A high-performance silicone sealant for electronic packaging

Abstract

The present invention provides a high-performance organosilicon sealant for electronic packaging, relating to the technical field of organosilicon sealants. The raw materials of the organosilicon sealant include methyl vinyl silicone oil, vinyl dimethyl silane, a platinum catalyst, fumed silica, a B4Cw@ZrO2 complex, ethynyl cyclohexanol, a silane coupling agent, a titanate coupling agent, a cerium-zinc composite antioxidant, and an auxiliary antioxidant; the B4Cw@ZrO2 complex is prepared from boron carbide whiskers and nano-zirconia sol; and the cerium-zinc composite antioxidant is prepared from cerium nitrate, zinc nitrate, and ammonia water. A method for preparing a high-performance organosilicon sealant for electronic packaging includes the steps of pretreating boron carbide whiskers, synthesizing the B4Cw@ZrO2 complex, preparing the cerium-zinc composite antioxidant, preparing a base rubber material, and preparing the organosilicon sealant. The organosilicon sealant prepared by the present invention has high mechanical strength, excellent elastic properties, and strong durability.

Description

Technical Field

[0001] The present invention relates to the technical field of organic silicon sealants, and in particular to an organic silicon sealant for high-performance electronic packaging. Background Art

[0002] With the rapid development of the global electronics industry toward miniaturization and high integration, emerging technologies such as 5G communications, artificial intelligence, and the Internet of Things (IoT) are placing higher demands on the reliability and environmental adaptability of electronic equipment. As a key component in ensuring component stability, the performance of sealing materials used in electronic packaging directly impacts the lifespan and safety of the equipment. Silicone sealants, due to their excellent performance, have become a mainstream choice in the electronic packaging field, playing a key role in chip packaging, sensor sealing, and battery pack protection.

[0003] Although traditional electronic packaging materials are relatively low in cost, they have defects such as high brittleness and insufficient weather resistance, making it difficult to meet the needs of high-end applications. Although silicone sealants have excellent comprehensive performance, they still face various problems. The prior art with publication number CN116496753A discloses a high-performance silicone sealant and a preparation method thereof. Montmorillonite is modified by phosphate deposition and phosphate crosslinker intercalation to form a three-dimensional network structure of "nano-montmorillonite skeleton + phosphate ceramic coating", which improves flame retardancy and shape stability; however, there is still a problem of poor mechanical properties, which limits its application in high-intensity scenarios. Moreover, in a long-term high-temperature environment, the silicon-oxygen bond is easily degraded, the compression permanent deformation may increase, and the durability is poor.

[0004] In summary, although the existing technical solutions have improved certain properties of silicone sealants to a certain extent, the following technical problems still exist: low mechanical strength, poor elasticity, and insufficient durability. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a high-performance silicone sealant for electronic packaging, and achieves the following invention objectives: to prepare a silicone sealant with high mechanical strength, excellent elasticity and strong durability.

[0006] To achieve the above objectives, the technical solutions adopted are as follows:

[0007] A high-performance organosilicon sealant for electronic packaging comprises the following raw materials, measured in parts by weight: 50-60 parts of methyl vinyl silicone oil, 10-15 parts of vinyldimethylsilane, 0.5-1 part of a platinum catalyst, 15-20 parts of fumed silica, 10-15 parts of a B4Cw@ZrO2 composite, 0.1-0.2 parts of ethynylcyclohexanol, 1-2 parts of a silane coupling agent, 1-2 parts of a titanate coupling agent, 0.5-1.5 parts of a cerium-zinc composite antioxidant, and 0.5-0.7 parts of an auxiliary antioxidant.

[0008] The methyl vinyl silicone oil has a viscosity of 1000-5000 cSt and a vinyl content of 0.3%-0.7%.

[0009] The purity of the vinyldimethylsilane is ≥97%.

[0010] The platinum catalyst is a complex of chloroplatinic acid and vinylsiloxane, and the platinum content is 3000-5000ppm.

[0011] The particle size of the fumed silica is 7-16 nm.

[0012] The B4Cw@ZrO2 composite is prepared from boron carbide whiskers and nano zirconium oxide sol.

[0013] The cerium-zinc composite antioxidant is prepared from cerium nitrate, zinc nitrate and ammonia water.

[0014] The auxiliary antioxidant is a hindered phenol antioxidant.

