Preparation method and application of high-insulation silicone gel for SiC device packaging

Abstract

This application relates to the technical field of insulating encapsulation materials for electronic components, and discloses a method for preparing and applying a high-insulation silicone gel for SiC device encapsulation. The method includes: uniformly dispersing silicone gel component A and crystalline anthrone at room temperature to obtain a premixed solution; adding silicone gel component B to the premixed solution and mixing uniformly, followed by vacuum degassing and defoaming; pouring the defoamed solution into a mold and curing at room temperature to obtain a high-insulation silicone gel. This invention directly dops anthrone into an addition-type silicone gel matrix, utilizing the difference in dielectric properties between the anthrone crystal and the matrix, as well as the polar groups, to construct a bimodal distribution of deep and shallow traps within the material. The resulting composite gel can synergistically capture charge carriers and dissipate electron kinetic energy, effectively suppressing space charge accumulation and partial discharge, improving the material's breakdown strength and heat resistance, and meeting the high-voltage insulating encapsulation requirements of next-generation high-power SiC devices.

Description

Technical Field

[0001] This invention relates to the field of insulating packaging materials for electronic components, specifically a method for preparing and applying a highly insulating silicone gel for SiC device packaging. Background Technology

[0002] High-voltage, high-power power electronic devices are widely used in new energy vehicles, rail transportation, and ultra-high-voltage flexible DC transmission. Organosilicon gels possess excellent heat resistance, high electrical insulation, and ease of processing and molding, making them promising candidates for encapsulation and insulation in high-voltage, high-power power electronic devices.

[0003] With the rapid development of next-generation wide-bandgap semiconductor materials such as SiC and GaN, the maximum operating temperature and withstand voltage levels of high-voltage, high-power power electronic devices have been further improved. Upgraded operating conditions place more stringent demands on the thermal stability and electrical insulation of packaging materials. Simultaneously, due to electric field distortion at the three junctions within high-voltage, high-power devices, conventional silicone gels are prone to partial discharge under high field strength, leading to eventual insulation failure. Therefore, it is necessary to conduct specialized research on the insulation withstand voltage of packaging materials.

[0004] Currently, methods to improve the insulation properties of silicone gels mainly include two approaches: introducing inorganic nanoparticles and chemical synthesis modification. Introducing inorganic nanoparticles such as SiC, BN, or SiO2 into the silicone gel matrix can increase the dielectric constant of the material and introduce traps, thereby suppressing electric field distortion in high-voltage, high-power power electronic devices. However, the intrinsic properties of inorganic particles and the polymer matrix differ significantly. Direct mixing can lead to a significant increase in the viscosity of the matrix resin and introduce structural defects within the material. Furthermore, at high doping levels, inorganic particles are prone to physical aggregation, which can reduce the macroscopic insulation properties of the composite material. On the other hand, some studies have introduced specific groups such as phenyl groups onto the molecular side chains of silicone gels through chemical synthesis, aiming to synergistically improve the electrothermal properties of the gel matrix. However, this chemical synthesis method based on molecular structure modification suffers from cumbersome steps and complex processes, and it easily generates numerous chemical byproducts during the grafting reaction, making it difficult to meet the requirements for high-purity encapsulation materials in practical engineering applications. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing and applying a high-insulation silicone gel for SiC device packaging. The aim is to solve the problems in existing silicone gel modification methods, such as the easy agglomeration of inorganic fillers introducing defects, complex chemical synthesis processes, and numerous byproducts, which make it difficult for packaging materials to effectively suppress electric field distortion and partial discharge within high-voltage SiC devices.

[0006] To address the above problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for preparing a highly insulating silicone gel for SiC device packaging, employing the following technical solution: A method for preparing a highly insulating silicone gel for SiC device packaging includes the following steps: Organosilicon gel component A is added to a container, followed by the addition of crystalline anthrone. The mixture is stirred at room temperature to disperse the crystalline anthrone evenly in the organosilicon gel component A, thus obtaining a premixed solution. Add organosilicon gel component B to the premixed solution, stir to mix evenly, and then perform vacuum degassing to remove air bubbles to obtain a defoamed solution. The defoamed solution is poured evenly into a mold and cured at room temperature to obtain the final highly insulating silicone gel.

[0007] By employing the above technical solution, and using crystalline anthrone as the dopant phase dispersed in a system containing organosilicon gel component A and component B, the addition curing of the two-component organosilicon constructs a microscopic physical phase interface and a bimodal trap energy level within the polymer matrix. Therefore, it achieves an insulating effect that synergistically regulates space charge and suppresses partial discharge. The specific reaction mechanism and insulation enhancement principle are as follows: The first step is the construction of the matrix crosslinking network. Organosilicon gel component A in the system contains active vinyl groups, and organosilicon gel component B contains silicon-hydrogen bonds. When mixed, they undergo a hydrosilylation reaction at room temperature. The reaction equation is: ≡Si-CH=CH2+≡Si-H→≡Si-CH2-CH2-Si≡, where ≡ represents three additional independent single bonds attached to the silicon atom. Through this addition curing reaction, linear polydimethylsiloxane segments form a three-dimensional cross-linked network, constituting a gel insulating matrix with a continuous phase. No low-molecular-weight volatiles are generated during this reaction, ensuring the density of the gel's interior.

[0008] The second step involves the formation of the physical phase interface and the construction of deep traps. Anthrone is uniformly dispersed in a crystalline state within the cross-linked organosilicon network. Due to the physical differences in dielectric constant and conductivity between the anthrone crystals and the organosilicon polymer matrix, a microscopic phase interface is formed at their contact region. The abrupt change in dielectric properties on both sides of the interface causes the Maxwell-Wagner polarization effect, resulting in local potential barrier distortion. This potential barrier difference at the physical phase interface constructs deep traps within the material. Specifically, when a material is composed of two or more materials with different dielectric constants and conductivity (such as anthrone crystals and the organosilicon matrix in this case), under the influence of an applied electric field, charge carriers migrating within the bulk are blocked due to the mismatch in electrical properties at the phase interface, leading to charge accumulation at the microscopic interface. Deep traps can capture high-energy charge carriers injected under a high-voltage electric field, restricting their migration within the free volume of the polymer and suppressing the accumulation of space charge deep within the insulating material, thereby mitigating the local electric field distortion caused by space charge.

[0009] The third step involves the introduction of polar groups and the construction of shallow traps. Anthrone molecules contain polar carbonyl groups, and the dipole moments of these groups create shallow traps within the polymer matrix. These shallow traps dissipate the kinetic energy of high-energy electrons through a continuous process of electron capture and release, weakening the collisional ionization ability of electrons accelerated by an electric field, and reducing the probability of partial discharge caused by polymer chain breakage. The synergistic effect of the bimodal distribution of these deep and shallow traps delays the initiation and growth of electrical trees, thereby improving the dielectric insulation strength of the gel composite material.

[0010] Preferably, during the preparation of the premixed liquid, a stirring device with a rotation speed of 100 r / min to 500 r / min is used to continuously stir for 6 h to 24 h.

