mold, control the temperature of the cavity protrusion to near the freezing point, and perform directional freezing to form an ice template-thermally conductive filler composite. Then, freeze-dry the composite to obtain a thermally conductive filler skeleton with the aforementioned topological structure.

[0055] S4. Based on the geometric model of the thermally conductive material, the prepolymer of the thermally conductive filler skeleton and the polymer matrix is ​​processed by vacuum impregnation to obtain a thermally conductive material suitable for local micro heat sources of integrated chips.

[0056] In one specific embodiment of the present invention, in step S1, topology optimization simulation of the optimal heat flow path of the thermally conductive material is performed based on the local micro-heat source parameters. An initial topology of the thermally conductive filler skeleton is designed based on the heat flow path, and a geometric model of the thermally conductive material is established. Specifically, a simulation model of the thermally conductive material is constructed, and finite element analysis is used to optimize the topology of the heat flow path of the thermally conductive material. The simulation model employs volume constraints, and the objective function is to minimize the overall average temperature.

[0057] Furthermore, the discretely distributed thermally conductive packing material, optimized by topology, is designed to be continuous. The spacing and shape of the thermally conductive packing skeleton are then fine-tuned based on the range of ice crystal growth controlled by the subsequent cold source, resulting in the final topological structure of the thermally conductive packing skeleton. Designing the thermally conductive packing skeleton to be continuous facilitates molding and enhances in-plane heat conduction.

[0058] In step S2, an ice template mold with a corresponding cavity is designed based on the final topology of the finely adjusted thermally conductive filler skeleton.

[0059] The heat-conducting metal block is made of any one of copper, aluminum, aluminum alloy, or titanium alloy. The cavity protrusion is made of the same material as the heat-conducting metal block and is integrally molded.

[0060] In one specific embodiment of the present invention, the temperature at which uniform crystal nuclei are formed on the cavity protrusion is ≤-3℃.

[0061] In one specific embodiment of the present invention, the near-freezing temperature in step S3 is 0°C to -5°C, and the ice crystal growth rate is controlled to be 0.75 μm / s to 1.25 μm / s. The cavity protrusions on the upper surface of the heat-conducting metal block serve as the cold source for the ice template, causing the ice crystals to grow slowly at a certain speed along a direction perpendicular to the cavity protrusions. Accompanying the ice crystal growth is the heat-conducting filler, which is axially compressed into a dense thin wall along the designed direction, with interconnected thin walls forming a pattern. In some preferred embodiments, the ice crystal growth rate is controlled to be 0.9 μm / s to 1.1 μm / s. More preferably, the ice crystal growth rate is controlled to be 1 μm / s.

[0062] Preferably, the near-freezing temperature is 0°C to -2°C.

[0063] In some specific embodiments of the present invention, in step S3, the volume fraction of the thermally conductive filler in the thermally conductive filler dispersion is 0.1 vol% to 20 vol%.

[0064] In some specific embodiments of the present invention, the thermally conductive filler dispersion further contains a dispersant to improve the dispersibility of the thermally conductive filler in water. Preferably, the mass of the dispersant is 2.5% to 5% of the mass of the thermally conductive filler.

[0065] In some specific embodiments of the present invention, the dispersant is carboxymethyl cellulose (CMC).

[0066] In some specific embodiments of the present invention, in step S3, the parameters for freeze drying are: vacuum degree ≤10Pa, cold trap temperature ≤-50℃, and freeze drying time 12-24h.

[0067] In some specific embodiments of the present invention, the prepolymer of the polymer matrix in step S4 is obtained by mixing the polymer matrix and the curing agent. Preferably, the mass ratio of the polymer matrix to the curing agent is (9-11):1.

[0068] In step S4, the prepolymer of the polymer matrix is ​​injected into the thermally conductive filler skeleton, then cured, cooled, and demolded to obtain the thermally conductive material suitable for local micro heat sources of integrated chips.

[0069] Preferably, the curing temperature is 90°C to 100°C and the curing time is 20-40 minutes.

[0070] The thermally conductive filler is any one of boron nitride, silicon carbide, graphene, or carbon nanotubes; the polymer matrix is ​​any one of polydimethylsiloxane (PDMS), polyurethane, polyethylene, or polyimide.

