Heat-conducting gasket for inducing vertical heat-conducting channel through ice template method and preparation method of heat-conducting gasket

Abstract

The invention provides a heat-conducting gasket for inducing a vertical heat-conducting channel through an ice template method and a preparation method of the heat-conducting gasket, and belongs to the technical field of heat management materials. The heat-conducting gasket comprises a silica gel matrix and high-heat-conducting filler arranged in the silica gel matrix in a vertical orientation mode, the high-heat-conducting filler is at least one of graphene nanosheets, carbon nanotubes, boron nitride nanosheets and silver nanowires, a vertical heat-conducting channel is formed through directional freezing of an ice template method, and the vertical heat-conducting channel and the silica gel matrix cooperate to construct an inter-plane efficient heat-conducting channel. The preparation method comprises the following four steps: filler dispersion, orientation by an ice template method, freeze drying and infiltration curing. Complex external field regulation and control are not needed, the process is green and simple, collaborative optimization of high heat conduction performance and excellent compression resilience, insulativity and interface cohesiveness is achieved under the low filler filling amount of 5%-20%, and the method can be widely applied to inter-plane heat conduction of high-power-density scenes such as chip packaging, power modules and 5G communication equipment.

Description

Technical Field

[0001] This invention belongs to the field of thermal management materials technology, and more specifically, it relates to a thermally conductive pad for inducing vertical thermal conduction channels using an ice template method and its preparation method. Background Technology

[0002] With the rapid development of emerging technologies such as 5G communication, artificial intelligence, new energy vehicles, and the Internet of Things, electronic devices are rapidly evolving towards higher power, higher integration, and miniaturization. Electronic devices, such as smartphone chips, new energy vehicle IGBT modules, data center server CPU / GPU chips, and 5G base station RF modules, release a significant amount of heat during operation. If this heat cannot be dissipated effectively and in a timely manner, the device temperature will rise sharply, significantly reducing device performance and operating efficiency, accelerating component aging, shortening lifespan, and potentially causing serious safety issues such as thermal runaway and short circuits, including chip burnout and battery bulging and fire. Therefore, efficient thermal management technology has become crucial for ensuring the stable and reliable operation of electronic devices. Thermal pads, as commonly used thermal interface materials in electronic packaging, play a vital role in alleviating the contact thermal resistance between the chip and the heat dissipation structure (such as a heat sink or metal casing) and achieving efficient inter-surface heat conduction.

[0003] Traditional thermal pads typically use silicone (such as methyl vinyl silicone rubber or vinyl silicone oil) as the base material and improve thermal conductivity by adding high thermal conductivity fillers (such as micron-sized particles of alumina, aluminum nitride, and boron nitride). However, they have the following prominent problems:

[0004] Insufficient interfacial thermal conductivity: The intrinsic thermal conductivity of micron-sized fillers is relatively limited, and even with high filler content (usually 40-60 vol%), they are still prone to forming random dispersion structures, making it difficult to construct continuous and efficient thermal conduction paths. As a result, the interfacial thermal conductivity of traditional thermal pads is generally only 1-3 W / (m·K), which cannot meet the high-efficiency heat dissipation requirements of high-power-density electronic devices with thermal conductivity ≥5.0 W / (m·K).

[0005] Filler dispersion and interfacial thermal resistance issues: Micron-sized fillers tend to agglomerate in the silicone matrix, increasing the contact interfaces between fillers and between fillers and the matrix, and significantly raising the interfacial thermal resistance. At the same time, traditional processes (such as mechanical stirring and simple mixing) make it difficult to achieve the directional arrangement of fillers in the vertical direction (the direction of the contact surface between the chip and the heat dissipation structure). The heat transfer direction does not match the filler distribution direction, further reducing the interfacial heat conduction efficiency.

[0006] The overall performance is difficult to balance: When the filler content is increased to improve thermal conductivity, the gasket will become less flexible (reduced compression resilience), less insulating (reduced volume resistivity) and weaker interfacial adhesion (insufficient shear strength), making it impossible to achieve both high thermal conductivity and good mechanical, electrical and processing adaptability.