[0015] The present invention also provides a method for preparing a high-performance silicone sealant for electronic packaging, comprising the following steps:

[0016] Step 1: Boron carbide whisker pretreatment

[0017] The boron carbide whiskers (B4Cw for short) are immersed in a sodium hydroxide solution, heated to 60-70°C, and ultrasonically treated at an ultrasonic power of 200-300W for 20-25 minutes. The solution is then filtered, washed, and washed 2-3 times with deionized water. After washing, the solution is dried at 80-90°C for 2-2.5 hours to obtain pretreated boron carbide whiskers.

[0018] The mass fraction of the sodium hydroxide solution is 5-8%.

[0019] Step 2: Synthesis of B4Cw@ZrO2 composite

[0020] Pretreated boron carbide whiskers were added to a nanozirconia sol at a mass ratio of 1:(10-12). The mixture was stirred at room temperature for 2-2.5 hours at a stirring rate of 200-300 rpm. The mixture was then heated to 60-70°C and stirred for 20-30 minutes to obtain a wet gel. The wet gel was then dried at 80-90°C for 10-12 hours to obtain a B4Cw@ZrO2 composite. The nanozirconia sol (model YC-GRJ35, with a particle size of 10 nm and a concentration of 20 wt%) was purchased from Shanghai Yingcheng New Materials Co., Ltd.

[0021] Step 3: Preparation of cerium-zinc composite antioxidant

[0022] Dissolve cerium nitrate and zinc nitrate in deionized water to prepare cerium nitrate and zinc nitrate metal salt solutions, respectively, at concentrations of 0.5-1.0 mol / L. Add the two metal salt solutions dropwise to a four-necked flask filled with deionized water. The molar ratio of cerium nitrate to zinc nitrate is (1-3):1. The amount of deionized water used should be 3-5 times the total mass of the two metal salt solutions. Stir while adding the solution at a speed of 500-800 rpm. Maintain the pH of the reaction system at 9-10 with ammonia. After the dropwise addition is completed, the reaction is carried out at a temperature of 50-70° C. for 1-2 hours, and the stirring speed is maintained at 500-800 rpm during the reaction; after the heat preservation is completed, the product is allowed to stand for aging for 12-16 hours; after the aging is completed, the product is dried at a temperature of 80-100° C. for 12-16 hours; the dried product is calcined by heating the product to 200-250° C. at a heating rate of 5-7° C. / min and calcining the product for 1-2 hours; and then heating the product to 500-600° C. at a heating rate of 2-3° C. / min and calcining the product for 3-4 hours to obtain a cerium-zinc composite antioxidant.

[0023] Step 4: Preparation of base rubber

[0024] Add methyl vinyl silicone oil into a planetary mixer at a stirring rate of 50-100 rpm, divide the fumed silica into three equal parts and add them into the mixer three times, with an interval of 5-8 minutes each time; after the fumed silica is added, vacuum stirring is performed with a vacuum degree of -0.09MPa to -0.095MPa, a speed of 1500-1600rpm, and a stirring time of 30-40min; adjust the speed to 1000-1100rpm, add the B4Cw@ZrO2 complex, and continue stirring for 40-45 minutes to obtain the base rubber compound.

[0025] Step 5: Prepare silicone sealant

[0026] A silane coupling agent and a titanate coupling agent are added to a base rubber compound and stirred at a rate of 100-150 rpm for 20-30 minutes. A platinum catalyst, vinyldimethylsilane, and ethynylcyclohexanol are added and stirred at a low speed of 50-100 rpm for 15-20 minutes. A cerium-zinc composite antioxidant and an auxiliary antioxidant are added and stirred at a high speed of 1500-1600 rpm for 20-30 minutes to obtain a mixed rubber compound. The mixed rubber compound is vacuum degassed at a vacuum degree of -0.095 MPa to -0.098 MPa for 30-40 minutes, and then returned to normal pressure to obtain a silicone sealant.

[0027] The mechanism of action of the present invention:

[0028] (1) Boron carbide whiskers dispersed in the silicone sealant matrix bear external loads in the form of a "microfiber skeleton", enhancing the mechanical properties of the silicone sealant; Boron carbide whiskers can form a "high-temperature resistant skeleton" in the silicone sealant matrix, delaying the degradation of the matrix at high temperatures and improving the high-temperature resistance of the sealant. The ZrO2 coating can improve the interfacial bonding between B4Cw and the silicone matrix, reduce filler agglomeration, and avoid performance degradation due to interface defects. The ZrO2 coating can isolate B4Cw from direct contact with oxygen, inhibiting the oxidation of B4Cw at high temperatures. At the same time, ZrO2 and the cerium-zinc composite antioxidant in the system form a dual anti-aging mechanism, improving the durability of the silicone sealant.