[0071] The present invention also provides a thermally conductive material suitable for local micro-heat sources in integrated chips, which is prepared by the above method.

[0072] The aforementioned thermally conductive material suitable for local micro-heat sources in integrated chips includes a polymer matrix and a thermally conductive filler skeleton with a topological structure. The thermally conductive filler skeleton is a patterned, dense, thin-walled structure with a wall thickness of 10 μm to 60 μm and a density of ≥85%. The inter-surface thermal conductivity of the thermally conductive material is ≥1 W / (m·K).

[0073] The thermally conductive material prepared above can be applied to localized micro-heat source heat dissipation. Specifically, it can be used in the core heating unit of integrated chips or high-frequency sensors. In application, the thermally conductive material is attached to the central heat source of the localized micro-heat source.

[0074] More preferably, the local micro-heat source is a millimeter-level local micro-heat source.

[0075] The following is a specific embodiment. In this embodiment, boron nitride nanosheets (BNNS) are used as thermally conductive fillers, and polydimethylsiloxane (PDMS) is used as a polymer matrix to prepare a thermally conductive material suitable for local micro-heat sources in integrated chips. The thermally conductive material in this embodiment is designed as a thermal interface material.

[0076] In this embodiment, a typical localized micro-heat source environment inside an integrated chip is considered. It is assumed that the localized micro-heat source is dispersed within a 10mm square, and the average heat source power is approximately 10W / cm². 2 Based on this heat source, a 10mm×10mm thermal interface material is designed. The ambient temperature is 25℃. The heat dissipation boundary is the four sides of the thermal interface material, and the heat dissipation is achieved through natural convection.

[0077] First, step S1 is executed to perform topology optimization simulation based on the 10mm heat source interface material. A simulation model is constructed based on the heat source parameters and the aforementioned conditions. Topology optimization is then used to calculate the optimal distribution of the interface material (optimal heat dissipation path) when the overall average temperature of the heat source is minimized. The topology optimization of the 10mm×10mm interface material structure is performed using the finite element analysis software Comosol 6.2. The interface material is defined using a density function, with "minimum overall average temperature of the heat source" as the objective function and volume as the constraint. The optimal heat flow path is calculated using a gradient optimization algorithm, and the optimal distribution morphology of the boron nitride framework in the interface material is output. The morphology distribution is shown in the figure below. Figure 1 As shown.

[0078] Based on the boron nitride framework topology output in step S1 and the actual ice template preparation, the boron nitride framework distribution in the thermal interface material was designed to be continuous to facilitate mold removal and enhance in-plane heat conduction. The spacing and shape of the boron nitride framework were then fine-tuned according to the range of ice crystal growth controlled by the subsequent cold source (within the near-freezing temperature range, the cold source provides good control over ice crystal growth within a 1mm range), thus forming... Figure 2 The structure of the thermal interface material shown.

[0079] Next, proceed to step S2, according to Figure 2 The obtained thermal interface material has a corresponding cavity ice template mold, including a thermally conductive metal block 1 and a patterned insulating plate 3, the structure of which is as follows: Figure 3 As shown, the upper surface of the heat-conducting metal block 1 is provided with cavity protrusion 2. The cavity protrusion 2 is designed according to the topological structure of the heat-conducting filler skeleton. The heat-conducting metal block 1 and the cavity protrusion 2 are integrally formed. The material is copper. The heat insulation plate 3 is provided with through holes corresponding to the cavity protrusion 2. The heat insulation plate 3 covers the upper surface of the heat-conducting metal block 1 and exposes the cavity protrusion 2 as the cold source of the ice template. The material of the heat insulation plate 3 is resin.

[0080] Next, step S3 is performed to prepare and oriented the boron nitride nanosheet dispersion. This specifically includes the following steps:

[0081] 1) Preparation of boron nitride nanosheet (BNNS) dispersion: Add boron nitride nanosheets (thickness 1~5nm, particle size 1~5μm) to deionized water to prepare BNNS suspension, then add 2.5% by weight of carboxymethyl cellulose (CMC) as dispersant, and then ultrasonically disperse in an ice bath for 60min to prepare a uniform dispersion of BNNS with a volume fraction of 1 vol%.

