Low-compression-stress low-density heat-conducting gasket and preparation method thereof

Abstract

The invention provides a low-compression-stress low-density heat-conducting gasket and a preparation method thereof.The heat-conducting gasket is prepared from, by weight, 100-300 parts of vinyl silicone oil, 1-3 parts of end chain hydrogen-containing silicone oil, 2-6 parts of side chain hydrogen-containing silicone oil, 0.2-0.6 part of platinum catalyst, 300-700 parts of heat-conducting filler, 0.1-0.5 part of coupling agent and 0.1-0.5 part of inhibitor. Wherein the vinyl silicone oil is prepared by matching two kinds of vinyl-terminated polydimethylsiloxane with different viscosities and vinyl contents; and the heat-conducting filler is a ternary combination of spherical aluminum oxide, spherical boron nitride and beta-type silicon nitride with a lubricating function. The preparation method comprises the following steps: adding the raw materials into stirring equipment, controlling the vacuum degree during stirring by adopting staged negative pressure, stirring under the conditions that the negative pressure is less than or equal to-0.095 MPa,-0.06 to-0.07 MPa and less than or equal to-0.095 MPa in sequence, fully mixing the materials, clustering, transferring to a calender, and carrying out high-temperature vulcanization molding at 120-140 DEG C. The heat-conducting gasket has the characteristics of low compression stress and low density, and the production efficiency is remarkably improved.

Description

Technical Field

[0001] This application relates to the field of thermally conductive materials, and in particular to a low-compressive-stress, low-density thermally conductive pad and its preparation method. Background Technology

[0002] Thermally conductive materials are widely used in modern industry and electronic equipment. As electronic devices become increasingly miniaturized and performant, the performance requirements for thermally conductive materials are also rising. Thermal pads, as a common type of thermally conductive material, directly affect the heat dissipation and stability of electronic devices.

[0003] Currently, commercially available thermal pads suffer from deficiencies in compressive stress, density, and manufacturing processes, severely limiting their further application and development in numerous fields. Therefore, there is an urgent need for a novel thermal pad and its manufacturing method that can effectively address these issues. Summary of the Invention

[0004] In view of the aforementioned problems, this application is made to provide a low-compressive-stress, low-density thermally conductive pad and a method for preparing the same, which overcomes or at least partially solves the aforementioned problems.

[0005] A low-compressive-stress, low-density thermally conductive pad, comprising, by weight: 100-300 parts of vinyl silicone oil, 1-3 parts of end-chain hydrogen-containing silicone oil, 2-6 parts of side-chain hydrogen-containing silicone oil, 0.2-0.6 parts of platinum catalyst, 300-700 parts of thermally conductive filler, 0.1-0.5 parts of coupling agent, and 0.1-0.5 parts of inhibitor.

[0006] Furthermore, the vinyl silicone oil includes a first vinyl silicone oil and a second vinyl silicone oil; The first vinyl silicone oil is a vinyl-terminated polydimethylsiloxane with a viscosity of 1000~3000 mPa·s, a vinyl content of 0.6~0.8%, and a proportion of 80~120 parts; The second vinyl silicone oil is a vinyl-terminated polydimethylsiloxane with a viscosity of 8000~12000 mpa.s, a vinyl content of 0.5~0.7%, and a proportion of 150~250 parts.

[0007] Furthermore, the end-chain hydrogen-containing silicone oil has a viscosity of 10~50 mPa·s, a hydrogen content of 0.07~0.09, and a proportion of 1~4 parts; the side-chain hydrogen-containing silicone oil has a viscosity of 50~250 mPa·s, a hydrogen content of 0.09~0.11, and a proportion of 3~6 parts.

[0008] Furthermore, the thermally conductive filler includes at least one of spherical alumina, near-spherical alumina, zinc oxide, aluminum nitride, silicon nitride, and boron nitride.

[0009] Furthermore, the thermally conductive filler comprises spherical alumina and spherical boron nitride, wherein the particle size of the spherical alumina is D50: 3-5μm, and the particle size of the spherical boron nitride is D50: 60-90μm.

[0010] Furthermore, the thermally conductive filler also includes silicon nitride, which is β-type silicon nitride.

[0011] Furthermore, the coupling agent comprises dodecylsiloxane; the inhibitor comprises acetylenecyclohexanol.