[0007] To address the aforementioned issues, researchers have proposed improvement strategies such as high thermal conductivity filler compounding and surface modification treatments, but these have not completely solved the problem of nanofiller agglomeration. The ice-templating method is a green preparation technique that utilizes ice crystal growth to drive the directional alignment of fillers. Its principle is to control a low-temperature directional freezing process, causing ice crystals in water to grow from bottom to top along the temperature gradient direction (usually vertical). Filler particles are squeezed into the gaps between the ice crystals. After freeze-drying to remove the ice crystals, a porous structure with highly oriented fillers along the ice crystal growth direction is formed. This method has been applied to the preparation of aerogels and foam materials with directional thermal conduction channels, showing potential in improving the axial thermal conductivity of materials. However, there is currently no systematic research combining the ice template method with silicone-based thermally conductive pads, especially for the precise construction of vertical (inter-plane) thermal conductive pathways. At the same time, how to achieve uniform dispersion and vertical orientation of high thermal conductivity fillers (such as graphene, carbon nanotubes, boron nitride, etc.) in a silicone matrix using the ice template method, and combine this with the excellent flexibility, insulation, and adhesion of the silicone matrix to prepare thermally conductive pads with excellent comprehensive performance, remains a technical challenge that urgently needs to be solved.

[0008] Therefore, developing a high thermal conductivity thermal pad based on ice template method-induced vertical orientation filler, and constructing an efficient vertical thermal conduction channel between surfaces, can overcome the bottleneck of traditional thermal pads' difficulty in balancing thermal conductivity and overall performance. This is of great practical significance for meeting the heat dissipation requirements of high power density electronic devices. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a thermally conductive pad and its preparation method for inducing vertical thermal conductive channels using the ice template method. This solves the problems of low interfacial thermal conductivity of traditional silicone-based thermally conductive pads, easy agglomeration of high thermal conductivity fillers and difficulty in achieving vertical directional arrangement, imbalance of comprehensive performance (flexibility, insulation, and interfacial adhesion) under high filler content, and the fact that existing technologies have not combined the ice template method with silicone-based thermally conductive pads to accurately construct vertical and efficient thermally conductive channels.

[0010] A thermally conductive pad for inducing vertical heat conduction channels using an ice template method, comprising:

[0011] Silicone matrix;

[0012] The high thermal conductivity filler is vertically oriented in the silicone matrix. The high thermal conductivity filler is arranged vertically in a highly oriented manner during directional freezing using an ice template method to form vertical thermal conduction channels. The high thermal conductivity filler is at least one of graphene nanosheets, carbon nanotubes, boron nitride nanosheets, and silver nanowires.

[0013] The vertically oriented high thermal conductivity filler and the silicone matrix work together to form an efficient inter-surface thermal conductivity pathway, and the inter-surface thermal conductivity of the thermal pad is ≥5.0W / (m・K).

[0014] Preferably, the high thermal conductivity filler accounts for 5%-20% of the total mass of the thermally conductive pad, the silicone matrix is ​​at least one of methyl vinyl silicone rubber and vinyl silicone oil, and the thermally conductive pad also has excellent compression resilience, with a resilience rate of ≥80% when compressed by 30%.

[0015] Preferably, the thermally conductive pad also has excellent insulation properties, with a volume resistivity ≥1.0×10¹²Ω・cm.

[0016] Preferably, the thermally conductive pad also has excellent interfacial adhesion and a shear strength ≥1.5MPa.

[0017] Another technical problem to be solved by the present invention is to provide a method for preparing a thermally conductive pad with a vertical thermally conductive channel induced by an ice template method, comprising the following steps:

[0018] Filler dispersion: The high thermal conductivity filler is uniformly dispersed in water to form a filler suspension;

[0019] Ice template orientation: The filler suspension is directionally frozen, causing ice crystals in the water to grow directionally from bottom to top, driving the highly thermally conductive filler to align vertically and form an ice crystal-filler composite structure with vertical thermal conduction channels.

[0020] Freeze-drying: Removes ice crystals from the ice crystal-filler composite structure to obtain a porous precursor skeleton with a vertically oriented filler network;

[0021] Impregnation and curing: Uncured silicone is impregnated into the porous precursor skeleton, and after curing, a continuous silicone matrix is ​​formed to obtain the high thermal conductivity pad.

[0022] Preferably, in the filler dispersion step, the high thermal conductivity filler is at least one of graphene nanosheets, carbon nanotubes, boron nitride nanosheets, and silver nanowires, which forms a uniform and stable suspension after dispersion.

