Two-component organic silica gel as well as preparation method and application thereof

Abstract

The invention discloses two-component organic silica gel as well as a preparation method and application thereof. The two-component organic silica gel comprises a component A and a component B, the component A and the component B both comprise modified hollow glass beads; the modified hollow glass beads are obtained by modifying hollow glass beads with a modifier; the modifying agent is prepared from trimethoxy single-end-capped polydimethylsiloxane. The hollow glass beads are modified by adopting a specific modifier, so that the dispersion stability of the beads in a matrix is improved, the beads are prevented from floating or settling in the curing process, the interface bonding strength between the beads and the matrix is enhanced, and the thermal conductivity of the hollow glass beads is improved while the overall mechanical property, heat conduction capacity and mass density of the material are maintained. The thermal expansion behavior is obviously improved.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, and particularly relates to a two-component silicone rubber, its preparation method and application. Background Technology

[0002] Silicone potting compounds are widely used for the encapsulation and protection of electronic components due to their excellent high and low temperature resistance, electrical insulation, and flexibility, especially in fields requiring long-term stable operation such as power modules, inverters, and automotive electronics. However, traditional silicone potting compounds typically have a high coefficient of thermal expansion (CTE) (>200ppm / ℃), which can easily lead to the following problems under conditions of drastic temperature changes (high and low temperature shocks) or long-term thermal aging: First, stress damage to components on the PCB: During high and low temperature cycling (e.g., -40℃ to 150℃), the thermal expansion coefficients of the silicone are mismatched with those of the PCB board and magnetic components (such as inductor and transformer cores), causing the silicone to repeatedly contract and expand, thus applying periodic mechanical stress to the components. Long-term effects may cause core cracking, solder joint fatigue, or even component failure. Magnetic components (such as ferrites) are inherently brittle and sensitive to tensile stress; high CTE silicone will contract and stretch the magnetic core during cooling, exacerbating the risk of damage. Secondly, there is the issue of volume expansion in hermetically sealed packaging: When potting silicone in a sealed container (such as a power module with a metal casing), the silicone expands in volume when heated (the CTE of silicone differs significantly from that of metal), but it cannot expand freely due to the constraints of the casing, leading to stress accumulation inside the silicone. After long-term thermal aging, the silicone may bulge locally (bulge), or even detach from the heat-generating components (such as power chips), forming air gaps and significantly reducing heat dissipation efficiency.

[0003] Existing technologies mainly reduce CTE by increasing fillers (such as alumina and silica powder), but high filler content leads to an increase in silicone density, resulting in an increase in the amount of adhesive used, which increases the cost for customers and affects the lightweighting of products. Another way to reduce CTE is to increase the crosslinking density of silicone. However, as the crosslinking density increases, the hardness of the adhesive increases accordingly, causing the material to lose its ability to buffer vibration and impact, which in turn exacerbates the stress on brittle components. Summary of the Invention

[0004] In order to overcome at least one of the problems existing in the prior art, one of the objectives of the present invention is to provide a two-component silicone material that, by adding specific modified hollow glass microspheres, can obtain a material with high thermal conductivity, low density and low coefficient of thermal expansion.

[0005] The second objective of this invention is to provide a method for preparing the above-mentioned two-component organosilicone.

[0006] The third objective of this invention is to provide an organosilicon material.

[0007] The fourth objective of this invention is to provide an application of the above-mentioned two-component silicone rubber.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a two-component silicone rubber compound, comprising component A and component B; component A comprises a bi-terminated ethylene polysiloxane, alumina, a silane coupling agent, a catalyst, and modified hollow glass microspheres; component B comprises a bi-terminated ethylene polysiloxane, a hydrogen-terminated polysiloxane, a hydrogen-side-contained polysiloxane, alumina, a silane coupling agent, an inhibitor, and modified hollow glass microspheres; the modified hollow glass microspheres are obtained by modifying hollow glass microspheres with a modifier; the modifier comprises trimethoxy-terminated polydimethylsiloxane.