[0029] (2) Cerium can be 3+ / Ce 4+ The reversible oxidation reaction efficiently scavenges free radicals. Zinc ions bind to peroxide decomposition products while stabilizing the redox cycle of cerium, forming a synergistic system. The calcined cerium-zinc complex reacts with the oxidation products of the organosilicon matrix at high temperatures, forming a dense glassy protective layer that isolates oxygen from the matrix. The cerium-zinc composite antioxidant exhibits a synergistic effect with hindered phenolic antioxidants. Cerium ions preferentially scavenge highly active free radicals, reducing the consumption of the hindered phenolic antioxidant. Zinc ions inhibit the catalytic oxidation of metal ions, reducing the oxidative degradation rate of the hindered phenolic antioxidant.

[0030] (3) The present invention provides an elastic skeleton by using methyl vinyl silicone oil. The vinyl groups in vinyldimethylsilane and the vinyl groups in silicone oil undergo a hydrosilylation crosslinking reaction under the action of a platinum catalyst to form a three-dimensional network structure. The platinum catalyst catalyzes the crosslinking reaction, and the ethynylcyclohexanol temporarily inhibits the activity of platinum through coordination, thereby slowing the curing speed at room temperature and extending the operating time. The silane coupling agent has a similar structure to the matrix and preferentially improves the compatibility between the filler and the silicone oil. The titanate coupling agent has a stronger affinity for polar fillers, which can reduce the surface energy of the filler and reduce agglomeration. The physical barrier of ZrO2 and the chemical anti-oxidation of cerium-zinc form a "double barrier" that jointly delays the thermal oxidative aging of the matrix.

[0031] The beneficial effects of the present invention are as follows:

[0032] (1) The organic silicone sealant prepared by the present invention has excellent mechanical strength, a tear strength of 43.9-46.4 kN / m, a Shore A hardness of 72-75 Shore A, and a shear strength of 2.9-3.4 MPa.

[0033] (2) The silicone sealant prepared by the present invention has excellent elastic properties, with a tensile strength of 4.63-4.82 MPa and an elongation at break of 387-398%. Higher tensile strength and elongation at break mean that the sealant has stronger elastic recovery ability under tensile load.

[0034] (3) The silicone sealant prepared by the present invention has excellent durability. After 672 hours of UV aging, the tensile strength reaches 4.57-4.76 MPa, and the elongation at break reaches 382-394%. After 672 hours of wet heat aging, the tensile strength reaches 4.41-4.58 MPa, and the elongation at break reaches 371-383%. After UV aging and wet heat aging, the high tensile strength and elongation at break are maintained. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0036] Example 1 A high-performance silicone sealant for electronic packaging

[0037] A high-performance organosilicon sealant for electronic packaging comprises the following raw materials, measured in parts by weight: 50 parts of methyl vinyl silicone oil, 15 parts of vinyldimethylsilane, 0.5 parts of a platinum catalyst, 20 parts of fumed silica, 10 parts of a B4Cw@ZrO2 composite, 0.1 parts of ethynyl cyclohexanol, 1 part of a silane coupling agent, 1 part of a titanate coupling agent, 1.5 parts of a cerium-zinc composite antioxidant, and 0.7 parts of an auxiliary antioxidant.

[0038] The auxiliary antioxidant is a hindered phenol antioxidant.

[0039] A method for preparing a high-performance silicone sealant for electronic packaging, comprising the following steps:

[0040] Step 1: Boron carbide whisker pretreatment

[0041] The boron carbide whiskers were immersed in a sodium hydroxide solution, heated to 60°C, and ultrasonically treated with an ultrasonic power of 200W and an ultrasonic time of 25 minutes; then filtered, washed, and washed twice with deionized water; and dried at 80°C for 2.5 hours after washing to obtain pretreated boron carbide whiskers.

[0042] The mass fraction of the sodium hydroxide solution is 5%.