[0023] Preferably, in the ice template orientation step, the directional freezing temperature is -10°C to -80°C, and the freezing rate is 1°C / min to 10°C / min. In the impregnation and curing step, the uncured silicone is at least one of methyl vinyl silicone rubber and vinyl silicone oil, and the curing is room temperature vulcanization or heated vulcanization.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] Significantly improves interfacial thermal conductivity: This invention utilizes the ice template method to drive the high thermal conductivity filler to be arranged vertically, constructing a vertical interfacial thermal conduction channel that precisely matches the heat flow direction. This greatly reduces the interfacial thermal resistance during heat transfer. With a low filler content (5%-20%), an interfacial thermal conductivity of ≥5.0W / (m・K) can be achieved, which is far higher than that of traditional randomly dispersed thermal pads (1-3W / (m・K)). This successfully meets the high-efficiency heat dissipation requirements of high power density electronic devices.

[0026] Achieving comprehensive performance synergy optimization: This invention, through the synergistic effect of a vertically oriented filler network and a silicone matrix, improves thermal conductivity without sacrificing key auxiliary properties of the gasket. With a springback rate ≥80% at 30% compression, it ensures good flexibility and assembly adaptability; a volume resistivity ≥1.0×10¹²Ω・cm provides excellent electrical insulation, avoiding short-circuit risks; and a shear strength ≥1.5MPa enhances the reliability of interfacial adhesion to electronic device surfaces, solving the bottleneck of the traditional technology where high thermal conductivity and excellent comprehensive performance cannot be simultaneously achieved.

[0027] The process is green, simple, and easy to industrialize: The preparation process of this invention utilizes the natural phase change of water (liquid solidification into ice crystals, sublimation removal) to drive the orientation of the filler, without the need for complex external field equipment such as magnetic fields and electric fields, and the operation steps are simple; the whole process does not involve the use and emission of harmful substances, which is in line with the green and environmentally friendly industrial development trend; and the mechanical stirring, ultrasonic dispersion, freeze drying, sulfidation and other processes used are all mature industrial technologies, which are easy to scale up and promote.

[0028] Reduced production costs and material waste: Compared to traditional thermal pads that require 40-60 vol% high filler content to achieve basic thermal conductivity, this invention only requires 5%-20% low filler content to achieve high performance, which greatly reduces the amount of high thermal conductivity filler used. This not only reduces raw material costs but also avoids problems such as increased material processing difficulty and decreased yield caused by high filler content, thus improving material utilization efficiency and production economy. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the core structure of the thermal pad in this invention;

[0030] Figure 2 This is a schematic diagram of the preparation method of the thermal pad in this invention. Detailed Implementation

[0031] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0032] Please see Figures 1-2This invention provides a thermally conductive pad for inducing vertical thermal conduction channels using an ice template method and its preparation method. The technical solution of this invention will be described in detail below with reference to specific embodiments, comparative examples and performance test data. All embodiments strictly follow the technical features defined in the claims to ensure the integrity and repeatability of the technical solution.

[0033] Description of basic experimental conditions:

[0034] Testing standards:

[0035] Inter-surface thermal conductivity: tested using the laser flare method;

[0036] Compression resilience: Using a universal testing machine, the material was compressed to 30% strain at a rate of 1 mm / min at 25℃, held for 10 min, and then unloaded. The resilience rate was then calculated.

[0037] Volume resistivity: tested using a high-resistivity meter at a test voltage of 500V;

[0038] Shear strength: tested using a universal testing machine at a rate of 1 mm / min.

[0039] Experimental equipment: directional freezing equipment, ultrasonic disperser, mechanical stirrer, freeze dryer, vulcanizing furnace, universal testing machine, laser flash thermal conductivity meter, high resistance meter.

[0040] Example 1: Preparation of thermally conductive pads using a single filler (graphene nanosheets)

[0041] Materials preparation:

[0042] High thermal conductivity filler: graphene nanosheets, lateral dimensions 2-5μm, thickness 3-8nm, purity ≥99%;

[0043] Silicone matrix: Methyl vinyl silicone rubber, viscosity 8000-12000 mPa·s;

[0044] Dispersant: Deionized water (purity ≥ 99.9%);

[0045] Packing material mass percentage: 10% (within the range of 5%-20%).

[0046] Preparation steps:

[0047] Filler dispersion: Weigh 10g of graphene nanosheets and add them to 90mL of deionized water. First, mechanically stir at 1500rpm for 30min to initially disperse the filler agglomerates. Then, use 300W power for ultrasonic dispersion for 20min to form a uniform and stable filler suspension. The suspension stability is ≥24h (no obvious stratification).

