High-thermal-conductivity silicone potting adhesive and preparation method thereof

Abstract

This invention provides a high thermal conductivity silicone potting compound and its preparation method. The silicone potting compound comprises component A and component B. Component A comprises the following raw materials in parts by weight: 35-50 parts vinyl silicone oil, 40-60 parts composite filler, 6-14 parts silane coupling agent, and 0.05-0.3 parts platinum catalyst. Component B comprises the following raw materials in parts by weight: 20-30 parts vinyl silicone oil, 5-15 parts modified silicone oil, 40-60 parts composite filler, and 0.01-0.05 parts inhibitor. The potting compound of this invention has the advantages of high thermal conductivity, strong flame retardancy, good mechanical properties, long life, and suitable viscosity, making it suitable for the high thermal conductivity potting requirements of electronic devices.

Description

Technical Field

[0001] This invention belongs to the field of potting compound technology, specifically relating to a high thermal conductivity silicone potting compound and its preparation method. Background Technology

[0002] With the rapid development of modern electronic technology, electronic components are constantly evolving towards miniaturization, high power, and high-density integration, resulting in a significant increase in the heat generated during operation. If this heat cannot be dissipated in a timely and effective manner, it will directly affect the performance stability, lifespan, and overall system reliability of the electronic components.

[0003] Encapsulating compounds, as an important component of electronic packaging materials, are widely used in power modules, LED lighting, power devices, automotive electronics, and other fields. Their main functions include mechanical protection, electrical insulation, moisture and dust protection, and thermal conduction. While traditional epoxy resin encapsulating compounds possess good adhesive strength and electrical insulation properties, their thermal conductivity is generally low, making it difficult to meet the high-efficiency heat dissipation requirements of high-power electronic devices. Furthermore, epoxy resins are prone to internal stress during curing and have limited high-temperature resistance, leading to aging and cracking with prolonged use, thus affecting the long-term reliability of the devices.

[0004] Silicone potting compounds have gained widespread attention in the high-end electronic packaging field in recent years due to their excellent high-temperature resistance, good flexibility and electrical insulation properties, as well as low stress and low shrinkage. However, the intrinsic thermal conductivity of ordinary silicone potting compounds is also relatively low, far from meeting the heat dissipation requirements of high-heat electronic devices. In addition, with the increasingly complex application environments of electronic devices, higher requirements are being placed on the comprehensive performance of potting materials, such as flame retardancy, service life, and low volatile content.

[0005] Therefore, there is an urgent need to develop a new type of silicone potting compound that combines high thermal conductivity, excellent flame retardancy, good process adaptability, and long-term reliability to meet the pressing needs of next-generation high-power electronic devices for packaging materials. Summary of the Invention

[0006] To address the existing technical problems, the present invention aims to provide a high thermal conductivity silicone potting compound and its preparation method. The potting compound of the present invention exhibits excellent high thermal conductivity and strong flame retardancy, showing promising application prospects.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a high thermal conductivity silicone potting compound, comprising component A and component B, wherein, Component A comprises the following raw materials in parts by weight: 35-50 parts vinyl silicone oil, 40-60 parts composite filler, 6-14 parts silane coupling agent, and 0.05-0.3 parts platinum catalyst; Component B comprises the following raw materials in parts by weight: 20-30 parts vinyl silicone oil, 5-15 parts modified silicone oil, 40-60 parts composite filler, and 0.01-0.05 parts inhibitor; The method for preparing the modified silicone oil includes the following steps: Hydrogen-containing silicone oil, N-[3-(trimethoxysilyl)propyl]ethylenediamine, and toluene were mixed and stirred under inert gas protection. Then, a catalyst was added, and the mixture was heated to 85℃~110℃. After cooling, anhydrous methanol was added to inactivate the mixture. The mixture was washed, the organic phase was collected, and the mixture was rotary evaporated to obtain modified silicone oil.

[0008] In some embodiments of the present invention, the vinyl silicone oil is a mixture of low-viscosity vinyl silicone oil and high-viscosity vinyl silicone oil in a mass ratio of 1:(1-2).

[0009] In some embodiments of the present invention, the low-viscosity vinyl silicone oil has a dynamic viscosity of 50-250 mPa·s at 25°C; and the high-viscosity vinyl silicone oil has a dynamic viscosity of 500-3000 mPa·s at 25°C.

[0010] In some embodiments of the present invention, the viscosity of the modified silicone oil is 10,000 to 20,000 mPa·s.

[0011] Furthermore, the hydrogen content of the hydrogen-containing silicone oil is 0.05% to 0.5%.