[0011] By employing the above technical solution, the set stirring speed and continuous mixing time can break the physical agglomeration of anthrone crystal particles, allowing them to achieve uniform dispersion in the matrix resin. This uniform dispersion is a prerequisite for constructing a continuous phase interface, avoiding the electric field concentration effect caused by excessively high local filler concentration and maintaining consistent insulation performance.

[0012] Preferably, the amount of crystalline anthrone added accounts for 0.1 wt% to 1.0 wt% of the total mass of the high-insulation silicone gel.

[0013] By adopting the above technical solution and controlling the anthrone content within this range, a sufficient density of deep and shallow traps can be introduced into the matrix to capture free charges; at the same time, it prevents excessive doping from causing physical contact between crystal particles, avoids the overlap of adjacent trap energy levels to form a through-conductivity channel, and maintains the low leakage current characteristics of the insulating material.

[0014] Preferably, the silicone gel component A is a vinyl-terminated polydimethylsiloxane, whose molecular backbone is composed of alternating silicon-oxygen bonds; the silicone gel component B is a polymethylhydrosiloxane, whose molecular chain contains multiple repeating methylhydrosiloxane units; the silicone gel component B acts as a crosslinking agent, and the mass ratio of the silicone gel component A to the silicone gel component B is 10:1, and it undergoes an addition curing reaction with the active vinyl groups in the silicone gel component A at room temperature.

[0015] By adopting the above technical solution, the highly flexible silicon-oxygen bond is used as the main chain to give the molded gel matrix low modulus characteristics, which enables it to absorb the thermomechanical stress generated by SiC devices during switching cycles; the addition-type curing system is used, and no by-products are generated in the crosslinking reaction process, eliminating micropore defects caused by the volatilization of chemical reaction by-products inside the insulating layer.

[0016] Preferably, in the step of removing air bubbles, the uniformly mixed solution is placed in a vacuum oven for treatment; in the step of uniformly pouring the defoamed solution into the mold, the defoamed solution is uniformly poured into a flat mold or a pre-embedded needle mold for partial discharge testing for molding.

[0017] By employing the above technical solutions, vacuum treatment can extract microbubbles entrained during stirring and material mixing. Air bubbles inside the insulating medium are prone to ionization and discharge under a strong electric field; vacuum debubbling eliminates the inducing factors for internal air gap discharge. Combined with the molding of different molds, it meets the process requirements for standardized electrical performance testing and actual device potting.

[0018] Preferably, the thickness of the cured high-insulation silicone gel is 300 μm to 3 mm. By adopting the above technical solution, the determined thickness range meets the electrical insulation gap requirements in the packaging of high-power SiC device modules, while ensuring that the internal reaction heat can be dissipated in time when the mixed solution is cured and formed inside the mold, preventing internal stress caused by inconsistent curing rates between the inside and outside due to excessive thickness.

[0019] Secondly, the present invention provides an application of highly insulating silicone gel in SiC device packaging.

[0020] This invention provides a method for preparing a high-insulation silicone gel for SiC device packaging and its application. It has the following beneficial effects: 1. This invention directly disperses crystalline anthrone in an organosilicon gel matrix. The preparation process only requires physical stirring at room temperature, without the need for surface modification of the filler, thus avoiding the problems of increased system viscosity and easy agglomeration introduced by traditional inorganic nanoparticle doping. Furthermore, compared to molecular side-chain chemical synthesis modification methods, the physical blending combined with room-temperature hydrosilylation curing process of this invention does not produce chemical byproducts, resulting in a simple preparation process and good engineering feasibility.

[0021] 2. This invention utilizes the difference in dielectric properties between anthrone crystals and the organosilicon gel matrix to form a microscopic physical phase interface to construct deep traps, and utilizes the polar carbonyl group of the anthrone molecule to construct shallow traps. The synergistic effect of deep and shallow traps captures charge carriers to suppress space charge accumulation on the one hand, and dissipates electron kinetic energy to weaken impact ionization on the other. This mechanism alleviates the electric field distortion inside the SiC device package caused by triple bonding points, improves the breakdown strength and partial discharge initiation voltage of the composite insulating material, and reduces the frequency of partial discharge under high voltage conditions.

[0022] 3. This invention, by limiting the anthrone doping ratio and combining it with vacuum degassing, eliminates internal air gap defects without compromising the low elastic modulus of the cross-linked gel matrix, thus preserving the material's buffering capacity against the thermomechanical stress generated by the switching cycles of SiC devices. Furthermore, the appropriate doping of anthrone crystals increases the initial thermogravimetric temperature of the composite insulating material, improving its overall heat resistance and meeting the thermal stability requirements of next-generation wide-bandgap semiconductor SiC devices under high operating temperatures and high withstand voltage environments. Attached Figure Description

[0023] Figure 1 This is a flowchart of the preparation method of the present invention; Figure 2 The X-ray diffraction pattern of the organosilicon gel composite insulating material and anthrone in the test examples of this invention; Figure 3 The Fourier transform infrared spectra of composite insulating materials containing different contents of anthrone organosilicon gels in the test examples of this invention are shown below. Figure 4 The Weibull distribution probability diagram of the breakdown voltage of the composite insulating material and the organosilicon gel film prepared in the test example of the present invention under AC voltage; Figure 5 This is a partial discharge initiation voltage diagram of the composite insulating material and organosilicon gel in the test examples of this invention; Figure 6 This is a partial discharge time-domain diagram of Comparative Example 1, in which the composite insulating material and organosilicon gel are subjected to a voltage of 6.5 kV for 600 s. Figure 7This is a partial discharge time-domain diagram of Example 2, in which the composite insulating material and organosilicon gel were subjected to a voltage of 6.5 kV for 600 s in the test examples of this invention. Figure 8 This is a partial discharge time-domain diagram of Example 1, in which the composite insulating material and organosilicon gel were subjected to a voltage of 6.5 kV for 600 s in the test examples of this invention. Figure 9 This is a partial discharge time-domain diagram of Example 3, in which the composite insulating material and organosilicon gel were subjected to a voltage of 6.5 kV for 600 s in the test examples of this invention. Figure 10 This is a partial discharge time-domain diagram of Example 4, in which the composite insulating material and organosilicon gel were subjected to a voltage of 6.5 kV for 600 s in the test examples of this invention. Figure 11 This is a schematic diagram showing the number of discharges of the composite insulating material and organosilicon gel under a 6.5kV voltage for 600s in the test examples of this invention; Figure 12 This is a diagram showing the trap energy levels and depths of composite insulating materials with different anthrone contents in the test examples of this invention. Figure 13 The relative permittivity diagram of the anthrone-organosilicon gel composite insulating materials with different contents in the test examples of this invention is shown. Figure 14 In the test examples of this invention, in 10 -1 Up to 10 6 Dielectric constant and dielectric loss diagram at Hz frequency; Figure 15 Thermogravimetric analysis (TGA) diagram of the composite insulating material with a total anthrone content of 0.5 wt% and the organosilicon gel in the test examples of this invention. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] raw material: The main component of silicone gel component A is vinyl-containing polymethylsiloxane, chemically named vinyl-terminated polydimethylsiloxane, CAS number 68083-19-2. The main molecular chain of this polymer compound is composed of alternating silicon-oxygen bonds, and its repeating unit is dimethylsiloxane, with the structural formula [-O-Si(CH3)2-]. The molecular chain contains active vinyl groups (-CH=CH2), and the structure is linearly arranged. It is a transparent liquid at room temperature and serves as the polymer matrix for addition-type silicone gels.