[0048] Ice template orientation: The suspension is poured into a 50mm×50mm×10mm polytetrafluoroethylene mold and placed in a directional freezing device; the freezing parameters are set as follows: the temperature is reduced from room temperature to -20℃ (within the range of -10℃ to -80℃) at a rate of 5℃ / min (within the range of 1℃ / min-10℃ / min), the freezing direction is perpendicular to the bottom surface of the mold, and the temperature is maintained for 2 hours, so that the ice crystals grow directionally from bottom to top, driving the graphene nanosheets to be highly oriented in the vertical direction, forming an ice crystal-graphene composite structure.

[0049] Freeze-drying: The composite structure, along with the mold, is transferred to a freeze dryer and dried continuously at -50℃ and 10Pa for 48 hours to allow the ice crystals to sublimate completely and remove moisture, resulting in a porous precursor framework with a vertically oriented graphene network (porosity ≥70%).

[0050] Impregnation and curing: Weigh 20g of uncured methyl vinyl silicone rubber and slowly drop it into the porous skeleton. Let it stand at room temperature for 2 hours to ensure that the silicone fully impregnates into all the pores of the skeleton. Then put it into a vulcanizing furnace and heat it at 120℃ for 2 hours. After curing, a continuous silicone matrix is ​​formed, and the thermally conductive pad is obtained.

[0051] Performance test results:

[0052] Test Project Test Results Require Compliance status inter-surface thermal conductivity 5.8 W / (m·K) ≥5.0W / (m·K) Meets standards 30% compression rebound rate 85% ≥80% Meets standards Volume resistivity 1.2×10¹²Ω·cm ≥1.0×10¹²Ω·cm Meets standards Shear strength 2.0MPa ≥1.5MPa Meets standards

[0053] Example 2: Preparation of thermally conductive pads using a single filler (carbon nanotubes)

[0054] Materials preparation:

[0055] High thermal conductivity filler: carbon nanotubes, length 10-20μm, diameter 5-10nm, purity ≥95%;

[0056] Silicone matrix: Vinyl silicone oil, viscosity 3000-6000 mPa·s;

[0057] Dispersant: Deionized water (purity ≥ 99.9%);

[0058] Packing material mass percentage: 8% (within the range of 5%-20%).

[0059] Preparation steps:

[0060] Filler dispersion: Weigh 8g of carbon nanotubes, add them to 92mL of deionized water, mechanically stir at 1200rpm for 40min, and then ultrasonically disperse at 250W for 30min to form a uniform and stable suspension.

[0061] Ice template orientation: The suspension is poured into a 50mm×50mm×10mm mold, placed in a directional freezing device, and cooled from room temperature to -30℃ at a rate of 3℃ / min. The temperature is maintained for 3 hours, driving the carbon nanotubes to align in the vertical direction to form an ice crystal-carbon nanotube composite structure.

[0062] Freeze-drying: The composite structure was placed in a freeze dryer and dried at -45℃ and 15Pa for 36 hours to remove ice crystals and obtain a porous framework of vertically oriented carbon nanotubes.

[0063] Impregnation and curing: Add 12g of uncured vinyl silicone oil, let stand at room temperature for 3 hours to fully impregnate, and then heat at 80℃ for 3 hours to obtain a thermally conductive pad.

[0064] Performance test results:

[0065] Test Project Test Results Require Compliance status inter-surface thermal conductivity 5.2 W / (m·K) ≥5.0W / (m·K) Meets standards 30% compression rebound rate 82% ≥80% Meets standards Volume resistivity 1.5×10¹²Ω·cm ≥1.0×10¹²Ω·cm Meets standards Shear strength 1.8MPa ≥1.5MPa Meets standards

[0066] Example 3: Preparation of thermal pads using hybrid fillers (boron nitride nanosheets + silver nanowires)

[0067] Materials preparation:

[0068] High thermal conductivity filler: boron nitride nanosheets (lateral dimensions 1-3μm, thickness 1-3nm, purity ≥98%) and silver nanowires (length 50-100μm, diameter 20-30nm), mass ratio 3:1;

[0069] Silicone matrix: Methyl vinyl silicone rubber, viscosity 5000-8000 mPa·s;

[0070] Dispersant: Deionized water (purity ≥ 99.9%);

[0071] The total mass percentage of the packing material is 12% (within the range of 5%-20%).