[0012] In some embodiments of the present invention, the method for preparing the composite filler includes the following steps: S1. Mix sodium citrate dihydrate and deionized water, stir, then add isopropanol and hexagonal boron nitride in sequence, stir, sonicate, heat and react at 150-200℃, cool, sonicate, centrifuge at low speed, take the supernatant and centrifuge at high speed, take the precipitate, add isopropanol, sonicate, centrifuge at high speed, repeat the steps 2-3 times, dry the final precipitate to obtain pretreated boron nitride. S2. Shake bis(dodecylmorpholine) and deionized water at 50-65°C for 0.5-1 h, add the pretreated boron nitride obtained in step S1, shake at 50-65°C for 2-4 h, centrifuge, wash, dry, grind and sieve to obtain modified hexagonal boron nitride. S3. Mix aluminum hydroxide and deionized water, sonicate, adjust the pH to 10-11, add the modified hexagonal boron nitride obtained in step S2, stir, centrifuge, wash, and dry to obtain the composite packing.

[0013] In some embodiments of the present invention, the mass ratio of sodium citrate dihydrate and hexagonal boron nitride in step S1 is (1-1.2):1.

[0014] In some embodiments of the present invention, the mass ratio of bis(dodecylmorpholine) and pretreated boron nitride in step S2 is (0.5-0.8) mg: 1 g.

[0015] In some embodiments of the present invention, the mass ratio of aluminum hydroxide and modified hexagonal boron nitride in step S3 is (0.2-0.6):1.

[0016] In some embodiments of the present invention, the aluminum hydroxide has a particle size of 50-150 nm, and the modified hexagonal boron nitride has a particle size of 5-15 µm.

[0017] In some embodiments of the present invention, the silane coupling agent is any one or more of 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0018] In some embodiments of the present invention, the inhibitor is one or a combination of several of the following: alkynyl alcohols, polyvinylsiloxanes, amides, and diesters containing double bonds.

[0019] Another aspect of the present invention provides a method for preparing a high thermal conductivity silicone potting compound, comprising the following steps: 1. Mix vinyl silicone oil, composite filler, silane coupling agent, and platinum catalyst, and stir to obtain component A; 2. Mix vinyl silicone oil, modified silicone oil, composite filler, and inhibitor, and stir to obtain component B; 3. Mix components A and B according to the specified ratio, and degas under vacuum to obtain silicone potting compound.

[0020] In some embodiments of the present invention, the mass ratio of component A to component B in step three is 1:(0.8 to 1.8).

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The potting compound of the present invention has the advantages of high thermal conductivity, strong flame retardancy, long life and suitable viscosity, and is suitable for the high thermal conductivity potting requirements of electronic devices.

[0022] This invention utilizes hydrogen-containing silicone oil and N-[3-(trimethoxysilyl)propyl]ethylenediamine to prepare a novel silicone oil. Compared to conventional hydrogen-containing silicone oil, the modified silicone oil has amine and methoxysilane side chains, resulting in superior adhesion strength to substrate surfaces and improved oxidation resistance of the potting compound. Furthermore, the high viscosity and cross-linked network of the modified silicone oil enhance tensile strength. In addition, the applicant discovered that the modified silicone oil exhibits a "slow-release effect" on platinum catalysts. Using the modified silicone oil slows down the curing time of the potting compound at room temperature, extending the workable time. Simultaneously, rapid curing can be achieved with minimal heating, effectively realizing controllable curing time.

[0023] This invention uses aluminum hydroxide and modified hexagonal boron nitride in a specific mass ratio as a composite filler. The applicant first pre-treats the hexagonal boron nitride with sodium citrate dihydrate, facilitating the subsequent introduction of bis(dodecylmorpholine), changing the hexagonal boron nitride from "hydrophilic" to "oleophilic," making it easier to mix with silicone oil and allowing the hexagonal boron nitride to better exert its high thermal conductivity. Furthermore, by controlling the particle size of aluminum hydroxide and modified hexagonal boron nitride, aluminum hydroxide is electrostatically adsorbed between the layers of modified hexagonal boron nitride. This not only avoids the agglomeration of aluminum hydroxide, enhancing the flame retardancy of the potting compound and reducing smoke density, but also allows the plate-like structure of the hexagonal boron nitride and the granular structure of the aluminum hydroxide to better disperse stress, improving mechanical properties and high-temperature resistance. Detailed Implementation

[0024] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0025] Prepare each potting compound according to the proportions and preparation methods of the raw materials specified in the following examples and comparative examples.