[0026] The main component of organosilicon gel component B is a hydrogen-containing polymethylsiloxane with a chemical name of polymethylhydrosiloxane and CAS number 63148-57-2. The molecular chain of this polymer compound contains multiple repeating units of methylhydrosiloxane with the structural formula [-O-Si(H)(CH3)-]. The molecular side chain has highly active silicon-hydrogen bonds (Si-H). It is a transparent liquid at room temperature and acts as a crosslinking agent to undergo an addition curing reaction with the vinyl groups in organosilicon gel component A at room temperature.

[0027] Preparation Examples 1-3: Preparation Example 1: This preparation example provides a method for preparing a premixed solution of organosilicon gel component A and anthrone, including the following steps: Add the accurately weighed organosilicon gel component A according to the formula requirements to the container, and then add the crystalline anthrone weighed according to the formula ratio. Stir at room temperature using a stirring device with a speed of 300 r / min for 12 hours to make the crystalline anthrone evenly dispersed in organosilicon gel component A, and obtain a premixed solution.

[0028] Preparation Example 2: This preparation example provides a method for preparing a premixed solution of organosilicon gel component A and anthrone, including the following steps: Add the accurately weighed organosilicon gel component A according to the formula requirements to the container, and then add the crystalline anthrone weighed according to the formula ratio. Stir at room temperature using a stirring device with a speed of 500 r / min for 6 hours to make the crystalline anthrone evenly dispersed in organosilicon gel component A, and obtain a premixed solution.

[0029] Preparation Example 3: This preparation example provides a method for preparing a premixed solution of organosilicon gel component A and anthrone, including the following steps: Add the accurately weighed organosilicon gel component A according to the formula requirements to the container, and then add the crystalline anthrone weighed according to the formula ratio. Stir at room temperature using a stirring device with a speed of 100 r / min for 24 hours to make the crystalline anthrone evenly dispersed in organosilicon gel component A, and obtain a premixed solution. Examples 1-5: Example 1:

[0030] This embodiment provides a method for preparing a high-insulation silicone gel for SiC device packaging, and the preparation method flow is as follows: Figure 1 As shown, it includes the following steps: (1) According to the ratio of 0.5wt% anthrone content in the high-insulation silicone gel, accurately weigh the required proportion of silicone gel component A and anthrone, and prepare a uniformly dispersed premixed liquid according to the method of Preparation Example 1. (2) Add organosilicon gel component B to the premixed solution, wherein the mass ratio of organosilicon gel component A to organosilicon gel component B is 10:1, and stir vigorously for 15 minutes to make the solution evenly mixed. (3) Add the well-mixed solution to a vacuum oven and vacuum-evacuate for 15 minutes to remove air bubbles introduced during stirring and other processes; (4) Pour the defoamed solution evenly into the flat plate mold and the pre-embedded needle mold for partial discharge testing, and cure at room temperature for 12 hours to obtain silicone gel composite films with thicknesses of 300μm, 500μm, and 1000μm, as well as a sample for partial discharge testing with a thickness of 3mm and an area of ​​30mm×40mm (denoted as SG-ET0.5). Example 2:

[0031] This embodiment provides a method for preparing a high-insulation silicone gel for SiC device packaging, and the preparation method flow is as follows: Figure 1 As shown, it includes the following steps: (1) According to the ratio of 0.25wt% anthrone content in the high-insulation silicone gel, accurately weigh the required proportion of silicone gel component A and anthrone, and prepare a uniformly dispersed premixed liquid according to the method of Preparation Example 1. (2) Add organosilicon gel component B to the premixed solution, wherein the mass ratio of organosilicon gel component A to organosilicon gel component B is 10:1, and stir vigorously for 15 minutes to make the solution evenly mixed. (3) Add the well-mixed solution to a vacuum oven and vacuum-evacuate for 15 minutes to remove air bubbles introduced during the stirring process; (4) Pour the defoamed solution evenly into the flat plate mold and the pre-embedded needle mold for partial discharge testing, and cure at room temperature for 12 hours to obtain silicone gel composite films with thicknesses of 300μm, 500μm, and 1000μm, as well as a sample for partial discharge testing with a thickness of 3mm and an area of ​​30mm×40mm (denoted as SG-ET0.25). Example 3:

[0032] This embodiment provides a method for preparing a high-insulation silicone gel for SiC device packaging, and the preparation method flow is as follows: Figure 1 As shown, it includes the following steps: (1) According to the ratio of 0.75wt% anthrone content in the high-insulation silicone gel, accurately weigh the required proportion of silicone gel component A and anthrone, and prepare a uniformly dispersed premixed liquid according to the method of Preparation Example 1. (2) Add organosilicon gel component B to the premixed solution, wherein the mass ratio of organosilicon gel component A to organosilicon gel component B is 10:1, and stir vigorously for 15 minutes to make the solution evenly mixed. (3) Add the well-mixed solution to a vacuum oven and vacuum-evacuate for 15 minutes to remove air bubbles introduced during the stirring process; (4) Pour the defoamed solution evenly into the flat plate mold and the pre-embedded needle mold for partial discharge testing, and cure at room temperature for 12 hours to obtain silicone gel composite films with thicknesses of 300μm, 500μm, and 1000μm, as well as a sample for partial discharge testing with a thickness of 3mm and an area of ​​30mm×40mm (denoted as SG-ET0.75). Example 4:

[0033] This embodiment provides a method for preparing a high-insulation silicone gel for SiC device packaging, and the preparation method flow is as follows: Figure 1 As shown, it includes the following steps: (1) According to the ratio of 1.0 wt% anthrone content in the high-insulation silicone gel, accurately weigh the required proportion of silicone gel component A and anthrone, and prepare a uniformly dispersed premixed liquid according to the method of Preparation Example 1. (2) Add organosilicon gel component B to the premixed solution, wherein the mass ratio of organosilicon gel component A to organosilicon gel component B is 10:1, and stir vigorously for 15 minutes to make the solution evenly mixed. (3) Add the well-mixed solution to a vacuum oven and vacuum-evacuate for 15 minutes to remove air bubbles introduced during the stirring process; (4) Pour the defoamed solution evenly into the flat plate mold and the pre-embedded needle mold for partial discharge testing, and cure at room temperature for 12 hours to obtain silicone gel composite films with thicknesses of 300μm, 500μm, and 1000μm, as well as a sample for partial discharge testing with a thickness of 3mm and an area of ​​30mm×40mm (denoted as SG-ET1). Example 5:

[0034] This embodiment provides a method for preparing a high-insulation silicone gel for SiC device packaging, and the preparation method flow is as follows: Figure 1 As shown, it includes the following steps: (1) According to the ratio of 0.1 wt% anthrone content in the high-insulation silicone gel, accurately weigh the required proportion of silicone gel component A and anthrone, and prepare a uniformly dispersed premixed liquid according to the method of preparation example 2. (2) Add organosilicon gel component B to the premixed solution, wherein the mass ratio of organosilicon gel component A to organosilicon gel component B is 10:1, and stir vigorously for 15 minutes to make the solution evenly mixed. (3) Add the well-mixed solution to a vacuum oven and vacuum-evacuate for 15 minutes to remove air bubbles introduced during the stirring process; (4) Pour the defoamed solution evenly into the flat plate mold and the pre-embedded needle mold for partial discharge testing, and cure at room temperature for 12 hours to obtain silicone gel composite films with thicknesses of 300μm, 500μm, and 1000μm, as well as a sample for partial discharge testing with a thickness of 3mm and an area of ​​30mm×40mm.