[0043] Step 2: Synthesis of B4Cw@ZrO2 composite

[0044] Pretreated boron carbide whiskers were added to a nanozirconia sol at a mass ratio of 1:10. The mixture was stirred at room temperature for 2 hours at a stirring rate of 300 rpm, then heated to 60°C and stirred for 30 minutes to obtain a wet gel. The wet gel was then dried at 80°C for 12 hours to obtain a B4Cw@ZrO2 composite. The nanozirconia sol (model YC-GRJ35, with a particle size of 10 nm and a concentration of 20 wt%) was purchased from Shanghai Yingcheng New Materials Co., Ltd.

[0045] Step 3: Preparation of cerium-zinc composite antioxidant

[0046] Cerium nitrate and zinc nitrate were dissolved in deionized water to prepare cerium nitrate and zinc nitrate solutions, respectively, at a concentration of 0.5 mol / L. The two metal salt solutions were added dropwise to a four-necked flask containing deionized water at a molar ratio of 1:1. The amount of deionized water was three times the total mass of the two metal salt solutions. The mixture was stirred at 500 rpm during the addition. Ammonia was used to maintain the pH of the reaction system at 9. After the addition, the reaction was incubated at 50°C for 2 hours, with stirring maintained at 800 rpm. The reaction was then allowed to stand for 12 hours and then dried at 80°C for 16 hours. The dried product was then calcined by heating to 200°C at a rate of 5°C / min for 2 hours, and then to 500°C at a rate of 2°C / min for 4 hours to obtain a cerium-zinc composite antioxidant.

[0047] Step 4: Preparation of base rubber

[0048] Add methyl vinyl silicone oil into a planetary mixer at a stirring rate of 50 rpm. Divide the fumed silica into three equal parts and add them into the mixer three times, with an interval of 5 minutes each time. After the fumed silica is added, vacuum stirring is performed with a vacuum degree of -0.09 MPa, a speed of 1500 rpm, and a stirring time of 40 minutes. Adjust the speed to 1000 rpm, add the B4Cw@ZrO2 complex, and continue stirring for 45 minutes to obtain the base rubber compound.

[0049] Step 5: Prepare silicone sealant

[0050] A silane coupling agent and a titanate coupling agent were added to the base rubber compound and stirred at a rate of 100 rpm for 30 minutes. A platinum catalyst, vinyldimethylsilane, and ethynylcyclohexanol were added and stirred at a low speed of 50 rpm for 20 minutes. A cerium-zinc composite antioxidant and an auxiliary antioxidant were added and stirred at a high speed of 1500 rpm for 30 minutes to obtain a mixed rubber compound. The mixed rubber compound was vacuum degassed at a vacuum degree of -0.095 MPa for 40 minutes and then returned to normal pressure to obtain a silicone sealant.

[0051] Example 2 A high-performance silicone sealant for electronic packaging

[0052] A high-performance organosilicon sealant for electronic packaging comprises the following raw materials, measured in parts by weight: 55 parts of methyl vinyl silicone oil, 10 parts of vinyldimethylsilane, 0.5 parts of platinum catalyst, 15 parts of fumed silica, 10 parts of B4Cw@ZrO2 composite, 0.1 parts of ethynyl cyclohexanol, 1.5 parts of silane coupling agent, 1.5 parts of titanate coupling agent, 1 part of cerium-zinc composite antioxidant, and 0.6 parts of auxiliary antioxidant.

[0053] The auxiliary antioxidant is a hindered phenol antioxidant.

[0054] A method for preparing a high-performance silicone sealant for electronic packaging, comprising the following steps:

[0055] Step 1: Boron carbide whisker pretreatment

[0056] The boron carbide whiskers were immersed in a sodium hydroxide solution, heated to 65°C, and ultrasonically treated with an ultrasonic power of 300W and an ultrasonic time of 25 minutes; then filtered, washed, and washed with deionized water three times; after washing, dried at 90°C for 2.5 hours to obtain pretreated boron carbide whiskers.

[0057] The mass fraction of the sodium hydroxide solution is 6%.

[0058] Step 2: Synthesis of B4Cw@ZrO2 composite

[0059] Pretreated boron carbide whiskers were added to a nanozirconia sol at a mass ratio of 1:12. The mixture was stirred at room temperature for 2.5 hours at a stirring rate of 300 rpm. The mixture was then heated to 65°C and stirred for 30 minutes to obtain a wet gel. The wet gel was then dried at 90°C for 11 hours to obtain a B4Cw@ZrO2 composite. The nanozirconia sol (model YC-GRJ35, with a particle size of 10 nm and a concentration of 20 wt%) was purchased from Shanghai Yingcheng New Materials Co., Ltd.