[0012] Furthermore, the platinum catalyst includes one of the Speier catalyst and the Karstedt catalyst, wherein the Pt content is 3000~6000ppm.

[0013] A method for preparing a low-compressive-stress, low-density thermally conductive pad as described above includes the following steps: Vinyl silicone oil, end-chain hydrogen-containing silicone oil, side-chain hydrogen-containing silicone oil, platinum catalyst, thermally conductive filler, coupling agent and inhibitor are added to a stirring device according to the formula to obtain the base material; The base material is subjected to vacuum negative pressure stirring in stages, specifically including: stirring continuously at a preset stirring speed for a first specified time under negative pressure ≤ -0.095MPa, then stirring continuously at a preset stirring speed for a second specified time under negative pressure -0.06-0.07MPa, and then stirring continuously at a preset stirring speed for a third specified time under negative pressure ≤ -0.095MPa. The agglomerated base material is transferred to a calender for high-temperature vulcanization molding, where the temperature is 120~140℃ and the calendering and cutting speed is 1m / min.

[0014] Furthermore, the base material is subjected to vacuum negative pressure stirring in stages, specifically including: Stir continuously at 15 rpm for 30 minutes under negative pressure ≤ -0.095 MPa and scrape the wall. Then, stir continuously at 15 rpm for 30 minutes under negative pressure -0.06-0.07 MPa and scrape the wall. Then, stir continuously at 15 rpm for 15 minutes under negative pressure ≤ -0.095 MPa and scrape the wall. If the base material does not clump together, continue stirring at 15 rpm for 5 minutes under negative pressure ≤ -0.095 MPa until the base material clumps together and then stop stirring.

[0015] This application has the following advantages: In the embodiments of this application, the low compressive stress, low-density thermally conductive pad comprises, by weight: 100-300 parts of vinyl silicone oil, 1-3 parts of end-chain hydrogen-containing silicone oil, 2-6 parts of side-chain hydrogen-containing silicone oil, 0.2-0.6 parts of platinum catalyst, 300-700 parts of thermally conductive filler, 0.1-0.5 parts of coupling agent, and 0.1-0.5 parts of inhibitor. The addition-type three-dimensional network cross-linked structure formed by vinyl silicone oil, end-chain / side-chain hydrogen-containing silicone oil, and platinum catalyst, compared to the existing two-dimensional non-cross-linked system, has a more uniform internal structure and better flexibility, resulting in lower deformation resistance during compression and thus significantly reducing compressive stress. Furthermore, the three-dimensional cross-linked structure allows for more uniform dispersion of the filler, preventing agglomeration and effectively reducing the pad density.

[0016] In terms of process optimization, the vacuum degree of the stirring process is controlled by staged negative pressure to precisely regulate the material state, and finally high-temperature vulcanization molding is carried out using a calender. By precisely controlling the vacuum degree and stirring time through the staged negative pressure stirring process, the rubber compound is ensured to form agglomerates and achieve uniform material dispersion and gas removal, resulting in a significant improvement in product quality and production efficiency compared to existing technologies.

[0017] This application utilizes an addition-type crosslinking system to form a three-dimensional network structure, combined with β-type silicon nitride to reduce inter-filler frictional resistance and achieve low compressive stress. Furthermore, it employs the particle size gradient and uniform dispersion of spherical fillers to reduce gasket density. Compared to existing technologies, the compressive stress is significantly reduced, the density is lower, and the manufacturing process effectively improves product quality stability and production efficiency, making it suitable for fields such as electronic devices with stringent requirements for heat dissipation and weight. Attached Figure Description

[0018] To more clearly illustrate the technical solution of this application, the drawings used in the description of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the steps of a method for preparing a low-compressive-stress, low-density thermally conductive pad according to an embodiment of this application. Detailed Implementation

[0020] To make the objectives, features, and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] The inventors analyzed existing technologies and discovered that: Currently, common thermal pads on the market present some problems in practical applications. Firstly, some thermal pads have excessive compressive stress. When installing thermal pads between heat sources and heat sinks, excessive compressive stress can subject the heat source or heat sink to additional pressure. This can not only affect the performance and lifespan of these components but may also lead to deformation or even damage over long-term use. For example, in some precision electronic devices, such as the thermal pads used between the CPU and heatsink in laptops, excessive compressive stress can put pressure on the CPU pins, affecting the stability of the connection between the CPU and the motherboard, and potentially causing computer crashes, blue screens, and other malfunctions.