[0035] Comparative Examples 1-4: Comparative Example 1: Compared with Example 1, the difference is that no anthrone filler was added, that is, the anthrone content was 0 wt%, and a pure organosilicon gel (denoted as SG) was obtained, while the rest were the same.

[0036] Comparative Example 2: The difference from Example 1 is that anthrone is replaced with an equal mass fraction of conventional inorganic nanoparticles (such as nano-SiO2), otherwise they are the same.

[0037] Comparative Example 3: Compared with Example 1, the difference is that a purely physical blending process was not used. Instead, a chemical reaction grafting method was used to graft modified groups onto the side chains of the organosilicon gel matrix. All other aspects are the same.

[0038] Comparative Example 4: The difference from Example 1 is that the amount of anthrone added is 3.0 wt%, while the rest are the same.

[0039] Test Examples 1-7: Test Example 1: Microstructure and Compatibility Test The surfaces of the 300 μm thick silicone gel film samples prepared in Examples 1 to 4 and Comparative Example 1 were wiped clean and cut into test pieces with a size of 20 mm × 20 mm. An appropriate amount of untreated pure anthrone powder was also prepared as a control sample.

[0040] X-ray diffraction (XRD) was used to analyze the crystal structure of each test sample and pure anthrone powder. The test conditions were set as follows: copper target Kα radiation, tube voltage 40 kV, tube current 40 mA. The scanning range 2θ was set from 5 to 60 degrees, and the scanning rate was 5 degrees / minute. XRD patterns of each sample were acquired.

[0041] Fourier transform infrared spectroscopy was used to analyze the chemical groups and molecular structure of the samples. An attenuated total reflectance accessory was used, and the atmospheric background spectrum was acquired and subtracted before testing. The spectral scanning range was set to 400 cm⁻¹. -1 Up to 4000cm -1 4cm resolution-1 The infrared transmission spectrum data of each sample at different wavenumbers were obtained by scanning 32 times.

[0042] Table 1. XRD and FTIR characteristic peak intensity test data of each embodiment and comparative sample Based on the data in Table 1 and the corresponding appendix Figure 2 and attached Figure 3 The analysis is as follows: Appendix Figure 2 The horizontal axis represents 2Theta (diffraction angle 2θ, in °), and the vertical axis represents Intensity (diffraction intensity, in arbitrary units). The graph includes the SG curve representing pure organosilicon gel and the SG-ET curve representing the composite materials of each embodiment. 0.25 To SG-ET 1.0 A series of curves, and an ET curve representing pure anthrone powder. (See attached image.) Figure 2 It can be seen that the SG curve did not show sharp crystalline diffraction peaks, and the matrix exhibited characteristics of an amorphous polymer. With the increase of anthrone blend content, characteristic peaks appeared in the SG-ET series curves at 2θ of 11.4° and 14.4°, and the positions of these characteristic peaks corresponded exactly to the positions of the strongest diffraction peaks in the ET curve (pure anthrone). The peak intensity increased from SG-ET... 0.25 To SG-ET 1.0 The growth gradually increases. This indicates that the intrinsic crystal structure of anthrone in crystalline form was not destroyed during the preparation of the amorphous organosilicon gel. Anthrone is mainly dispersed in the polymer network in the form of a crystalline phase, and the two exhibit the micro-phase separation characteristics of physical blending.

[0043] Appendix Figure 3 The horizontal axis represents the wave number (in cm). -1 The vertical axis represents transmission. The absorption bands of each group of SG-ET samples are consistent with those of the SG samples in most wavenumber regions, indicating that the main chain structure of polymethylsiloxane remains unchanged. At 1650 cm⁻¹... -1 (Corresponding to the C=O bond stretching vibration in the anthrone molecule) and 1580 cm⁻¹ -1 At the position corresponding to the C=C stretching vibration of the benzene ring in the anthrone molecule, when the anthrone blend content is low (0.25wt% and 0.5wt%), the transmittance change is not significant due to the instrument detection limit; when the blend content reaches 0.75wt% and above, obvious characteristic peaks are detected at these two wavenumbers, corresponding to the substantial decrease in transmittance values ​​in Table 1. No absorption peaks of new functional groups generated by chemical cross-linking were detected in the spectrum, indicating that anthrone was successfully blended into the organosilicon gel matrix.

[0044] The above tests confirmed the physical blending and microscopic phase separation mechanism within the composite material. Anthrone and polymethylsiloxane did not undergo complex chemical side reactions. This phase separation structure allows the composite material to maintain the flexibility and low viscosity processing characteristics of the silica gel itself, while simultaneously forming extensive physical phase interfaces between the amorphous silica gel matrix and the crystalline anthrone. These phase interfaces constitute numerous deep traps within the material, effectively capturing and confining high-energy charge carriers under high fields, limiting carrier mobility, and reducing electrical conduction losses. The tiny defects in the anthrone lattice itself and its inherent polar carbonyl groups constitute shallow traps, consuming carrier kinetic energy through frequent transient capture and release. The synergistic effect of deep and shallow traps is based on this multiphase physical structure, thereby regulating the charge transport behavior within the composite material and improving the uniformity of the electric field distribution.

[0045] Test Example 2: AC Breakdown Characteristics Test The surfaces of the 500 μm thick silicone gel film samples prepared in Examples 1 to 4 and Comparative Example 1 were wiped clean with anhydrous ethanol and placed in a vacuum drying oven for static removal treatment. The thickness was measured at five points around the center of the test area of ​​each sample using a high-precision thickness gauge, and the average measured value was recorded for electric field strength calculation.

[0046] The sample to be tested is fixed between the test electrodes of the electrical insulation breakdown tester. The test electrodes are standard stainless steel ball-ball electrode pairs with a diameter of 25 mm. To prevent flashover discharge on the surface and edges of the sample when high voltage is applied, the entire test electrode assembly with the sample fixed is immersed in insulating dimethyl silicone oil.

[0047] The AC power supply output frequency was set to 50Hz (power frequency), and the maximum output voltage range was set to 50kV. A continuous, uniform voltage ramp-up mode was used to apply AC voltage to the test electrodes, with the ramp-up rate set to 2kV / s. The critical voltage value at the moment the sample was broken down and a through-discharge channel was formed was observed and recorded.