[0009] This invention, while ensuring that the original hardness, density, and thermal conductivity of the two-component silicone rubber remain essentially unchanged, achieves effective control of the coefficient of thermal expansion (CTE) by introducing hollow glass microspheres. Traditional methods often sacrifice other key properties when reducing CTE, but the innovation of this invention lies in using modified hollow glass microspheres with specific structural characteristics for compound modification. This significantly improves the thermal expansion behavior while maintaining the overall mechanical properties, thermal conductivity, and mass density of the material. This technological breakthrough enables silicone rubber to better withstand high and low temperature shock environments, effectively alleviates stress damage to PCB components caused by thermal expansion mismatch, and avoids gel deformation and interface separation caused by thermal expansion in sealed packaging scenarios.

[0010] To address the technical bottlenecks of hollow glass microspheres' tendency to float and unevenly disperse in silicone matrices, this invention employs a specific modifier to surface-modify the hollow glass microspheres, significantly improving their interfacial compatibility with the silicone rubber matrix. This modification not only improves the dispersion stability of the microspheres in the matrix, preventing them from floating or settling during curing, but also enhances the interfacial bonding strength between the microspheres and the matrix. The optimized interfacial characteristics ensure effective stress transfer in the composite material, allowing the material to fully leverage the synergistic effects of its components, thereby achieving superior overall performance.

[0011] In this invention, the double-terminated ethylene polysiloxane in component A and the double-terminated ethylene polysiloxane in component B can be the same or different; the alumina in component A and the alumina in component B can be the same or different; the silane coupling agent in component A and the silane coupling agent in component B can be the same or different; the modified hollow glass microspheres in component A and the modified hollow glass microspheres in component B can be the same or different.

[0012] Preferably, the mass ratio of the hollow glass microspheres to the trimethoxy-terminated polydimethylsiloxane is 1:(0.05~0.3); more preferably 1:(0.07~0.2); and even more preferably 1:(0.08~0.15).

[0013] In some embodiments of the present invention, the chemical formula of the trimethoxy-terminated polydimethylsiloxane is as follows: n is 10~100. n-Bu represents n-butyl.

[0014] In some embodiments of the present invention, the weight-average molecular weight (Mn) of the trimethoxy-terminated polydimethylsiloxane is 1000~5000 g / mol; more specifically, it is 2000~4000 g / mol.

[0015] In some embodiments of the present invention, the trimethoxy-terminated polydimethylsiloxane is selected from FM-0815J.

[0016] Preferably, the modifier further includes trimethyl-terminated polydimethylsiloxane; more preferably, the trimethyl-terminated polydimethylsiloxane has a viscosity of 45~55 mPa·s at 25°C.

[0017] Preferably, the mass ratio of the hollow glass microspheres to the trimethyl-terminated polydimethylsiloxane is 1:(1~3); more preferably 1:(1.5~2.5); even more preferably 1:(1.8~2.2).

[0018] Preferably, the modified hollow glass microspheres in component A contain 1 to 10 wt%; more preferably 2 to 7 wt%; and even more preferably 4 to 6 wt%.

[0019] Preferably, the modified hollow glass microspheres in component B contain 1-10 wt%; more preferably 2-7 wt%; and even more preferably 4-6 wt%.

[0020] By precisely controlling the amount of glass microspheres added, the thermal expansion behavior can be further improved while maintaining the overall mechanical properties, thermal conductivity, and mass density of the material.

[0021] Preferably, the hollow glass microspheres have a particle size of 20-70 μm; more preferably, they have a particle size of 40-60 μm.

[0022] Preferably, the true density of the hollow glass microspheres is 0.15~1 g / cm³. 3 Further preferably, it is 0.15~0.25 g / cm³. 3 .

[0023] Preferably, the modified hollow glass microspheres are prepared by a method comprising the following steps: mixing the modifier with the hollow glass microspheres and heating the mixture to obtain the modified hollow glass microspheres; the heating temperature is 100~150℃.

[0024] Preferably, in the method for preparing the modified hollow glass microspheres, the heat treatment time is 1-3 hours.

[0025] Preferably, the viscosity of the double-ended ethylene polysiloxane at 25°C is 50~500 mPa·s; more preferably, it is 50~200 mPa·s.

[0026] Preferably, the vinyl content of the double-terminated ethylene polysiloxane is 0.4~2wt%; more preferably 0.5~2wt%.

[0027] Preferably, the chemical formula of the dual-terminated ethylene polysiloxane is: Where D is an integer, and the value of D ranges from 20 to 100.

