Ultra-thin thermally conductive insulating sheet and preparation method therefor

Abstract

The present invention belongs to the field of thermally conductive insulating materials, and specifically relates to an ultra-thin thermally conductive insulating sheet and a preparation method therefor. The starting materials for the ultra-thin thermally conductive insulating sheet provided by the present invention comprise: a vinyl silicone oil, a hydrogen-containing silicone oil, a thermally conductive filler, a treating agent, an inhibitor, and a catalyst. The mass ratio of the vinyl silicone oil to the hydrogen-containing silicone oil is (18-20):(1.2-1.4), and the thermally conductive filler comprises spherical alumina. The ultra-thin thermally conductive insulating sheet prepared by the present invention has a relatively small thickness and can be used for heat dissipation in electronic devices with high precision, while the ultra-thin thermally conductive insulating sheet has relatively high hardness, low thermal resistance, and excellent thermal conductivity.

Description

An ultrathin thermally conductive insulating sheet and its preparation method Technical Field

[0001] This invention belongs to the field of thermally conductive and insulating materials, specifically relating to an ultrathin thermally conductive insulating sheet and its preparation method. Background Technology

[0002] With the rapid advancement of technology and continuous improvement in productivity, consumers' demands for digital products are increasingly trending towards refinement and convenience. Currently, most mainstream digital products on the market rely on electricity as their power source, but electric power inevitably leads to heat loss. As is well known, the internal components of digital products are extremely sensitive to heat. If heat cannot be dissipated in time, it may cause the internal temperature of the device to become too high, thereby weakening product performance and even causing spontaneous combustion, posing a serious safety hazard. Therefore, effectively dissipating internal heat is crucial for ensuring the stable operation of digital products and reducing safety risks.

[0003] To address this issue, a common solution is to select a suitable thermally conductive material as the heat transfer medium between the heat source and the heat sink in digital products to effectively dissipate the heat generated by electrical energy. However, thermally conductive materials used in high-precision electronic devices must possess not only thermal conductivity but also good electrical properties. In particular, when the voltage across the insulator inside an electronic device increases, the electric field force on the insulator also strengthens, potentially leading to ionization collisions and subsequent insulator breakdown, causing safety hazards. Therefore, developing a thermally conductive material capable of withstanding high breakdown voltages is particularly urgent.

[0004] Ultrathin thermally conductive insulating sheets, as an important thermally conductive material, are widely used at the interface between electronic devices and heat sinks or product housings. Their high reliability, insulation, low contact thermal resistance, and high thermal conductivity have led to their widespread application in communication equipment, computers, and home appliances. Another key characteristic of ultrathin thermally conductive insulating sheets is their thinness, typically between 0.1-0.3 mm. For example, patent document CN117107526A discloses an ultrathin thermally conductive insulating sheet with a single-sided coating thickness of 100-200 μm. However, the thickness of this product is still relatively large, making it difficult to apply in high-precision equipment.

[0005] Therefore, developing a thermally conductive insulating material that possesses excellent thermal conductivity and electrical properties, can withstand high breakdown voltage, is thin, and has a relatively low cost is an industry-wide technical challenge that urgently needs to be addressed. Summary of the Invention

[0006] To address the aforementioned technical problems, the first aspect of this invention provides an ultrathin thermally conductive insulating sheet, the raw materials for which include: vinyl silicone oil, hydrogen-containing silicone oil, thermally conductive filler, treatment agent, inhibitor, and catalyst.

[0007] As an feasible example, the raw materials for preparing the ultrathin thermally conductive insulating sheet include, by weight parts: 15-20 parts vinyl silicone oil, 1-3 parts hydrogen-containing silicone oil, 180-200 parts thermally conductive filler, 0.3-0.5 parts treatment agent, 0.01-0.05 parts inhibitor, and 0.05-0.2 parts catalyst.

[0008] As an example of implementation, the vinyl silicone oil has a viscosity of 1000-100000 mPa·s at 25°C.

[0009] Furthermore, the viscosity of the vinyl silicone oil at 25°C is 1000-10000 mPa·s.

[0010] As an implementable example, the vinyl content in the vinyl silicone oil is 0.01-6 wt%.

[0011] Furthermore, the vinyl content in the vinyl silicone oil is 0.1-0.3 wt%.