[0048] Fifteen independent breakdown tests were performed on each sample with different ratios, and the breakdown voltage data was recorded for each test. The breakdown voltage value was divided by the actual thickness of the sample at the corresponding test point to calculate the breakdown field strength. The data was extracted and statistically fitted using a two-parameter Weibull distribution function to calculate the characteristic breakdown field strength corresponding to a cumulative failure probability of 63.2%.

[0049] Table 2. Test data of AC breakdown characteristics and Weibull distribution parameters for each group of samples. Note: "-" indicates that Comparative Example 1 is used as the benchmark reference group for calculating the improvement range and does not involve the corresponding improvement range calculation.

[0050] Based on the data in Table 2 and the corresponding appendix Figure 4 The analysis is as follows: Appendix Figure 4 The Weibull distribution probability plots of the breakdown voltage of the prepared silicone gel composite insulating material and the pure silicone gel film under AC voltage are shown. A 50Hz AC voltage was used during the test, and the maximum applied voltage of the test equipment was 50kV. In the figure, the horizontal axis represents the breakdown field strength (kV / mm), and the vertical axis represents the cumulative failure probability (%). When the cumulative failure probability on the vertical axis reaches 63.2%, the value on the horizontal axis corresponding to the fitted line is the characteristic breakdown field strength of the sample.

[0051] As shown in the figure, the breakdown field strength of Comparative Example 1 (SG) is 18.64 kV / mm. With the increase of anthrone blend content, the breakdown field strength of the composite insulation material shows a trend of first increasing and then decreasing. Specifically, Example 1 (SG-ET) 0.5 The characteristic breakdown field strength of the sample was the highest, reaching 22.56 kV / mm, which was 21.03% higher than that of Comparative Example 1 (SG). When the doping amount was further increased to 0.75 wt% and 1.0 wt%, the characteristic breakdown field strength decreased to 21.43 kV / mm and 20.21 kV / mm, respectively.

[0052] The aforementioned variation in AC breakdown voltage performance is controlled by the synergistic regulation mechanism of microscopic phase separation and deep / shallow traps within the material. In pure organosilicon gel, charge carriers readily accumulate kinetic energy and trigger electron avalanches under high AC fields. When an appropriate amount (0.5 wt% or less) of anthrone is introduced using a pure physical blending process, a wide physical phase interface is formed between the amorphous organosilicon matrix and the intact crystalline anthrone. These interfaces construct high-density deep traps within the material, effectively capturing and binding high-energy charge carriers and limiting the mean free path of electrons. Simultaneously, the polar carbonyl groups and lattice defects inherent in the anthrone molecule constitute shallow traps, which consume the kinetic energy acquired by charge carriers in the electric field through frequent transient capture and release. The synergistic effect of deep and shallow traps hinders the accumulation of space charge and the migration of high-energy electrons, effectively suppressing the collisional ionization process, thereby increasing the macroscopic AC breakdown field strength threshold of the material.

[0053] When the anthrone doping concentration exceeds the preferred range (greater than 0.5 wt%), excessive crystal particles physically aggregate within the polymer network. This aggregation reduces the specific surface area and the effective phase interface, resulting in a decrease in the density and depth of deep traps. Simultaneously, filler aggregation disrupts the structural uniformity of the gel matrix, and overlapping local defect sites form microscopic conductive channels, leading to severe distortion of the internal electric field. Under a high-voltage AC electric field, these distorted regions are more prone to inducing partial discharge and developing into penetrating dendritic channels, causing a decline in the breakdown field strength.

[0054] Test Example 3: Partial Discharge Initiation Voltage (PDIV) Test Pre-cured embedded needle test samples were selected. Silicone gel composite material and pure silicone gel were cured in a 40mm × 30mm × 3mm mold containing embedded needles, with the distance from the internal needle tip to the ground electrode controlled at 2mm. This needle-plate electrode structure was used to simulate the electric field distortion at the three-junction point in a high-voltage, high-power power electronic device.

[0055] The pre-embedded needle sample is fixed in an insulating container on the partial discharge test platform, and the container is filled with dimethyl silicone oil to prevent surface flashover during the test. The needle electrode leads of the sample are connected to a partial discharge-free power frequency high-voltage AC power supply, and the plate electrode leads are reliably grounded.

[0056] A high-frequency current sensor (HFCT) is connected in series in the grounding loop. The HFCT is used to acquire partial discharge signals, and its signal output is connected to the partial discharge detector and oscilloscope via a coaxial cable.

[0057] Set the test power supply frequency to 50Hz. Turn on the test equipment and apply AC voltage, increasing it uniformly from zero at a rate of 0.1kV / s. During the test, monitor the partial discharge signal acquired by the HFCT. Since the average background noise of the test environment is 0.9mV, according to the signal-to-noise ratio principle of 3:1, signals of 2.7mV and above are set as valid partial discharge signals.

[0058] When the detection system continuously observes discharge pulse signals with an amplitude of 2.7mV or higher, the voltage boost is stopped, and the applied voltage value at this time is recorded as the partial discharge initiation voltage (PDIV). Five parallel samples are selected for each ratio for repeated testing, and the data are recorded and the average value is calculated.

[0059] Table 3. Partial Discharge Initiation Voltage (PDIV) Test Data for Each Group of Samples Note: "-" indicates that Comparative Example 1 is used as the benchmark reference group for calculating the improvement range and does not involve the corresponding improvement range calculation.

[0060] Based on the data in Table 3 and the corresponding appendix Figure 5 The analysis is as follows: Figure 5 The partial discharge initiation voltage is defined as the composite insulating material and silicone gel. Before the partial discharge test, the silicone gel composite material was cured in a mold with dimensions of 40mm×30mm×3mm and a pre-embedded needle. The distance from the needle tip to the ground electrode was 2mm. The needle plate electrode was used to simulate the electric field distortion at the three junction point in a high-voltage, high-power power electronic device. An AC voltage was applied, and the partial discharge signal was acquired by HFCT. The average background noise was 0.9mV. According to the principle of signal-to-noise ratio of 3:1, signals of 2.7mV and above were collected as partial discharge signals.

[0061] Depend on Figure 5 As shown in Table 3, the partial discharge initiation voltage of Comparative Example 1 (SG) was 3.1 kV. The partial discharge initiation voltage initially increased and then decreased with increasing anthrone blending level. Specifically, Example 1 (SG-ET) 0.5 The highest partial discharge initiation voltage of the sample was 4.8 kV, which was 54.84% higher than that of Comparative Example 1 (SG). When the amount of anthrone added was further increased to 0.75 wt% and 1.0 wt%, the partial discharge initiation voltage values ​​dropped to 3.8 kV and 3.3 kV, respectively.