[0028] Preferably, the viscosity of the hydrogen-terminated polysiloxane at 25°C is 10~1000 mPa·s; more preferably, it is 20~100 mPa·s.

[0029] Preferably, the hydrogen content of the hydrogen-terminated polysiloxane is 0.01~0.18wt%; more preferably, it is 0.05~0.15wt%.

[0030] Preferably, the chemical formula of the hydrogen-terminated polysiloxane is: Where D' is an integer, and the value of D' ranges from 20 to 300.

[0031] Preferably, the viscosity of the side-containing hydrogen polysiloxane at 25°C is 20~200 mPa·s; more preferably, it is 20~110 mPa·s.

[0032] Preferably, the hydrogen content of the side-hydrogenated polysiloxane is 0.08~0.3wt%; more preferably 0.1~0.2wt%.

[0033] Preferably, the chemical formula of the side-containing hydrogen polysiloxane is: Where M and M' are both integers, with M ranging from 20 to 80 and M' ranging from 5 to 10.

[0034] Preferably, the silane coupling agent is trimethoxy-terminated polydimethylsiloxane, triethoxy-terminated polydimethylsiloxane, or a combination thereof; more preferably, the silane coupling agent is trimethoxy-terminated polydimethylsiloxane.

[0035] Specifically, the silane coupling agent used may be the same as or different from the trimethoxy-terminated polydimethylsiloxane used in the modifier.

[0036] In some embodiments of the present invention, the silane coupling agent is a trimethoxy-terminated polydimethylsiloxane, which is the same as the trimethoxy-terminated polydimethylsiloxane used in the modifier.

[0037] In some embodiments of the present invention, the silane coupling agent is selected from FM-0815J.

[0038] Preferably, the alumina has a particle size of 1~70μm; more preferably, it has a particle size of 2~50μm.

[0039] Preferably, the alumina includes alumina A, alumina B, and alumina C; the particle size of alumina A is greater than 30 μm and less than or equal to 70 μm; the particle size of alumina B is greater than 4 μm and less than or equal to 30 μm; and the particle size of alumina C is greater than or equal to 1 μm and less than or equal to 4 μm.

[0040] More preferably, the alumina A has a particle size of 35~45μm; the alumina B has a particle size of 4.5~6μm; and the alumina C has a particle size of 1~3μm.

[0041] Combining alumina of different particle sizes can significantly improve the anti-settling properties of two-component silicone rubber and form better thermal conductivity channels, thereby improving the thermal conductivity of the two-component silicone rubber.

[0042] Preferably, the mass ratio of alumina A, alumina B and alumina C is 1:(0.5~1.5):(0.5~1.5); more preferably, it is 1:(0.8~1.2):(0.8~1.2).

[0043] Preferably, the catalyst is a platinum catalyst; more preferably, the platinum catalyst includes at least one of diethylenetetramethyldisiloxane platinum complex, diethyleneoctamethyltetrasiloxane platinum complex, or chloroplatinic acid alcohol solution.

[0044] Preferably, the inhibitor comprises at least one selected from acetylenol, methylbutynol, tetramethyldivinyldisiloxane, or trimethyl-dodecynol; more preferably, the inhibitor comprises at least one selected from acetylenol, methylbutynol, or trimethyl-dodecynol. Using an inhibitor allows for control of the reaction rate during the curing of two-component silicone adhesives, providing excellent workability during dispensing.

[0045] Preferably, component A comprises the following components in parts by weight: 100-200 parts of bi-terminated ethylene polysiloxane, 600-1000 parts of alumina, 10-30 parts of silane coupling agent, 2-6 parts of catalyst, and 10-120 parts of modified hollow glass microspheres; component B comprises 60-100 parts of bi-terminated ethylene polysiloxane, 60-80 parts of end-hydrogen-containing polysiloxane, 5-15 parts of side-hydrogen-containing polysiloxane, 600-1000 parts of alumina, 10-30 parts of silane coupling agent, 1-5 parts of inhibitor, and 10-120 parts of modified hollow glass microspheres; the mass ratio of component A to component B is 1:(0.5-1.5).