[0060] Step 3: Preparation of cerium-zinc composite antioxidant

[0061] Cerium nitrate and zinc nitrate were dissolved in deionized water, respectively, to prepare cerium nitrate and zinc nitrate metal salt solutions, each with a concentration of 1.0 mol / L. The two metal salt solutions were simultaneously added dropwise to a four-necked flask containing deionized water. The molar ratio of cerium nitrate to zinc nitrate was 2:1, and the amount of deionized water was 5 times the total mass of the two metal salt solutions. The mixture was stirred at 500 rpm during the addition. Ammonia was used to maintain the pH of the reaction system at 10. After the addition, the reaction was incubated at 60°C for 2 hours, with stirring maintained at 800 rpm. The incubation period was then allowed to stand for 16 hours. After aging, the dried product was dried at 100°C for 16 hours. The dried product was then calcined by heating to 250°C at a rate of 7°C / min for 2 hours, and then to 600°C at a rate of 3°C / min for 4 hours to obtain a cerium-zinc composite antioxidant.

[0062] Step 4: Preparation of base rubber

[0063] Add methyl vinyl silicone oil into a planetary mixer at a stirring rate of 100 rpm. Divide the fumed silica into three equal parts and add them into the mixer three times, with an interval of 5 minutes between each addition. After the addition of the fumed silica, vacuum stirring is performed with a vacuum degree of -0.095 MPa, a rotation speed of 1600 rpm, and a stirring time of 40 minutes. Adjust the rotation speed to 1100 rpm, add the B4Cw@ZrO2 complex, and continue stirring for 45 minutes to obtain the base rubber compound.

[0064] Step 5: Prepare silicone sealant

[0065] A silane coupling agent and a titanate coupling agent were added to the base rubber compound and stirred at a rate of 150 rpm for 30 minutes. A platinum catalyst, vinyldimethylsilane, and ethynylcyclohexanol were added and stirred at a low speed of 100 rpm for 20 minutes. A cerium-zinc composite antioxidant and an auxiliary antioxidant were added and stirred at a high speed of 1600 rpm for 30 minutes to obtain a mixed rubber compound. The mixed rubber compound was vacuum degassed at a vacuum degree of -0.098 MPa for 40 minutes and then returned to normal pressure to obtain a silicone sealant.

[0066] Example 3 A high-performance silicone sealant for electronic packaging

[0067] A high-performance organosilicon sealant for electronic packaging comprises the following raw materials, measured in parts by weight: 60 parts of methyl vinyl silicone oil, 10 parts of vinyldimethylsilane, 1 part of a platinum catalyst, 15 parts of fumed silica, 15 parts of a B4Cw@ZrO2 composite, 0.2 parts of ethynyl cyclohexanol, 2 parts of a silane coupling agent, 2 parts of a titanate coupling agent, 0.5 parts of a cerium-zinc composite antioxidant, and 0.5 parts of an auxiliary antioxidant.

[0068] The auxiliary antioxidant is a hindered phenol antioxidant.

[0069] A method for preparing a high-performance silicone sealant for electronic packaging, comprising the following steps:

[0070] Step 1: Boron carbide whisker pretreatment

[0071] The boron carbide whiskers were immersed in a sodium hydroxide solution, heated to 70°C, and ultrasonically treated with an ultrasonic power of 300W and an ultrasonic time of 20 minutes; then filtered, washed, and washed with deionized water three times; after washing, dried at 90°C for 2 hours to obtain pretreated boron carbide whiskers.

[0072] The mass fraction of the sodium hydroxide solution is 8%.

[0073] Step 2: Synthesis of B4Cw@ZrO2 composite

[0074] Pretreated boron carbide whiskers were added to a nanozirconia sol at a mass ratio of 1:12. The mixture was stirred at room temperature for 2.5 hours at a stirring rate of 200 rpm. The mixture was then heated to 70°C and stirred for 20 minutes to obtain a wet gel. The wet gel was then dried at 90°C for 10 hours to obtain a B4Cw@ZrO2 composite. The nanozirconia sol (model YC-GRJ35, with a particle size of 10 nm and a concentration of 20 wt%) was purchased from Shanghai Yingcheng New Materials Co., Ltd.