[0022] Secondly, existing thermal pads have a high density. This higher density increases product weight, which is extremely disadvantageous for applications with strict weight restrictions, such as aerospace equipment and portable electronic devices. In the aerospace field, every gram of added weight can significantly impact an aircraft's energy consumption and flight performance. For portable electronic devices, excessive weight reduces the user experience and affects the product's market competitiveness.

[0023] Furthermore, traditional thermal pads have limitations in raw material selection and manufacturing processes. Some traditional thermal pads use unscientific raw material formulations that fail to effectively control compressive stress and density while ensuring good thermal conductivity. In terms of manufacturing processes, common mixing methods struggle to precisely control the material's state, resulting in poor product quality consistency and a high defect rate. This not only increases production costs but also negatively impacts the product's market reputation.

[0024] Patent CN117820865A discloses a thermally conductive mud pad with high thermal conductivity and low stress and its preparation method. It uses a non-crosslinked system with a two-dimensional network structure formed by physically mixing phenyl silicone oil and methyl silicone oil. It relies on a combination of heating at 130°C, vacuum stirring and hydraulic molding process. Although it can reduce the stress of the thermally conductive pad, there is still room for further reduction and the production efficiency is low.

[0025] To address this, this application achieves breakthroughs in performance and process through multiple innovations: In system construction, an addition-type crosslinking system composed of vinyl silicone oil, end-chain / side-chain hydrogen-containing silicone oil, and platinum catalyst is adopted, forming a three-dimensional network structure through hydrosilylation reaction; in filler design, a ternary combination of spherical boron nitride, β-type silicon nitride with lubricating function (which can reduce the frictional resistance between powders during compression, thereby reducing compressive stress), and spherical alumina is selected to synergistically improve thermal conductivity and regulate stress; in terms of process optimization, the vacuum degree of the stirring process is controlled by staged negative pressure to precisely regulate the material state, and finally high-temperature vulcanization molding is carried out using a calender. The above-mentioned addition-type crosslinking system, the filler ratio scheme containing β-type silicon nitride, and the molding process of staged negative pressure stirring combined with high-temperature vulcanization enable the thermally conductive gasket to effectively reduce internal frictional resistance during compression due to the lubricating effect of β-type silicon nitride, achieving low-stress performance. At the same time, the three-dimensional network structure and optimized filler dispersion result in lower density, significantly improving production efficiency compared to existing technologies.

[0026] This application provides a low-compression-stress, low-density thermally conductive pad, comprising, by weight: 100-300 parts of vinyl silicone oil, 1-3 parts of end-chain hydrogen-containing silicone oil, 2-6 parts of side-chain hydrogen-containing silicone oil, 0.2-0.6 parts of platinum catalyst, 300-700 parts of thermally conductive filler, 0.1-0.5 parts of coupling agent, and 0.1-0.5 parts of inhibitor.

[0027] In the embodiments of this application, the low compressive stress, low-density thermally conductive pad comprises, by weight: 100-300 parts of vinyl silicone oil, 1-3 parts of end-chain hydrogen-containing silicone oil, 2-6 parts of side-chain hydrogen-containing silicone oil, 0.2-0.6 parts of platinum catalyst, 300-700 parts of thermally conductive filler, 0.1-0.5 parts of coupling agent, and 0.1-0.5 parts of inhibitor. The addition-type three-dimensional network cross-linked structure formed by vinyl silicone oil, end-chain / side-chain hydrogen-containing silicone oil, and platinum catalyst, compared to the existing two-dimensional non-cross-linked system, has a more uniform internal structure and better flexibility, resulting in lower deformation resistance during compression and thus significantly reducing compressive stress. Furthermore, the three-dimensional cross-linked structure allows for more uniform dispersion of the filler, preventing agglomeration and effectively reducing the pad density.