[0026] To facilitate implementation of this invention by those skilled in the art, the manufacturers of some raw materials for the embodiments and comparative examples are described below: Hydrogen-containing silicone oil: purchased from Anhui Aiyota Silicone Oil Co., Ltd., with a hydrogen content of 1.55%; Unless otherwise specified, all other raw materials can be purchased from the market.

[0027] Preparation Example 1 The preparation method of modified silicone oil includes the following steps: 20g of hydrogen-containing silicone oil, 0.56g of N-[3-(trimethoxysilyl)propyl]ethylenediamine, and 40mL of toluene were mixed and stirred evenly under nitrogen protection. Then, 25µg of chloroplatinic acid was added, and the mixture was heated at 95℃ for 2h. After cooling to room temperature, 2mL of anhydrous methanol was added, and the mixture was stirred for 20min. The mixture was washed three times with deionized water, and the organic phase was collected. Toluene was removed by rotary evaporation at -0.095MPa in a 40℃ water bath to obtain modified silicone oil. The modified silicone oil has a viscosity of 18000 mPa·s.

[0028] Preparation Example 2 The preparation method of bis(dodecylmorpholine) includes the following steps: 2.2 mmol of 4-dodecylmorpholine, 1 mmol of 1,4-dibromobutane, and 100 mL of ethanol were mixed and stirred under reflux for 72 h. The mixture was cooled to room temperature, and the solvent was removed by rotary evaporation under reduced pressure. The mixture was washed three times with ethyl acetate, filtered, and dried in a vacuum drying oven for 48 h to obtain bisdodecylmorpholine.

[0029] Preparation Example 3 The preparation method of composite filler A includes the following steps: S1. Mix 0.33g sodium citrate dihydrate and 30mL deionized water, stir well, then add 50mL isopropanol and 0.3g hexagonal boron nitride, stir to disperse, sonicate at 300W for 1.5h, heat to 180℃, cool to room temperature, sonicate for 5min, centrifuge at 1000rpm for 5min, take the supernatant and centrifuge at 10000rpm for 5min, take the precipitate and add 20mL isopropanol, sonicate for 5min, centrifuge at 10000rpm for 5min, repeat the steps 3 times, dry the final precipitate at 40℃ for 48h to obtain pretreated boron nitride; S2. 0.6 mg of bis(dodecylmorpholine) and 10 mL of deionized water were shaken at 60 °C for 1 h. 1 g of pretreated boron nitride obtained in step S1 was added and shaken at 60 °C for 3 h. The supernatant was removed by centrifugation at 5000 rpm for 5 min. The supernatant was washed 4 times with deionized water, dried at 70 °C for 24 h, and ground through a 1500-mesh sieve to obtain modified hexagonal boron nitride. S3. Mix 0.4g aluminum hydroxide (particle size 100nm) with 100mL deionized water, sonicate for 5min, adjust the pH to 10, add 0.8g modified hexagonal boron nitride obtained in step S2, stir evenly, centrifuge at 5000rpm for 5min, wash 4 times with deionized water, and dry at 70℃ for 24h to obtain composite filler A.

[0030] Preparation Example 4 The preparation method of composite filler B includes the following steps: S1. 0.6 mg of bis(dodecylmorpholine) and 10 mL of deionized water were shaken at 60 °C for 1 h. 1 g of hexagonal boron nitride was added and shaken at 60 °C for 3 h. The supernatant was removed by centrifugation at 5000 rpm for 5 min. The supernatant was washed 4 times with deionized water and dried at 70 °C for 24 h. The mixture was then ground through a 1500-mesh sieve to obtain modified hexagonal boron nitride. S2. Mix 0.4g aluminum hydroxide (particle size 100nm) with 100mL deionized water, sonicate for 5min, adjust the pH to 10, add 0.8g modified hexagonal boron nitride obtained in step S1, stir evenly, centrifuge at 5000rpm for 5min, wash 4 times with deionized water, and dry at 70℃ for 24h to obtain composite filler B.

[0031] Preparation Example 5 The preparation method of composite filler C includes the following steps: Mix 0.4g aluminum hydroxide (particle size 100nm) with 100mL deionized water, sonicate for 5min, adjust the pH to 10, add 0.8g hexagonal boron nitride (obtained by grinding through a 1500-mesh sieve), stir evenly, centrifuge at 5000rpm for 5min, wash 4 times with deionized water, and dry at 70℃ for 24h to obtain composite filler C.