[0075] Step 3: Preparation of cerium-zinc composite antioxidant

[0076] Cerium nitrate and zinc nitrate were dissolved in deionized water, respectively, to prepare cerium nitrate and zinc nitrate metal salt solutions, each with a concentration of 1.0 mol / L. The two metal salt solutions were simultaneously added dropwise to a four-necked flask filled with deionized water. The molar ratio of cerium nitrate to zinc nitrate was 3:1, and the amount of deionized water was 5 times the total mass of the two metal salt solutions. The mixture was stirred at 800 rpm during the addition. Ammonia was used to maintain the pH of the reaction system at 10. After the addition, the reaction was incubated at 70°C for 1 hour, with stirring maintained at 500 rpm. The incubation period was then followed by aging for 16 hours. After aging, the product was dried at 100°C for 12 hours. The dried product was then calcined by heating to 250°C at a rate of 7°C / min for 1 hour, and then to 600°C at a rate of 3°C / min for 3 hours to obtain a cerium-zinc composite antioxidant.

[0077] Step 4: Preparation of base rubber

[0078] Add methyl vinyl silicone oil into a planetary mixer at a stirring rate of 100 rpm. Divide the fumed silica into three equal parts and add them into the mixer three times, with an interval of 8 minutes each time. After the fumed silica is added, vacuum stirring is performed with a vacuum degree of -0.095 MPa, a speed of 1600 rpm, and a stirring time of 30 minutes. Adjust the speed to 1100 rpm, add the B4Cw@ZrO2 complex, and continue stirring for 40 minutes to obtain the base rubber compound.

[0079] Step 5: Prepare silicone sealant

[0080] A silane coupling agent and a titanate coupling agent were added to the base rubber compound and stirred at a rate of 150 rpm for 20 minutes. A platinum catalyst, vinyldimethylsilane, and ethynylcyclohexanol were added and stirred at a low speed of 100 rpm for 15 minutes. A cerium-zinc composite antioxidant and an auxiliary antioxidant were added and stirred at a high speed of 1600 rpm for 20 minutes to obtain a mixed rubber compound. The mixed rubber compound was vacuum degassed at a vacuum degree of -0.098 MPa for 30 minutes and then returned to normal pressure to obtain a silicone sealant.

[0081] Comparative Example 1

[0082] Disclosed is an organosilicon sealant for electronic packaging. The raw materials comprise, by weight, 55 parts of methyl vinyl silicone oil, 10 parts of vinyldimethylsilane, 0.5 parts of a platinum catalyst, 15 parts of fumed silica, 0.1 parts of ethynylcyclohexanol, 1.5 parts of a silane coupling agent, 1.5 parts of a titanate coupling agent, 1 part of a cerium-zinc composite antioxidant, and 0.6 parts of an auxiliary antioxidant.

[0083] The auxiliary antioxidant is a hindered phenol antioxidant.

[0084] A method for preparing an organosilicon sealant for electronic packaging, comprising the following steps:

[0085] Step 1: Preparation of cerium-zinc composite antioxidant

[0086] This step is the same as the step of “preparing a cerium-zinc composite antioxidant” in Example 2.

[0087] Step 2: Preparation of base rubber

[0088] Add methyl vinyl silicone oil into a planetary mixer at a stirring rate of 100 rpm. Divide the fumed silica into three equal parts and add them into the mixer three times, with an interval of 5 minutes each time. After the fumed silica is added, vacuum stirring is performed with a vacuum degree of -0.095 MPa, a rotation speed of 1600 rpm, and a stirring time of 40 minutes to obtain a basic rubber compound.

[0089] Step 3: Prepare silicone sealant

[0090] This step is the same as the step of "preparing the organic silicone sealant" in Example 2.

[0091] Comparative Example 2

[0092] A silicone sealant for electronic packaging, comprising, by weight, 55 parts of methyl vinyl silicone oil, 10 parts of vinyldimethylsilane, 0.5 parts of a platinum catalyst, 15 parts of fumed silica, 10 parts of a B4Cw@ZrO2 composite, 0.1 parts of ethynylcyclohexanol, 1.5 parts of a silane coupling agent, 1.5 parts of a titanate coupling agent, and 0.6 parts of a secondary antioxidant. The secondary antioxidant is a hindered phenolic antioxidant.

[0093] A method for preparing an organosilicon sealant for electronic packaging, comprising the following steps:

[0094] Step 1: Boron carbide whisker pretreatment

[0095] This step is the same as the "boron carbide whisker pretreatment" step in Example 2.