[0028] In terms of process optimization, the vacuum degree of the stirring process is controlled by staged negative pressure to precisely regulate the material state, and finally high-temperature vulcanization molding is carried out using a calender. By precisely controlling the vacuum degree and stirring time through the staged negative pressure stirring process, the rubber compound is ensured to form agglomerates and achieve uniform material dispersion and gas removal, resulting in a significant improvement in product quality and production efficiency compared to existing technologies.

[0029] The following will further describe a low-compressive-stress, low-density thermally conductive pad in this exemplary embodiment.

[0030] In this embodiment, the vinyl silicone oil includes a first vinyl silicone oil and a second vinyl silicone oil. The first vinyl silicone oil is a vinyl-terminated polydimethylsiloxane with a viscosity of 1000-3000 mPa·s, a vinyl content of 0.6-0.8%, and a proportion of 80-120 parts. The second vinyl silicone oil is also a vinyl-terminated polydimethylsiloxane with a viscosity of 8000-12000 mPa·s, a vinyl content of 0.5-0.7%, and a proportion of 150-250 parts. The low-viscosity vinyl silicone oil reduces the initial viscosity of the raw material system, improves the dispersion efficiency of the thermally conductive filler, and avoids agglomeration. The high-viscosity vinyl silicone oil can construct the framework of a flexible cross-linked network, ensuring the elastic recovery of the gasket after molding. The combination of the two solves the problem of difficult mixing of a single high-viscosity silicone oil and avoids excessive compressive stress caused by a single low-viscosity silicone oil. Simultaneously, the flexible structure of the matrix further reduces the gasket density. By using a combination of vinyl silicone oils of different viscosities, a balance can be found between the flexibility and cross-linking degree of the gasket, effectively reducing compressive stress.

[0031] In this embodiment, the end-chain hydrogen-containing silicone oil has a viscosity of 10-50 mPa·s, a hydrogen content of 0.07-0.09%, and a proportion of 1-4 parts; the side-chain hydrogen-containing silicone oil has a viscosity of 50-250 mPa·s, a hydrogen content of 0.09-0.11%, and a proportion of 3-6 parts. The end-chain hydrogen-containing silicone oil contains active hydrogen only at both ends of the molecule, allowing it to form linear crosslinks with vinyl silicone oil, reducing the network crosslink density and preventing the gasket from becoming too hard. The side-chain hydrogen-containing silicone oil has active hydrogen distributed on the main molecular chain, allowing it to form branched crosslinks and enhancing the stability of the network structure. The combination of these two types ensures the gasket's resistance to deformation and further reduces compressive stress by controlling the crosslink density. Simultaneously, the low viscosity crosslinking agent is easily mixed with the matrix, avoiding performance fluctuations caused by uneven local crosslinking. By rationally proportioning different types of hydrogen-containing silicone oils, the crosslinking structure can be adjusted, playing a crucial role in controlling the product's rebound stress.

[0032] In this embodiment, the thermally conductive filler includes at least one of spherical alumina, near-spherical alumina, zinc oxide, aluminum nitride, silicon nitride, and boron nitride.

[0033] As an example, the thermally conductive filler is selected from spherical alumina and spherical boron nitride. The spherical alumina has a particle size D50 of 3-5 μm (i.e., median particle size / average particle size is 3-5 μm), and the spherical boron nitride has a particle size D50 of 60-90 μm. The skeletal support of the large-diameter filler reduces the accumulation of small-diameter filler, lowering the total filler volume ratio. Simultaneously, the smooth surface of the spherical particles minimizes damage to the flexible matrix network, further reducing compressive stress. This optimal combination of particle sizes improves thermal conductivity while also helping to reduce density.

[0034] Furthermore, to reduce the frictional resistance between the spherical alumina and spherical boron nitride fillers and lower the stress generated by friction, the thermally conductive filler also includes silicon nitride, specifically β-type silicon nitride. Adding an appropriate amount of silicon nitride reduces the frictional resistance between the fillers. Silicon nitride has good self-lubricating properties, and its crystal structure makes its surface relatively smooth. During friction, it can reduce the frictional force between the contact surfaces, reducing energy loss and wear. During friction, a silicon oxide protective film forms on the silicon nitride surface. This protective film has a low coefficient of friction, preventing direct contact between the silicon nitride surfaces, further reducing friction and providing a good lubrication effect.

[0035] In this embodiment, the coupling agent includes dodecylsiloxane, which can enhance the bonding force between the powder and the organic matrix, and further optimize the overall performance of the gasket.