[0046] More preferably, component A comprises the following components in parts by weight: 120-180 parts of bi-terminated ethylene polysiloxane, 700-900 parts of alumina, 15-25 parts of silane coupling agent, 3-5 parts of catalyst, and 13-100 parts of modified hollow glass microspheres; component B comprises 70-90 parts of bi-terminated ethylene polysiloxane, 65-75 parts of end-hydrogen-containing polysiloxane, 7-12 parts of side-hydrogen-containing polysiloxane, 700-900 parts of alumina, 15-25 parts of silane coupling agent, 2-4 parts of inhibitor, and 13-100 parts of modified hollow glass microspheres; the mass ratio of component A to component B is 1:(0.8-1.2).

[0047] Preferably, component A further includes carbon black paste; the carbon black paste has a mass fraction of 0.5 to 1.5 parts.

[0048] A second aspect of the present invention provides a method for preparing a two-component silicone rubber as described in the first aspect of the present invention, comprising the following steps: mixing a bi-terminated ethylene polysiloxane in component A with a silane coupling agent, adding alumina, heat-treating at 80-120°C, cooling to below 45°C, adding the remaining components and mixing to obtain component A; mixing a bi-terminated ethylene polysiloxane in component B with alumina, heat-treating at 80-120°C, cooling to below 45°C, adding the remaining components and mixing to obtain component B.

[0049] Preferably, the preparation method of the two-component silicone rubber includes the following steps: mixing the bi-terminated ethylene polysiloxane in component A with a silane coupling agent, sequentially adding alumina A, alumina B, and alumina C, heat-treating at 80-120°C, cooling to below 45°C, adding the remaining components and mixing to obtain component A; sequentially adding alumina A, alumina B, and alumina C to the bi-terminated ethylene polysiloxane in component B, heat-treating at 80-120°C, cooling to below 45°C, and then adding the remaining components and mixing to obtain component B.

[0050] A third aspect of the present invention provides an organosilicon material, which is obtained by mixing and curing the two-component organosilicon described in the first aspect of the present invention; the hardness of the organosilicon material is 28~35HA; and the density of the organosilicon material is 1.5~2.4g / cm³. 3 The thermal conductivity of the silicone material is 0.8~1.5 W / m·K; the linear expansion coefficient of the silicone material is 150~220 μm / (m·℃); and the viscosity of the mixed two-component silicone sample at 25℃ is 3000~4500 mPa·s.

[0051] The two-component silicone of this invention, when mixed, has a suitable viscosity, which can achieve good construction and potting effects. The silicone material obtained after further curing has the characteristics of low density, high thermal conductivity and low coefficient of linear expansion (CTE). Low density helps to reduce the amount of glue used, thereby achieving lightweighting, while high thermal conductivity promotes heat dissipation. The significant reduction in CTE can greatly reduce the expansion stress of later aging.

[0052] Specifically, the hardness was measured according to GB / T 2411-2008 standard; the density was measured according to GB / T 13354-1992 standard; the thermal conductivity was measured according to ISO 22007-2-2022 standard; the linear expansion coefficient was measured according to ASTM E831-2025 standard; and the viscosity was measured according to GB / T 2794-2022 standard. The test temperature was 25℃.

[0053] In some embodiments of the present invention, the hardness of the silicone material is 30~32HA; the density of the silicone material is 1.7~2.1g / cm³. 3 The thermal conductivity of the silicone material is 0.9~1.2 W / m·K; the linear expansion coefficient of the silicone material is 160~200 μm / (m·℃); and the viscosity of the mixed two-component silicone sample at 25℃ is 3500~4200 mPa·s.

[0054] Preferably, the curing temperature is 80~90℃.

[0055] Preferably, the curing time is 20-40 minutes.

[0056] A fourth aspect of the present invention provides an application of a two-component silicone rubber as described in the first aspect of the present invention in electronic packaging.

[0057] Specifically, the electronic packaging can be the packaging of electronic components such as power modules, inverters, automotive electronic components, inductors, and transformer cores; it can also be the packaging of electronic components on a PCB board; or it can be the packaging of electronic components in a sealed container, such as the packaging of a power module in a metal casing.