[0096] Step 2: Synthesis of B4Cw@ZrO2 composite

[0097] This step is the same as the step of “Synthesis of B4Cw@ZrO2 composite” in Example 2.

[0098] Step 3: Preparation of base rubber

[0099] This step is the same as the "basic rubber material preparation" step in Example 2.

[0100] Step 4: Prepare silicone sealant

[0101] A silane coupling agent and a titanate coupling agent were added to the base rubber compound and stirred at a rate of 150 rpm for 30 minutes. A platinum catalyst, vinyldimethylsilane, and ethynylcyclohexanol were added and stirred at a low speed of 100 rpm for 20 minutes. A hindered phenol antioxidant was added and stirred at a high speed of 1600 rpm for 30 minutes to obtain a mixed rubber compound. The mixed rubber compound was vacuum degassed at a vacuum degree of -0.098 MPa for 40 minutes and then returned to normal pressure to obtain a silicone sealant.

[0102] Example 4 Performance Test

[0103] (1) The silicone sealants prepared in Examples 1-3 and Comparative Examples 1-2 were tested for tear strength according to the test method provided in GB / T 36878-2018, for Shore hardness according to the test method provided in GB / T 531.1-2008, and for shear strength according to the test method provided in GB / T 13936-2014. The specific test results are shown in Table 1.

[0104] Table 1

[0105] As shown in the test results in Table 1, the tear strength of the silicone sealants prepared in Examples 1-3 is 43.9-46.4 kN / m, the Shore hardness is 72-75 Shore A, and the shear strength is 2.9-3.4 MPa, which are significantly improved compared with the comparative example, proving that the silicone sealant prepared in the present invention has excellent mechanical strength.

[0106] (II) The tensile strength and elongation at break of the silicone sealants prepared in Examples 1-3 and Comparative Examples 1-2 were measured according to the test method provided in GB / T 528-2009. The specific test results are shown in Table 2.

[0107] Table 2

[0108] The test results in Table 2 show that the organosilicon sealants prepared in Examples 1-3 exhibited tensile strengths ranging from 4.63 to 4.82 MPa and elongations at break ranging from 387 to 398%. These higher tensile strengths and elongations indicate that the sealants exhibit enhanced elastic recovery under tensile loads, demonstrating the excellent elastic properties of the organosilicon sealants prepared in accordance with the present invention.

[0109] (III) The silicone sealants prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to UV aging for 672 hours and damp heat aging for 672 hours, and then subjected to tensile strength and elongation at break measured according to the test methods provided in GB / T 528-2009. The specific test results are shown in Table 3.

[0110] Table 3

[0111] The test results in Table 3 show that the silicone sealants prepared in Examples 1-3 maintained a tensile strength of 4.57-4.76 MPa and an elongation at break of 382-394% after 672 hours of UV aging. After 672 hours of damp-heat aging, the tensile strength reached 4.41-4.58 MPa and the elongation at break reached 371-383%. The high tensile strength and elongation at break maintained after UV and damp-heat aging demonstrate the excellent durability of the silicone sealants prepared in this invention.

[0112] The specific parameters of the raw materials used in the present invention are as follows:

[0113] The methyl vinyl silicone oil has a viscosity of 1000-5000 cSt and a vinyl content of 0.3%-0.7%.

[0114] The purity of the vinyldimethylsilane is ≥97%.

[0115] The platinum catalyst is a complex of chloroplatinic acid and vinylsiloxane, and the platinum content is 3000-5000ppm.

[0116] The particle size of the fumed silica is 7-16 nm.

[0117] The ethynyl cyclohexanol has a purity of ≥98% and a melting point of 26-28°C.

[0118] Unless otherwise specified, all ratios and percentages described in the present invention are by mass ratios and percentages are by mass percentages.

[0119] Obviously, there are many specific implementation methods that can be changed under the concept of the present invention. Here, it should be stated that any changes made under the inventive concept of the present invention will fall within the scope of protection of the present invention.