[0032] Example 1

[0033] A high thermal conductivity silicone potting compound, comprising component A and component B; the mass ratio of component A to component B is 1:1.2, wherein, Component A includes the following raw materials in parts by weight: 42 parts vinyl silicone oil, 50 parts composite filler A, 10 parts γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 0.18 parts chloroplatinic acid with a platinum content of 5000 ppm. Component B comprises the following raw materials in parts by weight: 25 parts vinyl silicone oil, 10 parts modified silicone oil, 50 parts composite filler A, and 0.03 parts 3,5-dimethyl-1-hexynyl-3-ol; The vinyl silicone oil is a mixture of low-viscosity vinyl silicone oil and high-viscosity vinyl silicone oil in a mass ratio of 1:1.5; the low-viscosity vinyl silicone oil has a dynamic viscosity of 150 mPa·s at 25°C; and the high-viscosity vinyl silicone oil has a dynamic viscosity of 2000 mPa·s at 25°C.

[0034] The preparation method of the silicone potting compound in this embodiment includes the following steps: 1. Mix vinyl silicone oil, composite filler A, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and chloroplatinic acid, and stir until homogeneous to obtain component A; 2. Mix vinyl silicone oil, modified silicone oil, composite filler A, and 3,5-dimethyl-1-hexynyl-3-ol, and stir until homogeneous to obtain component B; 3. Mix components A and B according to the specified ratio, and degas under vacuum to obtain silicone potting compound.

[0035] Example 2

[0036] A high thermal conductivity silicone potting compound, comprising component A and component B; the mass ratio of component A to component B is 1:1.2, wherein, Component A comprises the following raw materials in parts by weight: 35 parts vinyl silicone oil, 40 parts composite filler A, 6 parts γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 0.05 parts chloroplatinic acid with a platinum content of 5000 ppm. Component B comprises the following raw materials in parts by weight: 20 parts vinyl silicone oil, 5 parts modified silicone oil, 40 parts composite filler A, and 0.01 parts 3,5-dimethyl-1-hexynyl-3-ol; The vinyl silicone oil is a mixture of low-viscosity vinyl silicone oil and high-viscosity vinyl silicone oil in a mass ratio of 1:2; the low-viscosity vinyl silicone oil has a dynamic viscosity of 150 mPa·s at 25°C; and the high-viscosity vinyl silicone oil has a dynamic viscosity of 2000 mPa·s at 25°C.

[0037] The preparation method of the silicone potting compound in this embodiment is the same as that in Example 1.

[0038] Example 3

[0039] A high thermal conductivity silicone potting compound, comprising component A and component B; the mass ratio of component A to component B is 1:1.2, wherein, Component A comprises the following raw materials in parts by weight: 50 parts vinyl silicone oil, 60 parts composite filler A, 14 parts γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 0.3 parts chloroplatinic acid with a platinum content of 5000 ppm. Component B comprises the following raw materials in parts by weight: 30 parts vinyl silicone oil, 15 parts modified silicone oil, 60 parts composite filler A, and 0.05 parts 3,5-dimethyl-1-hexynyl-3-ol; The vinyl silicone oil is a mixture of low-viscosity vinyl silicone oil and high-viscosity vinyl silicone oil in a mass ratio of 1:1; the low-viscosity vinyl silicone oil has a dynamic viscosity of 150 mPa·s at 25°C; and the high-viscosity vinyl silicone oil has a dynamic viscosity of 2000 mPa·s at 25°C.

[0040] The preparation method of the silicone potting compound in this embodiment is the same as that in Example 1.

[0041] Example 4

[0042] A high thermal conductivity silicone potting compound and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that an equal amount of composite filler B is used to replace composite filler A.

[0043] Example 5

[0044] A high thermal conductivity silicone potting compound and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that an equal amount of composite filler C is used to replace composite filler A.

[0045] Comparative Example 1 A high thermal conductivity silicone potting compound and its preparation method are described. The specific implementation method is the same as in Example 1, except that an equal amount of hydrogen-containing silicone oil is used instead of modified silicone oil.

[0046] Effect evaluation: The potting compounds prepared in Examples 1-5 and Comparative Example 1 were cured and tested. The specific results are shown in Table 1.

[0047] Performance testing: (1) Thermal conductivity: Refer to standard ASTM D5470-17; (2) Flame retardancy: Refer to standard UL 94-2023; (3) Tensile strength: Refer to standard GB / T1447.

[0048] Table 1 Performance Tests As shown in Table 1, the potting compounds of Examples 1-3 have high thermal conductivity, strong flame retardancy and excellent tensile strength.

[0049] Compared to Example 1, Examples 4-5 use composite filler B / C instead of composite filler A. In Example 4, the composite filler was not pretreated with hexagonal boron nitride, resulting in smaller interlayer gaps that affected its subsequent bonding with aluminum hydroxide. In Example 5, the composite filler was prepared by simply ultrasonically mixing hexagonal boron nitride and aluminum hydroxide, leading to poor dispersibility. Both of these factors negatively impact the overall performance of the potting compound.