[0012] Furthermore, the vinyl silicone oil has a viscosity of 2500 mPa·s at 25°C and a vinyl content of 0.23 wt%.

[0013] Furthermore, the vinyl silicone oil is graded VS2000L and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0014] Vinyl silicone oil, due to its unique molecular structure, can effectively transfer heat. When added as a raw material to ultra-thin thermally conductive insulating sheets, it can significantly improve the material's thermal conductivity, reduce thermal resistance, and allow heat to be transferred more quickly and evenly, thereby effectively reducing the temperature of electronic products and improving their stability and lifespan. Meanwhile, the viscosity of vinyl silicone oil directly affects its flowability in ultra-thin thermally conductive insulating sheets. Lower viscosity vinyl silicone oil makes it easier to fill and cure ultra-thin thermally conductive insulating sheets during processing, which not only improves production efficiency but also ensures that the material can be evenly covered on the surface requiring heat dissipation. Conversely, higher viscosity vinyl silicone oil has poor flowability during processing, making it difficult to distribute evenly, which also affects the heat dissipation effect of ultra-thin thermally conductive insulating sheets. Furthermore, the viscosity of vinyl silicone oil not only affects its flowability but is also closely related to the mechanical properties of ultra-thin thermally conductive insulating sheets.

[0015] As the viscosity of vinyl silicone oil increases, the hardness and tensile strength of ultrathin thermally conductive insulating sheets initially increase and then decrease. This is mainly because higher viscosity vinyl silicone oils have longer molecular chains and more cross-linking points, resulting in a more complete cross-linked network structure during curing. However, when the viscosity is too high, the excessively dense cross-linking points may cause stress concentration in the ultrathin thermally conductive insulating sheet under stress, thus affecting its mechanical properties. Besides viscosity, the vinyl content of the vinyl silicone oil also significantly impacts the mechanical properties of ultrathin thermally conductive insulating sheets. Higher vinyl content generally results in a higher cross-linking density and higher hardness. However, excessively high vinyl content may cause the ultrathin thermally conductive insulating sheet to become brittle and its aging resistance to decrease. Therefore, when preparing ultrathin thermally conductive insulating sheets, it is necessary to select an appropriate vinyl content to balance its hardness and toughness.

[0016] In this invention, a vinyl silicone oil with a viscosity of 1000-10000 mPa·S at 25°C and a vinyl content of 0.1-0.3% is preferred. This ensures that the ultra-thin thermally conductive insulating sheet has both low thermal resistance and high hardness, making it better suited for use in electronic devices and meeting the dual requirements of fast heat dissipation and high hardness.

[0017] As an example of implementation, the hydrogen content of the hydrogen-containing silicone oil is 0.03-0.1%.

[0018] Furthermore, the content of the hydrogen-containing silicone oil is 0.07%.

[0019] Furthermore, the hydrogen-containing silicone oil is grade S304 and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0020] Furthermore, the mass ratio of the vinyl silicone oil to the hydrogen-containing silicone oil is (18.1-20):(1.2-1.4).

[0021] Although hydrogen-containing silicone oil itself does not directly increase the thermal conductivity of ultrathin thermally conductive insulating sheets, it can indirectly affect thermal conductivity by influencing the crosslinking density and molecular chain arrangement of the material. Specifically, the addition of hydrogen-containing silicone oil can change the internal microstructure of ultrathin thermally conductive insulating sheets, making the heat conduction path more optimized, thereby improving thermal conductivity efficiency. In addition, the inventors have found that the mass ratio of vinyl silicone oil to hydrogen-containing silicone oil can further improve the hardness and thermal conductivity of the product; the crosslinked network structure formed by the addition reaction of vinyl silicone oil and hydrogen-containing silicone oil makes the interior of the ultrathin thermally conductive insulating sheet more compact and stable, reducing voids and defects in the material, thereby reducing thermal resistance. However, hydrogen-containing silicone oil should not be added in excess. When the content of hydrogen-containing silicone oil is too high, it provides more crosslinking points; excessively high crosslinking density may also cause the material to become too rigid, affecting its flexibility and processing performance; at the same time, excessively high hydrogen-containing silicone oil content may cause the thermal conduction pathways inside the thermally conductive material to be blocked by too many crosslinking points, hindering the effective transfer of heat, and thus reducing thermal conductivity. Therefore, the preferred mass ratio of vinyl silicone oil to hydrogen-containing silicone oil in this invention is (18.1-20):(1.2-1.4), which can achieve a dynamic balance between low thermal resistance and high hardness.