[0036] In this embodiment, the inhibitor includes acetylenecyclohexanol, which can precisely control the reaction rate and avoid product performance instability caused by excessively fast reaction, thereby helping to improve the consistency of product quality.

[0037] In this embodiment, the platinum catalyst includes either a Speier catalyst or a Karstedt catalyst, with a Pt content of 3000-6000 ppm. This content range allows for efficient catalysis of the hydrosilylation reaction while avoiding cost increases or excessively rapid sulfidation caused by excessive Pt. The accompanying inhibitor is acetylenic cyclohexanol (0.1-0.5 parts), which suppresses catalyst activity during the stirring stage, preventing premature sulfidation and agglomeration of the raw materials. During the high-temperature sulfidation stage (120-160°C), it automatically decomposes without affecting the sulfidation reaction, significantly improving processing stability.

[0038] Reference Figure 1 In this embodiment, a method for preparing the low compressive stress, low density thermally conductive pad as described above is also provided, comprising the following steps: S110. Vinyl silicone oil, end-chain hydrogen-containing silicone oil, side-chain hydrogen-containing silicone oil, platinum catalyst, thermally conductive filler, coupling agent and inhibitor are added to the mixing equipment according to the formula to obtain the base material.

[0039] S120. Perform staged vacuum negative pressure controlled stirring on the base material, including: continuously stirring at a preset stirring speed for a first specified time under negative pressure ≤ -0.095MPa, then continuously stirring at a preset stirring speed for a second specified time under negative pressure -0.06-0.07MPa, and then continuously stirring at a preset stirring speed for a third specified time under negative pressure ≤ -0.095MPa.

[0040] S130. The agglomerated base material is transferred to a calender for high-temperature vulcanization molding.

[0041] As an example, in step 110, vinyl silicone oil (including first vinyl silicone oil and second vinyl silicone oil), end-chain hydrogen-containing silicone oil, and side-chain hydrogen-containing silicone oil are first added to the stirring device, and then platinum catalyst, coupling agent, inhibitor, and thermally conductive filler are added in sequence to initially mix and obtain the base material. This order of addition can avoid local sulfidation caused by direct contact between the catalyst and the filler, and ensure the stability of subsequent stirring.

[0042] As an example, step 120 involves staged vacuum negative pressure controlled stirring of the base material, specifically including: stirring continuously at a stirring speed of 15 rpm for 30 minutes under a negative pressure ≤ -0.095 MPa and scraping the wall, then stirring continuously at a stirring speed of 15 rpm for 30 minutes under a negative pressure of -0.06-0.07 MPa and scraping the wall, then stirring continuously at a stirring speed of 15 rpm for 15 minutes under a negative pressure ≤ -0.095 MPa and scraping the wall; if the base material does not clump together, continue stirring at a stirring speed of 15 rpm for 5 minutes under a negative pressure ≤ -0.095 MPa until the base material clumps together and stirring is stopped.

[0043] As an example, in step 130, the temperature is 120~140℃ and the calendering and cutting speed is 1m / min.