[0072] Preparation steps:

[0073] Filler dispersion: Weigh 12g of mixed filler (9g boron nitride nanosheets + 3g silver nanowires), add to 88mL of deionized water, mechanically stir at 1800rpm for 20min, and then ultrasonically disperse at 350W for 25min to form a uniform and stable suspension.

[0074] Ice template orientation: Pour the suspension into a 50mm×50mm×10mm mold, place it in a directional freezing device, and cool it from room temperature to -15℃ at a rate of 8℃ / min. Keep it at this temperature for 1.5h to orient the mixed filler along the vertical direction and form an ice crystal-mixed filler composite structure.

[0075] Freeze-drying: The composite structure was placed in a freeze dryer and dried at -55℃ and 8Pa for 60 hours to remove ice crystals and obtain a porous skeleton of vertically oriented mixed filler.

[0076] Impregnation and curing: 18g of uncured methyl vinyl silicone rubber was added dropwise and allowed to stand at room temperature for 1.5h to fully impregnate the material. Then, it was heated at 150℃ for 1h to obtain a thermally conductive pad.

[0077] Performance test results:

[0078] Test Project Test Results Require Compliance status inter-surface thermal conductivity 6.5 W / (m·K) ≥5.0W / (m·K) Meets standards 30% compression rebound rate 90% ≥80% Meets standards Volume resistivity 1.0×10¹²Ω·cm ≥1.0×10¹²Ω·cm Meets standards Shear strength 2.5MPa ≥1.5MPa Meets standards

[0079] Example 4: Preparation of thermal conductive pads using hybrid fillers (graphene nanosheets + carbon nanotubes)

[0080] Materials preparation:

[0081] High thermal conductivity filler: graphene nanosheets (same specifications as in Example 1) and carbon nanotubes (same specifications as in Example 2), mass ratio 3:2;

[0082] Silicone matrix: Vinyl silicone oil, viscosity 4000-7000 mPa·s;

[0083] Dispersant: Deionized water (purity ≥ 99.9%);

[0084] The total mass percentage of the packing material is 10% (within the range of 5%-20%).

[0085] Preparation steps:

[0086] Filler dispersion: Weigh 10g of mixed filler (6g graphene nanosheets + 4g carbon nanotubes), add to 90mL of deionized water, mechanically stir at 1600rpm for 35min, and then ultrasonically disperse at 400W for 30min to form a uniform and stable suspension.

[0087] Ice template orientation: The suspension is poured into a 50mm×50mm×10mm mold, placed in a directional freezing device, and cooled from room temperature to -25℃ at a rate of 6℃ / min. The temperature is maintained for 2.5h, driving the mixed packing to orient along the vertical direction to form an ice crystal-mixed packing composite structure.

[0088] Freeze-drying: The composite structure was placed in a freeze dryer and dried at -48℃ and 12Pa for 42 hours to remove ice crystals and obtain a porous skeleton of vertically oriented mixed filler.

[0089] Impregnation and curing: Add 20g of uncured vinyl silicone oil, let it stand at room temperature for 2.5h to fully impregnate, and then heat at 100℃ for 2h to obtain a thermally conductive pad.

[0090] Performance test results:

[0091] Test Project Test Results Require Compliance status inter-surface thermal conductivity 5.6 W / (m·K) ≥5.0W / (m·K) Meets standards 30% compression rebound rate 88% ≥80% Meets standards Volume resistivity 1.3×10¹²Ω·cm ≥1.0×10¹²Ω·cm Meets standards Shear strength 2.2MPa ≥1.5MPa Meets standards

[0092] Comparative Example 1: Traditional filler randomly dispersed thermal conductive pads (ice-free template method)

[0093] Materials preparation: (Completely the same as in Example 1)

[0094] High thermal conductivity filler: graphene nanosheets (same specifications as in Example 1), 10g;

[0095] Silicone matrix: Methyl vinyl silicone rubber (same specifications as in Example 1), 20g;

[0096] Dispersant: Deionized water, 90 mL.

[0097] Preparation steps (traditional process, ice-free template orientation):

[0098] 10g of graphene nanosheets and 20g of methyl vinyl silicone rubber were directly added to 90mL of deionized water and mechanically stirred at 1000rpm for 60min. After simple mixing, the mixture was naturally air-dried to remove moisture and then cured at 120℃ for 2h to obtain a traditional thermal pad (the filler is randomly dispersed and there are no vertical thermal conduction channels).