[0082] 2) Ice crystal growth control and BNNS directional dense arrangement: First, the ice template mold is placed on the hot and cold table. The bottom surface of the heat-conducting metal block 1 is in direct contact with the hot and cold table. The heat insulation plate 3 is tightly fitted with the heat-conducting metal block 1. Only the cavity protrusion 2 of the heat-conducting metal block 1 is exposed as the cold source of the ice template. The temperature is controlled between -10℃ and -3℃, so that water vapor in the air undergoes heterogeneous sublimation on the surface of the cavity protrusion 2 of the heat-conducting metal block 1 to form uniform crystal nuclei, which increases the nucleation sites for ice crystal growth in the subsequent suspension. Then, the prepared boron nitride nanosheet (BNNS) dispersion was dropped into the cavity of the heat-conducting metal block 1 covered with the insulation plate 3. The temperature of the hot and cold stage was then adjusted to rise uniformly to about -1℃, causing ice crystals to grow slowly at a speed of about 1 μm / s along the direction perpendicular to the surface of the cavity protrusion 2 of the heat-conducting metal block 1. As the ice crystals grew, the boron nitride nanosheets (BNNS) were compressed into a dense thin wall along the designed direction, forming an ice template-boron nitride composite. The boron nitride thin wall is like... Figure 4 As shown in (b), the thickness of the thin wall is approximately 15 μm.

[0083] The ice template-boron nitride composite with completed boron nitride nanosheet arrangement was transferred to a freeze dryer, and the vacuum degree was set to ≤10Pa and the cold trap temperature to ≤-50℃. The freeze dryer was set for 12h to allow the ice crystals to sublimate and be removed, thus obtaining a boron nitride framework consistent with the topology optimization path.

[0084] Next, step S4 is performed, involving the infusion and curing of polydimethylsiloxane (PDMS). The details are as follows:

[0085] 1) Preparation of polydimethylsiloxane (PDMS) prepolymer: Mix PDMS base adhesive and curing agent at a mass ratio of 10:1, stir evenly, and then degas under vacuum for 10-15 minutes to obtain PDMS prepolymer;

[0086] 2) Infusion and Curing: The PDMS prepolymer was slowly injected into the boron nitride framework prepared above, ensuring that the prepolymer completely filled the framework pores. It was then cured in a 90℃ oven for 30 minutes, cooled to room temperature, and demolded to obtain a localized micro-heat source heat dissipation structure based on ice template regulation, namely, a boron nitride / polydimethylsiloxane composite thermal interface material, such as... Figure 4 As shown in (a).

[0087] Comparative Example

[0088] The material prepared in this comparative example is a disordered boron nitride / polydimethylsiloxane thermal interface material. The preparation method differs from that in the example in that: in step S3, the ice template mold is first placed on the hot and cold stage, the bottom surface of the heat-conducting metal block 1 is in direct contact with the hot and cold stage, the heat insulation plate 3 is tightly fitted with the heat-conducting metal block 1, and only the cavity protrusion 2 of the heat-conducting metal block 1 is exposed as the cold source of the ice template. The prepared boron nitride nanosheet (BNNS) dispersion is dripped into the cavity of the heat-conducting metal block 1 covered by the heat insulation plate 3. Then the temperature of the hot and cold stage is adjusted to -40°C to allow ice crystals to grow and randomly extruded and arranged to form disordered boron nitride (BNNS).

[0089] The performance of the boron nitride / polydimethylsiloxane composite thermal interface material prepared in the examples and the disordered boron nitride / polydimethylsiloxane thermal interface material prepared in the comparative examples were tested.

[0090] Thermal conductivity testing: The interfacial thermal conductivity of the thermal interface material was tested using the laser scintillation method (LFA467HT laser thermal conductivity meter (LFA)).

[0091] Temperature test: A 5mm center heat source test platform was built, and the heat interface material was attached to the heat source (interface pressure 0.1MPa). 0.8W of power was applied, and an infrared thermal imager (FLIRIM24-C-00023) was used to record the surface temperature of the heat source.