[0044] In one specific embodiment, prepared raw materials such as vinyl silicone oil, inhibitors, end-hydrogen-containing silicone oil, coupling agents, platinum catalysts, and thermally conductive powder are added to a mixing device. The mixing speed is set to 15 rpm, and the vacuum system is activated to maintain a negative pressure of -0.095 MPa during the mixing process, which is continued for 30 minutes. During this process, the vacuum pump continuously extracts gas from the material to prevent pores from appearing after the gasket is formed, thus affecting the density and compressive stress of the gasket. After mixing, a wall scraper is used to clean the inner wall of the mixing device to ensure uniform material distribution and no material adhering to the device wall. Maintaining the mixing speed at 15 rpm, the negative pressure is adjusted to -0.06-0.07 MPa, and mixing continues for 30 minutes, followed by another wall scraping. During this stage, under the specific negative pressure environment, the materials are further mixed evenly and begin to gradually agglomerate, laying the foundation for subsequent molding. Reinstate the negative pressure to -0.095 MPa, maintain a stirring speed of 15 rpm, and stir for 15 minutes. Scrape the walls of the mixture and carefully observe the state of the base material to determine if it has formed clumps. If the base material has not formed clumps, increase the stirring time by 5 minutes, then stop the machine again to observe if it has formed clumps. Repeat this step until the base material forms clumps, then immediately stop stirring. Continuous observation of the material's state is crucial during this process, as the formation of clumps indicates that the material mixture has reached an ideal state. Stopping stirring at this point avoids over-stirring and damaging the material structure. Finally, transfer the well-stirred base material to a calender and perform high-temperature vulcanization molding at 120~140℃ and a calendering speed of 1 m / min. The high-temperature vulcanization process allows the base material to further cross-link and solidify, forming a stable structure. By controlling the temperature and time of the high-temperature vulcanization, as well as the tension and speed of the calender, a high-performance, low-compressive-stress, low-density thermally conductive pad is ultimately obtained.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows: From the perspective of compressive stress: the addition-type three-dimensional network cross-linked structure formed by vinyl silicone oil, end-chain / side-chain hydrogen-containing silicone oil, and platinum catalyst has a more uniform internal structure and better flexibility compared to the existing two-dimensional non-cross-linked system, resulting in lower deformation resistance during compression. Simultaneously, the introduction of β-type silicon nitride with lubricating properties into the filler effectively reduces frictional resistance between powder particles during compression, minimizes internal stress accumulation, and prevents deformation or damage to electronic components due to excessive stress (such as CPU pin pressure issues).

[0046] In terms of density control: a combination of spherical alumina (3-5μm) and spherical boron nitride (60-90μm) particle size gradients is used to reduce the accumulation of small particle size fillers by utilizing the skeletal support of large particle size fillers, thereby reducing the total volume ratio of fillers; at the same time, the three-dimensional cross-linked structure makes the fillers more uniformly dispersed and avoids agglomeration, thus effectively reducing the density of the gasket and meeting the stringent requirements for lightweighting in aerospace, portable equipment and other applications.

[0047] From a manufacturing process perspective: the staged negative pressure stirring process, through precise control of vacuum and stirring time, ensures the agglomeration of the rubber compound and achieves uniform material dispersion and gas removal, which is a core step in guaranteeing product performance. Failure to follow the predetermined parameters will result in the rubber compound failing to agglomerate, leading to problems such as uneven mixing, uncontrolled filler dispersion, and gas residue. This can cause thermally conductive filler agglomeration or delamination, breaking the thermal conductivity path (potentially reducing thermal conductivity by 15%-30%), porosity defects causing abnormal density fluctuations (increasing by 5%-20%), or increased compressive stress by 20%-50% due to increased filler friction resistance. Simultaneously, loose rubber compound can lead to edge cracking and uneven thickness during calendering, causing the defect rate to soar to over 50%. Furthermore, uncontrolled crosslinking reactions affect interfacial bonding, resulting in deterioration of product mechanical properties and long-term reliability. Production efficiency also decreases significantly due to rework and equipment wear. Therefore, strictly adhering to these process parameters is a necessary condition for achieving low compressive stress, low density, and stable performance, and is a key innovation distinguishing it from traditional processes.

[0048] The low-compressive-stress, low-density thermally conductive pad and its preparation method of the present invention have achieved performance optimization in many aspects, have significant economic and social benefits, and have broad market application prospects.

[0049] To further verify the technical effects of the present invention, the following description is provided in conjunction with specific embodiments and comparative examples.

[0050] Example 1 This embodiment provides a low-compressive-stress, low-density thermally conductive pad and its preparation method, including the following steps: 1) Weigh out 100 parts of vinyl silicone oil with a viscosity of 2000, 200 parts of vinyl silicone oil with a viscosity of 10000, 0.1 parts of inhibitor, 2 parts of end-chain hydrogen-containing silicone oil, 4 parts of side-chain hydrogen-containing silicone oil, 0.3 parts of coupling agent, 0.4 parts of catalyst, 50 parts of spherical alumina, 496 parts of boron nitride, and 34 parts of β-type silicon nitride; 2) Add the raw materials from step 1 to the mixing equipment and vacuum mix at a speed of 15 rpm (vacuum degree -0.095 MPa) for 30 minutes, scraping the walls and scraping the paddle. Maintain the mixing speed of 15 rpm and adjust the negative pressure to -0.06~-0.07 MPa, mixing for 30 minutes to control the state of the rubber compound. When the rubber compound begins to agglomerate, increase the negative pressure back to -0.095 MPa and mix for 15 minutes. After mixing, observe whether the rubber compound forms agglomerates. If it does not form agglomerates, continue mixing for 5 minutes. 3) Transfer the mixed rubber compound from step 2 to a calender for high-temperature vulcanization molding. The baking temperature is 130℃ and the traction cutting speed is 1m / min. Finally, a high-performance, low-compression-stress, low-density thermally conductive pad is obtained.