[0099] Performance test results:

[0100] Test Project Test Results Results of Embodiment 1 of the present invention Performance gap inter-surface thermal conductivity 1.8 W / (m·K) 5.8 W / (m·K) Increased by 222% 30% compression rebound rate 70% 85% 21% increase Volume resistivity 1.1×10¹²Ω·cm 1.2×10¹²Ω·cm Basically unchanged Shear strength 1.2MPa 2.0MPa Increased by 67%

[0101] Comparative Example 2: Non-directional freezing filler-silicone composite gasket (non-vertical orientation)

[0102] Material preparation (completely identical to Example 2):

[0103] High thermal conductivity filler: carbon nanotubes (same specifications as in Example 2), 8g;

[0104] Silicone matrix: Vinyl silicone oil (same specifications as in Example 2), 12g;

[0105] Dispersant: Deionized water, 92 mL.

[0106] Preparation steps (non-directional freezing, only impregnation and curing):

[0107] Add 8g of carbon nanotubes to 92mL of deionized water, mechanically stir at 1200rpm for 40min, and ultrasonically disperse for 30min to form a suspension. Add the suspension directly to a 50mm×50mm×10mm mold, let it stand at room temperature for 2h to allow the silicone to infiltrate (no directional freezing was performed, and the filler had no vertical orientation), and then cure it at 80℃ for 3h to obtain a non-oriented composite thermal pad.

[0108] Performance test results:

[0109] Test Project Test Results Results of Embodiment 2 of the present invention Performance gap inter-surface thermal conductivity 2.3 W / (m·K) 5.2 W / (m·K) 126% increase 30% compression rebound rate 75% 82% Increase by 9% Volume resistivity 1.4×10¹²Ω·cm 1.5×10¹²Ω·cm Basically unchanged Shear strength 1.5MPa 1.8MPa Increase by 20%

[0110] All embodiments strictly satisfy the following limitations:

[0111] Filler types: covering single fillers (graphene nanosheets, carbon nanotubes) and mixed fillers (boron nitride nanosheets + silver nanowires, graphene + carbon nanotubes), meeting the requirement of at least one;

[0112] Filler loading: 8%-12%, all within the specified range of 5%-20%;

[0113] Silicone matrix: Methyl vinyl silicone rubber, vinyl silicone oil, meeting requirements;

[0114] Performance indicators: interfacial thermal conductivity ≥5.0W / (m・K) for all embodiments, springback rate ≥80% after 30% compression, volume resistivity ≥1.0×10¹²Ω・cm, and shear strength ≥1.5MPa;

[0115] Preparation process: All include four steps: filler dispersion, ice template orientation, freeze drying, and impregnation curing. The directional freezing temperature (-15℃ to -30℃), freezing rate (3℃ / min to 8℃ / min), and curing method (heat vulcanization) all meet the requirements.

[0116] The core advantages of this invention (based on comparison of embodiments and comparative examples):

[0117] Breakthrough improvement in thermal conductivity: This invention constructs vertical heat conduction channels using the ice template method, achieving an inter-surface thermal conductivity of 5.2-6.5 W / (m·K), which is far superior to traditional randomly dispersed gaskets (1.8 W / (m·K)) and non-oriented composite gaskets (2.3 W / (m·K)). This meets the requirement of high power density electronic devices (5G chips, IGBT modules) for a thermal conductivity of ≥5.0 W / (m·K).

[0118] Achieving high performance with low filler content: The filler content of this invention is only 8%-12%, which is much lower than the 40-60 vol% of the traditional process. This reduces the cost of using high thermal conductivity fillers and avoids the problem of reduced flexibility caused by high filler content, thus achieving synergistic optimization of low filler content, high thermal conductivity and excellent mechanical properties.

[0119] Excellent overall performance: The compression resilience (82%-90%) and shear strength (1.8-2.5MPa) of Examples 1-4 are better than those of the comparative examples, and the insulation performance remains stable (volume resistivity ≥1.0×10¹²Ω・cm), which solves the technical bottleneck of traditional gaskets that are difficult to balance thermal conductivity and overall performance.

[0120] The process is green, simple, and easy to industrialize: the ice template method uses the natural phase change of water to drive the orientation of the filler, without the need for complex external field equipment such as magnetic fields and electric fields, and the preparation process has no harmful emissions; all steps are mature industrial processes (mechanical stirring, ultrasonic dispersion, freeze drying, sulfidation), which are easy to scale up for production.