[0050] Compared to Example 1, Comparative Example 1 uses an equal amount of hydrogen-containing silicone oil instead of modified silicone oil. The dispersion ability of hydrogen-containing silicone oil for fillers mainly depends on physical mixing and weak chemical adsorption, which may indirectly affect the dispersion of composite fillers. At the same time, it will also reduce the crosslinking network of the potting compound, thereby affecting the overall performance of the potting compound.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present application in any way. Although the present application discloses the preferred embodiment as described above, it is not intended to limit the present application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A high thermal conductivity silicone potting compound, characterized in that, It includes component A and component B, wherein, Component A comprises the following raw materials in parts by weight: 35-50 parts vinyl silicone oil, 40-60 parts composite filler, 6-14 parts silane coupling agent, and 0.05-0.3 parts platinum catalyst; Component B comprises the following raw materials in parts by weight: 20-30 parts vinyl silicone oil, 5-15 parts modified silicone oil, 40-60 parts composite filler, and 0.01-0.05 parts inhibitor; The method for preparing the modified silicone oil includes the following steps: Hydrogen-containing silicone oil, N-[3-(trimethoxysilyl)propyl]ethylenediamine, and toluene were mixed and stirred under inert gas protection. Then, a catalyst was added, and the mixture was heated to 85℃~110℃. After cooling, anhydrous methanol was added to inactivate the mixture. The mixture was washed, the organic phase was collected, and the mixture was rotary evaporated to obtain modified silicone oil.

2. The high thermal conductivity silicone potting compound according to claim 1, characterized in that, The vinyl silicone oil is a mixture of low-viscosity end vinyl silicone oil and high-viscosity end vinyl silicone oil in a mass ratio of 1:(1-2).

3. The high thermal conductivity silicone potting compound according to claim 2, characterized in that, The low-viscosity vinyl silicone oil has a dynamic viscosity of 50–250 mPa·s at 25°C; the high-viscosity vinyl silicone oil has a dynamic viscosity of 500–3000 mPa·s at 25°C.

4. The high thermal conductivity silicone potting compound according to claim 1, characterized in that, The viscosity of the modified silicone oil is 10,000 to 20,000 mPa·s.

5. The high thermal conductivity silicone potting compound according to claim 1, characterized in that, The method for preparing the composite filler includes the following steps: S1. Mix sodium citrate dihydrate and deionized water, stir, then add isopropanol and hexagonal boron nitride in sequence, stir, sonicate, heat and react at 150-200℃, cool, sonicate, centrifuge at low speed, take the supernatant and centrifuge at high speed, take the precipitate, add isopropanol, sonicate, centrifuge at high speed, repeat the steps 2-3 times, dry the final precipitate to obtain pretreated boron nitride. S2. Shake bis(dodecylmorpholine) and deionized water at 50-65°C for 0.5-1 h, add the pretreated boron nitride obtained in step S1, shake at 50-65°C for 2-4 h, centrifuge, wash, dry, grind and sieve to obtain modified hexagonal boron nitride. S3. Mix aluminum hydroxide and deionized water, sonicate, adjust the pH to 10-11, add the modified hexagonal boron nitride obtained in step S2, stir, centrifuge, wash, and dry to obtain the composite packing.

6. The high thermal conductivity silicone potting compound according to claim 5, characterized in that, The mass ratio of bis(dodecylmorpholine) and pretreated boron nitride in step S2 is (0.5-0.8) mg: 1 g.

7. The high thermal conductivity silicone potting compound according to claim 5, characterized in that, The mass ratio of aluminum hydroxide to modified hexagonal boron nitride in step S3 is (0.2-0.6):

1.

8. The high thermal conductivity silicone potting compound according to claim 7, characterized in that, The aluminum hydroxide has a particle size of 50–150 nm, and the modified hexagonal boron nitride has a particle size of 5–15 µm.

9. The high thermal conductivity silicone potting compound according to claim 1, characterized in that, The silane coupling agent is any one or more of 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

10. A method for preparing a high thermal conductivity silicone potting compound according to any one of claims 1-9, characterized in that, Includes the following steps:

1. Mix vinyl silicone oil, composite filler, silane coupling agent, and platinum catalyst, and stir to obtain component A; 2. Mix vinyl silicone oil, modified silicone oil, composite filler, and inhibitor, and stir to obtain component B; 3. Mix components A and B according to the specified ratio, and degas under vacuum to obtain silicone potting compound.

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