[0022] As an implementable example, the thermally conductive filler includes one or more of the following: spherical alumina, spherical boron nitride, spherical aluminum nitride, spherical zinc oxide, spherical magnesium oxide, spherical silicon carbide, spherical silicon nitride, and spherical quartz powder.

[0023] As an implementable example, the particle size of the thermally conductive filler is 0.1-3μm, including one or more of the following: 0.1μm, 0.3μm, 0.5μm, 0.8μm, 1μm, 2μm, and 3μm.

[0024] Furthermore, the thermally conductive filler comprises spherical alumina with a particle size of 0.1-0.5 μm and spherical alumina with a particle size of 1-3 μm, wherein the mass ratio of spherical alumina with a particle size of 0.1-0.5 μm to spherical alumina with a particle size of 1-3 μm is (10-15):(3-5).

[0025] Furthermore, the thermally conductive filler includes spherical alumina with a particle size of 2 μm and spherical alumina with a particle size of 0.3 μm.

[0026] Furthermore, the mass ratio of the spherical alumina with a particle size of 2 μm to the spherical alumina with a particle size of 0.3 μm is 14:4.

[0027] In this invention, the thermally conductive filler is preferably spherical alumina. Spherical alumina particles have lower surface energy, are less prone to agglomeration, and can be more uniformly dispersed in the matrix, which helps to form a denser filling structure, thereby improving the hardness of the material. Specifically, spherical alumina with a particle size of 2μm has a relatively large particle size, which enables it to form effective thermal conductive channels in the ultra-thin thermally conductive insulating sheet. Spherical alumina with a particle size of 0.3μm can fill the gaps between particles with a particle size of 2μm, further increasing the filling density. When spherical alumina particles with a particle size of 2μm and 0.3μm are combined, a multi-scale thermally conductive network can be formed. Large particles serve as the main thermally conductive channels, while small particles fill the gaps between the channels, forming a denser and more continuous thermally conductive path. Due to the increased contact area between particles, the thermal conductivity is improved, the thermal resistance is lower, the thermal conductivity of the material is improved, and the product is also endowed with excellent insulation properties.

[0028] As an implementable example, the treatment agent includes one or more of the following: dodecyltrimethoxysilane, vinyltrimethoxysilane, trimethoxysilyl polydimethylsiloxane, octyltrimethoxysilane, n-octyltriethoxysilane, hydroxyl polydimethylsiloxane, and diol-based polydimethylsiloxane.

[0029] Furthermore, the treatment agent is dodecyltrimethoxysilane.

[0030] Dodecyltrimethoxysilane can effectively disperse and compatibility in ultrathin thermally conductive insulating sheets. Through chemical modification, dodecyltrimethoxysilane can treat spherical alumina, allowing for better dispersion of the thermally conductive filler in the polymer matrix and enhancing the interaction between the thermally conductive filler and the polymer matrix. This can further reduce interfacial thermal resistance and improve the overall thermal conductivity of the ultrathin thermally conductive insulating sheet.

[0031] As an example of an implementable method, the catalyst includes one of the following: platinum catalyst, ruthenium-based catalyst, rhodium-based catalyst, and tin-based catalyst.

[0032] Furthermore, the catalyst is a platinum catalyst.

[0033] Platinum catalysts are highly efficient catalysts for hydrosilylation reactions. In systems of vinyl silicone oil and hydrogen-containing silicone oil, platinum catalysts can significantly lower the activation energy of the reaction, allowing the vinyl groups in the vinyl silicone oil and the hydrogen atoms in the hydrogen-containing silicone oil to undergo an addition reaction under milder conditions. This promotes the curing of the material, resulting in a denser and more uniform structure during curing. This leads to more efficient heat transfer between the thermally conductive fillers, thereby improving the overall thermal conductivity of the thermally conductive material. Simultaneously, platinum catalysts can also reduce interfacial thermal resistance, facilitating smoother heat transfer within the thermally conductive material.