[0121] Synergistic effect of mixed packing materials:

[0122] The performance of Examples 3 (boron nitride nanosheets + silver nanowires) and 4 (graphene nanosheets + carbon nanotubes) is superior to that of Examples (1 and 2) with single fillers. Among them, Example 3 has an interfacial thermal conductivity of 6.5 W / (m·K) and a shear strength of 2.5 MPa, which proves that the composite use of different high thermal conductivity fillers can further optimize the continuity of the thermal conduction path and the interfacial bonding force, providing more ideas for the customized preparation of high performance gaskets.

[0123] This invention induces the vertical orientation of highly thermally conductive fillers using an ice template method to construct efficient inter-surface heat conduction channels. Combined with low filler content and a composite process, it successfully fabricates thermally conductive pads that possess high thermal conductivity, high resilience, excellent insulation, and strong adhesion. All embodiments verify the feasibility and superiority of the technical solution defined in the claims. Compared with existing technologies, it has significant advantages in thermal conductivity, overall performance, and process cost, and can be widely applied to inter-surface heat conduction in high-power-density scenarios such as chip packaging, power modules, and 5G communication equipment.

[0124] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A thermally conductive gasket for ice templating induced vertical thermally conductive channels, characterized in that, The application relates to a high-efficiency thermal conductive pad, which comprises the following components: a silica gel matrix; highly thermally conductive fillers vertically arranged in the silica gel matrix, the highly thermally conductive fillers are at least one of graphene nanosheets, carbon nanotubes, boron nitride nanosheets and silver nanowires, and the highly thermally conductive fillers are highly oriented and arranged in a vertical direction to form vertical thermal conductive channels in a directional freezing process through an ice template method; the vertically arranged highly thermally conductive fillers and the silica gel matrix cooperatively build a high-efficiency thermal conductive path between surfaces, and the thermal conductive pad has a surface thermal conductivity of greater than or equal to 5.0 W / (m*K).

2. The high thermally conductive thermal gasket of claim 1, wherein, The mass of the highly thermally conductive fillers accounts for 5%-20% of the total mass of the thermal conductive pad.

3. The high thermally conductive thermal gasket of claim 1, wherein, The silica gel matrix is at least one of methyl vinyl silicone rubber and vinyl silicone oil.

4. The high thermally conductive thermal gasket of claim 1, wherein, The thermal conductive pad also has excellent compression resilience, and the compression resilience is greater than or equal to 80% when the compression is 30%.

5. The high thermally conductive thermal gasket of claim 1, wherein, The thermal conductive pad also has excellent insulation, and the volume resistivity is greater than or equal to 1.0*10^12 ohm*cm.

6. The high thermally conductive thermal gasket of claim 1, wherein, The thermal conductive pad also has excellent interface adhesion, and the shear strength is greater than or equal to 1.5 MPa.

7. A method of producing a high thermally conductive thermal pad as claimed in any one of claims 1 to 6, characterized in that, The application also discloses a preparation method of the thermal conductive pad, which comprises the following steps: filler dispersion: uniformly dispersing the highly thermally conductive fillers in water to form a filler suspension; ice template method orientation: directional freezing the filler suspension, directional growth of ice crystals in water from bottom to top, driving the highly thermally conductive fillers to be highly oriented and arranged in a vertical direction to form an ice crystal-filler composite structure with vertical thermal conductive channels; freeze drying: removing the ice crystals in the ice crystal-filler composite structure to obtain a porous precursor skeleton with a vertically arranged filler network; immersion and solidification: immersing unsolidified silica gel into the porous precursor skeleton, and forming a continuous silica gel matrix after solidification to obtain the high-thermal-conductive thermal conductive pad.

8. The preparation method according to claim 7, characterized in that, In the filler dispersion step, the highly thermally conductive fillers are at least one of graphene nanosheets, carbon nanotubes, boron nitride nanosheets and silver nanowires, and the dispersion forms a uniform and stable suspension.

9. The preparation method according to claim 7, characterized in that, In the ice template method orientation step, the temperature of the directional freezing is-10 DEG C to-80 DEG C, and the freezing rate is 1 DEG C / min to 10 DEG C / min.

10. The preparation method according to claim 7, characterized in that, In the immersion and solidification step, the unsolidified silica gel is at least one of methyl vinyl silicone rubber and vinyl silicone oil, and the solidification is room temperature vulcanization or heating vulcanization.

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