[0051] Example 2 Weigh out 180 parts of vinyl silicone oil with a viscosity of 2000, 120 parts of vinyl silicone oil with a viscosity of 10000, 0.1 parts of inhibitor, 2 parts of end-chain hydrogen-containing silicone oil, 4 parts of side-chain hydrogen-containing silicone oil, 0.3 parts of coupling agent, 0.4 parts of catalyst, 50 parts of spherical alumina, 496 parts of boron nitride, and 34 parts of β-type silicon nitride. The difference between Example 2 and Example 1 is that the addition ratio of vinyl silicone oil is adjusted, while steps 2 and 3 remain unchanged.

[0052] Example 3 Weigh out 100 parts of vinyl silicone oil with a viscosity of 2000, 200 parts of vinyl silicone oil with a viscosity of 10000, 0.1 parts of inhibitor, 2 parts of end-chain hydrogen-containing silicone oil, 4 parts of side-chain hydrogen-containing silicone oil, 0.3 parts of coupling agent, 0.4 parts of catalyst, 100 parts of spherical alumina, 446 parts of boron nitride, and 34 parts of β-type silicon nitride. The difference between Example 3 and Example 1 is that the ratio of aluminum oxide to boron nitride added to the thermally conductive powder is adjusted, while steps 2 and 3 remain unchanged.

[0053] Example 4 Weigh out 80 parts of vinyl silicone oil with a viscosity of 2000, 220 parts of vinyl silicone oil with a viscosity of 10000, 0.1 parts of inhibitor, 4.5 parts of side-chain hydrogen-containing silicone oil, 0.3 parts of coupling agent, 0.4 parts of catalyst, 50 parts of spherical alumina, 496 parts of boron nitride, and 34 parts of β-type silicon nitride. The difference between Example 4 and Example 1 is that the amount of vinyl silicone oil added and the amount of side-chain hydrogen-containing silicone oil added are adjusted. At the same time, the end-chain hydrogen-containing silicone oil is removed from the formula. Steps 2 and 3 remain unchanged.

[0054] Example 5 Weigh out 100 parts of vinyl silicone oil with a viscosity of 2000, 200 parts of vinyl silicone oil with a viscosity of 10000, 0.1 parts of inhibitor, 2 parts of end-chain hydrogen-containing silicone oil, 4 parts of side-chain hydrogen-containing silicone oil, 0.3 parts of coupling agent, 0.4 parts of catalyst, 50 parts of spherical alumina, and 496 parts of boron nitride. In Example 5, the raw materials were changed compared to Example 1; the addition of silicon nitride was omitted, while steps 2 and 3 remained unchanged.

[0055] Example 6 Compared with Example 1, the proportion of raw materials remained unchanged, but the production stirring process was adjusted. The difference is that in Example 1, the stirring vacuum negative pressure was controlled in stages to achieve the purpose of agglomeration of the base material. In Example 6, the negative pressure of -0.095MPa was used for stirring for 1 hour throughout the process (the result showed that the base material could not agglomerate, and the hardness and thermal conductivity of the product fluctuated greatly).

[0056] Comparative Example 1 Conventional vinyl silicone oil and hydrogen-containing silicone oil crosslinked thermal pads.

[0057] The specific configurations of Examples 1 and 5 above are shown in Table 1 below:

[0058] The performance of the thermal pads in the above embodiments and comparative examples was tested, and the test results are shown in Table 2 below:

[0059] Table 2 shows that the stress required for 50% compression in Examples 1-4 is significantly lower than that in Comparative Example 1. The density properties of Examples 1-5 are significantly lower than those in Comparative Example 1.

[0060] In summary, this application can achieve low density and lightweight while having lower compressive stress, which greatly reduces the rolling of electronic components during long-term operation and extends their service life.