[0058] The beneficial effects of the present invention are as follows: The present invention uses a specific modifier to modify hollow glass microspheres, which improves the dispersion stability of the microspheres in the matrix, prevents them from floating or settling during the curing process, and enhances the interfacial bonding strength between the microspheres and the matrix. While maintaining the overall mechanical properties, thermal conductivity and mass density of the material, it significantly improves its thermal expansion behavior. Detailed Implementation

[0059] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0060] The following describes some of the raw materials used in the following examples and comparative examples: Double-ended ethylene polysiloxane: viscosity at 25℃ is 100 mPa·s, vinyl content is 0.5~2 wt%; chemical formula is: Where D is an integer, and the value of D ranges from 20 to 100; Hydrogen-terminated polysiloxane: viscosity at 25℃ is 20~100 mPa·s; hydrogen content is 0.05~0.15 wt%; chemical formula is: Where D' is an integer, and the value of D' ranges from 20 to 300; Hydrogen-containing polysiloxane: viscosity at 25℃ is 20~110 mPa·s; hydrogen content is 0.1~0.2wt%; chemical formula is: Where M and M' are both integers, with M ranging from 20 to 80 and M' ranging from 5 to 10; Silane coupling agent: Chemical formula: The weight-average molecular weight (Mn) is 3000 g / mol, and the model number is FM-0815J; The trimethoxy-terminated polydimethylsiloxane used in the modifier of modified hollow glass microspheres has the following chemical formula: The weight-average molecular weight (Mn) is 3000 g / mol, and the model number is FM-0815J; Dimethyl silicone oil: namely trimethyl-terminated polydimethylsiloxane, with a viscosity of 45~55 mPa·s at 25℃; 40μm alumina, 5μm alumina, and 2μm alumina refer to alumina with average particle sizes of 40μm, 5μm, and 2μm, respectively. Hollow glass microspheres: particle size 40~60μm, true density 0.15~0.25g / cm³ 3 .

[0061] Preparation Example 1 A modified hollow glass microsphere matrix is ​​prepared by the following method: In a 2L dynamic mixer, 400g of dimethyl silicone oil (viscosity 45~55mPa·s at 25℃) and 20g of trimethoxy-terminated polydimethylsiloxane were mixed evenly and heated to 120℃. Hollow glass microspheres (particle size 40~60μm, true density 0.15~0.25g / cm³) were then added. 3 200g of the mixture was stirred at a speed of 60 rpm for revolution and 600 rpm for dispersion. After stirring for 5 minutes, the mixture was stopped and scraped (the powder adhering to the stirring paddle was scraped into the vessel to facilitate uniform dispersion). The mixture was then heat-treated for 2 hours. After the reaction, the mixture was cooled to obtain the modified hollow glass microsphere matrix.

[0062] Preparation Example 2 A modified hollow glass microsphere matrix material differs from Preparation Example 1 in that it does not contain trimethoxy-terminated polydimethylsiloxane, and the mass reduction is made up by dimethyl silicone oil, i.e., 420g of dimethyl silicone oil and 0g of trimethoxy-terminated polydimethylsiloxane; all other conditions are the same as in Preparation Example 1.

[0063] Preparation Example 3 A modified hollow glass microsphere matrix material differs from Preparation Example 1 in that trimethoxy-terminated polydimethylsiloxane is replaced with methyltrimethoxysilane, a commonly used surface modifier for silicon micropowder; all other conditions are the same as in Preparation Example 1.

[0064] Example 1 A two-component silicone rubber compound is prepared by the following steps: Preparation of component A: Accurately weigh 150g of ethylene-terminated polysiloxane with a viscosity of 100mPa·s at 25℃ and place it in a double planetary stirred tank equipped with a heating and vacuum system. Add 20g of silane coupling agent and heat to 100℃. Add 276g of 40μm alumina, 250g of 5μm alumina, and 300g of 2μm alumina in batches. Set the stirring speed to 60r / min for revolution and 1500r / min for rotation, and heat-treat for 60min. Turn off the heating and cool to below 45℃ with circulating water. Add 4g of Pt catalyst (Heraeness 3000ppm Kares Tedt dilution), 1g of carbon black paste, and 15g of the modified hollow glass microsphere matrix from Preparation Example 1. Stir at 60r / min for revolution and 1500r / min for rotation, and vacuum stir at room temperature for 30min to obtain component A.