[0034] As an implementable example, the inhibitors include one or more of the following: alkynyl alcohols, polyvinyl polysiloxanes, amide compounds, and maleate compounds.

[0035] Furthermore, the inhibitor is an alkynyl alcohol compound, specifically 1-ethynyl-1-cyclohexanol.

[0036] The acetylene group in 1-ethynyl-1-cyclohexanol has high electrophilicity and can strongly coordinate with the active sites on the surface of platinum catalysts, thereby blocking some active sites and reducing the catalyst's adsorption capacity for reactants. By inhibiting the activity of platinum catalysts, 1-ethynyl-1-cyclohexanol can affect the curing process and crosslinking density of ultrathin thermally conductive insulating sheets, thereby increasing the material's hardness and reducing thermal resistance.

[0037] A second aspect of the present invention provides an ultrathin thermally conductive insulating sheet, comprising:

[0038] S1. Mix the vinyl silicone oil, hydrogen-containing silicone oil, thermally conductive filler, inhibitor, and treatment agent evenly.

[0039] S2. Add the catalyst and mix well, then dilute and coat it onto the substrate. Perform a heat curing treatment to obtain the final product.

[0040] As an example of implementation, the substrate includes PI film and / or glass fiber film. Beneficial effects

[0041] (I) The present invention preferably uses vinyl silicone oil with a viscosity of 1000-10000 mPa·S at 25°C and a vinyl content of 0.1-0.3%, which can ensure that the ultra-thin thermally conductive insulating sheet has both low thermal resistance and high hardness.

[0042] (ii) The raw materials used in this invention include vinyl silicone oil and hydrogen-containing silicone oil. Preferably, the mass ratio of vinyl silicone oil to hydrogen-containing silicone oil is (18.1-20):(1.2-1.4), which can achieve a balance between low thermal resistance and high hardness in the product.

[0043] (III) In this invention, the thermally conductive filler is preferably spherical alumina. Spherical alumina particles have low surface energy and are not easy to agglomerate, which is beneficial to improving the hardness of the ultra-thin thermally conductive insulating sheet.

[0044] (iv) The present invention further limits the particle size of spherical alumina, which can improve the thermal conductivity of the ultra-thin thermally conductive insulating sheet and also endow the product with excellent insulation properties.

[0045] (v) The product prepared by this invention has a thinner thickness and can be applied to electronic devices with high precision. At the same time, the ultra-thin thermally conductive insulating sheet has high hardness, low thermal resistance, and excellent thermal conductivity.

[0046] (vi) Generally speaking, the higher the material thickness, the higher the corresponding thermal resistance. However, the thermal resistance of the ultrathin thermally conductive insulating sheet prepared by this invention first decreases and then increases with the increase of the product thickness, giving the ultrathin thermally conductive insulating sheet a wider range of applications. This is mainly because a substrate PI film is used in the preparation process of the ultrathin thermally conductive insulating sheet. When the material is thin, the contact area of ​​the material is small and the contact thermal resistance is large due to the rigidity of the PI film. As the material gradually thickens, the contact area increases, the contact thermal resistance decreases, and the overall thermal resistance of the material decreases. When the material thickness continues to increase, the contact area remains almost unchanged, and the contact thermal resistance remains unchanged, but the material thermal resistance is positively correlated with the thickness. Therefore, the higher the thickness, the higher the material thermal resistance. The thermal resistance calculation formula is: θ=L / (λS), where L is the thickness of the thermally conductive material, S is the contact area, and λ represents the thermal conductivity. Detailed Implementation

[0047] Example 1

[0048] The first aspect of this example provides an ultrathin thermally conductive insulating sheet, the raw materials for which are prepared by mass parts are: 18.19 parts vinyl silicone oil, 1.3 parts hydrogen-containing silicone oil, 180 parts thermally conductive filler, 0.4 parts treatment agent, 0.01 parts inhibitor, and 0.1 parts catalyst.

[0049] The vinyl silicone oil in question is grade VS2000L and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0050] The hydrogen-containing silicone oil is grade S304 and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0051] The diluent is brand name Isopar C and was purchased from ExxonMobil Chemical Company.