[0062] The aforementioned variation in the partial discharge initiation voltage is related to the synergistic regulation mechanism of deep and shallow traps based on physical blending within the material. In the highly non-uniform electric field formed by the pre-embedded needle plate electrode, charge injection and collisional ionization easily occur at the tip of the pure organosilicon gel, leading to partial discharge at a relatively low voltage. After incorporating an appropriate amount of anthrone into the organosilicon gel matrix, a physical phase interface is formed between the intact crystalline anthrone and the amorphous gel. These interfaces introduce a large number of deep traps within the material, effectively capturing homopolar charge carriers injected from the needle tip under high electric fields. The captured charges accumulate near the needle tip to form a homopolar space charge layer, generating a reverse shielding electric field that weakens the strongest distorted electric field at the needle tip. Simultaneously, the shallow traps in the anthrone molecular structure consume the kinetic energy of high-energy charge carriers through frequent transient capture and release processes. The synergistic effect of deep and shallow traps improves the microscopic electric field distribution in the needle tip region, suppresses collisional ionization caused by local electric field concentration, and thus increases the macroscopic partial discharge initiation voltage.

[0063] When the anthrone doping concentration exceeds 0.5 wt%, the excess crystalline anthrone filler agglomerates within the gel matrix. This agglomeration reduces the filler's specific surface area and the effective phase interface, leading to a decrease in the density of deep traps and weakening the shielding effect of the space charge layer on the distorted electric field. Filler agglomeration also introduces physical defects into the polymer network, resulting in microscopic interfacial gaps or stress concentrations in localized areas. These defective sites are prone to further electric field distortion and induction of initial discharge under the influence of an electric field, causing the partial discharge initiation voltage of the material to decrease with increasing doping concentration.

[0064] Test Example 4: High Voltage Withstand and Partial Discharge Cycle Test Pre-cured embedded needle test samples were selected. The distance from the needle tip to the ground electrode inside the mold was controlled to be 2 mm. This needle-plate electrode structure was used to simulate the extremely non-uniform electric field distortion points inside the device. The sample was fixed in an insulating container, and dimethyl silicone oil was injected to prevent surface flashover. The needle electrode was connected to a high-voltage AC power supply, and the plate electrode was grounded.

[0065] A high-frequency current sensor (HFCT) is connected in series in the grounding loop to couple the partial discharge pulse signal. The output of the HFCT is connected to the partial discharge detection and data acquisition system. The background noise threshold of the test environment is set to filter out interference signals below 2.7mV.

[0066] Set the AC power frequency to 50Hz. Turn on the power and gradually increase the voltage to 6.5kV, maintaining a constant level. Start data logging and continuously apply voltage for 600 seconds.

[0067] Partial discharge events occurring during the 600s constant voltage test were monitored and recorded in real time. The total number of partial discharge pulses with a discharge amplitude greater than or equal to 2.7mV was counted, and the maximum amplitude of a single discharge was recorded. Five parallel samples were selected for each formulation, and the above 600s withstand voltage test was repeated. The number of partial discharges was counted, and the average value was calculated.

[0068] Table 4. Partial discharge characteristic test data of each group of samples within 600s under a constant AC voltage of 6.5kV. Based on the data in Table 4, combined with the appendix Figure 6 - Appendix Figure 11 The analysis is as follows: Figures 6-10 The horizontal axis represents time in seconds (s), and the vertical axis represents discharge amplitude in mV. Partial discharge test samples of different organosilicon gel composite insulation materials were subjected to a 6.5kV AC voltage for 600s, and all partial discharge signals above 2.7mV were collected and plotted in the time domain. As shown in the figure, SG-ET... 0.5 The number and amplitude of partial discharges were significantly reduced compared to SG.

[0069] Figure 11 The horizontal axis represents "Sample" (different test sample ratios), and the vertical axis represents "Number" (total number of partial discharges within 600 seconds). By statistically analyzing the number of partial discharge signals greater than 2.7 mV for different samples under a 600-second pressurization at 6.5 kV using time-domain plots, it was found that the number of partial discharges first decreased and then increased with increasing anthrone blend concentration, decreasing from 265 in Comparative Example 1 (SG) to [a decrease in Example 1 (SG-ET)]. 0.5 42 times. When the anthrone doping amount continued to increase to 0.75 wt% and 1.0 wt%, Example 4 (SG-ET) 1.0 The number of partial discharges rebounded to 550, and the discharge amplitude increased again.

[0070] The discharge evolution during the high-voltage withstand process verifies the dynamic regulation mechanism of space charge by deep and shallow traps within the physical blend system. Under a continuous high voltage of 6.5 kV, the needle-plate structure generates a highly non-uniform local distorted electric field, prompting charge injection into the matrix. Pure organosilicon gel lacks a charge trapping mechanism; the injected charge gains kinetic energy under a strong field, triggering collisional ionization, resulting in frequent and large-amplitude local discharges. When 0.5 wt% crystalline anthrone is incorporated, the microscopic physical phase interface formed between the intact anthrone crystals and the silica gel matrix provides deep traps. These deep traps trap the injected charges of the same polarity under continuous high voltage, forming a space charge shielding layer around the needle tip, weakening the actual electric field strength at the tip tip. The shallow traps formed by the polar groups of the anthrone molecules consume the kinetic energy of residual free electrons through the trapping and releasing process, making it difficult for them to reach the energy threshold of collisional ionization. The synergistic effect of the trap network suppresses electron avalanche, reducing the number of macroscopic discharge pulses and substantially suppressing the discharge intensity.

[0071] When the anthrone doping concentration exceeds 0.5 wt%, the crystalline anthrone physically aggregates in the gel network due to the excessively high filler concentration, disrupting the uniformity of microscopic phase separation. Aggregation leads to a reduction in the total interfacial area, a decrease in deep trap density, and an unstable space charge shielding layer, making it difficult to continuously resist charge injection induced by high voltage. Lattice dislocations and gaps exist within the aggregates, introducing micron-level physical defects or air gaps into the polymer matrix. Under a high-intensity electric field of 6.5 kV, these microscopic defects experience localized electric field concentration, becoming new discharge origin points within the material. This results in multi-point concurrent collisional ionization within the composite material, macroscopically manifested as an exponential increase in the number of partial discharges and a rise in discharge amplitude.

[0072] Test Example 5: Trap Energy Level and Depth Test (Surface Potential Decay Experiment) Samples of silicone gel and composite insulating material with a thickness of 1 mm prepared in Examples 1 to 4 and Comparative Example 1 were selected. The surface of the samples was cleaned with anhydrous ethanol and then placed in a vacuum environment to eliminate residual static electricity and internal stress.

[0073] The sample to be tested was placed in a surface potential decay test platform under constant temperature and humidity. The platform uses a corona discharge device to inject charge into the sample. The high-voltage DC power supply was adjusted to apply a DC high voltage corresponding to a field strength of 10 kV / mm (i.e., apply a 10 kV voltage) to the sample, and the voltage was maintained continuously for 15 minutes to allow the charge to be injected and reach saturation inside the sample.

[0074] After applying pressure for 15 minutes, quickly remove the DC voltage and immediately move the sample directly under the non-contact electrostatic probe, adjusting the test distance between the probe and the sample surface. Turn on the data acquisition system and continuously measure and record the decay of the sample surface potential over 40 minutes.