[0065] Preparation of component B: Accurately weigh 80g of ethylene-terminated polysiloxane with a viscosity of 100mPa·s at 25℃ into a double planetary stirred tank equipped with a heating and vacuum system, and heat to 100℃. Add 276g of 40μm alumina, 250g of 5μm alumina, and 300g of 2μm alumina in batches. Set the stirring speed to 60r / min for revolution and 1500r / min for rotation, and process for 60min. Turn off the heating and cool to below 45℃ with circulating water. Add 69g of hydrogen-containing polysiloxane (chain extender), 9g of hydrogen-containing polysiloxane (crosslinker), and 3g of acetylenecyclohexanol (inhibitor) to prepare 15g of modified hollow glass microsphere matrix for Example 1. Stir at 60r / min for revolution and 1500r / min for rotation, and vacuum stir at room temperature for 30min to obtain component B.

[0066] Example 2 A two-component silicone rubber compound differs from Example 1 in that the amount of hollow glass microsphere matrix in components A and B is changed to 30g each, while all other conditions are the same as in Example 1.

[0067] Example 3 A two-component silicone rubber compound differs from Example 1 in that the amount of hollow glass microsphere matrix in components A and B is changed to 60g each, while all other conditions are the same as in Example 1.

[0068] Example 4 A two-component silicone rubber compound differs from Example 1 in that the amount of hollow glass microsphere matrix in components A and B is changed to 90g each, while all other conditions are the same as in Example 1.

[0069] Comparative Example 1 A two-component silicone rubber compound differs from Example 1 in that neither component A nor component B contains hollow glass microsphere matrix, while all other conditions are the same as in Example 1.

[0070] Comparative Example 2 A two-component silicone rubber compound differs from Example 1 in that the modified hollow glass microsphere matrix added later in the preparation of components A and B is replaced with 30g of hollow glass microspheres and 60g of dimethyl silicone oil, and both are added to the reactor together with alumina in advance for heat modification treatment for 60min. All other conditions are the same as in Example 1.

[0071] Comparative Example 3 A two-component silicone rubber compound differs from Example 4 in that components A and B are both replaced with the modified hollow glass microsphere matrix from Example 1, while all other conditions are the same as in Example 4.

[0072] Comparative Example 4 A two-component silicone rubber compound differs from Example 4 in that components A and B are both replaced with the modified hollow glass microsphere matrix from Example 1, while all other conditions are the same as in Example 4.

[0073] Comparative Example 5 A two-component silicone adhesive differs from Example 1 in that neither component A nor B contains modified hollow glass microsphere matrix, and the specific amounts of some raw materials are adjusted, as shown in Table 1; all other conditions are the same as in Example 1. In this example, the material density is reduced to 2.0 g / cm³ by decreasing the solids content of the potting compound. 3 about.

[0074] The components and dosages of Examples 1-4 and Comparative Examples 1-5 are shown in Table 1.

[0075] Table 1. Components and amounts (in g) of Examples 1-4 and Comparative Examples 1-5

[0076] Performance testing Samples were prepared by mixing components A and B of Examples 1-4 and Comparative Examples 1-5 at a weight ratio of 1:1, and the following performance tests were conducted. The curing conditions were 85℃ / 30min.

[0077] (1) Viscosity testing method: First, weigh components A and B separately at a weight ratio of 1:1 (±5% deviation allowed), then stir manually for 1 minute and evacuate for 1 minute. Then, test using a BROOKFIELD viscometer with a No. 4 rotor at 20 rpm, according to the method specified in GB / T 2794-2022. The test temperature must be kept constant at 25℃. The viscosity unit is mPa·s. (2) Thermal conductivity test method: Use Hot Disk according to the method specified in ISO 22007-2-2022, and test after vacuum curing. The parameter is 10s / 200mW, and the thermal conductivity is in W / m·K. (3) Hardness test (ShoreA): First, weigh components A and B separately at a weight ratio of 1:1 (±5% deviation allowed), then manually stir for 2 minutes and vacuum for 5 minutes. Allow to cure at the specified temperature, and then test using a Shore A hardness tester. For details, refer to GB / T 2411-2008. (4) Density test: For testing the density of solid blocks, refer to GB / T 13354-1992, the unit of density is g / cm³. 3 ; (5) Linear expansion coefficient CTE test: Set the gas flow (N2) rate to 50 mL / min and increase the temperature from -40°C to 150°C at a rate of 10°C / min. Refer to ASTM E831-2025 for details, in μm / (m·°C).