[0092] The test results are as follows:

[0093] The interfacial thermal conductivity of the disordered boron nitride / polydimethylsiloxane thermal interface material in the comparative example was 0.163 W / (m·K), while the interfacial thermal conductivity of the boron nitride / polydimethylsiloxane composite thermal interface material prepared in the embodiment of the present invention was 1.13 W / (m·K), which is 593.25% higher than that of the comparative example.

[0094] Temperature test results as follows Figure 5As shown, the temperature of the heat source in this embodiment of the invention is reduced by approximately 14.6°C compared to the comparative example at a power of 0.8W.

[0095] The above results demonstrate that the boron nitride / polydimethylsiloxane composite thermal interface material prepared by combining "topology-optimized heat flow path" with "directional dense arrangement of boron nitride" can effectively dissipate heat in millimeter-scale heat source heat dissipation scenarios.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a thermally conductive material suitable for localized micro-heat sources in integrated chips, characterized in that, Includes the following steps: S1. The topological structure of the thermally conductive filler skeleton in the thermally conductive material is designed based on the parameters of the local micro heat source; S2. Design an ice template mold based on the topological structure of the thermally conductive filler skeleton. The ice template mold includes a thermally conductive metal block and an insulation board. The upper surface of the thermally conductive metal block is provided with cavity protrusions corresponding to the topological structure of the thermally conductive filler skeleton. The insulation board is provided with through holes corresponding to the cavity protrusions. It covers the upper surface of the thermally conductive metal block and exposes the cavity protrusions. The exposed cavity protrusions serve as the cold source of the ice template. S3. Control the temperature of the cavity protrusion to ≤-3℃, so that water vapor condenses on the surface of the cavity protrusion to form uniform crystal nuclei. Add the thermally conductive boron nitride dispersion to the ice template mold, control the temperature of the cavity protrusion to near the freezing point, and perform directional freezing to form an ice template-thermally conductive filler composite. Then, freeze-dry to obtain a thermally conductive filler skeleton with the topological structure, wherein the near-freezing point temperature is 0℃ to -5℃, and the ice crystal growth rate is controlled to be 0.75μm / s to 1.25μm / s. S4. The prepolymer of the thermally conductive filler skeleton and the polymer matrix is ​​processed by vacuum impregnation to obtain a thermally conductive material suitable for local micro heat sources of integrated chips.

2. The method for preparing a thermally conductive material suitable for localized micro-heat sources in integrated chips according to claim 1, characterized in that, In step S1, topology optimization simulation of the optimal heat flow path of the thermally conductive material is performed based on the local micro heat source parameters, and the initial topology of the thermally conductive filler skeleton is designed based on the heat flow path.

3. The method for preparing a thermally conductive material suitable for localized micro-heat sources in integrated chips according to claim 2, characterized in that, The discretely distributed thermally conductive packing material with topology optimization is designed to be continuous, and the spacing and shape of the thermally conductive packing skeleton are finely adjusted according to the range of ice crystal growth controlled by the subsequent cold source to obtain the final topology of the thermally conductive packing skeleton.

4. The method for preparing a thermally conductive material suitable for localized micro-heat sources in integrated chips according to claim 1, characterized in that, In step S3, the volume fraction of the thermally conductive filler in the thermally conductive filler dispersion is 0.1 vol% to 20 vol%.

5. The method for preparing a thermally conductive material suitable for localized micro-heat sources in integrated chips according to claim 1, characterized in that, In step S4, the prepolymer of the polymer matrix is ​​injected into the thermally conductive filler skeleton, then cured, cooled, and demolded to obtain the thermally conductive material suitable for local micro heat sources of integrated chips.

6. The method for preparing a thermally conductive material suitable for localized micro-heat sources in integrated chips according to any one of claims 1-5, characterized in that, The polymer matrix is ​​any one of polydimethylsiloxane, polyurethane, polyethylene, or polyimide.

7. A thermally conductive material suitable for localized micro-heat sources in integrated chips, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

8. The application of the thermally conductive material as described in claim 7 for local micro-heat sources of integrated chips in heat dissipation of local micro-heat sources of integrated chips.

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