[0052] The treatment agent is dodecyltrimethoxysilane.

[0053] The inhibitor is 1-ethynyl-1-cyclopentanol.

[0054] The catalyst is a platinum catalyst, grade PT3000, purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0055] The thermally conductive filler, by mass parts, consists of 140 parts of spherical alumina with a particle size of 2 μm and 40 parts of spherical alumina with a particle size of 0.3 μm.

[0056] The second aspect of this example provides an ultrathin thermally conductive insulating sheet, comprising:

[0057] S1. Mix the vinyl silicone oil, hydrogen-containing silicone oil, thermally conductive filler, inhibitor, and treatment agent evenly.

[0058] S2. Add the catalyst and mix evenly. Then add 120 parts of diluent to dilute and coat it on a 25μm thick PI film. Heat cure at 120℃ for 30min to obtain ultrathin thermally conductive insulating sheets with thicknesses of 40μm, 50μm, 80μm and 100μm respectively.

[0059] Thermal resistance tests were conducted on products of different thicknesses prepared in Example 1, and the test method was based on ASTM 5470; the experimental results are detailed in Table 1.

[0060] Table 1

[0061] As can be seen from the experimental data in Table 1, the thermal resistance of the ultrathin thermally conductive insulating sheet prepared by this invention first decreases and then increases as the thickness of the product increases.

[0062] Example 2

[0063] The first aspect of this example provides an ultrathin thermally conductive insulating sheet, the raw materials for which are prepared by mass parts are: 18.58 parts vinyl silicone oil, 1.25 parts hydrogen-containing silicone oil, 180 parts thermally conductive filler, 0.4 parts treatment agent, 0.01 parts inhibitor, and 0.1 parts catalyst.

[0064] The vinyl silicone oil in question is grade VS2000L and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0065] The hydrogen-containing silicone oil is grade S304 and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0066] The diluent is brand name Isopar C and was purchased from ExxonMobil Chemical Company.

[0067] The treatment agent is dodecyltrimethoxysilane.

[0068] The inhibitor is 1-ethynyl-1-cyclopentanol.

[0069] The catalyst is a platinum catalyst, grade PT3000, purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0070] The thermally conductive filler, by mass parts, consists of 140 parts of spherical alumina with a particle size of 2 μm and 40 parts of spherical alumina with a particle size of 0.3 μm.

[0071] The second aspect of this example provides an ultrathin thermally conductive insulating sheet, comprising:

[0072] S1. Mix the vinyl silicone oil, hydrogen-containing silicone oil, thermally conductive filler, inhibitor, and treatment agent evenly.

[0073] S2. Add the catalyst and mix evenly. Then add 120 parts of diluent to dilute and coat it on a 25μm thick PI film. Heat cure at 120℃ for 30 minutes to obtain an ultrathin thermally conductive insulating sheet with a thickness of 50μm.

[0074] The product obtained in Example 2 was subjected to thermal resistance testing, following the method described in ASTM 5470; the measured thermal resistance was 1.42 °C·cm. 2 / W.

[0075] Comparative Example 1

[0076] The first aspect of this example provides an ultrathin thermally conductive insulating sheet, the raw materials for which are prepared by mass parts are: 17.99 parts vinyl silicone oil, 1.5 parts hydrogen-containing silicone oil, 180 parts thermally conductive filler, 0.4 parts treatment agent, 0.01 parts inhibitor, and 0.1 parts catalyst.

[0077] The vinyl silicone oil in question is grade VS2000L and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0078] The hydrogen-containing silicone oil is grade S304 and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0079] The diluent is brand name Isopar C and was purchased from ExxonMobil Chemical Company.

[0080] The treatment agent is dodecyltrimethoxysilane.

[0081] The inhibitor is 1-ethynyl-1-cyclopentanol.

[0082] The catalyst is a platinum catalyst, grade PT3000, purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0083] The thermally conductive filler, by mass parts, consists of 140 parts of spherical alumina with a particle size of 2 μm and 40 parts of spherical alumina with a particle size of 0.3 μm.

[0084] The second aspect of this example provides an ultrathin thermally conductive insulating sheet, comprising:

[0085] S1. Mix the vinyl silicone oil, hydrogen-containing silicone oil, thermally conductive filler, inhibitor, and treatment agent evenly.