[0078] The performance test results of Examples 1-4 and Comparative Examples 1-5 are shown in Table 2.

[0079] Table 2 Performance test results of Examples 1-4 and Comparative Examples 1-5

[0080] Analysis of Table 2, comparing Examples 1-4 with Comparative Example 1, shows that as the amount of modified hollow glass microspheres added increases, the viscosity of the material increases to some extent, while the density and thermal conductivity decrease, and the coefficient of thermal expansion (CTE) also decreases to varying degrees. Specifically, compared to Comparative Example 1, the CTE of Example 1 decreased by 6.5%, and compared to Comparative Example 1, the CTE of Example 4 decreased by 27%. Comparing Example 4 with Comparative Example 2, it is evident that without prior modification of the hollow glass microspheres, wet modification was performed by mixing them with alumina. This method resulted in an increase in the viscosity, density, and CTE of the prepared two-component silicone rubber. The main reason is that the compressive strength of the hollow glass microspheres is insufficient, leading to breakage or grinding during prolonged stirring and heat treatment with alumina. Comparing Example 4 with Comparative Examples 3-4, it is evident that if the specific modifier of this invention is not used or is replaced with methyltrimethoxysilane when preparing the hollow microsphere base material, the viscosity of the resulting adhesive increases significantly, affecting the subsequent potting effect. A comparison of Example 3 and Comparative Example 5 shows that Example 3, by adding modified hollow glass microspheres, increased the material density from 2.5 g / cm³. 3 Reduced to approximately 2.0 g / cm³ 3 Comparative Example 5 reduced the density to approximately 2.0 g / cm³ by decreasing the total powder content. 3Comparing the data of the two, it is clear that the CTE of Example 3 is 35.6% lower than that of Comparative Example 5. Therefore, compared with silicone prepared by directly reducing the solid content, adding the modified hollow glass microsphere matrix of this invention to prepare silicone with the same density and similar thermal conductivity can achieve a lower coefficient of linear expansion (CTE), which is particularly suitable for scenarios with high requirements for thermal aging stress.

[0081] In this embodiment of the invention, although the addition of modified hollow glass microspheres will reduce the thermal conductivity of the adhesive to a certain extent, the reduction is within a controllable range, and the material still has good thermal conductivity. At the same time, the addition of modified hollow glass microspheres will also greatly reduce the density and CTE, so less adhesive is used when potting samples of the same volume, which is more beneficial to weight reduction. The significant reduction in CTE can greatly reduce the aging expansion stress in the later stage.

[0082] In addition, the prices of common thermally conductive fillers such as ordinary alumina and silicon micropowder are much lower than those of silicone oil. If more thermally conductive fillers can be added while keeping the density constant, the raw material cost of the adhesive can be reduced to a certain extent, thereby enhancing the product's competitiveness.

[0083] In summary, this invention uses a specific modifier to modify hollow glass microspheres, which improves the dispersion stability of the microspheres in the matrix, prevents them from floating or settling during the curing process, and enhances the interfacial bonding strength between the microspheres and the matrix. While maintaining the overall mechanical properties, thermal conductivity and mass density of the material, it significantly improves its thermal expansion behavior.

Claims

1. A two-component silicone rubber compound, characterized in that, The product comprises component A and component B; component A includes double-terminated ethylene polysiloxane, alumina, a silane coupling agent, a catalyst, and modified hollow glass microspheres; component B includes double-terminated ethylene polysiloxane, hydrogen-terminated polysiloxane, side-hydrogenated polysiloxane, alumina, a silane coupling agent, an inhibitor, and modified hollow glass microspheres; the modified hollow glass microspheres are obtained by modifying hollow glass microspheres with a modifier; the modifier includes trimethoxy-terminated polydimethylsiloxane.

2. The two-component silicone rubber according to claim 1, characterized in that, The mass ratio of the hollow glass microspheres to the trimethoxy-terminated polydimethylsiloxane is 1:(0.05~0.3). And / or, the modifier further includes trimethyl-terminated polydimethylsiloxane; the mass ratio of the hollow glass microspheres to the trimethyl-terminated polydimethylsiloxane is 1:(1~3). And / or, the modified hollow glass microspheres in component A contain 1~10 wt%; And / or, the content of modified hollow glass microspheres in component B is 1~10wt%.