Claims

1. A high-performance silicone sealant for electronic packaging, characterized by: The raw materials of the organic silicone sealant include methyl vinyl silicone oil, vinyl dimethyl silane, platinum catalyst, fumed silica, B4Cw@ZrO2 compound, ethynyl cyclohexanol, silane coupling agent, titanate coupling agent, cerium-zinc composite antioxidant, and auxiliary antioxidant, and the weight ratio is: 50-60 parts of methyl vinyl silicone oil, 10-15 parts of vinyl dimethyl silane, 0.5-1 part of platinum catalyst, 15-20 parts of fumed silica, 10-15 parts of B4Cw@ZrO2 compound, 0.1-0.2 parts of ethynyl cyclohexanol, 1-2 parts of silane coupling agent, 1-2 parts of titanate coupling agent, 0.5-1.5 parts of cerium-zinc composite antioxidant, and 0.5-0.7 parts of auxiliary antioxidant; The B4Cw@ZrO2 composite is prepared from boron carbide whiskers and nano zirconium oxide sol; The cerium-zinc composite antioxidant is prepared from cerium nitrate, zinc nitrate and ammonia water.

2. The method for preparing a high-performance silicone sealant for electronic packaging according to claim 1, characterized in that: The method includes the steps of pre-treating boron carbide whiskers, synthesizing a B4Cw@ZrO2 composite, preparing a cerium-zinc composite antioxidant, preparing a basic rubber material, and preparing an organic silicon sealant; The synthesis of the B4Cw@ZrO2 composite comprises adding the pretreated boron carbide whiskers to the nano-zirconia sol, stirring and reacting for 2-2.5 hours, then heating to 60-70°C, and continuing to stir for 20-30 minutes to obtain a wet gel; and drying the wet gel to obtain the B4Cw@ZrO2 composite. The method for preparing the cerium-zinc composite antioxidant comprises the following steps: preparing cerium nitrate and zinc nitrate into a cerium nitrate metal salt solution and a zinc nitrate metal salt solution, respectively, and simultaneously adding the solution dropwise to a reactor filled with deionized water while stirring; maintaining the pH value of the reaction system at 9-10 with ammonia water; and keeping the reaction warm; allowing the reaction to stand for aging for 12-16 hours; and after the aging is completed, drying and calcining in stages to obtain the cerium-zinc composite antioxidant.

3. The method for preparing a high-performance silicone sealant for electronic packaging according to claim 2, characterized in that: The mass ratio of the pretreated boron carbide whiskers to the nano zirconium oxide sol is 1:(10-12).

4. The method for preparing a high-performance silicone sealant for electronic packaging according to claim 2, characterized in that: The molar ratio of the cerium nitrate to the zinc nitrate is (1-3):

1.

5. The method for preparing a high-performance silicone sealant for electronic packaging according to claim 2, characterized in that: The staged calcination: the dried product is heated to 200-250°C at a heating rate of 5-7°C / min and calcined for 1-2 hours; Then heat to 500-600℃ at a heating rate of 2-3℃ / min and calcine for 3-4h.

6. The method for preparing a high-performance silicone sealant for electronic packaging according to claim 2, characterized in that: The boron carbide whisker pretreatment comprises immersing the boron carbide whisker in a sodium hydroxide solution and performing ultrasonic treatment; Then filtering, washing and drying are carried out; the mass fraction of the sodium hydroxide solution is 5-8%.

7. The method for preparing a high-performance silicone sealant for electronic packaging according to claim 2, characterized in that: The base rubber compound is prepared by adding methyl vinyl silicone oil to a blender at a stirring rate of 50-100 rpm, dividing fumed silica into three equal parts and adding them to the blender in three portions, each added 5-8 minutes apart; and vacuum stirring is performed. Then, the B4Cw@ZrO2 complex is added and stirring is continued for 40-45 minutes to obtain the base rubber compound.

8. The method for preparing a high-performance silicone sealant for electronic packaging according to claim 7, characterized in that: The vacuum stirring: the vacuum degree is -0.09 MPa to -0.095 MPa, the rotation speed is 1500-1600 rpm, and the stirring time is 30-40 min.

9. The method for preparing a high-performance silicone sealant for electronic packaging according to claim 2, characterized in that: The method for preparing the organic silicone sealant comprises the following steps: adding a silane coupling agent and a titanate coupling agent to a base rubber material and stirring the mixture uniformly; adding a platinum catalyst, vinyldimethylsilane, and ethynylcyclohexanol and stirring the mixture uniformly; adding a cerium-zinc composite antioxidant and an auxiliary antioxidant and stirring the mixture to obtain a mixed rubber material; performing vacuum degassing on the mixed rubber material at a vacuum degree of -0.095 MPa to -0.098 MPa for 30-40 minutes; and returning the mixture to normal pressure to obtain the organic silicone sealant.

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