[0075] The 40-minute surface potential decay time series data were extracted and the data were used to perform differential calculations using the isothermal surface potential decay theoretical model to obtain the trap energy level and corresponding trap depth distribution of each group of samples.

[0076] Table 5. Trap energy levels and density test data for each group of samples. Based on the data in Table 5, combined with the appendix Figure 12 The analysis is as follows: Figure 12 The horizontal axis represents the Trap Level (depth of the trap energy level in eV); the vertical axis represents the Trap Density (density of the trap in eV). -1 ·m -3 The bimodal structure on the curve corresponds to the distribution of shallow and deep traps, respectively. As mentioned above, a surface potential decay experiment was conducted on a 1 mm thick sample. A DC voltage of 10 kV / mm was applied to the sample for 15 min, and the decay of the sample surface potential was measured immediately after the voltage was removed. The measurement was performed for 40 min, and the trap energy level and depth in the graph were calculated.

[0077] The data shows that the peak density of shallow traps in Comparative Example 1 (SG) is 1.28 × 10⁻⁶. 18 eV -1 ·m -3 The peak density of deep traps is 7.85 × 10⁻⁶. 18 eV -1 ·m -3 With increasing anthrone doping concentration, the densities of deep and shallow traps in the composite system initially increase and then decrease. Example 1 (SG-ET) 0.5The density of both deep and shallow traps reached its highest level, with the peak density of shallow traps increasing to 2.87 × 10⁻⁶. 18 eV -1 ·m -3 The deep trap level shifts towards deeper levels to 0.96 eV, and its peak density reaches 9.82 × 10⁻⁶ eV. 18 eV -1 ·m -3 When the doping concentration is further increased to 0.75wt% and 1.0wt%, the trap energy level becomes shallower, and the trap density decreases accordingly.

[0078] The variation patterns of the trap properties described above reveal the physical regulation mechanism within the composite system. It was found that anthrone introduced into the organosilicon gel forms deep traps at the interface, confining the movement of charge carriers. At appropriate concentrations, a wide physical phase interface is formed between the intact crystalline anthrone and the amorphous organosilicon gel matrix. The potential barrier difference at these interfaces constructs a high-density deep trap, which can effectively capture externally injected high-energy charge carriers and form a local space charge shielding layer, weakening local electric field distortion. Simultaneously, shallow-level defects and polar groups in the anthrone lattice form shallow traps, exerting a transient binding effect on charge carriers and consuming the kinetic energy acquired by the charge carriers under the influence of the electric field through the capture and release process. The synergistic introduction of deep and shallow traps regulates the charge transport behavior within the composite material, suppressing carrier migration and collisional ionization, providing a structural basis for optimizing its dielectric properties.

[0079] When the anthrone content exceeds 0.5 wt%, the excess crystalline filler undergoes physical aggregation in the polymer matrix, leading to a reduction in the total interfacial area. This physical aggregation causes overlap of local trap regions, lowering the potential barrier height, resulting in shallower and less dense deep trap energy levels. The ability of deep traps to confine high-energy charges weakens, reducing the space charge shielding effect, and causing the insulation performance of the material under high-voltage electric fields to decrease with increasing doping concentration.

[0080] Test Example 6: Dielectric Constant and Dielectric Loss Test Samples of silicone gel and composite insulating material with a thickness of 1 mm, prepared in Examples 1 to 4 and Comparative Example 1, were selected. The samples were cut into 20 mm diameter discs, cleaned with anhydrous ethanol, and dried in a vacuum environment. Metal electrodes with a diameter of 20 mm were sputtered or coated onto the upper and lower surfaces of the samples to ensure good contact between the samples and the test probe during testing.

[0081] The surface-treated test sample is placed in the test fixture of the broadband dielectric spectrometer, and the fixture electrodes are adjusted to apply a fixed clamping force to the sample to avoid air gaps at the test interface.

[0082] The test environment temperature was set to a constant room temperature of 25℃. The test frequency range was set to 10 in the broadband dielectric spectrometer control software. -1 Hz to 10 6 Hz, AC test voltage is set to 1V RMS.

[0083] The testing equipment is started, and the instrument automatically performs logarithmic frequency sweep measurements within the set frequency range. The system continuously acquires and records the capacitance and loss tangent values ​​of the sample at different frequency points, and automatically calculates and outputs the relative permittivity and dielectric loss data corresponding to each frequency point based on the input sample thickness and electrode area parameters. The test results are extracted for subsequent analysis.

[0084] Table 6. Test data of dielectric constant and dielectric loss of each group of samples at different frequencies Based on the data in Table 6, combined with the appendix Figure 13 and attached Figure 14 The analysis is as follows: Figure 13 The horizontal axis represents Frequency (test frequency, in Hz), and the vertical axis represents Dilectric Constant (relative permittivity). Figure 14 The horizontal axis represents Frequency (test frequency, in Hz), and the vertical axis represents Dielectric Loss Tangent. Tests were performed on each group of samples, and the dielectric loss was obtained at 10... -1 Up to 10 6 Dielectric constant and dielectric loss data at Hz frequency.

[0085] The data in the charts show that the dielectric constant of each sample group remained stable over the wide testing range. The dielectric constant of Comparative Example 1 (SG) remained around 2.67. After the introduction of anthrone, the dielectric constant of the composite material showed a trend of first increasing and then decreasing with increasing doping concentration. Example 1 (SG-ET) 0.5 Compared to Comparative Example 1 (SG), the dielectric constant increased from 2.67 to 2.92. When the anthrone doping concentration continued to increase to 0.75 wt% and 1.0 wt%, the dielectric constant decreased, as in Example 4 (SG-ET). 1.0 The dielectric constant of ) decreased to around 2.47. Meanwhile, Example 1 (SG-ET) 0.5 The dielectric loss also decreased slightly.

[0086] The increase in dielectric constant is attributed to the polar carbonyl groups present in the anthrone molecule. At a physical blending concentration of 0.5 wt%, intact crystalline anthrone is uniformly dispersed within an amorphous organosilicon gel network. Under an alternating current field, the uniformly dispersed polar carbonyl groups undergo dipole orientation polarization in accordance with the direction of the external electric field. This enhanced polarization effect increases the overall polarizability of the system, manifested as an increase in the relative dielectric constant. The dielectric constant increases from 2.67 to 2.92, reducing the dielectric mismatch between the insulating potting material and the high-dielectric ceramic substrate and semiconductor chip. This results in a smoother transition of dielectric parameters, which is beneficial for mitigating electric field distortion at the triple junction of high-voltage, high-power power electronic devices.

[0087] The reduction in dielectric loss is controlled by the evolution of the micro-interfaces within the material. The phase interfaces formed by physical blending construct high-density deep traps. These deep traps effectively capture charge carriers, limiting the long-range migration of free charges and suppressing conductivity loss. Simultaneously, the ordered interface structure reduces the polarization relaxation loss of polar groups under alternating electric fields, thereby lowering the overall dielectric loss. This low-loss characteristic reduces the risk of heat generation in the material under high AC electric fields, which is beneficial for the application of composite insulating materials in high-voltage environments.