3. The two-component silicone rubber according to claim 1, characterized in that, The hollow glass microspheres have a particle size of 20~70μm; And / or, the true density of the hollow glass microspheres is 0.15~1 g / cm³. 3 .

4. The two-component silicone rubber according to claim 1, characterized in that, The modified hollow glass microspheres are prepared by a method comprising the following steps: mixing the modifier with the hollow glass microspheres and heating the mixture to obtain the modified hollow glass microspheres; the heating temperature is 100~150℃.

5. The two-component silicone rubber according to claim 1, characterized in that, The viscosity of the double-ended ethylene polysiloxane at 25°C is 50~500 mPa·s; And / or, the vinyl content of the dual-terminated ethylene polysiloxane is 0.4~2wt%; And / or, the viscosity of the hydrogen-terminated polysiloxane at 25°C is 10~1000 mPa·s; And / or, the hydrogen content of the hydrogen-terminated polysiloxane is 0.01~0.18 wt%; And / or, the viscosity of the side-containing hydrogen polysiloxane at 25°C is 20~200 mPa·s; And / or, the hydrogen content of the side-hydrogenated polysiloxane is 0.08~0.3wt%; And / or, the silane coupling agent is trimethoxy-terminated polydimethylsiloxane, triethoxy-terminated polydimethylsiloxane, or a combination thereof; And / or, the alumina has a particle size of 1~70 μm; And / or, the catalyst is a platinum catalyst; the platinum catalyst includes at least one of diethylenetetramethyldisiloxane platinum complex, diethyleneoctamethyltetrasiloxane platinum complex, or chloroplatinic acid alcohol solution; And / or, the inhibitor includes at least one of acetylenol, methylbutynol, tetramethyldivinyldisiloxane, or trimethyl-dodecynol.

6. The two-component silicone rubber according to claim 1, characterized in that, The alumina includes alumina A, alumina B, and alumina C; the particle size of alumina A is greater than 30 μm and less than or equal to 70 μm; the particle size of alumina B is greater than 4 μm and less than or equal to 30 μm; and the particle size of alumina C is greater than or equal to 1 μm and less than or equal to 4 μm.

7. The two-component silicone rubber according to claim 1, characterized in that, Component A comprises the following components in parts by weight: 100-200 parts of bi-terminated ethylene polysiloxane, 600-1000 parts of alumina, 10-30 parts of silane coupling agent, 2-6 parts of catalyst, and 10-120 parts of modified hollow glass microspheres; Component B comprises 60-100 parts of bi-terminated ethylene polysiloxane, 60-80 parts of end-hydrogen-containing polysiloxane, 5-15 parts of side-hydrogen-containing polysiloxane, 600-1000 parts of alumina, 10-30 parts of silane coupling agent, 1-5 parts of inhibitor, and 10-120 parts of modified hollow glass microspheres; the mass ratio of component A to component B is 1:(0.5-1.5).

8. A method for preparing a two-component organosilicone gel as described in any one of claims 1 to 7, characterized in that, The process includes the following steps: mixing the bi-terminated ethylene polysiloxane in component A with a silane coupling agent, adding alumina, heat-treating at 80-120°C, cooling to below 45°C, and then adding the remaining components to obtain component A; mixing the bi-terminated ethylene polysiloxane in component B with alumina, heat-treating at 80-120°C, cooling to below 45°C, and then adding the remaining components to obtain component B.

9. An organosilicon material, characterized in that, The silicone material is obtained by mixing and curing the two-component silicone material according to any one of claims 1 to 7; the hardness of the silicone material is 28 to 35 HA; and the density of the silicone material is 1.5 to 2.4 g / cm³. 3 The thermal conductivity of the silicone material is 0.8~1.5 W / m·K; the linear expansion coefficient of the silicone material is 150~220 μm / (m·℃); and the viscosity of the mixed two-component silicone sample at 25℃ is 3000~4500 mPa·s.

10. The application of a two-component silicone rubber as described in any one of claims 1 to 7 in electronic packaging.

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