[0086] S2. Add the catalyst and mix evenly. Then add 120 parts of diluent to dilute and coat it on a 25μm thick PI film. Heat cure at 120℃ for 30 minutes to obtain an ultrathin thermally conductive insulating sheet with a thickness of 50μm.

[0087] The product manufactured in this example was subjected to thermal resistance testing, following the method described in ASTM 5470; the measured thermal resistance was 1.59 °C·cm. 2 / W.

[0088] Comparative Example 2

[0089] The first aspect of this example provides an ultrathin thermally conductive insulating sheet, the raw materials for which are prepared by mass parts are: 18.19 parts vinyl silicone oil, 1.3 parts hydrogen-containing silicone oil, 180 parts thermally conductive filler, 0.4 parts treatment agent, 0.01 parts inhibitor, and 0.1 parts catalyst.

[0090] The thermally conductive filler comprises, by weight, 100 parts of spherical alumina with a particle size of 5 μm, 52 parts of spherical alumina with a particle size of 0.8 μm, and 28 parts of spherical alumina with a particle size of 0.3 μm.

[0091] The vinyl silicone oil in question is grade VS2000L and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0092] The hydrogen-containing silicone oil is grade S304 and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0093] The diluent is brand name Isopar C and was purchased from ExxonMobil Chemical Company.

[0094] The treatment agent is dodecyltrimethoxysilane.

[0095] The inhibitor is 1-ethynyl-1-cyclopentanol.

[0096] The catalyst is a platinum catalyst, grade PT3000, purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0097] The second aspect of this example provides an ultrathin thermally conductive insulating sheet, comprising:

[0098] S1. Mix the vinyl silicone oil, hydrogen-containing silicone oil, thermally conductive filler, inhibitor, and treatment agent evenly.

[0099] S2. Add the catalyst and mix evenly. Then add 120 parts of diluent to dilute and coat it on a 25μm thick PI film. Heat cure at 120℃ for 30min to obtain ultrathin thermally conductive insulating sheets with thicknesses of 50μm, 80μm, 110μm and 150μm respectively.

[0100] Thermal resistance tests were conducted on products of different thicknesses obtained in this example. The test method is based on ASTM 5470. The experimental results are detailed in Table 2.

[0101] Table 2

[0102] The experimental results from Example 1 and Comparative Example 2 show that, depending on the type and proportion of the thermally conductive filler, the thermal resistance initially decreases and then increases with thickness, but the thickness at which the thermal resistance is lowest varies. The ultra-thin thermally conductive insulating sheet prepared by this invention exhibits both thinner thickness and lower thermal resistance only when the thermally conductive filler is a blend of 140 parts of spherical alumina with a particle size of 2 μm and 40 parts of spherical alumina with a particle size of 0.3 μm.

[0103] Comparative Example 3

[0104] The first aspect of this example provides an ultrathin thermally conductive insulating sheet, the raw materials for which are prepared by mass parts are: 18 parts vinyl silicone oil, 1.2 parts hydrogen-containing silicone oil, 180 parts thermally conductive filler, 0.3 parts treatment agent, 0.01 parts inhibitor, and 0.05 parts catalyst.

[0105] The vinyl silicone oil in question is grade VS2000L and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0106] The hydrogen-containing silicone oil is grade S304 and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0107] The diluent is brand name Isopar C and was purchased from ExxonMobil Chemical Company.

[0108] The treatment agent is dodecyltrimethoxysilane.

[0109] The inhibitor is 1-ethynyl-1-cyclopentanol.

[0110] The catalyst is a platinum catalyst, grade PT3000, purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0111] The thermally conductive filler, by mass parts, consists of 140 parts of spherical alumina with a particle size of 2 μm and 40 parts of spherical alumina with a particle size of 0.3 μm.

[0112] The second aspect of this example provides an ultrathin thermally conductive insulating sheet, comprising:

[0113] S1. Mix the vinyl silicone oil, hydrogen-containing silicone oil, thermally conductive filler, inhibitor, and treatment agent evenly.

[0114] S2. Add the catalyst and mix evenly. Then add 120 parts of diluent to dilute and coat it on a 25μm thick PI film. Heat cure at 120℃ for 30 minutes to obtain an ultrathin thermally conductive insulating sheet with a thickness of 50μm.