[0088] When the anthrone doping concentration reaches 1.0 wt%, the excess crystalline filler agglomerates, and the steric hindrance effect restricts the free orientation of polar groups. The agglomerates introduce microscopic air gaps within the material, and the extremely low dielectric constant of air offsets the polarization contribution of anthrone, resulting in a decrease in the macroscopic dielectric constant.

[0089] Test Example 7: Thermogravimetric Analysis (TGA) Test The cured silicone gel and composite insulating material samples prepared in Examples 1 to 4 and Comparative Example 1 were selected. The samples were chopped with a scalpel, and 5 to 10 mg of the chopped sample was weighed and placed in an alumina ceramic crucible that had been pre-treated by calcination to remove impurities. The crucible was compacted to ensure good contact between the sample and the bottom of the crucible.

[0090] Place the crucible containing the sample into the heating chamber of the thermogravimetric analyzer. Close the chamber and evacuate it before introducing high-purity nitrogen as a protective gas. Adjust the nitrogen flow rate to a stable 50 mL / min to maintain an inert atmosphere and prevent oxidation of the sample during heating.

[0091] Set the test temperature program in the thermogravimetric analyzer control software. Set the initial temperature to 50℃ and linearly increase it to 750℃ at a constant rate of 10℃ / min.

[0092] The testing equipment is started, and the system automatically records real-time data on the change of sample mass with temperature during the heating process. After the test, the thermogravimetric curve (TGA curve) data is exported, and the temperature corresponding to the sample mass loss reaching 5% of the initial mass is extracted as the 5% thermal weight loss temperature (T5%), and the percentage of residual mass at 750℃ is extracted.

[0093] Table 7. Thermogravimetric analysis test data of each group of samples Based on the data in Table 7, combined with the appendix Figure 15 The analysis is as follows: Figure 15 The horizontal axis represents Temperature in °C, and the vertical axis represents Mass Fraction (mass fraction of the sample, in %). The dashed line indicates the position where the mass fraction is 95%, and the intersection of this line with each curve is the corresponding 5% thermal decomposition temperature (T5%). This indicator is used to characterize the initial thermal decomposition temperature and heat resistance of the material.

[0094] The incorporation of anthrone was found to improve the thermal stability of the organosilicon gel material. As shown in the graphs, the 5% thermal weight loss temperature of Comparative Example 1 (SG) was 332.4℃. After physical blending with anthrone, the thermal stability of the composite insulating material showed a trend of first increasing and then decreasing. Compared with SG, Example 1 (SG-ET) showed... 0.5 The temperature at which the mass begins to decrease shifts significantly towards the higher temperature range, and the temperature at which the 5% thermal weight loss occurs rises to 345.2℃. When the anthrone doping content continues to increase to 0.75wt% and 1.0wt%, the T5% of the composite material decreases. Example 4 (SG-ET) 1.0 The T5% of the sample decreased to 336.3℃, but was still higher than that of the control sample 1.

[0095] The improved initial thermal stability of the material is related to the formation of internal micro-phase interfaces. At a blend concentration of 0.5 wt%, crystalline anthrone particles are uniformly dispersed within the amorphous polymer network of the organosilicon gel. Anthrone molecules and siloxane segments form physical binding sites through intermolecular forces; these micro-phase interfaces act as physical cross-linking nodes within the polymer matrix. The introduction of these physical nodes restricts the thermal mobility of the siloxane macromolecular segments at high temperatures, increasing the activation energy required for segment depolymerization and breakage. During heating, the material absorbs more heat to initiate polymer network degradation, macroscopically manifested as a shift in the initial decomposition temperature (T5%) towards higher temperatures.

[0096] When the anthrone content exceeds 0.5 wt%, excess filler particles agglomerate in the matrix. The formation of agglomerates reduces the effective contact area between the anthrone and the silica gel matrix, weakening the restrictive effect of the phase interface on the thermal motion of polymer segments. Agglomeration introduces structural defects and free volumes into the material. These microscopic defects become thermal degradation initiation points at high temperatures, accelerating polymer segment breakage and causing the initial thermal decomposition temperature of the material to decrease with increasing doping concentration.

[0097] The improved thermal stability demonstrated in Example 1 can effectively ensure the operational reliability of high-voltage, high-power electrical equipment under long-term thermal stress and prevent insulation failure due to overheating.

Claims

1. A method for preparing a highly insulating silicone gel for SiC device packaging, characterized by, Includes the following steps: Organosilicon gel component A is added to a container, followed by the addition of crystalline anthrone. The mixture is stirred at room temperature to disperse the crystalline anthrone evenly in the organosilicon gel component A, thus obtaining a premixed solution. Add organosilicon gel component B to the premixed liquid, stir to mix evenly to obtain a uniformly mixed solution, and then perform vacuum degassing to remove air bubbles to obtain a defoamed solution. The defoamed solution is poured evenly into a mold and cured at room temperature to obtain the final highly insulating silicone gel.

2. The method for preparing high-insulation silicone gel for SiC device encapsulation according to claim 1, characterized in that, During the preparation of the premixed liquid, a stirring device with a rotation speed of 100 r / min to 500 r / min is used to continuously stir for 6 h to 24 h.

3. The method for preparing high-insulation silicone gel for SiC device encapsulation according to claim 1, characterized in that, The amount of crystalline anthrone added is 0.1 wt% to 1.0 wt% of the total mass of the high-insulation silicone gel.

4. The method for preparing high-insulation silicone gel for SiC device encapsulation according to claim 1, characterized in that, The organosilicon gel component A is vinyl-terminated polydimethylsiloxane, whose molecular backbone is composed of alternating silicon-oxygen bonds.

5. The method for preparing high-insulation silicone gel for SiC device encapsulation according to claim 4, characterized in that, The organosilicon gel component B is a polymethylhydrosiloxane, whose molecular chain contains multiple repeating methylhydrosiloxane units, and the mass ratio of organosilicon gel component A to organosilicon gel component B is 10:

1.

6. The method for preparing high-insulation silicone gel for SiC device encapsulation according to claim 5, characterized in that, The organosilicon gel component B acts as a crosslinking agent and undergoes an addition curing reaction with the active vinyl groups in the organosilicon gel component A at room temperature.

7. The method for preparing high-insulation silicone gel for SiC device encapsulation according to claim 1, characterized in that, In the step of uniformly pouring the defoamed solution into the mold, the defoamed solution is uniformly poured into a flat mold or a pre-embedded needle mold for partial discharge testing for molding.

8. The method for preparing high-insulation silicone gel for SiC device encapsulation according to claim 1, characterized in that, In the step of removing air bubbles, the uniformly mixed solution is placed in a vacuum oven for processing.

9. The method for preparing high-insulation silicone gel for SiC device encapsulation according to claim 1, characterized in that, The thickness of the highly insulating silicone gel obtained after curing is 300 μm to 3 mm.

10. The application of a highly insulating organosilicon gel prepared by the preparation method according to any one of claims 1-9 in SiC device packaging.

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