[0061] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0062] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0063] The above provides a detailed description of a low-compression-stress, low-density thermally conductive pad and its preparation method. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A low-compressive-stress, low-density thermally conductive pad, characterized in that, By weight, it includes: 100-300 parts of vinyl silicone oil, 1-3 parts of end-chain hydrogen-containing silicone oil, 2-6 parts of side-chain hydrogen-containing silicone oil, 0.2-0.6 parts of platinum catalyst, 300-700 parts of thermally conductive filler, 0.1-0.5 parts of coupling agent and 0.1-0.5 parts of inhibitor.

2. The low compressive stress, low-density thermally conductive pad according to claim 1, characterized in that, The vinyl silicone oil includes a first vinyl silicone oil and a second vinyl silicone oil; The first vinyl silicone oil is a vinyl-terminated polydimethylsiloxane with a viscosity of 1000~3000 mPa·s, a vinyl content of 0.6~0.8%, and a proportion of 80~120 parts; The second vinyl silicone oil is a vinyl-terminated polydimethylsiloxane with a viscosity of 8000~12000 mpa.s, a vinyl content of 0.5~0.7%, and a proportion of 150~250 parts.

3. The low compressive stress, low-density thermally conductive pad according to claim 2, characterized in that, The end-chain hydrogen-containing silicone oil has a viscosity of 10~50 mPa·s, a hydrogen content of 0.07~0.09, and a proportion of 1~4 parts; the side-chain hydrogen-containing silicone oil has a viscosity of 50~250 mPa·s, a hydrogen content of 0.09~0.11, and a proportion of 3~6 parts.

4. The low compressive stress, low-density thermally conductive pad according to claim 1 or 3, characterized in that, The thermally conductive filler includes at least one of spherical alumina, near-spherical alumina, zinc oxide, aluminum nitride, silicon nitride, and boron nitride.

5. The low compressive stress, low-density thermally conductive pad according to claim 4, characterized in that, The thermally conductive filler comprises spherical alumina and spherical boron nitride, wherein the particle size of the spherical alumina is D50: 3-5μm, and the particle size of the spherical boron nitride is D50: 60-90μm.

6. The low compressive stress, low-density thermally conductive pad according to claim 5, characterized in that, The thermally conductive filler also includes silicon nitride, which is β-type silicon nitride.

7. The low compressive stress, low-density thermally conductive pad according to claim 1, characterized in that, The coupling agent includes dodecylmethylsiloxane; the inhibitor includes acetylenecyclohexanol.

8. The low compressive stress, low-density thermally conductive pad according to claim 1, characterized in that, The platinum catalyst includes one of the Speier catalyst and the Karstedt catalyst, wherein the Pt content is 3000~6000ppm.

9. A method for preparing a low-compressive-stress, low-density thermally conductive pad as described in any one of claims 1-8, characterized in that, Includes the following steps: Vinyl silicone oil, end-chain hydrogen-containing silicone oil, side-chain hydrogen-containing silicone oil, platinum catalyst, thermally conductive filler, coupling agent and inhibitor are added to a stirring device according to the formula to obtain the base material; The base material is subjected to vacuum negative pressure stirring in stages, including: stirring continuously at a preset stirring speed for a first specified time under negative pressure ≤ -0.095MPa, then stirring continuously at a preset stirring speed for a second specified time under negative pressure -0.06-0.07MPa, and then stirring continuously at a preset stirring speed for a third specified time under negative pressure ≤ -0.095MPa. The agglomerated base material is transferred to a calender for high-temperature vulcanization molding.

10. The preparation method according to claim 9, characterized in that, The base material is subjected to vacuum negative pressure stirring in stages, specifically including: Stir continuously at 15 rpm for 30 minutes under negative pressure ≤ -0.095 MPa and scrape the wall. Then, stir continuously at 15 rpm for 30 minutes under negative pressure -0.06-0.07 MPa and scrape the wall. Then, stir continuously at 15 rpm for 15 minutes under negative pressure ≤ -0.095 MPa and scrape the wall. If the base material does not clump together, continue stirring at 15 rpm for 5 minutes under negative pressure ≤ -0.095 MPa until the base material clumps together and then stop stirring.

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