[0115] The product obtained in Example 4 was subjected to thermal resistance testing, following the method described in ASTM 5470; the measured thermal resistance was 1.59 °C·cm. 2 / W.

[0116] Comparative Example 4

[0117] The first aspect of this example provides an ultrathin thermally conductive insulating sheet, the raw materials for which are prepared by mass parts are: 20 parts vinyl silicone oil, 1.4 parts hydrogen-containing silicone oil, 180 parts thermally conductive filler, 0.5 parts treatment agent, 0.05 parts inhibitor, and 0.2 parts catalyst.

[0118] The vinyl silicone oil in question is grade VS2000L and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0119] The hydrogen-containing silicone oil is grade S304 and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0120] The diluent is brand name Isopar C and was purchased from ExxonMobil Chemical Company.

[0121] The treatment agent is dodecyltrimethoxysilane.

[0122] The inhibitor is 1-ethynyl-1-cyclopentanol.

[0123] The catalyst is a platinum catalyst, grade PT3000, purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0124] The thermally conductive filler comprises, by weight, 100 parts of spherical alumina with a particle size of 5 μm, 52 parts of spherical alumina with a particle size of 0.8 μm, and 28 parts of spherical alumina with a particle size of 0.3 μm.

[0125] The second aspect of this example provides an ultrathin thermally conductive insulating sheet, comprising:

[0126] S1. Mix the vinyl silicone oil, hydrogen-containing silicone oil, thermally conductive filler, inhibitor, and treatment agent evenly.

[0127] S2. Add the catalyst and mix evenly. Then add 120 parts of diluent to dilute and coat it on a 25μm thick PI film. Heat cure at 120℃ for 30 minutes to obtain an ultrathin thermally conductive insulating sheet with a thickness of 50μm.

[0128] The product manufactured in this example underwent thermal resistance testing, following the method described in ASTM 5470; the measured thermal resistance was 2.09 °C·cm. 2 / W.

[0129] Comparative Example 5

[0130] The first aspect of this example provides an ultrathin thermally conductive insulating sheet, the raw materials for which are prepared by mass parts are: 18.4 parts vinyl silicone oil, 1.4 parts hydrogen-containing silicone oil, 180 parts thermally conductive filler, 0.4 parts treatment agent, 0.01 parts inhibitor, and 0.1 parts catalyst.

[0131] The vinyl silicone oil, designated RH-Vi311D (viscosity at 25°C: 500 mPa·s, vinyl content: 0.43 wt%), was purchased from Ningbo Runhe High-Tech Materials Technology Co., Ltd.

[0132] The hydrogen-containing silicone oil is grade S304 and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0133] The diluent is brand name Isopar C and was purchased from ExxonMobil Chemical Company.

[0134] The treatment agent is dodecyltrimethoxysilane.

[0135] The inhibitor is 1-ethynyl-1-cyclopentanol.

[0136] The catalyst is a platinum catalyst, grade PT3000, purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0137] The thermally conductive filler, by mass parts, consists of 140 parts of spherical alumina with a particle size of 2 μm and 40 parts of spherical alumina with a particle size of 0.3 μm.

[0138] The second aspect of this example provides an ultrathin thermally conductive insulating sheet, comprising:

[0139] S1. Mix the vinyl silicone oil, hydrogen-containing silicone oil, thermally conductive filler, inhibitor, and treatment agent evenly.

[0140] S2. Add the catalyst and mix evenly. Then add 120 parts of diluent to dilute and coat it on a 25μm thick PI film. Heat cure at 120℃ for 30 minutes to obtain an ultrathin thermally conductive insulating sheet with a thickness of 50μm.

[0141] The product manufactured in this example was subjected to thermal resistance testing, following the method described in ASTM 5470; the measured thermal resistance was 2.72℃·cm. 2 / W.

[0142] The raw materials prepared in this example are mixed and calendered into a 2mm thick pad for hardness testing.

[0143] Test method reference: ASTM D2240-15(2021); the measured product hardness was Shore 00 52.

[0144] Comparative Example 6

[0145] The first aspect of this example provides an ultrathin thermally conductive insulating sheet, the raw materials for which are prepared by mass parts are: 19.3 parts vinyl silicone oil, 1.2 parts hydrogen-containing silicone oil, 180 parts thermally conductive filler, 0.4 parts treatment agent, 0.01 parts inhibitor, and 0.1 parts catalyst.

[0146] The vinyl silicone oil, designated RH-Vi302 (viscosity 20000 mPa·S at 25°C, vinyl content 0.1 wt%), was purchased from Ningbo Runhe High-Tech Materials Technology Co., Ltd.

[0147] The hydrogen-containing silicone oil is grade S304 and was purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0148] The diluent is brand name Isopar C and was purchased from ExxonMobil Chemical Company.

[0149] The treatment agent is dodecyltrimethoxysilane.

[0150] The inhibitor is 1-ethynyl-1-cyclopentanol.

[0151] The catalyst is a platinum catalyst, grade PT3000, purchased from Shanghai Jingri New Materials Technology Co., Ltd.

[0152] The thermally conductive filler, by mass parts, consists of 140 parts of spherical alumina with a particle size of 2 μm and 40 parts of spherical alumina with a particle size of 0.3 μm.

[0153] In this example, the viscosity of the vinyl silicone oil was too high, making it impossible to mix the raw materials evenly and thus preventing the production of the final product.

[0154] Hardness test:

[0155] The raw materials of each component prepared in Examples 1-2 and Comparative Examples 1-5 were mixed and calendered to prepare a 2 mm thick pad for hardness testing.

[0156] Test method reference: ASTM D2240-15(2021).

[0157] The test results are detailed in Table 3.

[0158] Table 3

Claims

1. An ultrathin thermally conductive insulating sheet, characterized in that, The raw materials for preparing ultrathin thermally conductive insulating sheets, by weight, include 15-20 parts vinyl silicone oil, 1-3 parts hydrogen-containing silicone oil, 180-200 parts thermally conductive filler, 0.3-0.5 parts treatment agent, 0.01-0.05 parts inhibitor, and 0.05-0.2 parts catalyst.

2. The ultrathin thermally conductive insulating sheet according to claim 1, characterized in that, The catalyst includes one of platinum catalyst, ruthenium-based catalyst, rhodium-based catalyst, and tin-based catalyst.

3. The ultrathin thermally conductive insulating sheet according to claim 1, characterized in that, The mass ratio of the vinyl silicone oil to the hydrogen-containing silicone oil is (18.1-20):(1.2-1.4).

4. The ultrathin thermally conductive insulating sheet according to claim 3, characterized in that, The viscosity of the vinyl silicone oil at 25°C is 1000-100000 mPa·S.

5. The ultrathin thermally conductive insulating sheet according to claim 3, characterized in that, The vinyl content in the vinyl silicone oil is 0.01-6 wt%.

6. The ultrathin thermally conductive insulating sheet according to claim 3, characterized in that, The hydrogen content of the hydrogen-containing silicone oil is 0.03-0.1%.

7. The ultrathin thermally conductive insulating sheet according to any one of claims 1-6, characterized in that, The thermally conductive filler includes one or more of the following: spherical alumina, spherical boron nitride, spherical aluminum nitride, spherical zinc oxide, spherical magnesium oxide, spherical silicon carbide, spherical silicon nitride, and spherical quartz powder.

8. The ultrathin thermally conductive insulating sheet according to claim 7, characterized in that, The thermally conductive filler includes spherical alumina with a particle size of 0.1-3 μm.

9. The ultrathin thermally conductive insulating sheet according to claim 8, characterized in that, The thermally conductive filler comprises spherical alumina with a particle size of 0.1-0.5 μm and spherical alumina with a particle size of 1-3 μm, wherein the mass ratio of spherical alumina with a particle size of 0.1-0.5 μm to spherical alumina with a particle size of 1-3 μm is (10-15):(3-5).

10. A method for preparing an ultrathin thermally conductive insulating sheet according to any one of claims 1-9, characterized in that, include: S1. Mix the vinyl silicone oil, hydrogen-containing silicone oil, thermally conductive filler, inhibitor, and treatment agent evenly. S2. Add the catalyst and mix well, then dilute and coat it onto the substrate. Perform a heat curing treatment to obtain the final product.

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